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Frankliniella schultzei (Trybom), an Invasive Flower Thrips Attacking Vegetable Crops in Southeastern Florida

Permanent Link: http://ufdc.ufl.edu/UFE0042303/00001

Material Information

Title: Frankliniella schultzei (Trybom), an Invasive Flower Thrips Attacking Vegetable Crops in Southeastern Florida Identification, Distribution and Biological Control
Physical Description: 1 online resource (136 p.)
Language: english
Creator: Kakkar, Garima
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: biological, distribution, flower, thrips
Entomology and Nematology -- Dissertations, Academic -- UF
Genre: Entomology and Nematology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: FRANKLINIELLA SCHULTZEI (TRYBOM), AN INVASIVE FLOWER THRIPS ATTACKING VEGETABLE CROPS IN SOUTHEASTERN FLORIDA: IDENTIFICATION, DISTRIBUTION AND BIOLOGICAL CONTROL Garima Kakkar 904-993-7959 garimaiari@ufl.edu Entomology & Nematology Chair: Dr. Dakshina R. Seal Master of Science December 2010 Frankliniella schultzei is a new pest of vegetable crops in south Florida and an economically important pest of various vegetable and ornamental crops across the globe. The study was conducted with an aim to understand the within field and within plant distribution of this pest. Result suggested that the pest forms pockets of aggregation in a big field, where flowers of its host plant were most susceptible to the attack by this pest. Among the five economically important vegetable crops, cucumber was the most suitable host for this pest. The infestation begins on the onset of flowering in the field until the conclusion. Information from this study will provide IPM personnel to understand an incipient stage of infestation as well as focal points of infestation in a crop field. Growers will be able to use this information to manage this pest judicially in a cost effective manner.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Garima Kakkar.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Seal, Dakshina.
Local: Co-adviser: Stansly, Phil A.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-12-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0042303:00001

Permanent Link: http://ufdc.ufl.edu/UFE0042303/00001

Material Information

Title: Frankliniella schultzei (Trybom), an Invasive Flower Thrips Attacking Vegetable Crops in Southeastern Florida Identification, Distribution and Biological Control
Physical Description: 1 online resource (136 p.)
Language: english
Creator: Kakkar, Garima
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: biological, distribution, flower, thrips
Entomology and Nematology -- Dissertations, Academic -- UF
Genre: Entomology and Nematology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: FRANKLINIELLA SCHULTZEI (TRYBOM), AN INVASIVE FLOWER THRIPS ATTACKING VEGETABLE CROPS IN SOUTHEASTERN FLORIDA: IDENTIFICATION, DISTRIBUTION AND BIOLOGICAL CONTROL Garima Kakkar 904-993-7959 garimaiari@ufl.edu Entomology & Nematology Chair: Dr. Dakshina R. Seal Master of Science December 2010 Frankliniella schultzei is a new pest of vegetable crops in south Florida and an economically important pest of various vegetable and ornamental crops across the globe. The study was conducted with an aim to understand the within field and within plant distribution of this pest. Result suggested that the pest forms pockets of aggregation in a big field, where flowers of its host plant were most susceptible to the attack by this pest. Among the five economically important vegetable crops, cucumber was the most suitable host for this pest. The infestation begins on the onset of flowering in the field until the conclusion. Information from this study will provide IPM personnel to understand an incipient stage of infestation as well as focal points of infestation in a crop field. Growers will be able to use this information to manage this pest judicially in a cost effective manner.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Garima Kakkar.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Seal, Dakshina.
Local: Co-adviser: Stansly, Phil A.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-12-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0042303:00001


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1 FRANKLINIELLA SCHULTZEI ( TRYBOM ) AN INVASIVE FLOWER THRIPS ATTACKING VEGETABLE CROPS IN SOUTHEASTERN FLORIDA: IDENTIFICATION, DISTRIBUTION AND BIOLOGICAL CONTROL By GARIMA KAKKAR A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2010

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2 2010 Garima Kakkar

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3 To my father and my husband

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4 ACKNOWLEDGMENTS I would like to thank my ad visor Dr. Dakshina R. Seal for his guidance and special training on thrips, which helped to complete this project. I extend my thanks to my committee, Drs. Philip A. Stansly and Oscar E. Liburd, for their input, advice and encouragement I owe my sincere thanks to Mr. Tom Skarlinsky from U S D epartment of A griculture A nimal and P lant H ealth I nspection S ervice (USDA APHIS), for helping me take thrips pictures and identify thrips species. I thank members of the Vegetable IPM Laboratory for their help in coll ecting and processing data. Special thanks go to the cucumber growers who allowed me to use their fields and collect data. I thank Debbie Hall for keeping me updated with deadlines and making me aware of the rules and system time to time. I thank my deares t friend, Megha for her timely support and for accompanying me to do fun activities to keep my stress level down during thesis writing. I thank my husband, Vivek, for helping me design my experiments and his support and motivation throughout the period of my study. Last but not the least I thank my fa ther who believed in me and sent me overseas to accomplish my goals

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 L IST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 8 ABSTRACT ................................ ................................ ................................ ................... 11 CHAPTER 1 LITERATURE REV IEW ................................ ................................ .......................... 13 Introduction ................................ ................................ ................................ ............. 13 Polyphagy ................................ ................................ ................................ ............... 14 Host Preference ................................ ................................ ................................ ...... 16 Nomenclature ................................ ................................ ................................ ......... 17 Color Morphs ................................ ................................ ................................ .......... 19 Damage Potential ................................ ................................ ................................ ... 19 Dispersion ................................ ................................ ................................ ............... 20 Biology and Management ................................ ................................ ....................... 21 Sampling ................................ ................................ ................................ .......... 21 Chemical and Biological Control ................................ ................................ ....... 22 Research Goals ................................ ................................ ................................ ...... 24 Specific Objectives ................................ ................................ ................................ 25 2 ABUNDANCE OF FRANKLINIELLA SCHULTZEI AND IDENTIFICATION OF ASSOCIATED THRIPS SPECIES ON VARIOUS VEGETABLE CROPS IN SOUTH FLORIDA ................................ ................................ ................................ ... 26 Materials and Methods ................................ ................................ ............................ 28 Crop Management ................................ ................................ ............................ 28 Sampling ................................ ................................ ................................ .......... 31 Statistical Analysis ................................ ................................ ................................ .. 31 Results ................................ ................................ ................................ .................... 32 Discussion ................................ ................................ ................................ .............. 33 3 IDENTIFICATION OF THRIPS SPECIES INFESTING VARIOUS VEGETABLE CROPS IN SOUTH FLORIDA ................................ ................................ ................ 38 Materials and Methods ................................ ................................ ............................ 39 Sampling ................................ ................................ ................................ .......... 39 Determination of Adult Thrips ................................ ................................ ........... 39 Insect Identification ................................ ................................ ................................ 40 Frankliniella schultzei (Trybom) ................................ ................................ ........ 40

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6 Frankliniella insularis (Franklin) ................................ ................................ ........ 41 Frankliniella occidentalis (Pergande) ................................ ................................ 42 Microcephalothrips abdominalis (Crawford) ................................ ..................... 42 Thrips palmi Karny ................................ ................................ ........................... 43 4 DISTRIBUTION AND SEASONAL ABUNDANCE OF FRANKLINIELLA SCHULTZEI ................................ ................................ ................................ ............ 65 Materials and Methods ................................ ................................ ............................ 67 Within Plant Distribution ................................ ................................ ................... 68 Season 1 (Fall 2008) ................................ ................................ .................. 68 Season 2 (Spring 2009) ................................ ................................ ............. 70 Season 3 (Fall 2009) ................................ ................................ .................. 70 Spatial Distribution ................................ ................................ ........................... 71 Season 1 (Fall 2008) ................................ ................................ .................. 72 Season 2 (Fall 2009) ................................ ................................ .................. 72 Sample Size Requirements ................................ ................................ .............. 75 Seasonal Abundance ................................ ................................ ....................... 75 Season 1(Fall 2008) ................................ ................................ ................... 76 Season 2 (Fall 2009) ................................ ................................ .................. 76 Results and Discussion ................................ ................................ ........................... 77 Within Plant Distribution ................................ ................................ ................... 77 Spatial Distribution ................................ ................................ ........................... 78 Sample size Requirement ................................ ................................ ................ 84 Seasonal Abundance ................................ ................................ ....................... 84 5 EFFICACY OF AMBLYSEIUS CUCUMERIS (OUDEMAN S) AND A. SWIRSKII (ATHIAS HENRIOT) IN REGULATING FRANKLINIELLA SCHULTZEI AND THRIPS PALMI POPULATIONS ON FIELD CUCUMBERS ( CUCUMIS SATIVUS L.) ................................ ................................ ................................ ......... 100 Materials and Methods ................................ ................................ .......................... 102 Predaceous Mites ................................ ................................ ........................... 102 Crop Management ................................ ................................ .......................... 103 Field Trial ................................ ................................ ................................ ........ 104 Statistical Analysis ................................ ................................ ................................ 105 Results ................................ ................................ ................................ .................. 106 Discussion ................................ ................................ ................................ ............ 110 6 CONCLUSIONS ................................ ................................ ................................ ... 123 LIST OF REFERENCES ................................ ................................ ............................. 126 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 136

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7 LIST OF TABLES Table p age 4 1 parameters for distribution of F. schultzei larvae sampled in fall 2008 ............... 87 4 2 parameters for distribution of F. schultzei adult s ................................ ................ 88 4 3 patchiness regression parameters for distribution of F. schultzei larvae ................................ ................................ ........................... 89 4 4 parameters for distribution of F. schultz ei adult s ................................ ............... 90 4 5 parameters for distribution of F. schultzei larvae ................................ ............... 91 4 6 parameters for distribution of F. schultzei adults ................................ ................ 92 4 7 ion and Index of dispersion parameters distribution of F. schultzei larvae ................................ .................... 93 4 8 parameters for distribution of F. schu ltzei adult ................................ ................. 94 4 9 Number of samples required for estimation of population density at three levels of precision ................................ ................................ ............................... 95 4 10 Seasonal ab undance of larvae and adults on cucumber flowers sampled at two fields in 2008 and 2009 ................................ ................................ ................ 96 5 1 Number of mites (mean SEM) per 10 flowers sampled on five sampling days from five treatment plots ................................ ................................ ........... 115 5 2 Number of mites (mean SEM) per leaf sampled on five sam pling days from treatment plots ................................ ................................ ................................ .. 116 5 3 Number of mite eggs (mean SEM) per leaf sampled on five sampling days from treatment plots ................................ ................................ .......................... 117 5 4 Number of cumulative Thrips palmi x days (mean SEM) and mite x days (mean SEM) per leaf on five sampling days from the following treatment plots ................................ ................................ ................................ .................. 118

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8 LIST OF FIGURES Figure page 1 1 Cucumber flower showing discoloration due to feeding by adult Frankliniella schultze i ................................ ................................ ................................ ............. 25 2 1 Number of F. schultzei adults (Mean SEM) on flowers of five host plants s .... 35 2 2 Number of F. schultzei larvae (Mean SEM) on flowers of five host plants ....... 36 2 3 Average number of adults of three thrips species sampled from five vegetable crops ................................ ................................ ................................ .. 37 3 1 Dorsal view of an adult F. schultzei ................................ ................................ .... 44 3 2 Slide mount of an adult of light form of F. schultzei ................................ ............ 44 3 3 Antenna of adult F. schultzei ................................ ................................ .............. 45 3 4 Head of an adult F. schultzei ................................ ................................ ............. 45 3 5 Head of an adult F. schultzei ................................ ................................ .............. 46 3 6 Prothorax of an adult F. schultzei ................................ ................................ ....... 46 3 7 Metanotum of an adult F. schultzei ................................ ................................ ..... 47 3 8 Forewing of an adult F. schultzei ................................ ................................ ........ 47 3 9 Abdomen of an adult F. schultzei ................................ ................................ ....... 48 3 10 Slide mount of an adult F. insularis ................................ ................................ ..... 48 3 11 Antenna of adult F. insularis ................................ ................................ ............... 49 3 12 Head of an adult F. insularis ................................ ................................ ............... 49 3 13 P ronotum of an adult F. insularis ................................ ................................ ........ 50 3 14 Mesonotum of an adult F. insularis bearing longitudinal lines ............................ 50 3 15 Metanotum of an a dult F. insularis ................................ ................................ ...... 51 3 16 Forewing of an adult F. insularis ................................ ................................ ......... 51 3 17 Abdomen of an adult F. insularis ................................ ................................ ........ 52 3 18 Slide mount showing an adult of F. fusca ................................ ........................... 52

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9 3 19 Antenna of adult F. fusca ................................ ................................ .................... 53 3 20 Head of an adult F. fusca ................................ ................................ ................... 53 3 21 Metanotum of an adult F. fusca ................................ ................................ .......... 54 3 22 Forewing of an adult F. fusca ................................ ................................ ............. 54 3 23 Abdomen of an adult F. fusca ................................ ................................ ............ 55 3 24 Slide mount of a pale form of an adult of F. occidentalis ................................ .... 55 3 25 Antenna of adult F. occidentalis ................................ ................................ .......... 56 3 26 Head of an adult F. occidentalis ................................ ................................ ........ 56 3 27 Metanotum of an adult F. occidentalis ................................ ................................ 57 3 28 Forewing of an adult F. occidentalis ................................ ................................ .. 57 3 29 Slide mount of an adult M. abdominalis ................................ .............................. 58 3 30 Antennae of an adult M. abdominalis ................................ ................................ 58 3 31 Head of an adult M. abdominalis ................................ ................................ ........ 59 3 32 Mesonotum of an adult M. abdominalis ................................ .............................. 59 3 33 Metanotum of an adult M. abdominalis ................................ ............................... 60 3 34 A bdomen of an a dult of M. abd ominalis ................................ ............................. 60 3 35 Forewing of an adult M. abdominalis ................................ ................................ .. 61 3 36 Slidemount of an adult T. palmi ................................ ................................ .......... 61 3 37 Seven segmented antennae of an adult T. palmi ................................ ............... 62 3 38 Head of an adult T. palmi ................................ ................................ ................... 62 3 39 Met anotum of an adult T. palmi ................................ ................................ .......... 63 3 40 Forewing of an adult T. palmi ................................ ................................ ............. 63 3 41 Abdomen of T. palmi ................................ ................................ .......................... 64 4 1 Pictorial view of the study areas used for within plant (A and B) and spatial distr ibution studies (A, B and C) ................................ ................................ ......... 97

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10 4 2 Mean number of larvae and adults in various plant parts sampled in fall 2008 spring 2009 and fall 2009.. ................................ ................................ ................. 98 5 1 Pictorial view of the biological control field ................................ ....................... 119 5 2 Number of F. schultzei larvae ( mean SEM ) per 10 flowers sampled on five sampling dates ................................ ................................ ................................ 120 5 3 Number of T. palmi larvae (mean SEM) per cucumber leaf sampled on five sampling dates ................................ ................................ ................................ 121 5 4 Linear regression showing the number of T. palmi larvae and mites abundance in plots treated with A. swirskii (40 mites/plant). ............................ 122

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11 Abstract of Thesis P resented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science FRANKLINIELLA SCHULTZEI TRYBOM AN INVASIVE FLOWER THRIPS ATTACKING VEGETABLE CROPS IN SOUTHEASTERN FLORIDA: IDENTIFICATION, DISTRIBUTION AND BIOLOGICAL CONTROL By G arima K akkar D ecember 2010 Chair: Dakshina R. Seal Cochair: Philip A. Stansly Major: Entomology and Nematology Frankliniella schultzei Trybom ( T hysanoptera: Thripidae), is an important pest of vegetable and ornamental crops across the globe. In Florida, it is a new pest of vegetable crops. The objective of this study was to determine the abundance of F. schultzei on five vegetable crops including cucumber, pepper, snap beans, squash and tomatoes. Among the five vegetable crops cucumber was the most preferred host of F. schultzei The number of larvae exceeded the adults count on cucumber plan ts indicating that cucumber is the true host of this pest. In addition, the distribution pattern of F. schultzei within the field and within the host plant was investigated The distribution study was conducted in field cucumbers and F. schultzei was found feeding on flowers of cucumber p lants. Adult counts on leaf samples were significantly low er th an flowers in all the experimental plots sampled during three seasons of the study. Both larvae and adults were aggregated in the field during peak populations of the pest. The distribution of F. schultzei varied in response to

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12 the pest density. At high pe st density, a clumped pattern was observed whereas regular or random distribution was observed at low pest density. Results from seasonal abundance study suggested that the population of F. schultzei build up in a week after the onset of flowering in a cr op. T hrips density was higher during fall 2009 than fall 2008. High temperature s during the fall 2009 may have increased the population growth rate and thus high thrips density during the season. Results from this study helped determine the peak population period during the season, which could be useful to develop sampling protocols for F. schultzei Field trial to determine the efficacy of two predatory mites, Amblyseius swirskii (Athias Henriot) and A. cucumeris (Oudemans) suggested that none of the two m in regulating F. schultzei population on cucumbers.

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13 CHAPTER 1 LITERATURE REVIEW Introduction Florida harbors a large number of native as well as invasive species of thrips. H igh temperatures and the humid climate are importa nt factors supporting huge populations of thrips ( Aliakbarpour et al. 2010, Kannan et al. 2001) in the state In the past few years, more than 130 species of thrips from Africa, Europe and the Mediterranean region were intercepted at various ports of entry in the United States (Nickle 2004). The most frequently encountered species were Frankliniella occidentalis Pergande, F. schultzei (Trybom), F. intonsa Trybom and F. tenuicornis (Uzel). The genus Frankliniella, including flower thrips, is one of the high ly evolved groups of thrips (Waring 2005) inhabiting tropical and temperate areas of the world (Mound 1997). In Florida, Frankliniella consists of a huge complex of species (Salguero Navas et al. 1991, Chellemi et al. 1994, Puche et al. 1995, Eckel et al. 1996) many of which are polyphagous feeding mainly on the contents of plant cells including fruits, leaves, inflorescence tissues and pollen (Waring 2005) of various vegetables, fruits and ornamental crops (Kendall and Capinera 1987). In the genus Frankl iniella, F schultzei is a new vegetable pest in south Florida (Fran tz and Fasulo 1997) It is a key pest in tomato and cucumber fields in South America (Jones 2005 and Monterio et al. 2001) Frankliniella schultzei has a wide distribution range and it is mainly found in tropical and subtropical areas throughout the world (Vierbergen and Mantel 1991). It has been reported from Belgium, mainland Spain, Netherlands, United Kingdom in Europe; Bangladesh, India, Indonesia, Iran, Iraq, Israel, Malaysia, Pakistan and Sri Lanka in Asia; Angola, Botswana, Cape Verde,

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14 Chad, Congo, E gypt, Ethiopia, Gambia, Ghana, Kenya, Libya, Madagascar, Mauritius, Morocco, Namibia, Niger, Somalia, South Africa, Sudan, Uganda, Zimbabwe in Africa; Central and southern Florida (Funderburk et al. 2007) and Hawaii in USA; Barbados, British Virgin Islands Cuba, Dominican Republic, Haiti, Jamaica and Puerto Rico in the Caribbean; Argentina (Rio de Janeiro), Brazil (Minas Gerais, Parana, Rio Grande do Norte, Santa Catarina, Sao Paulo), Colombia, Chile, Guyana, Paraguay, Peru, Uruguay, Venezuela in South Ame rica; New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia, French Polynesia and Papua New Guinea in Australia and the South Pacific (CABI, 1999). Polyphagy Frankliniella schultzei has a wide host range and it is k nown to feed on various ornamental and vegetable hosts in different parts of the world (Palmer 1990, Vierbergen and Mantel 1991, Milne et al. 1996) Frankliniella schultzei along with F. bispinosa (Morgan), F. occidentalis, and F. tritici (Fitch) (Cho et a l. 2000, Hansen 2000) are anthophilous species, inhabiting flowers of numerous field crops (Johansen 2002), and are mainly attracted to the color of the host flowers (Menzel & Shmida 1993, Lunau 2000). The m ajority of flower thrips feeding on floral parts derive nutrition from pollen. A pollen diet rich in protein and other nutrients increases the fecundity of adult thrips and shortens the development period of larval stages (Tsai et al. 1996). Milne (1996) studied the fecundity and development of F. schult zei and did not find any significant difference between petal and pollen diet s. The major recorded hosts of F. schultzei are cotton ( Gossypium sp. ), groundnut ( Apios Americana ) beans ( Phaseolus vulgaris ) and pigeon pea ( Cajanus cajan (L.)) (Gahukar 2004). However, due to its polyphagous feeding behavior, it also attacks

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15 tomato ( Lycopersicon esculentum ), sweet potato ( Ipomoea batatas ), coffee ( Coffea sp.), sorghum ( Sorghum sp.), chillies ( Capsicum annuum ), onion ( Allium cepa ), sunflower ( Helianthus annuus ) rose ( Rosa sp.), tobacco ( Nicotiana tabacum ), cotton ( Gossypium sp.), grain legumes (various sp.), lettuce ( Lactuca sativa ) cucumber ( Cucumis sativus ), okra ( Abelmoschus esculentus ), Japanese daisies, irises ( Iris ensata ), spinach ( Spinacia oleracea ), ca rnation ( Dianthus caryophyllus) pumpkin ( Curbita sp.), Carola aubergine and kidney beans ( P haseolus vulgaris subsp. Nunas) in different parts of the world (Hill 1975, Monteiro et al. 2001). In Australia, the primary host of this pest is a South American shrub, Malvaviscus arboreus in the absence of which F. schultzei infests other non native plants. The other hosts of this pest, belonging to 12 families includes; Hibiscus rosasiensis L ( Malvaceae ), Bauhinia variegate L. and B. galpinii N. E. Brown (Caesalpiniaceae), Vigna caracalla L. and Erythrina crista galli L. (Fabaceae), Ipomoea cairica (Convolvulaceae ) and Jacaranda mimosifolia D. Don (Bignoniaceae) (Kirk 1984, 1987; Wilson et al. 1996; Milne and Walter 2000; Coutts et al 2004; Coutts and Jones 2005). In addition to the vast herbivore group of thrips, many saprophytic, predatory and parasitic thrips species also exists. Surprisingly a few pest thrips are also known to be predaceo us The list includes F. occidentalis, T. tabaci and F. schultzei all three of which are known to feed on mite eggs (Agrawal et al. 1991 and Milne et al. 1997) Milne et al. ( 1997 ) studied the comparative effect of different diets on development of F. sc hultzei and found that diet s containing cotton ( Gossypium hirsutum L.) leaf tissue supplemented with mite eggs, decreased the development period and increased fecundity when compared to simple plant diet. In a choice test between pollen of the

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16 most preferr ed host and mite eggs under lab oratory conditions, an Australian population of F. schultzei showed equal preference s to Malvaviscus arboreus Cav. pollen and mite eggs suggesting that mite eggs could serve as a desirable food for this pest ( Milne et al. 19 97). Host Preference The association between a polyphagous pest like F. schultzei and its subsequent host plant is difficult to understand. There are many factors influencing the host preference by thrips. These interactions can be influenced by host culti var (Fery and Schalk 1991, de Kogel et al. 1998), food availability, host age (Ram and Mathur 1984, Stoddard 1986) plant architecture and flower color Flower color and structure plays an important role in attracting thrips populations (Menzel & Shmida 19 93, Lunau 2000) Mound (2005) suggested that widely open flowers or flowers with high nectar that attracts birds were usually not preferred by thrips. Such selective action is due to thigmotactic behavior where by thrips like to stay in touch with the surfa ce of their substrate and thus do not prefer widely open flowers Frankliniella schultzei exhibits such behavior and is thus abundant in the rolled petals of its most preferred host Malavaviscus arboreus in Brisbane, Australia (Milne & Walter 2000). Presen ce of secondary metabolites is another important character for selecting host plant s. However little research has been done in identifying the chemicals important for host plant and thrips interaction. The secondary metabolites include both kairomones and allomones produced by various plant parts, which may function as attractants or deterrents. The preference of F. occidentalis for unopened flower buds to flowers and leaves of chrysanthemum plants due to the presence of (E) farnesene in flower buds suggests an important role of these metabolites in influencing thrips attraction

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17 (Manjunatha et al. 1998). Flavonoids and carotenoids constitutes another group of such metabolites responsible for attracting thrips by giving colors to plant flowers (Ananthakrishnan and Gopichandaran 1993). For populations of F. occidentalis (Mound 2004), Heliothrips haemorrhoidalis and Pachaetothripine species, nitrogen content is an important compon ent of host selection in addition to other factors (Fennah 1965). Brodbeck et al. (2001) found increase d F. occidentalis populations inhabiting tomatoes provid ed with high nitrogen fertilizer. However, i n a study on cucumber and tomato Leite et al. (2005) evaluated several factors that may influence host preference of F. schultzei and determined that the abundance of F. schultzei on these plants was not influenced by plant age, leaf chemical composition, levels of leaf nitrogen and potassium and presence o f trichomes Besides behavioral and nutritional stimuli, many other factors interact in a complex manner to draw thrips population to the host plant (Mound 2004) Given that all potential host plants have an equal chance of being exploited by the populatio n of a polyphagous pest, it has been speculated that thrips show local preferences. Scirtothrips dorsalis Hood, a major pest of mango in Puerto Rico, has never been reported as a pest elsewhere on this host. Similarly, F. schultzei is a major pest of tomat o in Cuba, but in my study in Homestead, Florida I found it to prefer cucumber over tom ato. Considering this, there is a need to conduct an area specific study to assess feeding behavior as a step to protect economically important crops. Nomenclature Fran kliniella schultzei has been misidentified or assigned various names by different authors in the past. Mound (1968) reported the presence of a population of adults exhibiting different taxonomy under the taxon F. schultzei which was later

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18 suggested to be a complex of different thrips species (Vierbergen and Mantel 1991). In Australia, the population of F. schultzei was earlier known as F. lycopersici Steele and the South American population was described as F. paucispinosa Moulton (Sakimura 1969). The list of synonyms of F. schultzei includes F. interocellaris Karny, F. sulphurea Schmutz, F. delicatula Bagnall and F. dampfi Priesner (Mound 1968, Sakimura 1969) and others are listed in the table below. Scientific Names Common Names Frankliniella dampfi Prie sner, 1923 Frankliniella dampfi interocellularis Karny, 1925 Frankliniella lycopersici Andrewartha, 1937 Parafrankliniella nigripes Firault, 1928 Frankliniella paucispionosa Moulton, 1933 Frankliniella sulphurea Schmutz, 1913 Physopus schultzei Trybom, 191 0 Euthrips gossypii Shiraki, 1912 Frankliniella delicatual Bagnall, 1919 Frankliniella trybomi Karny, 1920 Frankliniella persetosa Karny, 1922 Frankliniella tabacicola Karny, 1925 Frankliniella africana Bagnall, 1926 Frankliniella angnlicana Bagnall, 1926 Frankliniella aeschyli Girault, 1927 Frankliniella kellyana Kelly & Mayne, 1934 Frankliniella dampfi nana Priesner, 1936 Frankliniella favoniana Priesner, 1938 Frankliniella pembertoni Moulton 1940 Frankliniella clitoriae Moulton 1940 Frankliniella schul tzei nigra Moulton, 1948 Frankliniella ipomoeae Moulton, 1948 Frankliniella insularis (Franklin) Morison, 1930 Cotton thrips Cotton bud thrips Tomato thrips Kromnek thrips Common blossom thrips

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19 Color Morphs Frankliniella schultzei exists as two differen t color morphs, a dark and a pale form (Sakimura 1969). The two forms are morphologically simi lar to each other (Mound 1968) and exhibit a varied distribution across the globe (Sakimura 1969) The dark form is mainly distributed in the south of Sudan to th e Cape in Africa, from the Philippines to the south shore of Australia in western Pacific region, from the Caribbean to the south of Argentina in South America, Florida and Colorado in North America, Netherland s in Europe, and throughout India in Asia. The pale form exists in Egypt, Sudan, Uganda and Kenya in Africa; Hawaii in North America, India, and New Guinea in the western Pacific region. Mixed colonies of both color forms were reported by Mound (1968) in Egypt, India, Kenya, Puerto Rico, Sudan, Ugand a, and New Guinea. The two color forms are known to interbreed freely and produce an intermediate form Frankliniella schultzei is known to reproduce both sexually and parthenogentically by arrhenotoky where males are produced from unfertilized eggs. Dama ge Potential Thrips are economic group of insects with broad host range and global expanse. Their small size, high reproducti ve rate and polyphagous nature allow them to disperse and successfully establish in new geographical regions. Thrips can cause both direct and indirect damage to their host crops where direct damage is due to feeding a nd oviposition on host plants. Both adults and nymphs of F. schultzei feed on pollen and floral tissue, leading to flower abortion. Serious infestations by this pest may lead to discoloration and stunted growth of the plant (Amin & Palmer 1985) (Figure 1 1). Indirect damage by F. schultzei is due to transmission of plant diseases to various

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20 economically important plants. Franklin i e lla schultzei was reported as the major v ector of various plant viruses in north of Australia until the introduction of western flow er thrips (Mound 2004). Tomato S potted Wilt Virus (TSWV), belonging to genus Tospovirus causes serious damage to wide range of plant species (Prins and Goldbach 199 8). In Florida, mainly three species in the genus Frankliniella are responsible for the transmission of TSWV: F rankliniella fusca (Hinds), F. occidentalis and F. schultzei (Mound 2002, 2004). The dark form of F. schultzei is known to vector at least four t os poviruses that includes Tomato Spotted Wilt V irus (TSWV) (Sakimura 1969), Tomato Chlorotic Spot V irus (TCSV), Ground nut R ing Spot V irus (GRSV) and Chrysan themum Stem Necrosis V irus (CSNV) (Nagata and de Avila 2000). However, the light form of F. schultze i reported to be a weak vector of TSWV and TCSV and a non vector of GRSV (Shakimura 1969, Cho et al. 1988, Mau et al. 1991). Dispersion Frankliniella schultzei known to originate from South America, is now distributed throughout the world (Mound 2002, Nag ata et al. 1999). This small insect could have dispersed either artificially or naturally. The artificial mode of dispersal includes the import of various agricultural products including cut flowers, fruits and vegetables infested with this tiny thrips, ai r passengers, crew and their baggage, air cargo etc. The natural mode includes the dispersal via flying. Another important mode of dispersal is wind; it affects the flight of these tiny thrips, thereby causing the widespread scattering of this group. Mound (2004) reported that F schultzei is highly vagile and thus ha s the ability to migrate great distances V agile behavior, good dispersal capability and the ability to feed on alternative hosts supports rapid dispersal and increase in population of this gro up including F. schultzei in a new habitat. Thus, the incidence of a large number

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21 of exotic thrips species in Florida emphasizes the need for correct identification to distinguish them from native thrips in the fauna. Biology and Management Thysanopterans have always been recorded as opportunistic species well adapted to dwell in unfavorable conditions. Descendents from detriophagous ancestral group, their life cycle pattern is much developed to survive in a habitat where optimal condition for survival is m inimal (Funderburk et al. 2001). Thrips life cycle is greatly influenced by abiotic factors including temperature that affects the development rate until their threshold level is reached. Given that thrips are hemimetabolic, there are two inactive and non feeding stages in its life cycle: the prepupa and the pupa. The life cycle of F. schultzei, includ es egg, first and second instar larvae, prepupa, pupa and adult. Gravid females lay eggs inside the plant tissue, which hatch in 2 5 days depending upon envi ronmental conditions. Frankliniella schultzei takes around 12.6 days to complete its life cycle at 24.5C (Silvia et al. 1998) The embryonic stage lasts f or four days, and the first instar, seco nd instar prepupa and pupa ta k es an average of 2.5, 2.5, 1.2, and 2.1 days, respectively. Adult female and male longevity is approximately 13 days (Silvia et al. 1998) Sampling Early detection and identification is a primary step towards developing an efficient management practice of any invasive pest. Monitoring p rovides information about composition of pest species pest and crop status, weather and soil factors affecting crops. From an IPM point of view, monitoring is done to evaluate the presence of the pest in the field, to determine its population density and field distribution in order to apply the most appropriate management practice. Monitoring may involve different

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22 sampling methods using sticky cards, in situ counts, traps, knockdown sampling or netting. In the past different sampling strategies have been developed by entomologists to determine the presence and status of thrips species. To study flight behavior of S. dorsalis Takagi (1978) constructed a sticky suction trap, which could also monitor abundance of various other pests. Use of colored sticky tr ap s is one of the most commonly used sampling strategies for thrips. It has been found that white sticky traps was the best trap to use for monitoring F. occidentalis in avocados (Hoddle et al. 2002), S. dorsalis on pepper (Saxons et al. 1996), F. bispinos a and F. tritici in blueberries (Finn, 2003, Liburd et al. 2009, Saona et al. 2010) and citrus (Childers and Brecht, 1996). Tsuchiya et al. (1995) performed a color preference test for S. dorsalis and found that the pest was attracted to yellowish green, g reen, and or yellow boards. Similarly, F. tritici also exhibits preference among different colored sticky traps. In a study, F. tritici was found to be most attracted to yellow in comparison to blue or white traps when sampled in tomato crop ( Cho et al. 19 95). All these studies suggest a possible role of host flower color, which may influence the attraction of thrips to a particular color of sticky trap. Frankliniella schultzei an anthophilous thrips species, is frequently found feeding on flowers of its host plants. Like other thrips, F. schultzei can also be sampled using colored sticky traps. Yaku et al. (2007) studied the color preference of male and female F. schultzei separately. T he two sexes were fou nd to exhibit varied preference for the different colored sticky traps, where male thrips were captured more on yellow sticky traps and female thrips were captured more on pink sticky traps. Chemical and Biological Control The most commonly used tool to control thrips in a field is chemical insecticides. However, the use of these insecticides is limited by the : 1. Resistance

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23 selection of resistant strain in response to non judicious use of insecticides, 2. Resurgence of the pest and 3. Replacement of a primary pest by the secondary pest in a treated area. Thus, in order to overcome these adverse effects of insecticide use there has been much emphasis on developing cultural and biological control strategies. Biocontrol agents known for controlling thrips include minute pirate bugs, big eyed bugs (Hemiptera); green lacewing larvae (Neuroptera); phytoseiid mites (Parasitiformes) and predatory thrips (Thysanoptera); (Miles et al. 1997). However, among various predators, the most commonly used predators for thrips control belong to genus Orius (Hemiptera: A nthocoridae) and Amblyseius (Acari: Phytoseiidae) In the genus Orius, O. insidiosus Say is known to feed on a wide range of thrips making it one of the most promising biocontrol agents for thrips control in Florida (Funderburk et al. 2000). S ilveira et al (2005) studied the association between F. schultzei and O. insidiosus by sampling various crops and weeds in field and greenhouse conditions in Brazil. Orius insidiosus was found to be associated with F. schultzei population and it was sugge sted as a predator of this pest. Phytoseiid mites constitute another important group of predators. Variable reports have been documented regarding the use of predatory mites as biocontrol agents of thrips. Gillespie (1989) found A. cucumeris ( Oudemans ) as an effective predator of Thrips tabaci Lindeman, on greenhouse cucumber in Europe. Later, Van de Veire and Degheele (1995), and Jacobson (1997) evaluated the efficacy of A. cucumeris against flower thrips ( Frankliniella sp.) in greenhouse conditions and reported these mites to be an efficient biocontrol agent In a greenhouse study on tomato, A. cucumeris was found to give a better suppression than O. insidiosus on F. occidentalis (Shipp and Wang

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24 2003). Despite numerous success reports, A. cucumeris did n ot perform well in some studies and such variability was attributed to its response to change in humidity and temperature (Shipp and Van Houten 1997). Another phytoseiid mite widely known for its generalist behavior is A mblyseius swirskii (Athias Henriot). Amblyseius swirskii has shown promising results in regulating chilli thrips on pepper (Arthurs et al. 2009) and broad mites and white studies (Stansly and Castillo, 2009) in Florida. Amblyseius swirskii was compared with A. cucumeris in regulating broad mites and was found to be more effective than A. cucumeris in suppressing broad mites (Stansly and Castillo, 2009). Similar results were obtained by Arthurs et al. (2009) who reported A. swirskii as a better predator of chill i thrips on pepper than A. cucumeris However, in the majority of the studies done in past, the use of these mites are restricted to greenhouse or controlled conditions. Thus, evaluating and comparing the effect of these mites under field conditions will b e an interesting study. Research Goals Considering the damage potential of F. schultzei to various vegetable crops in Miami Dade County and other adjoining regions largely under agriculture, it is important to develop a management program for this pest. B iology, identification and monitoring techniques of a pest are one of the few important areas to focus before developing control programs. Thus, one of the goal s of my study is to learn how to correctly identify F. schultzei which is difficult because of its small size and ambiguous common features amongst various thrips species that co exists in the environment. In addition, I evaluate d the role of phytoseiid mites in regulating F. schultzei population in the field and determine d seasonal abundance and di stribution pattern of F. schultzei

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25 Specific Objectives 1) Investigate the a bundance of F. schultzei and identi fy associated thrips species on various vegetable crops in south Florida 2) Examine the d istribution and seasonal abundance of F. schultzei in south Florida cucumber fields. 3) To evaluate A. cucumeris and A. swirskii as potential biocontrol agents for F. schultzei in field cucumbers. Figure 1 1. Cucumber flower showing discoloration due to feeding by adult Frankliniella schultzei

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26 CHAPTER 2 ABUNDANC E OF FRANKLINIELLA SCHULTZEI AND IDENTIFICATION OF ASSOCIATED THRIPS SPECIES ON VARIOUS VEGETABLE CROPS IN SOUTH FLORIDA Thrips are ubiquitous due to their ability to exist in a wide range of habitats. Tropic al and temperate regions are the most suitable regions for thrips survival (Mound 1997), making Florida a vulnerable region for thrips invasion and subsequent establishment. Furthermore, the diverse flora of Florida offers free choice to this opportunistic group of insects. While the majority of econom ically important thrips species are polyphagous in nature, there exists a range of preferred hosts for this group of insects. Several thrips species including Frankliniella occidentalis (Pergande) have been reported to exhibit varied host preference in the same geographical region (Doeder lein and Sites 1993). However, very little information is presently available on the host switching behavior of this group. In the past, various researchers have often been confused in identifying host plants of a polyphago us thrips species leading to incor rect documentation of hosts of thrips Plant species have be en merely designated as a host based on the presence or absence of adults of the thrips species unde r study (Mound 2005). T here is a very thin line between primar y and a secondary host of thrips, thus defining proper host plants is very important While thrips are known to forage on wide range of plant species, a primary host is known by its ability to support thrips reproduction in addition to providing food and s helter. However, a provisional or secondary host is usually soug ht for food and shelter, and does not provide a substrate for reproduction (Mound 2005). Once a true host is identified, it is important to determine the preferred hosts among broad list o f ho st species.

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27 Host preference by a species dwelling in a geographical region can be affected by several factors. Doederlein and Sites (1993) found that F. occidentalis did not possess any preferred host among the 11 plant spe cies sampled during the season as the abundance of F. occidentalis on different plant species varied in a two year study. They suggested that environmental factors and presence of flower s on hosts can be important in explaining such plasticity in feeding preferences. Other factors influen cing host selection include drought, flooding and various other stressing factors Lewis (1973) suggested that stressed plants are vulnerable to thrips attack, as the stress restrains plants from protein synthesis resulting in increased nitrogenous compoun ds Frankliniella schultzei (Trybom) is a polyphagous herbivore known to feed on wide range of plant species. However, it is not an exclusively phytophagous pest as it has been reported to feed on eggs of two spotted mites Tetranychus urticae Koch on cott on (Trichilo and Leigh 1986, Wilson et al. 1996) Frankliniella schultzei is one of the major pests of various ornamental and vegetable crops a round the globe. I t has been cited as a pest of cotton, groundnut and beans in many parts of the world. In Cuba a nd Brazil, it is one of the key pests of tomato and hence called tomato thrips ( Haji et al. 1998 and Jones 2005 ). However, in Florida it has been found to be associated more with flowers of ornamental plants (Funderburk et al. 2007), and cucumbers in south eastern Florida (P ersonal observation). Considering t he paucity of information on host plants under risk in Miami Dade County, largely known for fresh vegetable production, this study was conducted with an objective to determine a bundance of F. schultzei on five major vegetable crops in this new geographical area of infestation The results from the study helped in determining

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28 crops susceptible to attack by F. schultzei in this region. This information will be useful to growers and scouting personnel in de veloping monitoring programs and applying preventive measures in time. Material s and Methods Abundance of F. schultzei was studied on Cucumber ( var.` var. King Arthur), s nap beans ( var. Opus), s quash ( var. Straightneck) and t omato ( var. F lora Dade). These are commonly grown vegetable crops in south Florida. The study was conducted in a field at the University of Florida, Tropical Research and Education Center ( TREC ) Homestead during fall 2009. Five vegetable hosts selected for this study were planted in plots laid adjacent to each other in a same field. A 9 m wide non planted buffer area separated two adjacent crops. The soil type of the field was Krome gravelly loam (loamy skeletal, carbonatic hyperthermic lithic Udorthents), which consis ts of about 33% soil and 67% limestone pebbles (>2mm). Fields were prepared using standard commercial practices (Olson and Santos 2010). Crop M anagement Cucumber ( Cucumis sativus 17 on a flat ground. Seed s were sown 15.2 cm apart within the row and 91.4 cm apart between rows. The plot measured 251 m 2 with 30 m long ten rows of plants. At planting, 8 16 16 (N P K) was applied at 908 Kg/ha in a furrow (20 cm apart from the seed row). H alosulfuron methyl (San dea Gowan Company LLC., Yuma, Arizona) at 55 ml/ha was used as a pre emergence herbicide to control weeds. Copper hydroxide (Kocide 3000, BASF Ag Products, Research Triangle Park, NC) at 0.8 l/ha and Chlorothalonil (Bravo Syngenta Crop Protection, Inc ., Greensboro, NC) at 1.75 l/ha were used in rotation at two week intervals to prevent fungal diseases. The crops were irrigated twice a week

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29 with 3 cm of water using overhead sprinklers in fields. Fertilizer 4 0 8 (N P K) at 236 l/ha/wk was used once a we ek as an in furrow band in the field to provide 2.4 kg N 2 /ha/wk and its use was initiated three weeks after planting. Bacillus thuringiensis based insecticides, Dipel DF ( var kurstaki) at 1.1 Kg/ha and Xentari DF ( var. kustaki) at 1.2 l/ha (Valent Biosc iences Corporation, Libertyville, IL) were used to control melon and pickle worms in the experimental field. Pepper ( Capsicum anuum epper transplants were planted 25 cm apart within rows on raised beds in the field on Aug, 17. These raised beds were 91 cm wide, 15 cm high, and 182 cm apart between centers, covered with 1.5 ml thick black polyethylene mulch. Each plot consisted of 10 raised beds 30 m long making a plot of ~500 m 2 Management of crop including use of fertilizes, herbicides an d fungicide is same as described for cucumber. Bacillus thuringiensis based insecticides, Dipel DF ( var kurstaki) at 1.1 Kg/ha and Xentari DF ( var. kustaki) at 1.2 l/ha (Valent Biosciences Corporation, Libertyville, IL) were used to beet army worm Spod optera exigua (Hubner) in the experimental field. Thiamethoxam (Actara 25WG, Syngenta Crop Protection, Inc., Greensboro, NC) was added at the rate of 220 ml/ha twice during the cropping to control pepper weevil Anthonomus eugenii Cono and whitefly Bemis ia argentifolii Snap beans ( Phaseolus vulgaris flat ground, placed 7.5 cm apart within the row and 91.4 cm between rows on Aug, 18. The plot measured 251 m 2 with ten rows 30 m long in the plot. The field was p repared using standard cultural practices as described for cucumber. C rops were irrigated twice a week with 3 cm of water using overhead sprinklers in fields. Fertilizer 4 0 8 (N P K) at 236 l/ha/wk was used once a week as an in furrow band in the field to provide 2.4 kg

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30 N 2 /ha/wk and its use was initiated three weeks after planting. Imidacloprid (Admire Pro, Bayer CropScience, NC) was applied to the soil at the rate of 591 ml/ha once when plants were two wee k s old plants to control whitefly Squash ( Cucurb ita maxima): ground in a plot measuring 251 m 2 on Sep, 2. Each plot consisted of 30 m long ten rows of squash plants. Seeds were sown 21 cm apart within the row and 91.4 cm apart between rows. Crop manag ement practic es were similar to cucumber. Squash was planted two weeks after the other four crop s to avoid differences in the onset of flowering. This was to help ensure that all the plant species had equal chances of being infested by F. schultzei. Toma to ( Solanum Lycopersicon ): `Flora seedlings were trans planted 30 cm apart within rows on raised beds on Aug, 18. The raised beds were 91 cm wide, 15 cm high, and 182 cm apart between centers, covered with 1.5 ml thick black polyethylene mulch. Each plot consisted of 10 raised beds 30 m long, making a plot of 501 m 2 The field was prepared in accordance with standard cultural practices as described above. The crop was drip irrigated twice a week. Fertilizer 4 0 8 (N P K) was used at 236 l/ha onc e a week beginning three weeks after planting through the drip to provide 2.4 kg N 2 /ha Bacillus thuringiensis based insecticides, Dipel DF ( var kurstaki) at 1.1 Kg/ha and Xentari DF ( var. kustaki) at 1.2 l/ha (Valent Biosciences Corporation, Libertyvil le, IL) were used to control beet armyworm in the experimental field. Imidacloprid (Admire Pro, Bayer CropScience, NC) was applied as a soil drench at the rate of 591 ml/ha once to three wee k old plants to control whitefly.

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31 Sampling Samples were collected and processed independently for each of the plant hosts. In each plot belonging to a host plant type, five flowers (a flower/plant) were randomly collected from every row of the plot. All flower samples belonging to each row of the various hosts were plac ed in separate ziplock bags (17 X 22 cm) marked with the date of collection row number and host type. Samples were transported t o the Univ. of Florida, v egetable IPM laboratory, TREC, Homestead where samples were placed in a one quart plastic cup with 75 % ethanol for 30 minutes to dislodge various life stages of thrips. The samples were carefully taken out of the cup leaving the thrips in alcohol. The contents in alcohol were sieved using a 25 m grating, USA Standard Testing Sieve (W. S. Tyler, Inc.) as per Seal and Baranowski (1992 ). The residue in the sieve was washed off with 75% alcohol in to a Petri dish and checked under a dissecting microscope at 12X to record various species of thrips. Frankliniella schultzei and a dult thrips not identified as F. schultzei were separated and stored in 75% ethanol for further identification (discussed in chapter 3) Samples were taken during fifth, sixth and seventh week after planting. Statistical Analysis Data were analyzed independently for larvae and adults Da ta on the abundance of larvae and adults on each crop were averaged for all samplings. T he mean number of larvae and adults per crop was compared using one way analysis of variance (ANOVA) ( P ROC GLM, SAS Institute Inc. 2003). Data were transformed by log 10 (x+1) to comply with model assumptions before analysis. Untransformed means and standard

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32 errors are reported in figures. Differences among means of larvae and adult on various c rops (Honestly Significant D ifference) proced ure ( P < 0.05). Results Frankliniella schultzei abundance on five host plants: Four of the five potential hosts were found to be infested with F. schultzei adults. Infestation of adults on tomato flowers was not significantly different to squas h and cucumb er flowers test, P < 0.005) (Figure 2 1). The least number of adults were captured on beans and no ne was found on pepper flowers. T he number of adults on tomato and squash was significantly greater than in bean flowers ( F = 6.56; df = 4, 45; P < 0.001). Mean number of F. schultzei larvae was highest on cucumber flowers (Figure 2 2). The infestation level on cucu mber flowers was significantly higher than the other four hosts ( F = 32.52; df = 4, 45; P < 0.001) (Figure 2 2 ). Not a single larv a w as found on pepper (Figure 2 2). There was no significant difference in the number of larvae sampled from squash, tomato and beans (Tukey HSD test = 0.05). In the course of sampling five vegetable crops, other thrips species were also encountered. The predominant species besides F. schultzei was Thrips palmi Karny, followed by Frankliniella occidentalis (Pergande) and F. fusca (Hinds) (Figure 2 3) While, T. palmi was the second most abundant species encountered on various vegetable crops (excluding tomato) after F. schultzei, the number of T. palmi encountered in total was low when compared with F. schultzei count s in flowers on various crops. The highest number of T. palmi was found in beans flowers with an average of six adults per five flowers, followed by squash, and cucumber The l east number of T. palmi was collected from pepper flowers (Figure 2 3)

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33 Frankliniella bispinosa (Morgan) was foun d on bean flowers but the number was fewer than four specimens in the total number of thrips adults collected from various crops during the study. Frankliniella occidentalis was collected from squash, t omato cucumber and bean flower, with the number of ad ults ranging between 0.2 1.0 per five flowers sampled from various hosts in the study Frankliniella fusca was collected from tomato flowers with an average number of 0.6 adults per five flowers (Figure 2 3). Discussion Results of this study suggested th at the five vegetable crops were infested with at least four different thrips species. These we re F schultzei, F fusca F. occidentalis and T. palmi The number of thrips species other than F. schultzei encountered on flower s of sampled crops was small w ith insignificant damage potential. Thus, the pest of major concern was F. schultzei. Frankliniella schultzei is reported as a pest of several ornamental and vegetable crops in the scientific literature. In my study, a dult F. schultzei densities on variou s plant species sampled was consistent for the top three preferred host, which includes tomato, squash and cucumber High density of F. schultzei on tomato flower s was in agreement with Jiminez et al. (2006 ), Montei ro et al. (2001) and Sakurai (2004), who reported tomato to be a major host of F. schultzei in Cuba, Brazil and Paraguay respectively. However, when plant species in the present s tudy were ranked according to host status based on larval density, a different pattern was observed. Only cucumber wa s identified as a suitable host of F. schultzei with the number of larvae greater than the adults, suggesting cucumber to be a breedin g site for this pest. The larval count s were lower than adult count s on other hosts and thus these crops including tomato can be regarded as low er ranked hosts of this pest in south Florida.

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34 Variation in host plant preferences of pest s inhabiting different geographical regions has also been reported for several other insect species in the literature. Probable reasons for su ch plasticity in behavior are suggested to be genetic or environmental variations (Jaenike 1990) although there is little published evidence for the role of genetic variation in host preference. Environment ally induced variation is known to cause differen ces in host preferences for a species in different regions. Jaenike (1990) explained that the abundance of the most preferred host in a region can result in high er thresholds for low ranked host plant, which may be disregarded by the pest in that area. Abs ence of this preferred host in another geographic region changes the threshold and thus the preference level for low ranked host changes for a species. However, preference f or cucumber over tomato by F. schultzei in my study, where the pest was given free choice is still ambiguous. Nevertheless, a more comprehensive picture about the true host range for F. schultzei in this region has emerged. Further studies on the seasonal abundance on these hosts will broaden our knowledge on the dispersal and interactio n with various hosts on which F. schultzei prospers.

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35 Figure 2 1. Number of F. schultzei adults (Mean SEM) on flowers of five host plants sampled during fall 2009. Means with the same letter are not significantly different (P > 0.05, est ). 0 5 10 15 20 25 30 35 40 Bean Tomato Pepper Cucumber Squash Avg no. of F. schultzei adults/ 5 flowers Plant species Adult b ab a a

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36 Figure 2 2. Number of F. schultzei larvae (Mean SEM) on flowers of five host plants sampled during fall 2009. Means with the same letter are not significantly different (P > 0.05, ) 0 10 20 30 40 50 60 70 80 90 100 Bean Tomato Pepper Cucumber Squash Avg no. of F. schultzei larvae / 5 flowers Plant species Larvae a b b b

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37 Figure 2 3. Average number of adults o f three thrips species sampled from five vegetable crops 0 1 2 3 4 5 6 7 bean tomato pepper cucumber squash Avg no. of thrips adults/ 5 flowers Plant species T. palmi F. occidentalis F. fusca

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38 CHAPTER 3 IDENTIFICATION OF THRIPS SPECIES INFESTING VARIOUS VEGETABLE CROPS IN SOUTH FLORIDA The beginning step of any management practice is correct identification of the insect pest. In the p ast several integrated pest management strategies have been developed against various thrips species. The success and sustainability of these approaches are dependent on several factors including correct ident ification of the target species because m anagem ent practices vary greatly with different thrips species belonging to a single genus. In Florida the genus Frankliniella consists of a huge complex of species (Salguero Navas et al. 1991). The presence of several other thrips species makes thrips identifi cation difficult for non specialist s including growers. The s mall size and presence of several dark color ed thrips including F. fusca (Hinds) F. schultzei Trybom and F insularis (Franklin) makes color based field identification difficult. Thus, identif ication of thrips is mainly based on characters like antennal segments, body setae, presence or absence of a comb on the VIII abdominal segments in addition to color. By using traditional taxonomic keys, thrips can be assigned to a particular genus, but du e to high intraspecific morphological variation (color morphs) of many c onspecifics of Frankliniella expertise is required for identification to species level. The objective of this study is to present important identification features of six thrips speci es inhabiting five vegetable crops cucumber, squash, pepper, snap beans and tomato in south Florida. The images of morphological features of thrips species will help scouting personnel and researchers in the identification of m ajor thrips species encounte red.

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39 Materials and Methods Sampling In the present study, adult thrips were collected during the course of sampling various crops (mentioned above) to study the abundance of F. schultzei Thrips were processed for identification to the species level. In a ddition to the selected crops, 10 flowers were collected from a weed, Bidens alba (L.) DC var. Radiate growing adjacent to experimental plots at the TREC field. These flowers were infested with dark thrips and samples were collected to determine if this w eed served as a reservoir for F. schultzei in the field. Determination of Adult Thrips Slide m ounting: Twenty thrips of each distinct morph and five specimen of F. fusca collected from the various host crops were used for the identification. Thrips colle cted in vials containing 75% alcohol and then transferred to a 10% KOH (Potassium hydroxide solution) solution prepared in 50% ethanol to lighten the dark color of cuticle on various body parts. D uration of keeping specimen in the solution was standardized to 15 25 min depending on the darkness of th r i ps cuticle. While still in KOH, the insect was then gently punctured in the abdomen (close to the thorax to avoid disrupting features near the ovipositor) using a fine insect pin to facilitate the removal of i ts abdominal contents. S pecimen were then passed through a series of alcohol concentrations starting from 65%, followed by 75%, 85%, 90% and 95% ethanol to i nitiate gradual dehydration of the specimen. Thrips were placed in each of the above mentioned alco hol concentrations for 5 8 minutes to avoid any moisture interaction at the final stage of slide mounting. Each specimen was placed ventrally on a slide with a ss cover slip. The adult

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40 female thrip s were identified using t hrips identification key (Nakahara 1994) and pictures were taken using Insight Firewire Spotimaging (4 Megapixel) camer a (Vegetable IPM Lab, TREC University of Florida ). Insect Identification The identification of thri ps collected from various crops and weeds surrounding ( B. alba ) the experimental plot in Homestead suggested that the plants were infested with at least six different thrips species. They were F schultzei, F insularis, F fusca, F occidentalis T. palmi Thrips flo rum Schmutz and Microcepalothrips abdominalis (Crawford) Following are the morphological features that helped in the identification of these thrips. Frankliniella schultzei ( Trybom ) The common blossom thrips F. schultzei (Thysanoptera: Thripidae) exists in two different color morphs ( Figure 3 1and 3 2). The dark form of F. schultzei is dark brown in color (Frantz and Fasulo 1997) ( Figure3 1).There are eight antennal segments with pale bases of segments 3 5. The eight h segment is slightly longer than seve nth segment ( Figure3 3). The interocellar setae or the third pair of ocellar setae arises between the anterior ends of the two hind ocelli ( Figure3 4). The postocular setae (1) are shorter than interocellar setae (2) on the head ( Figure3 5). The pronotum o f species from genus Frankliniella have five pairs of developed setae. In F. schultzei the anteromarginal setae (1) are slightly shorter than anteroangular setae (2) ( Figure3 6). The metanotum lacks campaniform sensilla ( Figure3 7). Forewing bears two comp lete rows of veinal setae (Figure 3 8). Posteromarginal comb on the eight abdominal segment is not fully developed and is incomplete medially bearing short microsetae on either ends (Figure 3 9).

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41 Frankliniella insularis (Franklin) Frankliniella insularis (Thysanoptera: Thripidae) is a pest of South America origin. Its geographical range extends from Central America to Argent ina and southern states of the US. In my study, I sampled this species from B. alba flowers. Females are dark brown in color (Figure 3 10). There are eight antennal segments with pale bases of third, fourth and fifth segments (Figure 3 11). The segment three and four bears a forked sensorium. The head bears three pairs of ocellar setae and third pair of ocellar setae arises from the sid es of the ocellar triangle and a long pair of fourth postocular setae (Figure 3 12). The pronotum have five pairs of developed setae and the anteromarginal setae are shorter than anteroangular setae (Figure 3 13). Metanotum bears two pairs of long setae on anteromarginal end and two campaniform sensilla (Figure 3 15). Forewing has a distinct pale base bearing two complete rows of veinal setae (Figure 3 16). Posteromarginal comb on eight abdominal segment is fully developed, arising from triangular bases (Fi gure 3 17). Frankliniella fusca (Hinds) The tobacco thrips, F. fusca (Thysanoptera: Thripidae) has two different wing morphs. Morphs with wings are known as micropterous and wingless f orms are known as brachypterous (Figure 3 18) Adults of F. fusca are brown in color with eight antennal segments (Figure 3 19). Head bears three pairs of ocellar setae and the third pair originates above the two hind ocelli and out of the ocellar triangle. The postocular setae on head are small (Figure 3 20). The pronotum h ave five pairs of developed setae and in F. fusca ; anteromarginal setae are distinctively shorter than anteroangular setae (Figure 3 20). The metanotum has the campaniform sensilla (Figure 3 21) and forewing

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42 has two complete rows of veinal setae (Figure 3 22). Posteromarginal comb on eight abdominal segment is absent in this species (Figure 3 23). Frankliniella occidentalis (Pergande) The western flower thrips, F. occidentalis (Thysanoptera: Thripidae) is a pest of US origin. It exists in dark, pale and an intermediate color forms. The adult body is yellow in color with brown bands on tergite (Figure 3 24) There are eight antennal segments, where the yellow colored third, fourth and fifth segments have brown apices (Figure 3 25). Head possesses three pairs of ocellar setae and the third pair arises from the anterior margin of the two hind ocelli (Figure 3 26). The ocellar setae and postocular setae on head are equal in length (Figure 3 26). The pronotum have five pairs of developed setae and in F. occidenta lis; anteromarginal setae are slightly shorter than anteroangular setae. The metanotum bears campaniform sensilla (Figure 3 27). Forewing consists of two complete rows of veinal setae (Figure 3 28). Posteromarginal comb on eight abdominal segment is fully developed bearing a row of microtrichia. Microcephalothrips abdominalis (Crawford ) The composite thrips, M. abdominalis (Thysanoptera: Thripidae) is the only species of genus Microcephalothrips. Childers et al. (1999), Childers and Nakahara (2006) reporte d the infestation of this species on citrus trees and citrus groves in southern Florida. In my study, I sampled this species from B. alba flowers. The adult body is brown in color (Figure 3 29) bearing seven segmented antennae (Figure 3 30). Head possesses only two pairs of ocellar setae unlike various species of Frankliniella as described above (Figure 3 31). The third pair arises from the anterior end of ocellar triangle. Anteromarginal setae on pronotum are absent. The pronotum bears two pairs of small p osteroangular setae and five pairs of posteromarginal setae. A pair of setae is

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43 centrally located in mesonotum (Figure 3 32) and metanotum (Figure 3 33) separating this species from other thrips collected in the study. The metanotum bears campaniform sensi lla (Figure 3 33). Forewing has incomplete rows of setae, with two and three setae on the distal end of the rows, respectively (Figure 3 35). Posteromarginal comb on eight abdominal segment is fully developed bearing a complete row of microtrichia (Figure 3 34). Thrips palmi Karny The melon thrips Thrips palmi Karny (Thysanoptera: Thripidae), is an economically important pest of various greenhouse and field crops in south Florida. It is a pest of Southeast Asia origin from where it spread to the rest of As ia, North Africa, Australia, Central and South America, and the Caribbean. In Florida, it was first observed in 1990. The adult body is yellow in color (Figure 3 36). The antenna is seven segmented with darker terminal segments (Figure 3 37). Head bears tw o pairs of ocellar setae and the interocellar setae arises from a region closer to the posterior end of the apical ocelli. The interocellar setae are longer than the postocular setae (Figure 3 38). The pronotum of T. palmi has two pairs of posteroangular s etae and it lacks both the pairs of anteroangular and anteromarginal setae. The anterior end of metanotum possesses distinct transverse lines and toward the posterior end are present a pair of campaniform sensilla (Figure 3 39). The first vein of forewing has three setae on distal end (Figure 3 40 ). Posteromarginal comb on eight abdominal segment is fully developed bearing a row of long microtrichia (Figure 3 41 ).

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44 Figure 3 1 Dorsal view of an adult F. schultzei with dimensions marked Figure 3 2. Slide mount of an adult of light form of F. schultzei

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45 Figure 3 3. Antenna of adult F. schultzei showing 8 antennal segments with pale bases of 3 5 th segment Figure 3 4. Head of an adult F. schultzei showing interocellar setae at 40 X magnifica tion

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46 Figure 3 5. Head of an adult F. schultzei showing postocular setae (1) smaller than interocellar setae (2) at 40 X magnification. Figure 3 6. Prothorax of an adult F. schultzei showing the anteromarginal setae (1) slightly shorter than a nteroangular setae (2) on the anterior of the prothorax

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47 Figure 3 7. Metanotum of an adult F. schultzei lacks campaniform sensilla Figure 3 8. Forewing of an adult F. schultzei showing two complete rows of veinal setae

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48 Figure 3 9. Abdomen of an adult F. schultzei showing a weakly developed comb on the eight abdominal segment Figure 3 10. Slide mount of an adult F. insularis showing dorsal view

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49 Figure 3 11 Antenna of adult F. insularis showing 8 antennal segments with pale 3 5 th Figure 3 12. Head of an adult F. insularis showing 3 rd pair of interocellar setae and 4 th pair of postocular setae

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50 Figure 3 13. Pronotum of an adult F. insularis showing five pairs of pronotal setae, anteromarginal setae are shorter th an Figure 3 14. Mesonotum of an adult F. insularis bearing longitudinal lines

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51 Figure 3 15. Metanotum of an adult F. insularis bearing two campaniform sensilla Figure 3 16. Forewing of an adult F. insularis with a pale base, bearing two complete rows of setae

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52 Figure 3 17. Abdomen of an adult F. insularis showing comb on the eight abdominal segment Figure 3 18. Slide mount showing an adult of F. fusca

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53 Figure 3 19. Antenna of adult F. fusca showi ng 8 antennal segments with pale 3 rd and 4 th Figure 3 20. Head of an adult F. fusca with 3 pairs of ocellar setae and pronotum bearing anteroangular and anteromarginal setae

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54 Figure 3 21. Metanotum of an adult F. fusca bears campaniform sensilla Figure 3 22. Forewing of an adult F. fusca bears two complete rows of setae

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55 Figure 3 23. Abdomen of an adult F. fusca lacks comb on the eight abdominal segment Figure 3 24. Slide mount of a pale for m of an adult of F. occidentalis

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56 Figure 3 25. Antenna of adult F. occidentalis showing 8 antennal segments with dark apices of 3 5 th segment Figure 3 26. Head of an adult F. occidentalis showing pair of ocellar and postocular setae

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57 Figure 3 27. Metanotum of an adult F. occidentalis bears two campaniform sensilla Figure 3 28. Forewing of an adult F. occidentalis showing two complete rows of setae

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58 Figure 3 29. Slide mount of an adult M. abdominalis Figure 3 30 Antennae of an adult M. abdominalis

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59 Figure 3 31. Head of an adult M. abdominalis showing third pair of ocellar setae Figure 3 32 Mesonotum of an adult M. abdominalis with a pair of setae

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60 Figure 3 33. Metanotum of an adult M. abdominalis with campaniform sensilla Figure 3 34. Adult of M. abdominalis with a complete comb on the eight abdominal segment

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61 Figure 3 35. Forewing of an adult M. abdominalis with incomplete rows of setae Figure 3 36. Slidemo unt of an adult T. palmi

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62 Figure 3 37. Seven segmented antennae of an adult T. palmi Figure 3 38. Head of an adult T. palmi with two pairs of ocellar setae

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63 Figure 3 39. Metanotum of an adult T. palmi bears a pair of campaniform sensi lla Figure 3 40. Forewing of an adult T. palmi

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64 Figure 3 41. Abdomen of T. palmi showing complete comb on the eight abdominal segment

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65 CHAPT ER 4 DISTRIBUTION AND SEA SONAL ABUNDANCE OF FRANKLINIELLA SCHULT ZEI Thrips are economic group o f insects posing serious threat s to various commercially important crops. Ow ing to their polyphagous behavior, they attack a wide range of hosts in variable environments and geographical locations. T hrips exhibit diverse population dynamics, which are larg ely affected by overlapping host ranges of different thrips species (Cho et al. 2000, Ramachandran et al. 2001 and Reitz et al. 2003). Reitz et al. (2003) reported that Frankliniella occidentalis (Pergande) is very common in Florida during winter, but late r at the beginning of spring, it is displaced by competitive Frankliniella tritici (Fitch) and Frankliniella bispinosa (Morgan) populations. Similarly, Thrips palmi Karny p in fall and spring seasons, co mpared to summer due to their low reproductive success at high summer temperatures (Seal 1997). In Florida, T. palmi infestations begin early in the crop growing season during October and continue until June (Seal 1997). Such information on seasonal popula tion dynamics of various insects helps scouting personnel to locate pest infestation early in the season. Unfortunately, information on seasonal abundance of F. schultzei in Florida is lacking. Thus, we studied the populatio n dynamics of this pest in fall 2008 and 2009, which is a growing season for cucumber in Homestead. Thrips distribution in any field is highly affected by its ecology. Due to its ability to exploit vast range of host p lants, thrips take refuge in weeds (uncultivated area) surrounding th e cultivated crops until the availability of preferred host. Once crop is ready, these thrips are attracted to food offered by the cultivated crops (preferred host) and make local dispersions to the cultivated areas. Seal and Stansly (2000) found that

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66 the distribution of T. palmi was aggregated in field grown beans Similar distribution pattern was observed for Scirtothrips dorsalis infesting pepper plants in St. Vincent (Seal et al. 2006). Seal et al. (2001) also found that infestation by T. palmi began on the edges of the field, slowly progressing toward the interior. In general, insect populations can be random, clumped or uniformly distributed. The distribution of insects is often influenced by its density in a field. Lower number of insects in a field leading to low capture rate during sampling suggests a random distribution of insects in the field (Southwood 1978). Similarly, denser the population of the pest, the more aggregated is the pest in a field. Majority of the insect group possesses such popul ation distribution trends in the field. However, regardless of the clumped, regular or random distribution pattern of insects, traditionally, insecticides are applied uniformly to fields (Weisz et al. 1996) aggravating ecological, economical and environmen tal damage. Consequently, such disturbances to the natural system inaugurate the need of within field distribution study of a pest. But, the distribution patterns of insects affect the number of samples required and the reliability of data to be used for t hrips population estimation in a field. Thus, it is important to validate the minimum number of samples required from an area to reduce the variability of the data to an acceptable level. Considering the lack of information in this area, I also calculated the desired number of samples required for monitoring clumped population of F. schultzei in cucumber field. In addition to within field distribution, lack of information on within plant distribution of this pest is another important issue to be addressed. Thrips exhibit differential feeding preference for various parts of its host plants. Thrips like F. fusca feeds on flowers; thus,

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67 blossoms have commonly been used as a sampling unit for this pest. Likewise, F. schultzei is also an anthophilous species, but there are reports indicating its presence on leaves as well. Jacobson (1997) reported that adults of F. schultzei mainly feed on young leaves and flowers of a pple, whereas larvae were found feeding on leaf buds. Tave lla et al. (1996) reported that adults and larvae of F. occidentalis were most abundant in flowers of greenhouse grown pepper ( Capsicum annum L.) which is contradictory to the study by Higgins (1992), who found larvae feeding on leaves of greenhouse grown pepper. Seal et al. (2006) observed va riable abundance of chilli thrips, S. dorsalis Capsicum chinense Jacq. They found chilli thrips were most abundant on the top young leaves followed by middle leaves and lower leaves. Such reports trigger the nee d to select an appropriate sampling unit for an in depth study of F. schultzei feeding behavior. The goal is to develop management programs to address populations according to pest distribution patterns. Thus, the main objective of this study is to invest igate within field distribution of F. schultzei and determine the sample size required for estimation of F. schultzei population in a field. Furthermore, efforts have been made to understand the within plant distribution pattern of F. schultzei and its abu ndance during the cucumber growing season in Homestead, FL. Materials and Methods Field P reparation : The soil type for all experimental fields in this study is Krome gravelly loam (loamy skeletal, carbonatic hyperthermic lithic Udorthents), which consists of about 33% soil and 67% limestone pebbles (> 2mm). The fields were prepared by using standard commercial practices (Olson and Santos 2010).

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68 Crop management : At all the sites, cucumber, Cucumis sativus L. var.` directly seeded on a flat gro und. Seeds were sown 15.2 cm apart within the row and 91.4 cm apart between rows. At planting, 8 16 16 (N P K) was applied at 908 Kgs / ha in furrow; and Halosulfuron methyl 55 ml/ha (Sandea Gowan Company LLC., Yuma, Arizona) was used as a pre emergence herbicide to control weeds. Pyraclostrobin at 0.8 l/ha (Pristine BASF Ag Products, Research Triangle Park, NC) and Chlorothalonil at 1.75 l/ha (Bravo Syngenta Crop Protection, Inc., Greensboro, NC) were used in rotation at two week intervals to prevent fungal diseases. The crops were irrigated twice a week with 3 cm of water using overhead sprinklers. Fertilizer 4 0 8 (N P K) at a rate of 2.2 Kg.ha 1 was used once a week as an in furrow band in all the fields and its use was initiated three weeks after planting. Bacillus thuringiensis based insecticides, Dipel DF ( var kurstaki) at 1.1 Kg.ha 1 and Xentari DF ( var. kustaki) at 1.2 L.ha 1 (Valent Biosciences Corporation, Libertyville, IL) were used to control melon worms, Diaphania hyalinata (L.) and pic kle worms, D. nitidalis (Stoll) in the field. Within P lant Distribution Within plant distribution of F. schultzei on cucumber was studied during three cropping seasons, fall 2008, spring 2009 and fall 2009 in two commercial fields (Field A & B) each season The size of different fields in the study ranged from 0.05 0.5 hectares (ha). Selection of these study areas at various sites was to extract information on the distribution of F. schultzei in a wider area. Season 1 (Fall 2008) Study Area A : During the f irst cropping season, cucumber was planted on a 0.4 ha plot which was a part of a commercial field in Homestead (N 25 o o The field was planted on Sep 10, 2008 and managed using cultural practices as described

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69 above. The field was divided int o four equal blocks, where each block consisted of 20 meter long, 40 rows of plants. Each block was divided into 10 plots, consisting of 20 m long 4 rows of cucumber plants. On 10 th and 17 th Oct, ten plants from each plot were randomly selected. Each plant was stratified into three sections: a freshly emerged terminal leaf bud (2 5 days old), a middle leaf (5 th leaf from the top), a bottom leaf (8 th fully grown leaf from the top) and a flower with no preference for the site of flowers to be picked. Thus, fr om each plant, a newly emerged leaf bud, two leaves and a flower were collect ed at the time of sampling. The s amples belonging to a stratum of a plant collected from one plot were placed in one ziplock bag (17 X 22 cm) marked with the date, plot number, b lock number and sample type. All samples were transported to the Vegetable IPM laboratory, TREC, Homestead where samples were placed in a one quart plastic cup with 75% ethanol for 30 minutes to dislodge various life stages of thrips. The samples were care fully taken out of the cup leaving thrips in alcohol. The contents in alcohol were sieved using a 25 m grating, USA Standard Testing Sieve (W. S. Tyler, Inc.) as per Seal and Baranowski (199 2 ). The residue in the sieve was washed off with 75% alcohol in t o a Petri dish and checked under a dissecting microscope at 12X to record various life stages of thrips. Study Area B: The study area (N 25 o o 2008 by direct seeding and managed following cultural practices as describe d above. A ~0.11 ha study area in t he field was divided into 3 equal sized blocks, each consisting of 56 rows of cucumber plants each 15 m long Blocks were divided into 14 equal sized plots consisting of 10 m long four adjacent rows. The field was sample d on Oct 18 and

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70 Oct 26. In order to collect samples, 10 plants were randomly selected, and samples were collected and processed as above Season 2 (Spring 2009) Study Area A: The study area (N 25 o o was planted on March 2 nd and for sampling t he designated study area was divided into four equal blocks, where each block consisted of 10 rows 15 m long, covering a 0.08 ha area. The field was sampled on 11 and 17 April, 2009 during 6 th and 7 th week after planting. For sampling, twenty plants were randomly selected in each plot, stratified, sampled and processed as described above Study Area B: The study area (N 25 o o was planted by direct seeding on March 10, 2008. The study area ~0.2 ha was divided into six equal sized blocks measuri ng 0.03 ha, where each plot consisted of 4 rows of plants 61 m long The field was sampled on 8 and 17 April, 2009 during 4 th and 5 th week after planting. On each sampling date, 20 plants were randomly selected in each plot. Each plant was stratified to c ollect a flower, upper leaf, middle leaf and lower leaf sample. Samples collected from different plots were placed in separate bags (17 X 22 cm) marked with the date, plot number, block number and sample type. Samples were processed as discussed above Sea son 3 (Fall 2009) Study Area A Sep1, in a commercial field (N 25 o o was designated (Figure 4 1). The study area was divided into four equal blocks co nsisting of 35 rows of cucumber plants 15 m long Each block was divided into seven equal plots carrying 15 m long, 5 rows of cucumber plants. Ten plants were randomly selected in

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71 each plot. Each plant was stratified and sampled as above from the beginnin g until the end of flowering. Samples were collected on Sep 25, Oct 3, 10, 17, 24 and 29. All materials and methods involved in collection and processing of s amples were as discussed above Study Area B: The s tudy area B was in an adjacent field ( N 25 o W 80 o under the same management program. It was a 0.27 ha field, seeded on Sep 8 The field was sampled on Oct 5, 12, 18, 24 and 31. Materials and methods for planting and sectioning field, and sampling and processing samples were as discussed above Statistical analysis Data were analyzed independently for each field and growing season. Data on the abundance of larvae and adults from each field was averaged for all the samplings. Because I wanted to determine the preferred plant parts by larvae and a dult, the mean number of larvae and adults per 10 crown, middle leaf, bottom leaf and flower per field was analyzed using one way analysis of variance (ANOVA) ( PROC GLM, SAS Institute Inc. 2003) Data were transformed by log 10 (x+1) to comply with model ass umptions before analysis. Untransformed means and standard errors are reported in figures. Differences among means of larvae and adult on various plant parts were separated (Honestly significant difference) test ( P < 0.05). Spatial D istri bution S patial distribution of F. schultzei was studied during the fall cropping season s of 2008 and 2009. Each season, three study areas within commercial fields were ground and fields were managed following standard cultural practices as described above.

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72 Season 1 (Fall 2008) Study Area A: The study area measuring 0.24 ha and loc a ted at N 25 o o ach plot of area 37 m 2 consisted of 12.5 m long three rows of cucumber. From each of these plots, ten flowers (one flower/ plant) were randomly collected and processed as described in the previous study to record thrips count. These plots were later pooled for analysis in various combinations for ming vari able sized plots for the study i.e., 74 m 2 148 m 2 296 m 2 and 592 m 2 corresponding to 2, 4, 8 and 16 combined plots. Study Area B: The study was conducted in study area B (N 25 o o used for within plant distribution study in fall seas on (2008). The study area was divided into 42 equal sized plots of 23.33 m 2 Samples were taken and processed as above. P lots were pooled for analysis in a combination of 3, 7 and 14 plots forming bigger plots of size 70 m 2 180 m 2 and 360 m 2 respectively Study Area C: The study was conducted in study area A (N 25 o o used for within plant distribution study in the fall of 2008. The field was divided into 40 equal sized plots of 100 m 2 and sampled as above. The plots were pooled in sets of 2, 4, and 10 forming plots of size 200, 400 and 1000 m 2 area for analysis Season 2 (Fall 2009) In fall 2009, study areas A, B and C were located at N 25 o o and samples were collected from onset until conclusion of flowers in the crop. Figure 4 1 shows the arrangement of the three study area within a commercial field under the same management

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73 Study areas A and B were also used for within plant distribution study during fall 2009, although only flowers were used for the present study. Planting d ates were Sep 1 and Sep 8, respectively. Sampling dates for the two study areas are given in Table 4 3 and Table 4 5 Study Area C: The study area was planted on Sep 15 The study area was divided into four equal sections consisting of 15 m long 35 rows of cucumber plants. Each block was further divided into seven equal plots made up of 15 long, 5 rows of cucumber plants. Samples were collected on Sep 25 and Oct 3, 10, 17, 24 and 29 as discussed above. Statistical analysis S patial distribution was determi ned separately for larvae and adults on flower s for (Iwao 1968). In season 2008, distribution of F. schultzei was determined for only one time during the season. While di stribution of F. schultzei in second season (Fall 2009) power law determines the relationship between variance ( s 2 ) and mean density of larvae and adults per sample by m eans of linear regression model: log 2 = log + log [1 1 ] where, slope ( b ) signifies degree of aggregation and log a, is a sampling factor expressed as: + = + [ 1 2]

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74 (mean crowding index) = 2 1 and s 2 and are the sample variance and mean respectively. The mean crowding index was given by Lloyd (1967) to expr ess the degree of crowding by mobile animals and it was Index of basic contagion, which measures the tendency of insects towards crowding, contagiousness coefficient and is analogous to the b b Iwao patchiness regression model respectively, w hen greater than 1.0 represent an aggregated distribu significantly < 1.0 and not significantly > 1.0, indicate a uniform and random distribution, respectively. R egression parameters were estimated using general linear regression model (PROC GLM) of Statistical analys is system (SAS Institute Inc. 2003). The goodness of fit of data set from each field to both the linear models was evaluated by the r 2 value. Student t test was used to determine whether slope ( b these two models were significantly differe nt from 1.0. In addition to these two models, an Index of dispersion (ID) was calculated as: ID = 2 [ 1 3] where, s 2 is sample variance and x is mean number of F. schultzei per sample. The distribution estimated using ID is said to be aggregat ed if ID > 1.0 and regularly distributed if ID approaches zero. Morista (1962) suggested that the distribution changes from aggregated to random with the change in the size of area occupied by insects. To address this, we determined spatial distribution of different sized plots in

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75 each of the experimental fields. These plots were formed by adding up small sub plots at each field in different combination forming a range of different sized plots for analysis. Sample Size Requirements Sample numbers were eva luated at three levels of precision (0.10, 0.20 and 0.40) using Wilson and Room (1982) equation, given as: = 2 2 2 [ 1 4] Where, a and b c is the reliability, n= sample size, t is student t value at n 1 degree of freedom and is the mean density. The sample size was estimated for average cumulative thrips number from three experimental fields under study in fall 2009. Estimates were made for three levels of density of F. schultzei larvae ( = 0.5, 2 and 5) per sample. These densities were determined based on various samples collected in three plots during the period of study. Estimation of sample size at three levels of t hrips density will help scouting personnel or growers to collect right number of samples at different levels of infestation in the field and thus apply c ontrol measures accordingly. Seasonal Abundance Study on seasonal abundance of F. schultzei on cucumb er was conducted for fall cropping season in year 2008 and 2009. In both the years, the study was conducted at two commercial fields, where all the designated study areas ranged between 0.25 0.5 ifferent dates following standard cultural practices as described earlier (Olson and Santos 2010).

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76 Season 1 ( Fall 2008 ) The first trial was conducted in two fields adjacent to each other (N 25 o o a Rockdale soil in the first week of Sep (2008). Seeds were spaced 15 c m within the row and 91.4 cm between rows Cucumber was irrigated twice a week with 3 cm of water using overhead sprinklers. For sampling, each field was divided into 4 equal blocks. Ea ch block consisted of 56 rows 15 m long of cucumber plants. Blocks were then divided into 14 plots consisting of 15 m long four adjacent rows. In each plot, ten flowers (one flower/plot) were randomly selected and placed in separate ziplock bags (17 cm x 22 cm), marked with the date and block number and transported to the Vegetable IPM laboratory, TREC where samples were placed in a one quart plastic cup with 75% ethanol for 30 minutes to dislodge various life stages of thrips The samples were carefully taken out of the cup leaving thrips in alcohol. The contents in alcohol were sieved using a 25 m grating, USA Standard Testing Sieve (W. S. Tyler, Inc.) as per Seal and Baranowski (1992 ). The residue in the sieve was washed off with 75% alcohol in to a P etri dish and checked under a dissecting microscope at 12X to record various life stages of thrips. Since, flower was the sampling unit in the study; sampling was initiated at the onset till conclusion of flowering Samples were collected once a week for s ix weeks dur ing the period of study (Table 4 10) Season 2 ( Fall 2009 ) The second trial to study seasonal abundance of F. schultzei was conducted in 2009 at two study areas also used for spatial distribution study during fall 2009 (field A and B located at N 25 o o For sampling fields at both sites were divided into four equal blocks and each block consisted of 17 m long 30 rows of cucumber plants.

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77 The block was divided into 10 plots with three 17 m long rows in each plot. Ten flowers (a flower /plant) were randomly selected in each of the plot and placed in separate zip lock bags, marked with the date and block number and transported back to the Vegetable IPM laboratory, TREC, where samples were processed and number of thrips was recorded as dis cussed for trial conducted in 2008. Sampling date s have been mentioned in table 4 10. Statistical Analysis Data were analyzed independently for each year. However, the number of adults and larvae from two fields in each year (2008, 2009) was averaged over various sampling dates. The data was transformed using the square root of ( X + 0.25) to stabilize error variance prior to analysis of variance. The averaged number of larvae and adults per sampling over two seasons in each year was analyzed by one way anal ysis of variance (ANOVA) ( PROC GLM, SAS Institute Inc. 2003). Differences between means of larvae and adult count for all the sampling date s were separated using the HSD test ( < 0.05) using SAS Institute Inc. 2003. Results and Discussion Within P lant Distribution The number of larvae and adults captured on flowers was significantly higher than the leaves sampled from various sections of a plant at study area A in 2008 ( F = 22 4.45; df = 2, 117; p < 0.001 for larvae F = 186.57; df = 2, 117; p < 0.001 for adults) (Figure 4 2a ). Similar results were obtained for Study area B in 2008 (Figure 4 2b) Leite et al. (2002) reported that F. schultzei prefers to feed on the upper leaves to middle and lower leaves of tomato plants. Similar ly, Pinent and Carvalho (1998) reported on studies where they fed F. schultzei on tomato leaflets to study its biology

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78 and life cycle. Surprisingly we did not find F. schultzei feeding on tomato leaves d uring the past two years in Homestead (discussed in Chapter2). Gonzalez et al. (2001), while sampling cucumber leaves to monitor T. palmi found F. schultzei on leaf samples collected in Cuba, which was contradictory to our results. In order to confirm the se reports, t he study was repeated in spring 2009 and fall 2009. At the two fields sampled in spring 2009, we did not find any difference in the feeding preference of this pest and the mean number of F. schultzei was significantly larger in flowers with a few numbers on other plant parts (Figure 4 2c, d). Similar results have been documented from the studies conducted at two sites in fall 2009. The number of F. schultzei adults and la rvae were significantly higher i n flower than other plant parts (Fig ure 4 2e, f ). In addition to F. schultzei T. palmi was captured on cucumber plants during the study The majority of T. palmi was found infesting leaves of cucumber plants. The number of T. palmi on flower samples was low. Leaves of cucumber plants sampled at all the plots during the three season study were heavily infested with T. palmi Thrips palmi has a wide host range and prefers host of family Cucurbitaceae and Solanaceae where a dults and larvae of T. palmi preferably feed on leaves of its host plant ( Capinera 2000) Spatial Distribution Study area A and B ( 2008 ): At the two sites, l arvae of F. schultzei exhibited an aggr egated distribution. The slope ( b from two linear regression models for the entire plot sizes were significantly > 1 ( P < 0.05, Table 4 1). The coefficients of determinant ( r 2 regression over Study area A, where slope values

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79 for ( b 2.65 and 1.10 to 1.29, respectively were significantly > 1 ( P < 0.05) (Table 4 2) T he results for distribution pattern of adults in the smallest plot from two regression models higher r 2 value provided a better fit to the data. The coefficient of determinant for bigger plots of Study area A and Study area B model. The l ow r 2 F. schultzei (Table 4 1, 2). The values of Index of dispersion (ID) ranging from 5.00 to 17.00 for larvae and 3.46 to 5.86 for adult in all the plots at Study area A were significantly > 1 ( P < 0.05) (Table 4 regression confirming an aggregated distribution of larvae a nd adult populations of F. schultzei in the field. Milne (2006) also observed such aggregated behavior of F. schultzei in his study. He suggested that, aggregation by F. schultzei males on plant parts is primarily to attract conspecifics for mating, possib ly by release of sex pheromones. In addition, there are several reports suggesting the clumped distribution of other thrips species of family Thripidae including, T. Flavus Schrank, T. Major Uzel, T. Atratus Haliday, F. occidentalis (Pergande) and a group of flower thrips (Arevalo and Liburd 2007, Morison 1957, Kirk 1985, Terry 1995, Terry and Dyreson 1996) on various plant parts. Besides reproduction as a factor inducing clumping of F. schultzei population, there is not much information available on factor s responsible for the

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80 aggregates forming behavior of various thrips species. We speculate that aggregations in the area could be under the influence of plant phenology, flower aggregates, temperature, fertilizer, presence of natural enemies, reproduction, low dispersal by larvae, thigmotactic behavior etc. Lack of information on these aspects is an open challenge to researchers working on thrips and any knowledge on the interplay of these factors influencing distribution will open new prospects to exploit thrips biology for developing a sound management program. Study area C (2008): Dispersion pattern of F. schultzei was different from the other two fields. Lower b P < 0.05)) for larvae and adults distribution, suggested a random to regular distribution o f the pest in the field (Table 4 r 2 values ranging from 0.1 to 0.97 for larvae and a dults distribution provided a moderate to good fit to the data (Table 4 1, r 2 values did not show good fit to the data. Such varied distribution pattern of F. schultzei in various fields is in agreement with other published studies on thrips species. Seal et al. (2006) in their study reported variability in the distribution pattern of chilli thrips in two fields sampled at the same time. The reason for fluctuating distribution pattern for thrips between field s in the same season is not known Given that, F. schultzei infestation in field cucumber starts at onset of flowering in the fourth week after planting. I assume that, while we sampled the field in the seventh week after planting, thrips invading the fiel d had enough time to infest the whole area and establish during the course of time. Thus, with increasing competition amongst conspecifics for food and space, there could have been local dispersion by various life stages leading to a more random distributi on of the pest in the

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81 infested area. However, these assumptions were made based on single sampling done in each of the three plots. Thus, in year 2009 we sampled another three cucumber fields beginning the flower initiation until the conclusion. Plots in e ach of the three study area s were pooled in a combination of seven and fourteen. S tudy area A ( 2009 ): T he results from the first sampling suggested an aggregated distribution of larvae and adults in larger plots (1260 m 2) of the field. The slope ( b model were, b .50, 5.51, respectively (Table 4 3, 4). In our field studies, we observed that F. schultzei infestation begins from the edges of a field, with gradual dispersal inside the field. Thus, the aggregation observed in our plots during the first sampling could be due to the presence of thrips in the outer edges of the field. The b not significantly > 1 ( P < 0.05) indicating a random to regular distribution pattern (Table 4 3). The r 2 values from from 0.73 to 0.99, indicating a good fit to the data collected from larger plots during these sampling. However, the coefficient of determination ( r 2 ) for data from smaller pl ots for the two models was low, suggesti ng poor fit to the data (Table 4 3). The random distribution during the early three weeks could be attributed to the low thrips density in the field that reduced the chances of thrips captured during samplings (Southwood 1978). High b aggregation of thrips larvae in the field, while thrips population was at peak during this time of the cropping season. We assume that the aggregation of thrips larvae is due to the increa se in population density of thrips in the area, which concurs with Morisita

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82 (1962). The author from his study suggested that any change in distribution from random to aggregate or vice versa could results from change in the thrips density. Correspondingly, the distribution pattern of adults was also clumped in larger plots (1260 m 2 ) for remaining five samplings except fourth and sixth sampling during the study. The values of b s patchiness regression (Table 4 4). Apparently, adults exhibited an aggregated distribution in the area until the last sampling. The regular distribution of adults in the matured crop during last sampling was due to low density of adults in the field. The l ow population density could be due to the movement of adults to neighboring plots planted later in the season and offering more food resources (Fig ure 4 7). S tudy area B ( 2009 ): The low coefficient of determinants ( r 2 ) suggested that the models did not fi t well to larvae data. This could be due to low thrips density in the field, which was at initi al stage of infestation (Table 4 5). However, in the next week with increase in larvae population, the two models gave a comparatively better fit to the data and slope values indicated a regular distribution of larvae (Table 4 5). Similarly, adults in the first week of sampling were aggregated owing to large thrips density at the edges of the field and were randomly distributed in the next week. Both larvae and ad ults during the subsequent weeks showed fluctuation in distribution pattern that could be due to the environmental conditions, which affected thrips population density in the ta improved with subsequent samplings for both larval and adult distribution. The two regression models were consistent in describing the aggregation pattern of thrips, while

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83 I ndex of dispersion did not show agreement for larvae and adult distribution in t his study. S tudy area C ( 2009 ) : S lope values for larvae ( b first week were not significantly >1 ( P < 0.05), suggesting a random distribution of larvae in the field (Table 4 7). Conversely, on comparing the adults distribu tion we found that slope values ( b P < 0.05) describing an aggregated distribution of adults. The aggregated distribution could be due to high adults count on the edges of the field. The three models used for des cribing larvae distribution were in agreement with each other having high r 2 values suggesting a good fit of the models to the data (Table 4 population described a regular distribution during the first two weeks. The results of ID During the subsequent weeks (2 nd and 3 rd ) with an increase in thrips density, both larvae and adults were aggregated in their pattern of distribution. These results were well supported by high r 2 values for the two regression models (Table 4 7, 8). The Index of dispersion was in agreement with the two models for larvae and adults distribution during third and fourth week of sampling. On comparing the overall p attern of F. schultzei between different fields in two years of study, we conclude that depending on thrips density, F. schultzei exhibited varied distribution patterns. During peak population densities, F. schultzei was found to be aggregated at all the f ields, forming hot spots in the entire area under infestation. Between the two linear models used to estimate population distribution, high r 2 for using this model than

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84 power law. This informati on will help to determine the distribution pattern of F. schultzei in the field relative to its population density and response of various models to species specific data to conduct selective management practices. Sample size R equirement The results for e stimation of sample size based on various population densities are given in Table 4 9. We observed that the sample size increased with increase in levels of precision ranging from 0.30 to 0.20. At an average number of two larvae per flower in 0.27 ha field the number of samples required ranged from 35 to 79 at 0.30 to 0.20 levels of precision, respectively. The number of samples required at this density for three levels of precision to inspect an infestation in a field is economical and practical. However, the large sample sizes like 273, required at 0.20 precision level when the predetermined population density was 0.5, is time consuming and economically unsound. Southwood (1978) suggested 0.25 as the recommended precision level to assess the population de nsity; damage inflicted and control studies. At 0.25 level we determined 175 as the size of samples to be collected in a 0.27 ha field, which is feasible and non destructive to the crop in field. Since, the study was conducted with the aim to reduce the ef forts of collecting large samples in the field by growers and scouting personnel. We assume that the estimates made on sample sizes for two levels of infestation will help growers collect minimum and adequate samples required to determine the correct thr es hold level of pest in fields. Seasonal Abundance In fall 2008, we found that density of adults and larvae during the growing season was inconsistent Frankliniella schultzei is a flower thrips and thus the infestation in the

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85 field began in a week after the flower initiation (Table 4 10).The adult populations peaked during the third (Oct. 8) and fifth (Oct. 22) week of sampling. The highest number of adults was reported during the fifth week with average number of 34 adults per ten flowers. The larvae popula tion varied during the season. It grew rapidly in the second week of sampling and was highest during the fourth (Oct. 15) and fifth (Oct. 22) week of sampling. Both larvae and adults counts gradually started decreasing by the sixth week as the crop begins to senesce. Similarly, in fall 2009, the adult population increased with increase in flower number in cucumber crop. The population peak for adults was observed during the fifth week (Oct. 25) of sampling, with average number of 25 adults per ten flowers ( Table 4 10). The larvae number also increased with the progression of time during the cropping season, where the highest number of larvae was recovered during the fifth week. On comparing the average number of thrips obtained in 2008 and 2009, we found th at thrips density was higher in 2009. This could be due to the high temperature during fall 2009, as speculated by Leite et al. (2002), while working on F. schultzei ; a pest of tomato plants in Brazil. The average temperature (60 cm above ground) during 20 09 cropping season was 78 3.0 o F (Average temperature Std. dev) in comparison to 76 5.0 o F during fall 2008 cropping season (Florida Automated Weather Network at http://www.fawn.ifas.ufl.edu). High temperature during fall 2009 may have increased the p opulation growth rate and thus high thrips density during the season. Our observations on F. schultzei were in agreement with other studies suggesting that increasing temperatures leads to increased thrips development rate and population density (Lowry e t al. 1992, Lewis 1997, Kirk 1997).

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86 During the two cropping seasons, we observed the invasion of F. schultzei with the onset of flowering in the field. We assume that this could be due to the local dispersion by the thrips population from adjacent unculti vated crops to host plants. Chellemi et al. (1994) reported that, flower thrips belonging to the genus Frankliniella often colonize their host plant in large number s during the flowering stage. However, colonization by these flower thrips lasts only for s hort period due to the short flowering period of vegetable crops (Salguero Navas et al. 1991). Given that the flower initiation does not assure the immediate infestation of thrips population s as different thrips species var y in their timing of infestation, it is important to determine the species specific population dynamics in the field. Through this study, we addressed the population dynamics of F. schultzei in fall cropping season and determined the peak population period during the growing season. The r esults from our study will help develop suitable sampling protocols for F. schultzei and will guide the scouting personnel and growers to time control measures effectively.

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87 Table 4 1. sion parameters for distribution of F. schultzei larvae sampled in fall 2008 Stud y area N Plot size ( m 2) regression Index of dispersion ID r 2 a b r 2 A 2 4 8 16 74 148 296 592 0.25 0.46 0.70 0.53 1.83 1.72 2.69 3.11 2.21 Agg 2.50 Agg 3.16 Agg 3.53 Agg 0.95 0.87 0.81 0.64 3.66 16.07 16.21 25.19 1.25 Agg 1.52 Agg 1.56 Agg 1.84 Agg 5.00 Agg 10.66 Agg 12.53 Agg 17.00 Agg B 3 7 14 70 180 360 0.08 0.35 0.99 0.12 1.59 9.41 0.76 Reg 3.08 Agg 12.82Agg 0.68 0.74 0.97 1.99 3.88 21.63 1.41 Agg 1.74 Agg 4.55 Agg 1.67 Agg 1.89 Agg 2.10 Agg C 2 4 10 200 400 1000 0.10 0.23 0.15 1.65 1.62 1.03 0.16 Reg 0.01 Reg 0.42 Reg 0.16 0.56 0.77 10.63 5.91 1.01 0.62 Reg 0.82 Reg 1.04 Ran 4.54 Agg 3.52 Agg 2.94 Agg *N= Number of plots pooled. Agg, aggregated distribution, b significantly ( P 0.05) >1; Reg, regular distribution, b significantly < 1 ( P random distribution, b not significantly different from 1 ( P >0.05).

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88 Table 4 2 parameters for dis tribution of F. schultzei adult sampled in fall 2008 Stud y area N Plot size ( m 2) regression Index of dispersion ID r 2 a b r 2 A 2 4 8 16 74 148 296 592 0.19 0.11 0.36 0.18 2.45 0.09 1.90 0.49 2.66 Agg 1.33 Agg 2.65 Agg 1.77 Agg 0.88 0.92 0.82 0.75 0.01 0.88 6.24 2.40 1.06 Ran 1.10 Agg 1.29 Agg 1.26 Agg 3.4 6 Agg 4.07 Agg 5.80 Agg 5.86 Agg B 3 7 14 70 180 360 0.17 0.44 0.89 0.17 0.36 0.79 1.25 Agg 1.99 Agg 2.80 Agg 0.55 0.78 0.97 0.36 1.26 2.17 1.31Agg 1.57Agg 1.79Agg 1.81 Agg 1.88 Agg 1.83 Agg C 2 4 10 200 400 1000 0.36 0.39 0.28 0.35 0.21 2.07 1.16 Ran 1.15 Ran 0.73 Reg 0.88 0.97 0.90 0.10 0.10 4.44 1.03 Ran 1.01 Ran 0.70 Reg 1.52 Agg 1.12 Ran 2.03 Agg *N= Number of plots pooled. Agg, aggregated distribution, b significantly ( P b significantly < 1 ( P random distribution, b not significantly different from 1 ( P >0.05).

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89 Table 4 3 of F. sc hultzei larvae sampled in fall 2009 at Study area A on various sampling dates Sampling date N Plot size (m 2) regression Index of dispersion ID r 2 a b r 2 Sep 2 7 7 14 630 1260 0.19 0.83 0.34 0.33 2.62 Reg 2.08 Agg 0.02 0.98 0.94 1.04 0.36 Reg 1.50 Agg 0.52 Reg 0.47 Reg Oct 3 7 14 630 1260 0.05 0.73 0.16 0.10 0.53 Reg 0.87 Ran 0.06 0.89 1.16 0.37 0.44 Reg 0.90 Ra n 1.32 Agg 1.22 Agg Oct 10 7 14 630 1260 0.01 0.86 2.96 3.05 0.03 Reg 0.07 Reg 0.58 0.82 33.11 36.09 0.67 Reg 0.60 Reg 18.35 Agg 17.86 Agg Oct 17 7 14 630 1260 0.03 0.99 2.89 2.27 1.10 Ran 1.14 Ran 0.71 0.85 31.36 27.68 0.79 Reg 0.84 Ran 18.72 Agg 18.36 Agg Oct 24 7 14 630 1260 0.02 0.99 2.63 1.37 0.90 Ran 1.97 Agg 0.79 0.97 34.04 20.98 0.85 Ran 1.99 Agg 22.02 Agg 21.48 Agg Oct 29 7 14 630 1260 0.81 0.99 0.8 9 1.09 2.20 Ran 2.32 Agg 0.96 0.92 7.89 6.00 1.43 Agg 1.39 Agg 16.67 Agg 16.32 Agg *N= Number of plots pooled. Agg, aggregated distribution, b significantly ( P b significantly < 1 ( P random distribution, b not significantly different from 1 ( P >0.05).

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90 Table 4 4 parameters for distribu tion of F. schultzei adult sampled in fall 2009 at Study area A on various sampling dates Sampling date N Plot size (m 2 ) regression Index of dispersion ID r 2 a b r 2 Sep 29 7 14 630 1260 0.91 0.98 0.13 0.20 5.12 Agg 6.51 Agg 0.90 0.91 3.20 4.11 4.50 Agg 5.51 Agg 0.79 Reg 0.74 Reg Oct 3 7 14 630 1260 0.79 0.95 0.04 0.73 1.66 Agg 5.31 Agg 0.65 0.86 0.43 7.7 1.67Agg 6.05Agg 1.75 Agg 2.09 Agg Oct 10 7 14 630 1260 0.96 0.99 2.8 1.59 3.89 Agg 2.86 Agg 0.98 0.97 8.3 5.59 1.73 Agg 1.56 Agg 5.7 Agg 5.50 Agg Oct 17 7 14 630 1260 0.57 0.90 1.07 0.82 2.47 Agg 1.08 Ran 0.73 0.98 1.71 7.02 1.27Agg 1.03 Ran 8.72 Agg 8.79 Agg Oct 24 7 14 630 1260 0.10 0.91 0.98 0.62 1.03 Ran 1.28 Agg 0.38 0.99 9.61 6.70 1.03 Ran 1.11 Agg 11.63 Agg 10.79 Agg Oct 29 7 14 630 1260 0.11 0.99 1.34 5.04 0. 62 Reg 2.5 Reg 0.38 0.99 9.45 39.58 0.89 Ran 1.21Reg 8.91 Agg 9.07 Agg *N= Number of plots pooled. Agg, aggregated distribution, b significantly ( P b significantly < 1 ( P random distribution, b not significantly different from 1 ( P >0.05).

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91 Table 4 5 parameters for distributi on of F. schultzei larvae sampled in fall 2009 at Study area B on various sampling dates *N= Number of plots pooled. Agg, aggregated distribution, b significantl y ( P b significantly < 1 ( P random distribution, b not significantly different from 1 ( P >0.05). Sampling date N Plot size (m 2 ) regression Index of dispersion ID r 2 a b r 2 Oct 5 7 14 630 1260 0.01 0.03 0.84 1.14 0.88 Ran 1.01Ran 0.02 0.10 0.14 0.07 0.90Ran 0.94Ran 1.00Reg 1.00Reg Oct 12 7 14 630 1260 0.56 0.87 0.07 0.11 0.93Ran 0.02Reg 0.61 0.99 0.47 1.24 0.83Reg 0.03Reg 1 .16Agg 1.11Agg Oct 18 7 14 630 1260 0.59 0.95 2.72 1.31 5.24Agg 3.15Agg 0.75 0.93 2.97 2.47 1.72Agg 1.60Agg 1.38Agg 1.30Agg Oct 24 7 14 630 1260 0.92 0.96 12.6 3.01 9.7Agg 0.34Reg 0.96 0.98 61.07 19.17 2.97Agg 0.66Reg 8.79Agg 8.58Agg Oct 31 7 14 630 1260 0.22 0.97 1.15 5.62 2.25Agg 1.37Reg 0.69 0.99 10.98 56.85 1.38Agg 0.42Reg 17.1Agg 17.1Agg

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92 Table 4 6 parameters for distribu tion of F. schultzei adult sampled in fall 2009 at Study area B on various sampling dates *N= Number of plots pooled. Agg, aggregated distribution, b significantly ( P b significantly < 1 ( P random distribution, b not significantly different from 1 ( P >0.05). Sampling date N Plot size (m 2 ) regression Index of dispersion ID r 2 a b r 2 Oct 5 7 14 630 1260 0.86 0.93 0.10 0.19 1.42 Agg 1.78 Agg 0.79 0.98 0.57 0.82 2.06 Agg 2.43 Agg 0.91 Reg 0.84 Reg Oct 12 7 14 630 1260 0.19 0.98 0.20 0.13 0.67 Reg 0.83 Ran 0.10 0.9 6 0.79 0.08 0.05 Reg 0.86 Ran 0.81 Reg 0.73 Reg Oct 18 7 14 630 1260 0.76 0.99 0.18 0.18 0.91 Ran 1.31 Agg 0.53 0.98 0.69 0.00 0.83 Ran 1.53 Agg 1.55 Agg 1.46 Agg Oct 24 7 14 630 1260 0.24 0.92 1.07 0.52 0.67 Ran 1.12 Ran 0.99 0.95 0.49 3.37 0.88 Ran 1.02 Ran 4.33 Agg 4.97 Agg Oct 31 7 14 630 1260 0.86 0.95 1.1 5.11 2.51 Agg 1.85 Reg 0.87 0.98 6.82 0.94 1.63 Ran 0.30 Reg 10.75 Agg 12.31 Agg

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93 Table 4 7 regression and Index of dispersion parameters distribution of F. schultzei larvae sampled in fall 2009 at Study area C on various sampling dates *N= Number of plots pooled. Agg, aggregated distribution, b significantly ( P b significantly < 1 ( P random distribution, b not significantly different from 1 ( P >0.05). Sampling date N Plot size ( m 2 ) regression Index of dispersio n r 2 a b r 2 Oct 13 7 14 630 1260 0.98 0.99 0.28 0.46 1.13 Ran 1.20 Ran 0.93 0.99 0.22 0.28 1.55 Ran 1.14 Ran 0.98 Ran 1.01 Ran Oct 21 7 14 630 1260 0.38 0.93 0.21 0.04 1.14 Agg 2.07 Agg 0.17 0.98 0.30 1.12 1.31 Agg 2.22 Agg 1.76 Agg 1.63 Agg Oct 28 7 14 630 1260 0.05 0.86 0.56 3.06 1.71 Ran 2.45 Agg 0.43 0.99 0.37 4.33 0.98 Ran 1.43 Agg 1.26 Agg 1.20 Agg Nov 5 7 14 630 1260 0.65 0.99 0.07 0.51 1.55Agg 1.67 Agg 0.89 0.83 0.90 3.53 1.15Agg 1.25 Agg 4.97 Agg 5.57 Agg

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94 Table 4 8 parameters for distribution of F. schultzei adult sampled in fall 2009 at Study area C on various sampling dates *N= Number of plots pooled. Agg, aggregated distribution, b significantly ( P b significantly < 1 ( P random distribution, b not significantly different from 1 ( P >0.05). Sampling date N Plot size ( m 2 ) regression Index of dispersion r 2 a b r 2 Oct 13 7 14 630 1260 0.99 0.98 0.04 0.12 1.35 Agg 1.24 Agg 0.81 0.92 0.53 0.30 1.46 Agg 1.25 Agg 0.76 Reg 0.73 Reg Oct 21 7 14 630 1260 0.28 0.93 0.19 0.02 0.17 Reg 2.07 Agg 0.08 0.99 0.48 1.05 0.13 Reg 2.11 Agg 0.83 Reg 0.77 Reg Oct 28 7 14 630 1260 0.97 0.99 2.80 1.47 6.15Agg 4.00 Agg 0.91 0.99 4.42 3.62 2.45 Agg 2.22 Agg 1.61 Agg 1.62 Agg Nov 5 7 14 630 1260 0.76 0.97 0.74 1.40 2.25 Agg 3. 15 Agg 0.97 0.98 4.85 9.83 1.78 Agg 2.52 Agg 5.78 Agg 9.82 Agg

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95 Table 4 9. Number of samples required for estimation of population density at three levels of preci sion Plot size (ha) Levels of precision Number of samples at two population densities = 0.5 = 2.0 = 5.0 0.27 0.20 273 79 20 0.25 175 51 13 0.30 122 35 9 = number of larvae

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96 Table 4 10. Seasonal abundance of larvae and adults on cucumber flowers sampled at two fields in 2008 and 2009 Means within a column followed by the same letter are not significantly Fall 2008 (Larvae: F = 74.23; df = 5, 162 ; Adults: F = 79.45; df = 5, 162 ) Fall 2009 (Larvae: F = 56.24 ; df = 5, 162 ; Adults: F = 35.16; df = 5, 162 ) Fall 2008 Sampling Date Number of Larvae (Mean SEM) Number of Adult (M ean SEM) Sep 26 0.92 0.17 c 1.32 0.19 d Oct 2 7 0.76 c 4 0.57 d Oct 8 23.64 1.65 b 32.53 2.63 a Oct 15 55.07 4.61 a 25.35 1.9 b Oct 22 54.42 4.82 a 34.39 2.59 a Oct 29 19.82 2.31 b 12.21 2.36 c Fall 2009 Sampling Dat e Number of Larvae (Mean SEM) Number of Adult (Mean SEM) Sep 30 1.03 0.13 d 0.85 0.15 c Oct 5 1.5 0.25 d 1.75 0.35 c Oct 12 48.75 5.63 c 17.78 1.92 b Oct 18 66. 42 6.8 b 22 2.65 ab Oct 25 87.39 8.7 a 25.89 3.14 a Oct 30 5 4.46 6.22 bc 14.25 2.09 b

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97 Fig ure 4 1 Pictorial view of the study areas used for within plant (A and B) and spatial distribution studies (A, B and C) during Fall 2009. (Source: www.maps. g oogle.c om) Field B Field A Field C

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98 A Fall 2008: Study Area A B Fall 2008: Study Area B C Spring 2009: Study Ar ea A D Spring 2009: Study Area B E Fall 2009: Study Area A F Fall 2009: Study Area B Fig ure 4 2 Mean number of larvae and adults in various plant parts sampled i n fall 2008 sp ring 2009 and fall 2009. (* and ** indicates significant difference in mean number of larvae and adults collected from various plant parts using ANOVA at = 0.05). A) Larvae : F = 224. 45; df =2, 117; P < 0.001; Adult: F = 186.57; df = 2, 117; P < 0.001 B) Larvae: F = 117.30; df =3, 164; P < 0.001; Adult: F 0 5 10 15 20 25 FLOWER UPPER LEAF MIDDLE LEAF LOWER LEAF Mean no. of F. schultzei Plant parts sampled Larvae Adult ** 0 5 10 15 20 25 FLOWER UPPER LEAF MIDDLE LEAF LOWER LEAF Mean no. of F. schultzei Plant parts sampled LARVAE ADULT ** 0 5 10 15 20 FLOWER UPPER LEAF MIDDLE LEAF LOWER LEAF Mean no. of F. schultzei Plant parts sampled LARVAE ADULT ** 0 10 20 30 40 50 60 FLOWER UPPER LEAF MIDDLE LEAF LOWER LEAF Mean no. of F. schultzei Plants parts sampled LARVAE ADULT ** 0 10 20 30 40 50 60 70 FLOWER UPPER LEAF MIDDLE LEAF LOWER LEAF Mean no. of F. schultzei Plant parts sampled LARVAE ADULT ** 0 5 10 15 20 25 FLOWER UPPER LEAF MIDDLE LEAF LOWER LEAF Mean no. of F. schultzei Plant parts sampled LARVAE ADULT **

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99 = 67. 90; df = 3, 164; P < 0.001 ; C) Larvae: F = 50. 79; df =3, 28; P < 0.001; Adult: F = 22.33; df = 3, 28; P < 0.001. D) Larvae: F = 64.8; df =3, 60; P < 0.001; Adult: F = 173.82; df = 3, 60; P < 0.001 ; E) Larvae: F = 76. 43; df =3, 108; P < 0.001; Adult: F = 45.17; df = 3, 108; P < 0.001. F) Larvae: F = 108.54; df =3, 108; P < 0.001; Adult: F = 34.96; df = 3, 108; P < 0.001

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100 CHAPTER 5 EFFICACY OF AMBLYSEIUS CUCUMERIS (OUDEMANS) AND A. SWIRSKII (ATHIAS HENRIOT) IN REGULATING FRANKLINIELLA SCHULTZEI AND THRIPS PALMI POPULATIONS ON FIELD CUCUMBERS ( CUCUMIS SATIVUS L.) Thrips palmi Karny is a po lyphago u s pest of vegetable crops in various parts of the world (CABI 1998 ). In North America, its distribution confines to Hawaii, Puerto Rico and southern parts of Florida. Since, its advent in south Florida in 1991, it has been reported as a serious pes t of various greenhouse and field crops including, eggplants ( Solanum melongena L.), pepper ( Capsicum annum L.), potatoes ( Solanum tuberosum L.), beans ( Phaseolus vulgaris L.), and cucumber ( Cucumis sativus L.) (Seal and Baranowski 1992). In 1993, T. palmi infesting pepper in Palm Beach County alone was responsible for the economic damage of over 10 million US $ (Nuessly and Nagata 1995). Besides, the feeding and oviposition damage, it is a vector of various plant vir al diseases including T omato Spotted Wil t V irus (TSWV) (Honda et al 1989) Thrips palmi has a wide host range and prefers plants in the family Cucurbitaceae and Solanaceae (Capinera 2000) Adults and larvae of T. palmi preferably feed on leaves of its host plant s leading to bronzing of leaves, which eventually dries and dies off. Heavy infestation of T. palmi on cucumber may lead to production of scarred, damaged or deformed fruit with no marketable value. In Homestead, T. palmi is one the major pests of field cucumbers and is a challenge to cuc umber growers in the area ( P ersonal observation). I n this region, i nvasion by a new adventive thrips species Frankliniella schultzei (Trybom) in last two years on various vegetable crops has further aggravated the problem encountered by the se growers Fr ankliniella schultzei earlier known to make few encounters in flowers of ornamental plants in southern and central Florida (Funderburk et

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101 al. 2007), has now est ablished in southeastern Florid a In our preliminary study conducted to evaluate the abundance o f F. schultzei on five different vegetable crops, Cucumber ( var.` var. King Arthur), Snap beans ( var. Opus), Squash ( var. Straightneck) and Tomato ( var. Flora Dade) we found that F. schultzei is a potential pest of cucumber. Franklinie lla schultzei a key pest of tomato in several parts of South America has been reported as an important pest of cucumber also. R esults from within plant distribution study, suggested that it is an anthophilous pest inhabiting flowers of its host crop. Thus, c onsidering the pest status of T. palmi and damage potential of F. schultzei it is important to develop a management program for the two thrips species affecting field cucumbers, an important vegetable crop grown in the County. Chemical control has alwa ys been a primary mode of controlling thrips infesting various field crops (Morse and Hoddle 2006). However, the use of insecticides is not an absolute solution to thrips problem owing to its high cost of application, rapid selection for resistance by high ly reproducing thrips and adverse effects on natural enemies and environment (Herron et al. 2007, Jensen 2000). These adverse effects of insecticides usage emphasize the need to introduce biological control agents for thrips including F. schultzei and T. p almi Predators of the genus Orius (Heteroptera: Anthocoridae) are native natural enemies and have been shown to control western flower thrip s F. occidentalis (Pergande) The ability of O. insidiosus (Say) to feed on a wide range of thrips species makes i t a promising biological control agent (Baez et al. 2004). Seal (1997) observed O. insidiosus to prey on T. palmi and found that the first nymphal instar fed on 15 25 larvae of T. palmi each day. A study by Silveira et al. (2005) in Brazil showed that O. insidiosus was also effective in controlling F. schultzei Other predators

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102 used for control of various thrips species include phytoseiid mites belonging to genus Amblyseius (Phytoseiidae). The predatory mite, A. swirskii (Athias Henriot) is receiving much attention and has been documented as a potential biological control agent of whiteflies and thrips. A nother species in this genus, A. cucumeris (Oudemans) has been reported as an effective predator of onion thrips on greenhouse cucumber in Europe (Gillespi e 1989, Van Houten and Van Stratum 1993). Furthermore, Van de Veire and Degheele (1995), and Jacobson (1997), found A. cucumeris to be efficient in regulating flower thrips in greenhouse conditions. Shipp and Wang (2003) used A. cucumeris and O. insidiosus as predators for the regulation of F. occidentalis in greenhouse tomatoes and found A. cucumeris to be more effective in reducing the pest population. However, Messelink et al. 2006 found A. swirskii to provide a better control of F. occidentalis than A. cucumeris Considering the success of phytoseiid mites in regulating various thrips species, we evaluated the role of A. swirskii and A. cucumeris as a potential predator of F. schultzei and T. palmi inhabiting different microhabitats of the same crop. Pre sence of two thrips species on cucumber plants may affect the predatory behavior of the two mite species. Thus, we also investigated the persistence of predacious mites on leaves and flowers of cucumber in the presence of two thrips species Materials and Methods Predaceous M ites Amblyseius swirskii and A. cucumeris were obtained from Koppert Biological Systems Inc. (Romulus MI). Upon arrival, mites were stored in a growth chamber maintained at 11 2 o C, RH 605 %, and 14:10 h L:D until the day of release The mites were shipp ed in plastic bottles of 50, 000 mites mixed with bran and bran mites as a food for the predatory mites and were stored for a maximum period of 3 4 days before release

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103 In order to release a desired number of mites per plant, mite num ber in a fixed volume of bran was estimated and standardized before release by repeatedly drawing a known volume and counting predatory mites under a stereoscopic microscope. The bottle containing bran with mites was shaken each time to ensure homogenous d istribution of mites in the container before withdrawing bran for standardization. Individual estimates were made for A. cucumeris and A. swirskii The bran used for estimation was the same commercial product to be used for release obtained from Koppert Bi ological Systems. The results suggested that 0.32 g and 1.70 g are the required amounts of bran to obtain 20 and 40 mites of both, A. cucumeris and A. swirskii Crop M anagement Cucumber seeds ( var. gravelly loam soil, consisting of about 33% soil and 67% limestone pebbles (>2mm) on April 22, 2010. Seeds were spaced 15 cm within the row and 91.5 cm between rows. At planting, fertilizer 8 16 16 (N P K) was applied at 908 Kg/ha in furrow; and Halosulfur on methyl at 55 ml/ha (Sandea Gowan Company LLC., Yuma Arizona) was used as a pre emergence herbicide to control weeds. Pyraclostrobin at 0.8 l/ha (Pristine, BASF Ag Products, Research Triangle Park, NC) and Chlorothalonil at 1.75 l/ha (Bravo, Syngenta Crop Protection, Inc., Greensboro, NC) were used in rotation at two week intervals to prevent fungal diseases. The crops were irrigated twice a week using overhead sprinklers delivering 3 cm of water. Additional fertilizer 4 0 8 (N P K) was added once a we ek as an in furrow band from the third week onwards after planting. Bacillus thuringiensis based insecticides, Dipel DF ( var kurstaki) at 1.1 Kg/ha and Xentari DF ( var. kustaki) at 1.2 l/ha (Valent Biosciences Corporation, Libertyville, IL) were used in rotation to control

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104 melon worms ( Diaphania hyalinata L.) and pickle worms ( D. nitidalis Stoll) in the experimental field. Field T rial The experiment was conducted at TREC, Homestead, FL. Phytoseiid mites were eva luated as a curative practice where the fi ve treatments evaluated were 1) A cucumeris (20 mites/plant), 2) A. cucumeris (40 mites/plant), 3) A swirskii (20 mites/plant), 4) A. swirskii (40 mites/plant) and 5) control (no mites). The treatments in this study were arranged in a RCB design with fou r replications. Each replicate (=block) was carrying five equal sized plots, which represented a treatment. A buffer zone measuring 4.5 m was maintained between two adjacent blocks. Each plot in a block measuring 45 m 2 was also separated by a 4.5 m long bu ffer zone. The buffer zones between plots and blocks were planted to sunhemp plants, Crotalaria juncea L. to restrict the movement and mixing of predatory mites amon g different treatments (Figure 5 1 ). In situ counts were done during the first week of flow ering to check the abundance of thrips larvae. On detection of larvae in flowers, a single release of A. swirskii and A. cucumeris was made by the end of first week of flowering (May 27, 2010). Releases of mites were done by using ziplock bags filled wit h a standardized volume of bran + mites as described above. Each time before withdrawing bran from the bottles, it was shaken gently to ensure uniform spread of mites in the bran. In each treatment plot, these bags with an opening at its end were held upri ght above the plant canopy with a distance of 15 cm between plant and the bag, while I walked with a uniform speed between rows releasing fixed dosage of mites on each plant. Sampling was initia ted on the sixth day after mites release (June 3, 2010) and th e subsequent four samplings were done at four day intervals during the study. Sampling units were

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105 cucumber flowers and leaves to check the persistence and effectiveness of phytoseiid mites during the study. Ten flowers and five leaves (one flower and leaf per plant) were randomly selected from each treatment plot and placed in separate ziplock bags (17 X 22 cm), marked with date, treatment and plot numbers. Bags were transported to the Vegetable IPM laboratory, TREC, Homestead where flower samples were pla ced in a one quart plastic cup with 75% ethanol for 30 minutes to dislodge various life stages of thrips. The samples were removed from the cup leaving thrips in alcohol. The contents in alcohol were sieved using a 25 m grating, USA Standard Testing Sieve (W. S. Tyler, Inc.) as per Seal and Baranowski (1992 ). The residue in the sieve was washed off with 75% alcohol in to a Petri dish and checked under a dissecting microscope at 12X to record various life stages of thrips. Thrips and mites present on leaf s amples were directly counted under stereo microscope. Thrips collected from plant samples were identified to species level using t hrips identification key (Nakahara 1994) Statistical Analysis Data was analyzed independently for flower and leaf samples col lected. The mean number of thrips larvae, mites and mite eggs sampled on different dates from all the treatments were compared using one way analysis of variance (ANOVA) (PROC GLM, SAS Institute Inc. 2003 ). Data were transformed by log 10 (x+1) to homogeniz e variance before analysis. Differences among treatment means for sampling dates were separated using the Tukey Linear regression analysis was done to test the relationship between th rips and mite density using PROC REG. Mites and T. palmi density was expressed as a ccumulated mite x days and Thrips palmi x da ys per leaf a nalyzed using ANOVA. Mite days and Thrips palmi days were

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106 calculated by averaging the count of mite and T. palmi o ver successive pairs of sampling days pe r leaf and multiplied by four ( number of int ervening day between two samplings ) and accumulated over the entire study period: + + 4 2 [5 1] Where = number of mites or T. palmi at n th sampling and t is number of intervening days between two successive samplings. All the analysis for this study was done on Statistical Analysis S ystem (SAS Institute Inc. 2003). Results Effect of A. swirskii and A. cucumeris on F. schultzei population s : Neither of the two treatment rates of A. swirskii (20 and 40 mites/plant) or A. cucumeris (20 and 40 mites/plant) was effective in reducing the F schultzei population inhabiting flowers of cucumber plants. On the 6 th day after mite release (DAR), mean numbers of F. schultzei in various treatment plots did not differ from the control plot ( F = 0.62; df = 4, 15; P = 0.649) (Figure 5 2). Similar resu lts were obtained for subsequent samplings done on the 10 th DAR ( F = 0.43; df = 4, 15; P = 0.783), 18th DAR ( F = 1.43; df = 4, 15; P = 0.248) and 22 nd DAR ( F = 1.63; df = 4, 15; P = 0.197) except on the 14 th DAR ( F = 5.22; df = 4, 15; P = 0.003) during the study. The number of F. schultzei was higher in plots treated with A. cucumeris than control plots on the 14 th DAR (Figure 5 2). On observing the effect of four treatments on T. palmi after mite release, we found that high rate of A. swirskii (40 mites/pl ant) was effective in reducing the T. palmi larvae population on 6 th DAR ( F = 4.53; df = 4, 95; P < 0.001) (Figure 5 3) and it was consistent in suppressing T. palmi population during the entire cropping season. The number of T. palmi in the plots treated with high rate of A. swirskii was significantly lower than the

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107 control plots on 10 th DAR ( F = 14.98; df = 4, 95; P < 0.001), 14 th DAR ( F = 12.66; df = 4, 95; P < 0.001), 18 th DAR ( F = 9.74; df = 4, 95; P < 0.001), and 22 nd DAR ( F =16.96; df = 4, 95; P < 0.00 1) (Figure 5 3). However, the low rate of A. swirskii was effective beginning the 14 th DAR and samples collected from these plots on 14 th DAR ( F = 12.66; df = 4, 95; P < 0.018), 18 th DAR ( F = 9.74; df = 4, 95; P < 0.001), and 22 nd DAR ( F = 16.96; df = 4, 9 5; P < 0.001) had significantly lower thrips population than control plots (Figure 5 3). On comparing the thrips number obtained from plots treated with high and low rate of A. swirskii, we found that thrips were significantly lower in high rate treated pl ots on 6 th and 10 th DAR than the plots receiving low rate of A. swirskii P < 0.05). There was no difference in thrips number in plots receiving the two rates of A. swi r skii sampled on 14 th 18 th and 22 nd DAR (Figure 5 3). The results fr om accumulated Thrips palmi x days analysis suggested that differences among various treatments were significant ( F = 54.76; df = 4,295; P < 0.0001), with least accumulated thrips days on plots receiving high rate of A. swirskii and most observed on contro l plots (Table 5 4). Unlike A. swirskii, neither of the two rates of A. cucumeris was effective in regulating T. palmi larvae in our study. The two rates of A. cucumeris showed reduction of T. palmi on 18 th DAR ( F = 9.74; df = 4, 95; P < 0.001) (Figure 5 3 ). The t test suggested no significant difference in thrips density on leaves for the two different rates of A. cucumeris on 18 th DAR ( t = 0.67 ; df = 3 8; P = 0.20) (Figure 5 3). Population abundance of Amblyseius swirskii and A. cucumeris on cucumber flow ers: Average number of mites recovered from flowers samples during the study was small, with the highest number of mites captured from the two treatment plots on 18 th DAR (Table 5 1). Similar results were obtained for A. cucumeris where the number of

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108 mite s recovered from flower samples on various sampling dates was minimal. Maximum number of A. cucumeris mites was captured on 10 th and 6 th DAR from plots treated with low and high rate of mites, respectively (Table 5 1). There was no significant difference i n the number of mites recovered from treated plots than control plots during the study ((6 th DAR: F = 1.12; df = 4, 15; P = 0.36), (10 th DAR: F = 0.35; df = 4, 15; P = 0.84), (14 th DAR: F = 1.63; df = 4, 15; P = 0.19), (18 th DAR: F = 1.90; df = 4, 15; P = 0. 14), (22 th DAR: F = 1.63; df = 4, 15; P = 0.19)) (Table 5 1). Population abundance of Amblyseius swirskii and A. cucumeris on cucumber leaves: Mean number of mites recovered from the plots receiving A. swirskii on first sampling was low and no mites were recovered from leaves sampled from control plots ( F = 6.61; df = 4, 95; P <0. 0001) (Table 5 2). However, on the 10 th DAR, there was an increase in number of mites recovered from plants treated with high rate of A. swirskii Average number of mites captur ed on the 10 th DAR from plots treated with high rate was significantly larger than the plots treated with low rate of A. swirskii ( F = 81.68; df = 4, 95; P < 0.0001) (Table 5 2). There was a sudden decrease in A. swirskii abundance on the 14 th DAR As the s eason progressed, mites captured from the plots treated with high rate of A. swirskii decreased with the lowest count observed on the 22 nd DAR. The data suggest s decreasing trend in response to T. palmi population In ord we performed linear regression on the mites and thrips collected on all the sampling dates, excluding 6 th DAR. The r 2 value of 0.44 with P value of 0.0005 indicated an association b etween thrips and mite density, suggesting that thrips density was an 4). In plots treated with

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109 low rate of A. swirskii there was a gradual increase in number of mites recovered from vari ous samplings until 14 th DAR, after which decrease in mite number was observed (Table 5 2) The decreasing mite count with every sampling complies with decreasing thrips density as exhibited by high rate treatment plots. Given that large number of mites we re recovered from low rate of A. swirskii treated plots, the accumulated mite days per leaf sampled from plots receiving high rate of A. swirskii was significantly greater than plots receiving low rate of A. swirskii P < 0.05) (Table 5 4 ). The results from mite egg counts in high treatment plots suggest that the egg A. swirskii eggs from high treatment plots was counted on the 10 th DAR. The egg co unt was significantly higher than the eggs recovered from the low treatment plots on 10 th DAR ( F = 60.76; df = 7, 95; P < 0.0001) (Table 5 3). The number of eggs decreased on the subsequent sampling dates in plots treated with higher rates. On comparing th e results with plots treated with low rate of A. swirskii we found that mean number of eggs/ sample showed increasing trend with the progression of sampling period except on the 18 th DAR. Amblyseius cucumeris populations on cucumber leaves fluctuated thro ughout the cropping period in plots treated with high rate of A. cucumeris where the highest count was on 6 th DAR (Table 5 2). Although the number of mites recovered from plots increased numerically as the season progressed, but there was no marked increa se in mite number (Table 5 2). The accumulated mite days per leaf from the plots receiving two rates of A. cucumeris was low and significantly different from plots receiving A. swirskii indicating low and constant reproduction rate of A. cucumeris during t P < 0.05) (Table 5 4). There was no significant difference in the mites captured from the two

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110 treatment plots on any sampling day ( P 2). On comparing mite eggs count we found that, in plots tr eated with high rate of A. cucumeris the eggs count was highest on the 6 th day after release. The number of eggs counted on leaf samples for the two treatment plots on the 6 th DAR was not different ( F = 1.03, df = 4, 95; P = 0.412) (Table 5 3). Similar re sults were obtained for the two treatment plots on 10 th DAR and 14 th DAR, exhibiting no significant difference in the eggs counted on leaf samples ( P treatment plots sampled on 18 th DAR and thereafter (Table 5 3). Discussion Amblyseius cucumeris and A. swirskii failed to control F. schultzei inhabiting cucumber flowers as there was no significant difference in thrips number between control plots and mites treated plots. These results are in agreement with Arevalo et al. ( 2009 ) who found that A. cucumeris was not effective in regulat ing flower thrips inhabiting blueberry flowers. In the present study, the number of mites recover ed from flower samples from plots receiving A. cucumeris and A swirskii was low. Based on this we an important reason for the failure of thrips control in cucumber flowers. The low mite density in flowers could be the results of a behavioral preference for the microhabitat as it is possible that leaves offered better refuge and a better breeding area in comparison to flowers for the two mite species. A biological control study by Chow et al. (2008) using O. insidiosus suggested t hat O. insidiosus often switched between its available preys on the crop. They reported that the minute pirate bug owing to its generalist feeding behavior exhibits preferred feeding on the easily available prey whether foraging on flowers or foliage. Simi larly, we speculate

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111 that the presence of highly abundant T. palmi population on cucumber leaves might have been an important factor resulting in low persistence of mites on flowers leading to failure of F. schultzei control. Furthermore, leaves might have offered an open arena for mites to feed on leaf feeding T. palmi In order to confirm that mites were feeding on T. palmi mites and T. palmi counts on leaf samples collected at t he time of flower collection were recorded. The number of T. palmi among the plots treated with two rates of A. swirskii was found to be significantly lower than the control plots. High rate of A. swirskii was effective in regulating T. palmi beginning the sixth DAR and it continued to give suppression over T. palmi during the stud y. A. swirskii was recovered from sampled leaves and the large number of mite eggs on leaves suggested the successful reproduction of these mites. The high rate of A. swirskii performed better than the low rate by providing suppression of T. palmi within a week of application. However, the low rate of A. swirskii was effective beginning 14 DAR. Thus, early application of this lower dosage before the threshold number of thrips population is reached can yield maximum suppression with lower resources usage. T he early application of A. swirskii will give opportunity to these phytoseiid mites to adapt, reproduce and establish successfully on the host crop in order to suppress forthcoming high thrips abundance on the host. Thus, the application of low rate of A. swirskii during 2 3 weeks old crop with low thrips infestation can perform better in regulating thrips population than the application in six week old crop as in our study. Amblyseius swirskii and A. cucumeris exhibited differential predation on T. palmi inhabiting cucumber lea ves. One of the important reasons explaining varied predation by this mite species is differential feeding behavior, i.e., T. palmi as an unsuitable prey for A.

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112 cucumeris In order to confirm this, we counted mites on the leaf sample s to determine if mites are reproducing by feeding on another alternative food source. Results from the A. cucumeris mites and A. cucumeris eggs counts on leaf samples suggest that their density was low during most of the cropping season and it was signifi cantly lower than A. swirskii P < 0.05) (Table 5 2,3). Amblyseius cucumeris exhibited little activity by reducing thrips number during the end of the cropping season, supported by high mite and mite eggs number during the end of the seas on. Such delayed response by A. cucumeris towards prey could be due to their slow rate of adaptability to the environment. Another probable reason for the decreased thrips count in the plots could be due to the invasion of A. swirskii in A. cucumeris treat ed plots. However, this possibility was overruled due to the absence of mites in flower and leaf samples collected from control plots of the study. Absence of mites in the control plots suggested that the sunhemp barriers were effective in limiting mites i n their respective plots and there was no intermixing of mites among treatment plots. Thus, mites sampled from plots receiving A. swirskii were assumed to be A. swirskii and A. cucumeris to be A. cucumeris sampled from respective plots in the study. Anot her potential reason for the failure A. cucumeris in control ling T. palmi could be the low survival rate of these mites in the environment. Results from our study are in accordance with Arthurs et al. (2009) who reported that A. swirskii performed better t han Neoseiulus cucumeris in regulating Scirtothrips dorsalis Hood on pepper plants under landscape conditions. This suggests that A. swirskii could be a better thrips predator in general than other phytoseiid species that have been studied. Relating our st udy to their report, we speculate that a possible reason for such differential behavior by these two

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113 mite species in our study may be due to the better adaptability by A. swirskii to adverse environmental conditions. Owing to its Mediterranean origin (Mora es de et al. 2004), A. swirskii was tolerant to the hot climate of Homestead, where average temperature ranged from 18 o C (min) to 35 o C (max) during the period of study, exhibiting better performance when compared to A. cucumeris. Ferreira et al. ( 2008 ) suggested that plants having leaf domatia, offer a good refuge to phytoseiid mites by protecting them against unsuitable climatic conditions. However, in our study we found that irrespective of the absence of leaf domatia on cucumb er plants (Arthurs et al. 2009) A. swirskii was efficient in reducing thrips population under adverse field conditions. Thus, the effectiveness of A. swirskii on T. palmi inaugurates the perspective of this mite species as potential bio logical control agent when compared to the ch emical control strategies generally used for the management of this pest. These chemical insecticides have been used on a calendar basis making it uneconomical for growers and inflicting the long term ecological and environmental damage. In the past two de cades, T. palmi has been known to exhibit reduced susceptibility towards various groups of insecticid es including Spinosad (Seal 2010 ), demanding the introduction of bio logical control agents for this pest. Very few studies have been conducted to evaluate mites as predator of thrips species in uncontrolled field conditions. Results from our study is an advancement over the previous available reports on phytoseiid mites as predator of thrips and adds one important thread to the study of Arthurs et al. (2009 ), who concluded these mites to be an effective predator of S. dorsalis on pepper. However, the success rate of phytoseiid mites as predators in field conditions or in nursery depends on various factors including

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114 dissemination of this information among gro wers and educating them about the importance of these mites.

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115 Table 5 1. Number of mites (mean SEM) per 10 flowers sampled on five sampling days from five treatment plots: 1) Low rate of A. cucumeris (20 mites/plant), 2) High rate of A. cucumeris (40 mites/plant), 3) Low rate of A. swir sk ii (20 mites/plant), 4) High rate of A. swirskii (40 mites/plant) and 5) Control Means in columns followed by the same letter are not significantly different (6 th DAR: F = 1.12; df= 4, 15 ; P = 0.36; 10 th DAR : F = 0.35; df= 4, 15 ; P = 0.84; 14 th DAR: F = 1.63; df= 4, 15 ; P = 0.19; 18 th DAR: F = 1.90; df= 4, 15 ; P = 0.14; 22 nd DAR: F = 1.63; df= 4, 15 ; P = 0.19). Treatments Mean numbers of mites recovered 6 th DAR 10 th DAR 14 th DAR 18 th DAR 22 nd DAR A. cucumeris Low rate (20mites/plant) 0.160.10a 0.330.30a 0a 0a 0.160.10a High rate (40mites/plant) 0.500.30a 0.160.10a 0a 0a 0a A. swirskii Low rate (20mites/plant) 0.500.20a 0.330.30a 0a 2.331.5a 0.500.34a High rate (40mites/plant) 0.160.10a 0.160.10a 1.000.68a 2.001.3 a 0.330.33a Control 0a 0a 0a 0a 0a

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116 Table 5 2 Number of mites (mean SEM) per leaf sampled on five sampling days from treatment plots: 1) Low rate of A. cucumeris (20 mites/plant), 2) High ra te of A. cucumeris (40 mites/plant), 3) Low rate of A. swirskii (20 mites/plant), 4) High rate of A. swirskii (40 mites/plant) and 5) Control Means in columns followed by the same letter are not significantly different (6 th DAR: F = 1.61; df= 4, 95 ; P <0. 37; 10 th DAR : F = 81.68 ; df= 4, 95; P < 0.0001; 14 th DAR: F = 26.82; df= 4, 95; P < 0.0001; 18 th DAR: F = 11.16; df= 4, 95 P < 0.0001; 22 nd DAR: F = 3.23; df= 4, 95; P < 0.0 00 1). Treatments Mean number of mites recovered 6 th DAR 10 th DAR 14 th DAR 18 th DAR 22 nd DAR A. cucumeris Low rat e (20mites/plant) 0.530.19a 0c 0.060.06c 0.200.1b 0b High rate (40mites/plant) 0.930.18a 0.20 0.10c 0.460.10c 0.600.3b 0b A. swirskii Low rate (20mites/plant) 2.800.25a 12.532.0b 26.462.5a 24.607.5a 16.002.1a High rate (40mites/plan t) 1.930.50a 67.404.74a 9.131.6b 11.932.8a 4.800.5b Control 0a 0 c 0 c 0.200.1b 0b

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117 Table 5 3 Number of mite eggs (mean SEM) per leaf sampled on five sampling days from treatm ent plots: 1) Low rate of A. cucumeris (20 mites/plant), 2) High rate of A. cucumeris (40 mites/plant), 3) Low rate of A. swirskii (20 mites/plant), 4) High rate of A. swirskii (40 mites/plant) and 5) Control Means in columns followed by the same letter are not significantly different (6 th DAR: F = 1.03; df = 4, 95 ; P = 0. 41; 10 th DAR : F = 60.76; df = 4, 95; P < 0.0001; 14 th DAR: F = 9.98; df= 4, 95; P < 0.0001; 18 th DAR: F = 7.24; df = 4, 95; P < 0.0001; 22 nd DAR: F = 8.23; df = 4, 95; P < 0.0001). Treatments Mean number of mite eggs 6 th DAR 10 th DAR 14 th DAR 18 th DAR 22 nd DAR A. cucumeris Low rate (20mites/plant) 0.130.09a 0.200.10b 0.11 0.0 8 b 0b 0b High rate (40mites/plant) 0.800.30a 0.200.10b 0b 0b 0.400.13b A. swirskii Low rate (20mites/plant) 0.600.0a 5.401.20a 10.00 2.40a 6.002.00a 15.002.55a High rate (40mites/plant) 1.200.71a 16.931.56a 5.401.00ab 5.802.02a 2.800.68b Control 0 a 0b 0b 0b 0b

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118 Table 5 4 Number of cumulative Thrips palmi x days (mean SEM) and mite x days (mean SEM) per leaf on five sampling days from the following treatment plots: 1) Low rate of A. cucumeris (20 mites/plant), 2) High rate of A. cucumeris (40 mites/plant), 3) Low rate of A. swirskii (20 mites/pla nt), 4) High rate of A. swirskii (40 mites/plant) and 5) Control Treatment Thrips palmi x days (No./leaf) Mite x days (No./leaf) A. cucumeris (low rate) 947 .7353.8b 1.930.2c A. cucumeris (high rate) 1 4 35.1386.3a 4.630.6c A. swirskii (low rate ) 800.0748.9 c 160.5316.5b A. swirskii (high rate) 2668.8 d 282.9014 .0 a Control 958 .1756.3b 0.570.1c Means in columns followed by the same letter are not significantly different Thrips palmi x days: F = 54.76 ; df = 4, 295 ; P < 0.00 0 1; Mite x days: F = 173.76; df = 4, 295 ; P < 0.00 0 1).

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119 Figure 5 1 Pictorial view of the bio logical control field showing five solid rows of sunhemp (buffer ) separating f our blocks of treatment A small plot of sunhemp separa tes each treatment plot. (Source: www.maps.google.com ) Treatments Bu ffer Buffer

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120 Figure 5 2. Number of F. schultzei larvae ( mean SEM ) per 10 flowers sampled on five sampling dates after the release of A. swirskii (high rate and low rate) and A. cucumeris ( high rate and low rate). Mites were released on day 0 indicated by an arrow On each day of sampling, treatments with no letters are not significantly different ( P > 0.05

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121 Figure 5 3 Number of T. palmi larvae (mean SEM) per cucumber leaf sampled on five sampling dates after the release of A. swirskii (high and low rate) and A. cucumeris (high and low rate). Mites were released on day 0 indicated by an arrow. On each day of sampling, treatments with same letter (s) are not significantly different ( P > 0.05 ).

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122 Figure 5 4 Linear regression showing the number of T. palmi larvae and mites abundance in plots treated with A. swirskii (40 mites/plant) during the period of study. y = 0.6631x 0.2652 r = 0.4437 P = 0.0005 0 20 40 60 80 100 120 0 10 20 30 40 50 60 70 80 90 Mite abundance Thrips density

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123 CHAPTER 6 CONCLUSIONS Frankliniella schultzei ( Trybom) is one of the key pest of tomato and other economically important vegetable and ornamental crops across the globe. It is a pest of South Am erica origin from where it dispersed to other parts of the world. Frankliniella schultzei e arlier known to make few encounters in flowers of ornamental plants in southern and central Florida (Funderburk et al. 2007), has now established in southeastern Flo rida. One of the important factors supporting F. schultzei establishment is the broad polyphagy and ability to survive under intermittent suboptimal conditions. Frankliniella schultzei is a new vegetable pest in this region and there is not much informatio n on its distribution seasonal abundance, and most importantly on their management. Considering the lack of information about this pest and future needs of our industries as well as growers I conducted various studies. The first study was to determine t he abundance of F. schultzei on five economically important vegetable crops (cucumber, tomato, squash, pepper and beans) grown in Florida. We found that irrespective of high adult count of F. schultzei on tomato, number of larvae was significantly higher o n cucumber than on the other hosts Tomato, reported as one of the major hosts of F. schultzei in Cuba, Brazil and Paraguay did not serve as primary host of this pest in Florida This information will be useful to determine the reproductive host of this p est and c rops largely at risk in this region Within plant distribution study was conducted to determine the plant parts preferred by F. schultzei as feeding and oviposition sites The study was conducted in field cucumber at three different sites for thre e season s and we found that F schultzei feed and reproduces on flowers of its host plant s It is an anthophilous pest exhibiting

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124 thigmotactic behavior and stays in tight secluded areas of the flower. Gonzalez et al. ( 2001 ) found adults of F. schultzei on cucumber leaves in Cuba, but in my study, F. schultzei was observed only on flower samples with insignificant number on other plant parts Frankliniella schultzei exhibited an aggregated distribution in the field. The distribution of larvae and adults in the field was studied in fall 2008 and fall 2009. The distribution pattern of larvae and adults varied in accordance to the thrips density. During peak population density, F. schultzei was aggregated and it formed hot spots in the area under infestation. H owever, irrespective of the low population density at the beginning of infestation, slope values significantly > 1, for the two models suggested the aggregated distribution. Such clumped pattern could be due to the presence of thrips on the outer edges of the field, as F. schultzei infestation begins from the edges of a field. The density of F. schultzei larvae and adults during the cucumber cropping season in fall 2008 and 2009 was irregular. During the two cropping seasons, we observed the invasion of F. schultzei with the onset of flowering in field s Frankliniella schultzei number increased with the progression of time during the cropping season, where the peak population was observed during the fifth week. The invasion of F. schultzei with the onset of flowering could be due to the local dispers ion by the thrips population fro m adjacent uncultivated crops to host plants. Between the two phytoseiid mites tested for biological control of F. schultzei in field cucumber, we found that none of the two treatm ent rates of A. swirskii and A. cucumeris was effective in reducing F. schultzei population inhabiting flowers of cucumber plants. Average number of A. swirskii and A. cucumeris recovered from

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125 flower samples during the study was low in comparison to the nu mber of mites released in plots. There was no significant difference in the number of mites recovered from various treatment plots. A large number of A. swirskii mites were recovered from leaf samples collected from plots treated with high rate. Mites coun t from high rate treated plots was higher than plots treated with low rate of A. swirskii on 10 th DAR. On comparing, the number of T. palmi between control plots and plots treated with high rate of A. swirskii it was found that mites were effective in reg ulating T. palmi inhabiting leaves of cucumber plants. The high rate of A. swirskii significantly reduced T. palmi number by the 6 th DAR. Mites recovered from leaves samples collected from plots treated with A. swirskii was significantly higher than plots treated with A. cucumeris. Mean number of A. cucumeris recover e d from leaf samples collected from treatment plots was significantly lower than A. swirskii treated plots.

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126 LIST OF REFERENCES Agrawal, A A., C. Kobayashi, and J S. Thaler. 1999. Influence o f prey availability and induced host plant resistance on omnivory by western flower thrips. Ecology 80: 518 523. Aliakbarpour, H., M R. Che Salmah, and H. Dieng. 2010. Species composition and population dynamics of thrips (Thysanoptera) in mango orchards of northern Peninsular Malaysia. Environ. Entomol 39: 1409 1419. Amin, P. W., and J. M. Palmer.1985. Identification of groundnut T hysanoptera. Tropical Pest Management. 31: 268 291. Ananthakrishnan, T. N., and R. Gopichandran. 1993. Chemical Ecology in T hrips Host Plant Interactions, Oxford and IBH, New Delhi. 1 125. Arevalo, H. A., A. B. Fraulo, and O. E. Liburd. 2009. Management of flower thrips in blueberries in Florida. Florida Entomologist. 92: 14 17. Arthurs, S., C. L. McKenzie, C. Jianjun, M. Dogr amaci, M. Brennan, K. Houben, and L. Osborne. 2009. Evaluation of Neoseiulus cucumeris and Amblyseius swirskii (Acari: Phytoseiidae) as biological control agents of chilli thrips, Scirtothrips dorsalis (Thysanoptera: Thripidae) on pepper. Biol Control. 49 : 91 96. Baez, I., S. R. Reitz, and J. E. Funderburk. 2004. Predation by Orius insidiosus (Heteroptera: Anthocoridae) on species and life stages of Frankliniella flower thrips (Thysanoptera: Thripidae) in pepper flowers. Environ. Entomol. 33: 662 670. Brod beck, B. V., J. Stavisky, J. E. Funderburk, P. C. Andersen, and S. M. Olson. 2001. Flower nitrogen status and populations of Frankliniella occidentalis feeding on Lycopersicon esculentum Entomol. Exp. Appl 99: 165 172. CABI. 1998 Thrips palmi Karny Dist ribution Maps of Plant Pests http://www.cabi.org/dmpp/FullTextPDF/2006/20066600480.pdf (11 November 2010). CABI. 1999. Distribution Maps of Plant Pests. Map 598. http://www.cabi.org/dmpd/default.aspx?LoadModule=Review&ReviewID=15454&s ite=164&page=1173 Capinera J. L. 2000. Thrips palmi Karny, online publication. Featured Creatu res. Entomology and Nematology Department, Institute of Food and Agricultural Sciences, University of Florida. http://entnemdept.ufl.edu/creatures/veg/melon_thrips.htm

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136 BIOGRAPHICAL SKETCH Garima Kakkar was born in New Delhi India in 1983. Sh e received Bachelor of Science (hons.) in b otany from Sri Guru Teg Bahadur Khalsa College, University of Delhi, India degree in same school studying a grochemicals and pest m anagement. In 2005 she joined Indian Agricultural Research Institut e as a Senior Research Fellow for two years Standardization of Nitrification Inhibitory Principles of Neem ( Azadirachta indica degree in the Entomology and Nematology D epartment, University of Florida under the supervision of Dr. Dakshina R. Seal. She studied population dynamics and biological control of F. schultzei an invasive thrips species in Homestead. She also identified F. schultzei and various other commonly fou nd thrips in vegetable crops of south Florida. In 2010 Garima married Vivek Kumar a fellow entomology graduate of the University of Florida. She will begin with her PhD program on biology of t ermites at University of Florida in spring 2011.