New chemicals for control control of leafminers on tomato

Material Information

New chemicals for control control of leafminers on tomato
Translated Title:
Bradenton AREC research report - UF Agricultural Research & Education Center ; BRA1983-12 ( English )
Schuster, David J.
Everett, P. H.
Place of Publication:
Bradenton, Fla.
Agricultural Research & Education Center, IFAS, University of Florida
Publication Date:


Subjects / Keywords:
Insecticides ( jstor )
Tomatoes ( jstor )
Leaves ( jstor )

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University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
62507506 ( OCLC )


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Bradenton AREC Research Report BRA1983-12 May 1983


D. J. Schuster and P. H. Everett2

Although Liriomyza spp. leafminers are considered secondary pests of
tomato (Oatman and Kennedy 1976, Johnson et al. 1980), up to 70% by weight of
the 5th harvest may be lost if populations are not contained (Schuster, unpub-
lished data). In addition, fruit exposed by defoliation due to leafmining may
become sunscorched and unmarketable (Keularts 1980). Insecticides have been
used to avoid this loss of foliage but usually have become ineffective,-apparently
due to the development of resistance by Liriomyza spp. (Genung 1957, Parrella
et al. 1982). Utilization of insecticides in integrated pest management (IPM)
programs based upon periodic scouting and action thresholds has been shown to be
feasible for leafminer control on tomato (Pohronezny and Waddill 1978, Schuster
et al. 1980) and should reduce or delay the appearance of insecticide resistance.
Information regarding the specific action of a given.insecticide against the'
various life stages of Liriomyza spp. is necessary in order to incorporate the
insecticide into an-IPM program.

Several experiments have been conducted to identify new insecticides that-
are effective in controlling Liriomyza spp. in the field and to evaluate in-the
laboratory the impact of these insecticides on the various life stages of L.
trifolii (Burgess). This species is the most abundant leafminer attacking tomato
on the west coast of Florida at the present time.

Field Experiments:

Two insecticide experiments were completed on unstaked (ground) tomatoes
at the ARC-Immokalee during the spring crops of 1981 and 1982. Sprays were
applied weekly beginning 3-4 weeks after transplanting. After 8 applications
in the first experiment, only foliage sprayed with either MK 936 (a mixture of
80% avermectin Ba and 20% avermectin B ) or the 1.0 lb ai/100 gal rate of
SD 52618 had fewer leafmines than foliage sprayed only ith water (Table 1).
Applications of the 1.0 lb ai/100 gal rate of Penncap M (encapsulated methyl
parathion) resulted in more leafmines relative to the water check. The appli-
cation of either of the pyrethroids Ammoa or PydrinO or the organophosphate
Lorsban did not result in reduced leafmining damage. After 5 applications in
the second experiment, 30 leaflet samples were collected from each plant and*
held in the laboratory to permit leafminer larvae to pupate. Fewer leafminer
puparia were obtained from plants sprayed with either Trigard or MK 936
(except the .005 lb ai/100 gal rate) than were obtained from plants sprayed
with water (Table 2). Significant reductions in the numbers of puparia were
not obtained with the organophosphate'MonitorO or the pyrethroid Pay OffcO.

1Mention of a pesticide does not constitute or imply a recommendation or endorse-
ment by the.authors or the University of Florida.
2Associate Professor of Entomology (AREC-Bradenton) and Professor of Soil Chemistry
(ARC-Immokalee, Rt. 1, Box 2G, Immokalee, FL 33931), respectively.

Another insecticide experiment was conducted on staked tomatoes at the
AREC-Bradenton during the fall crop of 1982. Sprays were applied weekly begin-
ning 2 weeks after transplanting. After 11 applications, Trigard and I1K 936
resulted in fewer large leafmines (> 0.5 in.) per 30 leaflet samples compared
to the water check (Table 3). When these foliage samples were held in the
laboratory to permit leafminer larvae to pupate, fewest puparia were also noted
from foliage sprayed with Trigard or MK 936. Application of Monitor, Ammo or
CymbushC did not result in fewer leafmines or puparia. The puparia were then
held in the laboratory for adult emergence. While no insecticide significantly
reduced the number of emerging adult leafminers relative to the water check,
very few adults emerged from foliage sprayed with MK 936. No adults were
obtained from foliage sprayed with Trigard since no larvae successfully pupated.
All adults recovered were L. trifolii.

Laboratory Experiments;

A series of laboratory experiments were conducted to determine the effects
of selected insecticides on L. trifolii adults, eggs and larvae. Trigard and
MK 936, two promising insecticides as indicated by the field experiments, were
compared to presently available insecticides including Monitor, Pydrin, and

In the first experiment, adults were caged 24 h on individual tomato leaf-
lets that had been dipped in the insecticide preparations. Subsequent fly
survival, oviposition and feeding (stippling) were noted. Natural mortality
of flies caged on tomato leaflets without an additional food source was high
averaging 35.6%. Nevertheless, mortality of flies exposed to insecticide
residues was significantly higher only for flies exposed to Monitor-dipped
leaflets (Table 4). Fewer eggs and feeding punctures stippless) were noted
in foliage dipped in MK 936 preparations than in foliage dipped in other
preparations except Pydrin and Monitor. Since about 80% of the flies died
after exposure to Monitor-dipped leaflets, reduced oviposition and feeding
would be expected. However, mortality of flies exposed to Pydrin- or MK'936-
dipped leaflets was not significantly different from mortality of flies exposed
to water-dipped leaflets, indicative of an effect of these compounds on the
ovipositional and feeding activity of females. To evaluate this effect further
for MK 936, oviposition and stippling of L. trifolii was observed either when
females were given a choice of treated or untreated foliage or when they were
confined without a choice on treated or untreated foliage. When females were
given a choice, no difference in the number of eggs deposited was detected
between MK 936- or water-dipped leaflets (1.5 and 2.2 eggs/leaflet, respectively).
However, the number of stipples was significantly less on MK 936-dipped leaflets
(10.1/leaflet) compared to water-dipped leaflets (48.4/leaflet). When the flies
were not given a choice, fewer eggs.were deposited and stipples observed after
L. trifolii were exposed 24 h to MK 936-dipped leaflets relative to water-dipped
leaflets (< 0.1 eggs and 1.8 stipples/leaflet vs 7.0 eggs and 117.2 stipples/
leaflet). When flies previously exposed 24 h to MK 936-dipped leaflets were
transferred to leaflets that had not been dipped, egg laying or stippling did
not resume even 24 h after the end of the initial exposure.

In a second group of laboratory experiments, leaflets containing eggs or
1-day old or 3-day old L. trifolii larvae were dipped in the same preparations
as the first laboratory experiment. More eggs in leaflets dipped in Monitor
or MK 936 preparations did not complete hatching compared to eggs in leaflets

dipped in other preparations (Table 5). The largest reduction in egg hatch
occurred in leaflets dipped in MK 936 preparations.- MK 936, Monitor and
Trigard preparations killed 100% of the 1-day old dipped leaflets.
Significantly more 3-day old larvae were killed in leaflets dipped in MK 936
or Trigard than were killed in leaflets dipped in other preparations.

In summary, since both MK 936 and Trigard are lethal to L. trifolii larvae,
the compounds should have use in IPM programs based upon periodic assessment
of larval numbers. However, since current programs also assess relative adult
and stippling activity, MK 936 should be more flexible in its use since the
compound reduces both egg deposition as well as egg hatch. Applications could
then be timed to coincide with either adult or larval abundance.

References Cited.

1. Genung, W. G. 1957. Some possible cases of insect resistance to insecti-
cides in Florida. Proc. Fla. State Hort. Soc. 74:18--152.

2. Johnson, M. W., E. R. Oatman, and J. A. Wyman. 1980. Effects of insecti-
cides on populations of the vegetable leafminer and associated parasites
on summer pole tomatoes. J. Econ. Entomol. 73:61-66.

3. Keularts, J.L.W. 1980. Effect of the vegetable leafminer, Liriomyza
sativae Blanchard, and the associated plant pathogens on yield and
quality of the tomato, Lycopersicon esculentum Mill. cv. Walter.
Univ. of Fla., IFAS, PhD Dissertation. 153 pp.

4. Oatman, E. R., and G. G. Kennedy. 1976. Methomyl induced outbreak of
Liriomyza sativae on tomato. J. Econ. Entomol. 69:667-668.

5. Parrella, M. P., K. L. Robb, and P. Morishita. 1982. Response of Liriomyza
trifolii (Diptera:Agromyzidae) larvae to insecticides, with notes about
efficacy testing. J. Econ. Entomol. 75:1104-1108.

6. Pohronezny, K. L., and V. Waddill. 1978. Integrated pest management -
development of an alternative approach to control of tomato pests in Florida.
Univ. of Fla. Extension Plant Pathol. Rept. No. 22. 7 pp.

7. Schuster, D. J., R. T. Montgomery, D. L. Gibbs, G. A. Marlowe, Jr.,
J. P. Jones, and A. J. Overman. 1980. The tomato program
in Manatee and Hillsborough Counties, 1978-1980. Proc. Fla. State Hort.
Soc. 93:235-239.

Table 1. Foliar damage of Liriomyza spp. on field-grown tomato
sprayed weekly with insecticide (Spring 1981)

Rate Leafmines/30
Insecticide (lb ai/100 gal) leaflets
MK 936 0.o4SL 0.04 0.0 a
MK 936 0.04SL 0.02 0.0 a
MK 936 0.04SL 0.01 0.3 a
SD 52618 85WP 1.00 12.3 ab
SD 52618 85WP 0.50 18.7 bc
SD 52618 85WP 0.25 29.0 bc
Ammo 2.5EC 0.075 25.7 bc
Pydrin 2.4EC 0.10 29.0 bc
Lorsban 4EC 1.00 33.5 c
Penncap M 2F 0.50 36.7 c
Penncap M 2F 1.00 53.7 d
Check (water) 35.0 c

aTransplants were set 4 March and
and 29 April, and 6 and 13 May.

sprayed 25 March, 1, 9, 15, 22

Means followed by the same letter are not significantly different
at the P = 0.05 level, Duncan's new multiple range test.

Table 2. Pupation of Liriomyza trifolii from foliage of field-grown
tomato sprayed weekly with insecticide (Spring 1982)a

Rate Puparia/30
Insecticide (lb ai/100 gal) leaflets
Trigard 0.4EC 0.50 0.0 a
Trigard 0.4EC 0.25 0.0 a
MK 936 0.03SL 0.04 0.0 a
MK 936 0.03SL 0.01 0.0 a
MK 936 0.03SL 0.005 1.8 ab
Monitor 4EC 1.00 1.4 ab
Pay Off 2.5EC 0.04 7.3 c
Check (water) -5.0 be

aTransplants were
6 and 13 May.

set 4 March and sprayed 8, 16, and 29 April and

Means followed by the same letter are not significantly different
at the P = 0.05 level, Duncan's new multiple range test.

Table 3. Control of Liriomyza trifolii in foliage of field-grown tomato
sprayed weekly with insecticide (Fall 1982)a

Number/30 leaflets
Rate Large Emerging
Insecticide (lb ai/100 gal) leafmines Puparia adults

MK 936 0.03SL 0.002 4.5 ab 2.7 a 1.5. a
MK 936 0.03SL 0.001 19.2 a 1.0 a 1.0 a
Trigard 0.4EC 0.50 16.5 a 0.0 a
Trigard 0.4EC 0.25 18.2 a 0.0 a -
Monitor 4EC 1.00 71.0 bc 30.0 b 20.2 a
Ammo 2.5EC 0.04 94.5 bcd 63.0 c 44.2 b
Ammo 2.5EC 0.06 98.7 bcd 64.2 c 48.7 b
Pydrin 2.hEC 0.10 l01.7T-ed 53.2 c 46.5 b-
Cymbush 3EC 0.04 114.0 cd 64.5 c. 43.5 b
Cymbush 3EC 0.06 120.0 d 76.0 d 55.5 b
Check (water) -63.0 b 28'.7 b 21.5 a

aTransplants were set
23 Nov; and 3, 9, 17
bMeans within columns
different at the P =

Table 4. Adult morta:
exposed 24 h to in;

24 Sept. and sprayed 7, 14,
and 22 Dec.

21 and 28 Oct; 9, 18 and

followed by the same letter are not significantly
0.05 level, Duncan's new multiple range test.

lity (n = 90) and oviposition of Liriomyza trifolii
secticide residues on tomato foliage in the laboratory.

Rate % Eggs/ Stipple
Insecticide (lb ai/100 gal) mortality leaflet rating

Monitor 4EC 1.00 80.1 a 10.2 cd 1.0 c
Pydrin 2.4EC 0.10 47.5 b 9.2 cd 0.6 c
Ambush 2EC 0.10 47.4 b 18.2 bc 4.4 b
Trigard 0.hEC 0.50 38.8 bc 27.7 ab 4.7 b
MK 936 0.03SL 0.01 38.3 bc 0.8 d 0.6 c
MK 936 0.03SL 0.005 38.0 bc 1.6 d 0.7 c
Trigard 0.4EC 0.25 23.9 c 20.6 bc 3.9 b
Check (water) 35.6 bc 38.2 a 6.7 a

aThe number of stipples (feeding and oviposition punctures) were estimated on
the basis of percent leaf area affected: 1 = 0-10%; 2 = 10-20%; 3 = 30-40%;

Means within columns followed by the same letter are not significantly differ-
ent at the P = 0.05 level, Duncan's new multiple range test.

Table 5. Percent mortality of Liriomyza trifolii eggs and 1- and 3-day
old larvae in tomato foliage dipped in insecticide preparations in
the laboratory.

Rate Larvae
Insecticide (lb ai/100 gal) Eggs 1 day 3 days

MK 936 0.03SL 0.01 93.3 aa 100.0 a 93.1 a
MK 936 0.03SL 0.005 89.7 a 100.0 a 99.0 a
Monitor 4EC 1.00 40.2 b 100.0 a 93.0 ab
Trigard O.hEC 0.25 10.4 c 100.0 a 89.5 ab
Ambush 2EC 0.10 7.0 c 57.3 b 52.8 cd
Trigard 0.4EC 0.50 5.2 c -.. 100.0 a 86.0 ab
Pydrin 2.4EC 0.10 4.9 c 35.2 c 29.8 d
Check (water) 2.7 c 34.9 c 11.3 e

aMeans within columns followed by the same letter are not significantly
different at the P = 0.05 level, Duncan's new multiple range test.

A '*'