AMERICAN COCKROACH SURVIVAL AND CONTROL IN WOOD VOIDS By DALLIN ASHBY 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 U NIVERSITY OF FLORIDA 2017
2017 Dallin Ashby
To my wife and children
ACKNOWLEDGMENTS I thank Dr. Philip Koehler for his persistent support and ideas that helped to shape my research. I thank Dr. Rob erto Pereira for his assistance in helping me develop the analytical and computational aspects of my findings, and the direction he offered in formatting the text within my thesis. I thank Dr. Rebecca Baldwin for being a source of encouragement and empathy throughout the process as well as providing sound scientific viewpoints regarding the creation of this thesis I thank my wife for her constant support and loving friendship despite my many days away from home. Her patience and understanding were invalua ble to the process of completing this thesis.
5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 8 ABSTRACT ................................ ................................ ................................ ................... 10 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 12 2 LITERATURE REVIEW ................................ ................................ .......................... 15 Origin ................................ ................................ ................................ ...................... 15 Distribution ................................ ................................ ................................ .............. 16 Biology ................................ ................................ ................................ .................... 17 Importance ................................ ................................ ................................ .............. 21 Control ................................ ................................ ................................ .................... 22 3 LONGEVITY OF STARVED, WATER DEPRIVED AMERICAN COCKROACHES IN WOOD HARBORAGES AT VARIOUS WOOD MOISTURE LEVELS ................................ ................................ ................................ .................. 29 Materials and Methods ................................ ................................ ............................ 30 Insects ................................ ................................ ................................ .............. 30 Harborages ................................ ................................ ................................ ....... 31 Bioassay ................................ ................................ ................................ ........... 31 Analysis ................................ ................................ ................................ ............ 33 Results ................................ ................................ ................................ ............. 33 Discussion ................................ ................................ ................................ .............. 35 4 EFFICACY OF POSSIBLE PRECONSTRUCTION WALL VOID TREATMENTS AGAINST AMERICAN COC KROACHES, SILVERFISH AND CARPENTER ANTS ................................ ................................ ................................ ...................... 49 Materials and Methods ................................ ................................ ............................ 50 Insects ................................ ................................ ................................ .............. 50 Wood Blocks ................................ ................................ ................................ .... 52 Treatments ................................ ................................ ................................ ....... 53 Bioassays ................................ ................................ ................................ ......... 54 Analysis ................................ ................................ ................................ ............ 55 Results ................................ ................................ ................................ .................... 56
6 Discussion ................................ ................................ ................................ .............. 58 5 CONCLUSIONS ................................ ................................ ................................ ..... 68 LIST OF REFERENCES ................................ ................................ ............................... 72 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 82
7 LIST OF TABLES Table page 3 1 Days to mortality for starved and water deprived 1st instar nymphs, 3rd 4th instar nymphs and adult American cockroaches at 0 30% wood moisture and resulting relative humidities. ................................ ................................ ............... 43
8 LIST OF FIGU RES Figure page 3 1 Wood block harborage with acetate paper circle stapled over the top and a 1st instar nymph inside. Four holes were used as wells for increasing wood moisture. ................................ ................................ ................................ ............. 44 3 2 Fecal pellets of an adult American cockroach, derived from standard cockroach diet (left) and white pine (collected from the wood harborage in which it lived w hile deprived of food and wat er ................................ .................. 44 3 3 Mean longevity in days of 1st instar nymphs, 3rd 4th instar nymphs and adults of American cockroaches living in wood harborages at different moisture levels.. ................................ ................................ ................................ .. 45 3 4 Longevit y of 1st instar nymphs, 3rd 4th instar nymphs, and adults of the American cockroach while starved and water deprived in wood harborages of various wood moisture levels. ................................ ................................ ............. 46 3 5 Linear regressions of fecal pellet (composed of wood) and body weights of starved and water depr ived 3rd 4th instar nymphs and adults of the American cockroach. ................................ ................................ .......................... 48 3 6 Mean weight of wood composed fecal pellets (feces weight at mortality/days lived) produced by starved, water deprived male (M) and female (F) American cockroaches. ................................ ................................ ...................... 48 4 1 Experimen tal unit used to test the efficacy of insecticide treatments on wood against cockroaches, silverfish and carpenter ants. A 60 mL deli cup was secured to the treated surface of white pine with elastic bands. ......................... 62 4 2 Mortality rates of 3rd 4th instar American cockroaches, silverfish and Florida carpenter ants combined, after seven days of exposure to sev en pesticide treatments on wood ................................ ................................ ........................... 63 4 3 Mortality rates of 3rd 4th instar American cockroaches after 24 hours of exposure to , or a combination of and with treatments having been variably aged. ................................ .... 64 4 4 Mortality rates of 3rd 4th instar American cockroaches after 7 days of exposure to alone Arilon Phantom or after aging ................................ ................................ ................................ .................. 65 4 5 Mortality rates of silverf ish after 7 days of exposure to alone mixed with: Arilon Phantom or one day or accelerated aging of 1 year, 2 years or 5 years post treatment. ......................... 66
9 4 6 Mortality rates of Florida carpenter ants after 7 days of exposure to alone mixed with: Arilon Phantom or after variable aging. ................................ ................................ .... 6 7
10 Abstract of Thesis Presented to the Graduate School of the Unive rsity of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science AMERICAN COCKROACH SURVIVAL AND CONTROL IN WOOD VOIDS By Dallin Ashby August 2017 Chair: Philip Koehler Cochair: Rebecca Baldwin Major: Entom ology and Nematology This is the first study to measure the longevity of starved, water deprived American cockroaches in wood harborages and specifically measure the longevity of 1st instar ny mphs of the species. Longevity was correlated with wood moistur e content and resulting relative humidity levels. T hose cockroaches in blocks at higher wood moisture levels survived longest. B oth 3rd 4th instar nymphs and adults consumed wood in which they were kept during this research C onsumption of wood did not all ow these otherwise starving cockroaches to thr ive ; therefore, though wood feeding activity was prolonged by high wood moisture in wood void s feeding did not su stain individuals Maintenance of wall void humidity to control i nsects is not always fea sible. Wood treated with mortality rates never exceeded 80% after seven days of exposure in two of three species. Phantom and mixed their efficacy was maintained over the accelerated aging equivalent of five years, never dropping significantly below 100% mortality Of the toxicants tested in this research, only is currently labeled for application to wood framing T he addition of to preconstruction treatments
11 would save resources, as post construction wall void treatments should be unnecessary within the first five years. Though the other pesticides tested are not currently labeled fo r use as termiticides appli ed to wood framing, tank mixing with for improved longevity is plausible for at least Phantom and
12 CHAPTER 1 INTRODUCTION American cockroaches ( Periplaneta americana Linnaeus) are one of the most common cock roaches in the United States (Tarshis 1959). They can be found inside and outside of homes (Hagenbuch et al, 1988), including inside wall voids and attics (Owens and Bennett 1982, Appel 1997). Wall voids are especially ideal for American cockroach harborag e when water damage is present or moisture problems exist (Benson 1987). This is due to the need these cockroaches have for readily accessible water as well as moderate to high humidity (Willis and Lewis 1957). Besides cockroaches, there are several insec t s known to inhabit wall voids. Florida c arpenter ants ( Camponotus floridanus ) can infest wall voids (Fowler 1986) and silverfish ( Lepisma saccharina ) often spend part or all of their lives in hidden areas like wall voids, thus making a treatment to such v oids with long lasting residual insecticides requisite (Ebeling et al. 1969). Cockroaches and termites have classically been viewed as the most important structure infesting insects in the in the United States (Ebeling 1978). Homes are routinely treated ag ainst termites during the construction process, but not so for cockroaches or other structure infesting pests. Ebeling et al. (1969) argue that treating inside of walls against cockroaches and other insects during construction will help mitigate needed tre atments to living spaces over time. One of the steps that regularly occurs in preconstruction treatments against termites is spraying the lower portions of wood frame members with boric acid solution, which absorbs into the wood surface (Grace and Yamamoto 1994). Recently, a new bifenthrin product by FMC, has also been approved for use as a termiticide on wood frame members during home
13 construction (FMC 2017). Like the boric acid treatments, absorbs into the wood. Bifenthrin is also use d as a broad spectrum insecticide in many chemical formulations, with myriad insects listed as target organisms (Zaim et al 2000, Anon 2002, Hougard et al 2002). In theory, the application of a desiccant dust tank mixed with to the framing timber s of a house in lieu of the standard boric acid spray could save time and money in the long run by providing protection from more than just termites in a single application. Liquid sprays may be absorbed into the substrate upon which they were applied, suc h as wood, which could render the pesticide residues inaccessible to target pests crawling on the surface (Ebeling et al. 1969). Application of a tank mixed toxicant and desiccant dust as a single treatment against both termites and cockroaches could be ad vantageous in that a fraction of the toxicant may remain on surface. Besides being the most important structural pests, termites and cockroaches share other characteristic s in common, including a relatively thin wax layer (Ebeling and Wagner 1959) similar digestive systems (Watanabe and Tokuda 2010), the consumption of cellulose (Wharton et al. 1965a, Gijzen et al. 1994), and engaging in coprophagy (Cruden and Markovetz 198 4). Recent molecular phylogenic work puts these two groups of insects into a single order, Blattodea (Inward 2007). Whereas wood consumption by termites is common knowledge, only a few cockroaches are known to regularly feed on cellulosic material (Schrive ner et al. 1989, Slaytor 1992, Watanabe and Tokuda 2010), with the genus Cryptocercus being a well known example (Inward et al. 2007). American cockroaches prefer to eat starches and sugars to cellulose (Bell
14 and Adiyodi 1981), though they have been docum ented to eat paper (Wharton et al. 1965, Gijzen et al. 1994) with the nutritional value of the cellulose consumed being under debate (Gijzen et al. 1994, Watanabe and Tokuda 2010). While similarities exist between them, American cockroaches and termites ex hibit very different life histories. With their propensity to associate with filth (Asahina 1961, Bell and Adiyodi 1981), American cockroaches are known to be carriers of several disease causing bacteria and other pathogens (Fathpour 2003, Pai et al. 2005, Vahabi et al 2011). With American and other cockroach species living and breeding in wall voids, it is important to understand their control within these harborages. The habits of domiciliary cockroaches in buildings are similar enough that one represent ative species can be used to discuss other domiciliary cockroaches (Ebeling 1978). The proceeding research was conducted using American cockroaches as a model for domiciliary cockroaches in general, partly because of the broad knowledge already available o n the species. Two studies were conducted t o help gain a better understanding of American cockroach survival in wall voids, and what measures can be taken to prevent wall void infestations including: a) determining the longevity of starved, water deprived American cockroaches in wood harborages at various wood moisture levels (Chapter 3) and b) assess the efficacy of possible preconstruction wall void treatments against American cockroaches, silverfish and Florida carpenter ants over accelerated aging of up to five years (Chapter 4)
15 CHAPTER 2 LITERATURE REVIEW Origin The radiation of insects during the Carboniferous was due, in part, to the advent of flight and the evolution of wings that could be folded back over the abdomen for protection while at re st. Cockroaches are an example of the success of this design. In the fossil record of the Upper Carboniferous Period (359 299 Mya), cockroaches have been the most ubiquitous insects found, comprising about 80% of insect fossil specimens (Carpenter and Burn ham 1985). Modern cockroaches date back to the Early Cretaceous period (120 Mya). Early cockroaches are readily distinguished from more modern species by the presence of an ovipositor on the females. Modern cockroaches lack these ovipositors (Carpenter and Burnham 1985, Legendre et al. 2015). The morphological characteristics used to identify cockroaches are usually not preserved in fossils. There are only about four or five families that fossil cockroaches are commonly placed in because they are so difficu lt to identify. Cockroach fossils of the Upper Carboniferous period are most often found in coal shale, indicating that they probably lived in swamps and other wet environments (Carpenter and Burnham 1985), which probably lent to their rapid decay and lack of preservation. There are no known prehistoric records of cockroaches, which means that we are uncertain of when they started associating with man made structures or dwellings. Individual cockroach species becoming synanthropic over evolutionary time is convergent, meaning that the several extant domestic species became so without a common synanthropic ancestor (Grandcolas 1998).
16 The cockroach genus Cryptocercus is an evolutionary intermediate to the termites (Lo et al. 2000) and is considered to be a si ster clade (Inward et al. 2007). Intracellular symbiosis is ubiquitous in cockroaches but only one species of termite shares this. It is apparent that cockroaches and termites shared a common ancestor that originally had these intracellular symbionts (Band i et al. 1995). Early work on the degradation of cellulose in American cockroaches ( Periplaneta americana Linnaeus) showed that there might be endosymbionts responsible for cellulose degradation (Bignell 1976), which would imply the ability of these roache s to use wood as a food source, much like the termites. More recent work has shown that this is not the case, but rather, hindgut bacteria and protozoa do not play a role in carbohydrate digestion in either the American cockroach or a decaying wood eating cockroach ( Panesthia cribrata ) (Scrivener et al. 1998). In fact, Cryptocercus is the only cockroach lineage to share the same suite of oxymonadid and hypermastigid endosymbionts with termites (Termitidae) (Klass et al. 2008). Distribution American cockroa ches belong to the family Blattidae, within the order Blattodea (Triplehorn and Johnson 2005). There are over 20 species within the genus Periplaneta worldwide. Four of these, P. americana, P. australasiae (Fabricus), P. brunnea (Burmeister) and P. fuligi nosa (Serville) are found in the United States though none of these are native to the North American continent. Periplaneta americana originated in tropical Africa where they can still be found inside and outside of dwellings. They are likely to have arriv ed in the Americas by 1625 or earlier (Bell and Adiyodi 1981). American cockroaches have also been found indoors and outdoors in Thailand
17 (Sriwichai, et al. 2002) and Japan (Asahina 1961). They are currently cosmopolitan in distribution, having been spread by world commerce (Bell and Adiyodi 1981). roaches are currently considered peridomestic, causing serious problems because of their propensity to breed outdoors but periodically m ake their way into inhabited structures (Hagenbuch et al 1988). As examples, Fleet et al, (1978) listed several peridomestic cockroaches they found around a Texas home: P. fuliginosa Parcoblatta fulvescens (Saussure and Zehntner), Parcoblatta pennsylvanic a (DeGeer), Pseudomops septentrionalis Hebard (Blattellidae), P. americana Picnoscelus surinamensis (L.) (Blaberidae). Unlike the domestic cockroach Blattella germanica (Linnaeus), these cockroaches do not rely on people, their dwellings and products for survival. Biology American cockroaches are the most common cockroaches in city sewer systems worldwide (Jones 2008). Population growth pressure of American cockroaches in sewer systems may lead to migration indoors, especially where old or broken plumbing allows for access. This is especially true in warmer months when populations increase the most (Haines and Palmer 1953). In summer time, they can be found in alleyways and yards next to infested buildings (Gould and Deay 1938). In Hawaii, they have been fo und in great numbers at night on thorn producing Tribulus blossoms (Bryan 1926). Similarly, Seelinger (1984) found them feeding on fallen flowers of coconut palms and hibiscus in Jamaica. Gould and Deay (1940) also reported finding American cockroaches in palm trees and decaying maple trees. They can sometimes be found in caves as well (Bell and Adiyodi 1981). American cockroaches do not share the same
18 local distributions as P. fuliginosa P. brunnea or P australasiae (Haines and Palmer 1955, Brenner 1988 Seelinger 1984). For example, P. americana tend to occupy lower strata than P. australasiae in a shared environment outdoors (Seelinger 1984). However, P. americana will readily aggregate when presented with odors of other species of cockroach, unlike mo st species which are repelled by the scents of non conspecific individuals (Leoncini and Rivault 2005). In many countries around the world, populations of American cockroaches can build up in homes when food and water are available. However, they are at le ast as well adapted for living outside as inside human dwellings (Seelinger 1984). They only become resident pests under conducive conditions. People in the US tend to have low tolerance thresholds for any cockroaches (Schal and Hamilton 1990) such that ev en cockroaches that only occasionally find their way into buildings from the outside are considered pests. Indoors, American cockroaches can often be found in restaurants, grocery stores, food processing facilities, warehouses (Bell and Adiyodi 1981), base ments and cellars (Gould and Deay 1938). Established populations can also be found in wall and ceiling voids (Appel 1997, Owens and Bennett 1982), especially those with water damage (Benson 1987). Inasmuch as American cockroaches require relatively high h umidity and ready access to water, females tend to deposit their eggs in moist and secluded areas (Bell and Adiyodi 1981). Their eggs are contained within an egg capsule, or ootheca, which provides protection from desiccation and predation until the eggs hatch. Each ootheca usually contains about 14 eggs, though 16 eggs is the highest number any ootheca can
19 contain. After an ootheca is deposited, it may take about 55 days for the eggs to hatch. An adult female may produce upwards of 90 oothecae in her life time (Gould and Deay 1938). Nymphs that successfully emerge from the ootheca undergo up to 13 molts before reaching adulthood, though this number is variable. The first molt usually occurs within about a month of emergence from the ootheca. The nymphal sta ge is normally completed in between 285 and 616 days, depending on abiotic factors such as temperature and humidity. The adult stage may last anywhere from 125 to 1212 days (Gould and Deay 1940). Several factors are known to affect longevity of American c ockroaches including relative humidity (Smith et al. 1999), amount of life spent in captivity (Rau 1940), excessive light (Solomon et al. 1977), temperature (Wharton et al. 1965) and access to food and water (Willis and Lewis 1957). For the present study, it is important to note that adult American cockroaches may live more than twice as long when they have been kept captive their entire lives as compared to those adults that were captured as late instar nymphs (Rau 1940). American cockroaches are opportun istic feeders, eating both plant and animal based products (Bell and Adiyodi 1981). Nigam (1933) reported these roaches feeding on such things as bread, fruit, paper, leather and hair. Where the following items are available, they may also eat prepared fis h, bean cake, rice, putrid sake, oil paper, peanuts, starchy paste, crepe de Chine and other cloth, and dead insects (Takahashi 1924). Also, of the carbohydrates they ingest, American cockroaches prefer consuming starches and sucrose to cellulose (Scrivene r et al. 1998).
20 Cockroaches can eat food without water though much less food is consumed when they are deprived of water. When American cockroaches are dehydrated, the rectum reabsorbs water such that concentrated fecal pellets are produced. In order to re cycle needed water, the rectum fills, filters and then refills with waste. The process of reabsorption in the gut is able to take place against an increasing osmotic gradient (Wall 1969). When cockroaches are starved, they experience an increase in total w ater content in relation to body weight. Additionally, blood volume is much lower in starved cockroaches than non starved cockroaches (Wharton et al. 1965). Though food and water are needed to survive, water alone allows for greater cockroach longevity th an does food alone or complete deprivation of food and water. Also, bigger cockroach species tend to live longer than smaller cockroach species when subjected to water deprivation. American cockroach adult females are able to survive 3 months on water alon e in 36 to 40% relative humidity in glass containers. To compare, the longevity of adult American cockroaches living at 36% relative humidity but without food or water is about 28 days for males and 41 days for females. (Willis and Lewis 1957). Relative h umidity is important for cockroach survival not only under conditions of food and/or water deprivation (Dambach and Goehln 1998), but in normal conditions, too. Air movement is repellent to American cockroaches because moving air can wick away moisture fro m their bodies faster than still air. As the velocity of air increases, the rate of desiccation of an exposed cockroach will also increase (Oswalt et al. 1997). Desiccant dusts are also repellent to cockroaches for the same reason. Cockroaches can learn to avoid insecticidal dusts, including desiccant dusts (Ebeling et al. 1967).
21 Cuticular permeability has a positive relationship with change in relative humidity. Increasing the relative humidity around a cockroach causes its cuticle to become more permeable and thus more susceptible to dehydration. The amount of water in cockroach feces increases with an increase in relative humidity (Appel and Rust 1984) thus highlighting important coping mechanisms cockroaches are able to employ in order to avoid desiccati on. However, when faced with desiccation from a highly sorptive dust such as silica gel, lipid synthesis in cockroaches is too slow to keep up with the absorption that takes place. Large quantities of lipid are drawn from deep within the cuticle by highly sorptive dusts (Ebeling 1971). Importance Some cockroaches pose real threats to human health such as mechanically spread surface pathogens. As an example, E. coli was the most common surface pathogen found on cockroaches by Vahabi et al. (2011) in Sanand aj city houses in Iran. About 80% of the cockroaches tested were contaminated exteriorly with E. coli American cockroaches were contaminated more frequently than German cockroaches in this study. Cockroaches can also serve as reservoirs and vectors of dru g resistant Salmonella. Devi and Murray (1991) found this to be the case after sampling cockroaches from hospitals, houses, animal sheds, grocery stores and restaurants in South Kanara District, India, where 4.1% of these cockroaches ( Blatta and Periplanet a species) harbored Salmonella. Additionally, a study conducted in Iran (Fathpour et al. 2003) found that American cockroaches were the most abundant species in hospitals, houses and poultry sheds, and that up to 70% of the roaches collected from hospitals harbored drug resistant Salmonella The authors also determined that Salmonella is
22 stable inside a cockroach for more than 10 months. American cockroaches have been found to carry Salmonella in the United States as well. Rueger and Olson (1969) sampled ov er 6,000 cockroach specimens found throughout 19 cities (all state capitals) and discovered a 1.24% natural infection rate. Pai et al. (2005) found that American and German cockroaches collected from homes in Taiwan both harbored a total of 25 different sp ecies of bacteria on average. American cockroaches were found in kitchens about 70% of the time. In an earlier study by Pai et al. (2003), about 37% of hospitals sampled in Taiwan had American cockroaches present and non tuberculous mycobacteria were found on these roaches. Besides harboring and spreading pathogens, cockroaches are also known to cause allergic reactions in sensitive people. Cockroach allergens are capable of sensitizing humans, which means that through exposure to these allergens, people ca n gain sensitivity and become allergic. These allergens are known to provoke constitutional (generalized) and local reactions (Bernton and Brown 1964). According to Gelber et al. (1993), the primary sight of cockroach allergen accumulation in homes is in t he kitchen. Cockroach allergens can also be found in bedroom carpet, bedding, and sofas. They found that about 20 to 40% of homes sampled in Delaware with no visible cockroaches present had detectable cockroach allergens in dust. Sources of cockroach aller gen can include cockroach saliva, feces, secretions, cast skins, debris, and dead bodies. Control American cockroaches can be both domestic (Pope 1953) and peridomestic (Fleet et al. 1978), being well adapted for living indoors and outdoors (Seelinger 1984 ). American cockroaches are not found as often around homes in the US as Australian or
23 smokybrown cockroaches (Brenner 1988, Fleet et al. 1978), but their biology and control are similar. Mechanical exclusion is a critical part of controlling all peridomes tic cockroaches. For example, because tree branches contacting roofs may allow for attic entry by smokybrown and American cockroaches (Hagenbuch et al. 1988), keeping branches trimmed away from contact with any roof can be an important part of pest managem ent. One of the most effective strategies for controlling peridomestic cockroaches is baiting on the outside of the structure so they do not come inside. As an example, 2.0% Chlorpyrifos bait around a home was shown to be more effective than 0.04% chlorpy rifos spray solution applied to the exterior (Hagenbuch et al. 1988). Also, the combination of chlorpyrifos pellet bait and hydramethylnon gel bait was found to be more effective against Smokybrown cockroaches than a targeted spray of trelamethrin on the s ame species (Smith et al. 1997). Once peridomestic cockroaches are inside, treatment strategies must be reevaluated. Domiciliary cockroaches can move in and out of hollow walls and can breed there in enormous numbers. The number of cockroaches in a wall v oid can be exacerbated by treatments outside of the wall with repellent insecticides (Ebeling 1978). Treatment inside such voids with long lasting residual insecticides would likely remedy the situation and prevent future infestations (Ebeling et al. 1969) Because cockroaches can be readily transported inside from outside locations, applying pesticides to wall and attic voids against cockroaches is not a guarantee of freedom from infestation. It should, however, decrease the need for treating inside living spaces against them (Ebeling 1978).
24 Of the many residual pesticides available today, pyrethroids generally have higher lethal toxicities than formulations that have been relied on historically such as carbamates or organophosphorous insecticides (Valles e t al. 1999). With the advent of permethrin, the first photostable pyrethroid to show promise, interest of the agrochemical industry in pyrethroids was renewed (Soderlund and Bloomquist 1989). Pyrethroids fall into two categories, or classes, depending on t heir action on sensory nerves (Gammon et al. 1981). Type I, or cyano containing pyrethroids, elicit repetitive firing in these nerves after stimulation because of permanent binding to the voltage gated sodium ion channels. Type II, or non ciano containing pyrethroids, cause bursts of spikes being fired off due to intermittent binding of the sodium ion channels. Type I and type II pyrethroids also produce different effects on sodium channel tail currents (Soderlund and Bloomquist 1989). Cyano containing pyre throids inhibit Ca+Mg ATP hydrolysis in American cockroaches better than non cyano containing pyrethroids (Clark and Matsumura 1987). Intermediates of type I and type II pyrethroids have intermediate effects, which supports the idea that one major physiolo gical target is being affected. Primary target sites for types I and II are likely sodium ion channels. Because interruption of the neuroendocrine system, which is calcium dependent, by low concentrations of pyrethroids has been implicated as one of the fa ctors contributing to irreversible toxification, calcium ion channels could also be a minor target (Soderlund and Bloomquist 1989). Though pyrethroids interact with several neurochemical processes, not all of these interactions are likely to be involved wi th disruption of nerve function (Soderlund and Bloomquist 1989).
25 Because of the heavy use of pyrethroid insecticides, resistan ce to these chemicals is becoming more and more of a problem for some pest species ( Potter et al. 2014 ). Within cockroaches, pest icide resistance is primarily known in the German cockroach, probably owing to a short lifecycle and heavy insecticide exposure, as compared to other cockroach species such as P. americana (WHO 1999). Because of the constant battle with insecticide resista nce development, more and more pest control professionals may turn to desiccating dusts (Potter et al 2014). With the mode of action of sorptive dusts being mechanical, it is not likely that resistances will develop (Tarshis 1959 Potter et al. 2014 ). Addi tionally, though some c onventional insecticides cause more rapid knockdown than desiccating dusts, death may not be as quickly accomplished by conventional treatments as by highly sorptive dusts (Ebeling and Wagner 1961). A comparative study between 20 con ventional insecticides and two silica gel desiccant dusts showed that these two dusts were superior in their overall insecticidal capabilities (Tarshis 1959). Despite the benefits of desiccating dusts, their efficacy can be diminished under certain circum stances. For example, while desiccating dust residues are wet, the time required to affect 100% cockroach mortality increases, indicating a decrease in insecticidal efficacy. If dust residues become wet, extra time should be allowed for pest populations to decrease (Tarshis 1959). Stagnant air and humidity may also decrease sorptive dust efficacy (Ebeling and Wagner 1959). In the high moisture and humidity environment of a sewer system, microencapsulated chlorpyrifos spray provided one year of protection ag ainst American cockroaches whereas silica gel with synergized pyrethrins only provided one month of insecticidal activity (Rust et al. 1991).
26 The addition of ammonium fluorosilicate to silica gel does not increase speed of insect dehydration upon contact, but seems to be more effective than non fluorinated silica under conditions of high humidity or available surface moisture. It is presumed that this increase in insecticidal efficacy is caused by the activation of fluoride because of the presence of availa ble water (Ebeling 1971). If silica gel deposits are wet, the presence of fluoride in the silica is important for 100% mortality (Ebeling and Wagner 1959). This is likely due to silica particles not being available, being adhered to the substrate too tight ly (Appel et al. 2004). Fluorinated silica gels have an advantage over non fluorinated silica products in that fluorination imparts to the particles a positive charge, which helps bind particles to insect cuticle. This advantage is lost, however, if fluori nated silica gel is exposed to open air for more than two or three months. Also, the same benefits obtained by adding ammonium fluorosilicate to silica gel are not seen against all arthropods (Ebeling 1971). Ingestion of silica gel is not required for it t o be effective. Insects need merely to crawl over a dusted surface, obtaining some of the dust on their cuticle for the dust to be effective (Tarshis 1959). Not all insects will be able to pick up lethal doses of silica gel when only thin deposits are left on surfaces. For example, cockroaches require their bodies, not just their feet, to contact the powder in order to obtain a lethal dose. When thicker deposits are required, using water as a carrier instead of applying a dry dust can be done. When water is used as a carrier, however, less of the dust deposit will be available to passing insects once dry because of caking. Solvents used as carriers allow for dust deposits that are more available to insects, but present possible explosion or health hazards (E beling and Wagner 1959).
27 Sorptive dusts have been shown over time to be more insecticidal than abrasive dusts (Ebeling and Wagner 1959). Diatomaceous earth is both abrasive and sorptive but is inferior to silica aerogels in their capacity to desiccate ins ects. As an example, grain infesting beetles should be particularly susceptible to abrasive desiccants, but sorptive dusts still desiccate them more quickly (Ebeling 1971). Field tests have been done using sorptive dusts against oriental, German, and brow nbanded cockroaches, each with great success. No field tests have been done using sorptive dusts against American cockroaches, but lab tests indicate that treatments like those used against oriental cockroaches in the field should be as effective against A merican cockroaches (Tarshis 1959). T o test for improvement of efficacy of several toxicants, Ebeling and Wagner (1961) mixed insecticides such as Dibrom, DDVP, malathion, parathion and Dylox into inert but sorptive dust diluents. It was discovered that these sorptive dusts as carriers did not always increase efficacy, and sometimes, decreased efficacy significantly. Specifically, sorptive dusts decreased effectiveness of organophosporous toxicants, did not increase or decrease effectiveness of lindane a nd increased the effectiveness of Sevin on German and brownbanded cockroaches. In a separate experiment, Ebeling (1971) treated wood blocks with five chlorinated hydrocarbon insecticides in combination with three different sorptive dusts as carriers. He ap plied the same chlorinated hydrocarbon insecticides to other pieces of wood without dust carriers and hung all wood pieces in an attic for 17 months. After this time, only those wood pieces that w ere dusted had any effect on drywood termites ( Incistermes m inor ) Additionally, it was discovered that the more sorptive the dust carrier, the faster the termites died.
28 Based on the literature reviewed herein, desiccant dusts can be used as carriers of toxicant pesticides to provide long term insecticidal activity in wall voids. American cockroach populations should be controllable by limiting access to harborage, food and water, but when these are not feasible or possible, chem ical treatments may be effective
29 CHAPTER 3 LONGEVITY OF STARVED, WATER DEPRIVED AMER ICAN COCKROACHES IN WOOD HARBORAGES AT VARIOUS WOOD MOISTURE LEVELS American cockroaches are considered pests due to their ability to mechanically vector pathogens (Rueger and Olsen 1969, Fathpour et al. 2003, Pai et al. 2005 ) cause allergic reactions (Be rnton and Brown 1964, Gelber et al. 1993 ) and damage food and some househ old items including clothing and footwear (Takahashi 1924, Nigam 1933 ) Preventing populations of these cockroaches from grow ing in and around homes is an important measure in protec ting health and property Being able to identify conditions conducive to infestation is critical to the success of a program aimed at controlling American cockroach populations. American cockroaches are peridomestic (Fleet et al. 1984) living and breeding in outdoor locations such as palm trees and decayin g maple trees (Gould and Deay 1940 ), but will move inside when conditions outsid e may not be favorable (Pope 1953 ). Once inside, Ameri can cockroaches act as domestic cockroaches (Seelinger 1984 ) harborin g in dark, da mp and protected areas (Bell and Adiyodi 1981 ) such as wall voids, especiall y those that are moist (Owens and Bennett 1982, Benson 1987, Appel 1997 ) While in wall voids, food and water sources for the cockroaches may be limited. Ameri can co ckroaches are known to consume paper (Nigam 1933, Wharton et al. 1965, Gijzen et al. 1994 ) which is found on t he back of drywall (Ferguson 2012 ) There are several cockroach species that are known to eat wood (Wharton et al. 1965, Scrivener et al. 1988, K lass et al. 2008 ). American cockroaches may also be able to eat wood or other wood products besides paper It is important to find out how long American cockroaches may be able to live in wall voids and what factors help determine their
30 longevity includin g dependence on wood moisture and their ability to consume cellulosic material The main goal o f this study was to analyze the ability of American cockroaches to survive without food or water in wood harborages at various wood moisture levels. Three resea rch objectives addressed this goal: a) discover the relative humidity inside experimental units at 0, 5, 10, 15, 20, 25 and 30% wood moisture b) discover optimum and suboptimum wood moisture levels for American cockroach survival at various life stages, a nd c) determine amounts of wood consumed by American cockroaches under these same test conditions th rough weighing fecal pellets composed of wood post mortem Materials and Methods Insects American cockroach 1st instar nymphs, 3rd 4th instar nymphs and ad ults were collected from laboratory colonies for this study. All cockroaches had been maintained in the Urban Entomology laboratory located at the University of Florida in Gainesville, Florida. Cultures of American cockroaches have been kept in colony at t he University of colonies remained in the rearing room under the following controlled conditions: approximately 26 o C, 55%RH and 12:12 h (L:D) photoperiod. Colonies were ke pt in large glass jars (25 cm height by 22.5 cm diameter) covered with a cloth lid secured by an elastic band. The cockroaches could seek refuge within various cardboard harborages, were fed dry dog food (Pedigree Puppy, Mars Inc., McLean, VA), and provid ed with water. Ultimate instar nymphs were separated out into a jar where they were reared to adulthood under the conditions aforementioned. Adults used in this experiment were
31 drawn from this separate jar before reaching two weeks of age. Oothecae were al so kept in a thrid jar under the conditions aforementioned from which 1st instar nymphs were collected. Harborages Untreated white pine 2X4 studs (Home Depot Model # 161640) were cut to 9 X 9 X 3.8 cm with one 5.4 cm hole drilled to a depth of 1.5 cm in th e center. Four 0.6 cm holes were drilled per block, one into each corner of the block, creating small wells into whic h water could be pipetted (Figure 3 1 ). Prepared blocks were oven dried at 104 o C for 2 days, weighed, and then placed into Ziploc quart s ized freezer bags to prevent uptake of atmospheric moisture. Using the pre drilled wells, the blocks were wetted to 0, 5, 10, 15, 20, 25 or 30% wood moisture, relative to oven dry, and left to allow uniform water absorption for four days in the plastic bag The amount of water needed per block was determined using the formula: W=WDW x WM where W=needed water in grams, WDW= wood dry weight in grams and WM=% wood moisture desired. The seven wood moisture treatments were tested against the three life stage gro ups: 1st instar, 3rd 4th instar and adult. There were five replicates of each life stage group/treatment combination, making a total of 105 experimental units and 105 cockroaches used. Bioassay Cockroaches were anesthetized and then placed singly inside o f the wetted wood block harborages using featherweight forceps. Adult cockroaches were sexed before placement into harborages. Pre cut circles of acetate paper (3M Dual Purpose Transparency Film #CG5000) were placed over the harborages and secured with sta ndard staples and an office stapler to prevent the cockroach from leaving the
32 harborage. The harborage unit was then secured in the plastic bag and weighed. To maintain constant wood moisture, this baseline weight was maintained weekly by the addition of w ater to the corner wells as needed throughout the duration of the experiment. Adding water to the corner wells allowed for wood moisture to be kept near constant while preventing the water added from becoming directly available to the cockroach within the block. On a weekly basis, wood moisture was measured gravimetrically and water was added as needed to reestablish the baseline weight, thus maintaining the intended moisture level. Water added ranged from 0.9 g for 30 25% wood moisture blocks, to 0 g for 0 5% wood moisture blocks. No food or available water was provided inside the wood harborages. Relative humidity and temperature were measured by placing Onset HOBO Data Loggers (U10 003) into selected bags with the blocks and cockroaches (one data logge r per moisture level per life stage). Mortality was assessed daily until all individuals were dead. Cockroaches were considered dead if unable to right themselves within 10 seconds after being flipped onto their dorsum. After the death of the last cockroac h, each block was removed from its bag and placed in an oven at 104 o C for two weeks. After being removed from the oven, the acetate paper was removed and cockroach dry body weight and fecal pellet dry weight were measured using a Mettler To ledo scale (Mode l MS105DU), and aluminum weigh boat s (Fisherbrand TM Cat alog No. 08 732 106). Fecal pellets were analyzed microscopically for wood content. Only f ecal pellets composed of wood were i ncluded in the measurements (Figure 3 2 ).
33 Analysis This experiment was a random block design. Three analyses of variance (ANOVAs) were conducted to determine: 1) the effect of wood moisture content on longevity, in days, for each of three life stages (1st instar nymphs, 3rd 4th instar nymphs and adults) of the American cockroac h, 2) the effect of cockroach longevity, while starved and water deprived, on cockroach dry body weight at mortality, and 3) the tests were used to separate means as sign ificant differences in outcomes were detected by the ANOVAs. The significance of the difference between male and female adult cockroach rate of wood consumption (feces weight at mortality/days lived) was determined using a t test. Longevity data were log t ransformed and feces production per day data were square root transformed for analysis P values 0.05 were considered significant. All statistical analyses were completed using JMP version 12.1.0. 2015 SAS Institute, Inc. Results Wood moisture had a significant impact on the longevity of 1st instar nymphs (F=62.8033; df=6; p<0.0001), 3rd 4th insta r nymphs (f=21.5101; df=6; p<0.0001) and adults (f=9.7070; df=6; p<0.0001 ) (fig. X) According to a connecting letters report for this data set, there were significant increases in longevity between the 5 and 20% wood moisture levels for 1st instar nymphs. There was no significant increase in longevity from 20% to 30% wood moisture within the same age group. By the same report, there were significant increases in longevity between 0 and 15% wood moisture for both the 3rd 4th instar nymphs and adults, but no significant increases in longevity between 15 and 30% wood moisture fo r these two age groups ( Figure 3 3 ).
34 No 1st instar nymphs were able to survive one full day with the 0% or 5% wood moisture treatments. The longest lived cockroach for each life stage w as in the 25% wood moisture treatment, at 25 days for 1st instar nymphs, 104 days for 3rd 4th instar nymphs and 53 days for adults. Except for the 0% wood moisture treatment, 3rd 4th instar nymphs survived longer than 1st instar nymphs or adults. The longe vity trends of 1st instar nymphs within 25 and 30% wood moisture treatments were very similar. The longevity trends of 3rd 4th instar nymphs between 20 and 30% wood moisture treatments were similar and distinctly separated from the longevity trends of the four lower wood moisture treatments for the group. For the adults within the 15, 20 and 30% wood moisture treatments, 20% survivorship was reached within 21 24 days. Only the longevity of the 25% wood moisture group was consistently higher for the adults ( Figure 3 4 ) Wood moisture levels between 0 and 30% resulted in relative humidity values ranging from 15% to 98%. Wood moisture levels between 15 and 30% resulted in relative humidity levels >89% for all three cockroach life stages tested. Poor wood moist ure (0%) resulted in all life stages dying in 1 2 days. For 1st instar nymphs in 10 and 15% wood moisture treatments, or 72 89% relative humidity, the first cockroaches started dying by day 3. At the highest relative humidity levels (97.8 98%), 1st instar nymphs began dying between days 9 and 15. Mortality of 3rd 4th instar nymphs began between days 4 and 7 in the 42 73% relative humidity range, and between days 32 and 42 in the 96 98% relative humidity range. Adult cockroaches in the 47 to 77% relative hum idity range started dying at day 4. At the 97% relative humidity level, adults began dying between 8 and 24 days ( Table 3 1 ).
35 Dry body weight of cockroaches was lower for individua ls that lived longer. This was significant for 3rd 4th instar nymphs (f=27.6 1; df=1; p<0.0001) and adults (f=6.30; df=1; p=0.0172) but dry body weight of 1st instar nymphs was not measured due to their extremely small size. Fecal weight also was not measured for 1st instar nymphs due to no fecal material being found in their block s. Longevity significantly affected the amount of wood fecal pellets produced for both 3rd 4th instar nymphs (f=323.2171; df=1; p<0.0001) and adults (f=523.0593; df=1; p<0.0001) by mortality Dallin visually observed a decrease in body mass of the 3rd 4th instar nymphs and adults while fecal pellets composed of wood continued to be produced. As longevity increased, dry body weight at mortality tended to decrease for both 3rd 4th instar nymphs and adults according to the line equations Y=61.96 0.4441*X and Y =199.1 2.466*X, respectively. Conversely, as longevity increased, dry fecal weight at mortality tended to increase for both 3rd 4th instar nymphs and adults according to the line equations Y=0.706+0.2077*X and Y=6.569+0.483 9*X, respectively ( Figure 3 5 ) B etween all wood moisture levels combined, adult male cockroaches produced significantly more fecal pellets composed of wood, while alive in their harborages, than did adult females (t=2.49; df=1; p=0.0202), at a ratio of 2.3/1. Discussion For cockroaches t hat harbor in wood voids when food and water are not available, wood moisture is important for survival. In the present study, it was discovered that wood moisture positively influenced longevity of American cockroaches in wood voids. This result was not a direct consequence of wood moisture but rather relative humidity imparted by respective wood moisture levels. Other studies have looked at the effect of relative humidity on longevity of starved, water deprived
36 cockroaches, but have not looked at the impa ct wood moisture has on longevity. Termites depend on moisture in the wood they ingest for survival ( McManamy et al. 2008). Some stored product pests are able to increase their body water content from ingesting grains with low moisture content (Bhattachary a et al. 2003, Benoit et al. 2005). American cockroaches are not known to consume raw wood as a food source, but wood moisture is nevertheless key to their differential survival while deprived of food and drinking water. Wood moisture had an effect on rela tive humidity within the experimental units used. Over the range of wood moisture levels used in this study (0 30%), corresponding changes in relative humidity were discovered. However, the stepwise change in wood moisture employed did not result in stepwi se increases in relative humidity. Indeed, relative humidity resulting from wood moisture levels between 20 and 30% did not vary by more than about 3%. This was true for all three cockroach life stages tested. However, relative humidity changed greatly thr ough increasing wood moisture between 0% and 15%. The water in the white pine used for these wood harborages was continuously in flux with the air immediately around the blocks, following bidirectional diffusion, with all but the bottom faces of each block being available for evaporation. to the wood and within each bag (Droin et al. 1988). 1st instar nymphs have an optimal and suboptimal relative humidity, which depe nds on wood moisture level. Dambach and Goehlen (1998) assessed the longevity of 1st instar German cockroaches under various relative humidity levels in plastic containers and found that humidity played a key role in the survival of these
37 cockroaches when starved and deprived of water. They recorded 1st instar German cockroaches living up to 9 days under 2% relative humidity and up to 11 days under 22.5% relative humidity. This contrasts sharply with the longevity of 1st instar American cockroach nymphs in conditions of 15 to 41% relative humidity in the present experiment, which all lived less than one day. Additionally, 1st instar German cockroach nymphs in the 1998 study lived up to 18 days at 50.5% relative humidity and more than 30 days at 75.5% relativ e humidity. None of the 1st instar American cockroach nymphs in the present study lived beyond 25 days, even under 98% relative humidity. The disparity in longevity between American and German cockroach 1st instar nymphs may be explained by the difference in cuticluar permeabilities between the species. Appel et al. (1983) measured the cuticular permeability of adult male German cockroaches to be about 20 g/cm 2 /hr/mmHg and that of adult male American cockroaches to be about 54 g/cm 2 /hr/mmHg. The authors suggest that cockroach species with lower cuticular permeability are better adapted to xeric environments than those with high cuticular permeability. Ame rican cockroaches are therefore less capable of withstanding desiccation than German cockroaches. Relative humidity levels between 95 and 98% in the present study allowed 1st instar American cockroach nymphs to live the longest. This range of relative hum idity was provided by wood moisture contents between 20 and 30%, indicating this range to be optimal for the survival of 1st instar nymphs. Wood moisture levels below this are suboptimal for their survival. The optimal relative humidity range for survival of the other life stages of the American cockroach may differ from that of the 1st instar nymphs.
38 Tucker (1977) indicated that older cockroach nymphs could live longer than younger nymphs under food and water deprivation conditions due to lipid reserves in the fat body. The cockroach fat body has been likened to the vertebrate liver in function, These reserves are used for fuel and water under conditions of starvation and water de privation. Tucker (1977) explained that older nymphs should have accumulated more lipid reserves than younger nymphs. It is possible, therefore, that 3rd 4th instar nymphs of the American cockroach could be less susceptible to dehydration and starvation th an 1st instar nymphs. Results of this study indicate that this is indeed the case. For all wood moisture levels and accompanying humidity levels, 3rd 4th instar nymphs lived longer than 1st instar nymphs. Of the 35 nymphs in the 3rd 4th instar range, five were observed to have molted within the first week of being placed into their harborages. These were within the 5, 10 and 15% wood moisture treatment groups. It is possible that individuals in the higher wood moisture groups also shed, but consumed the co mplete exuvium. With all instances of shedding taking place within a matter of six to seven days following placement in blocks, it is possible that the nymphs that molted were close to molting before being isolated. Starvation and water deprivation arreste d the development of the nymphs. While cockroach nymphs will molt until adulthood, adult cockroaches do not continue to molt. The development time of American cockroach nymphs varies with several environmental conditions, but can take almost two years in t otal, with anywhere from 6 to 13 molts occurring during the process. Adult female American cockroaches
39 can live over three years. Under normal conditions, the adult stage lasts longer on average than any of the nymphal stages (Bell and Adiyodi 1981). Under suboptimal conditions, adult cockroaches may not live longer than nymphal stages. While starved and water deprived in the present study, adult cockroaches lived longer than 3rd 4th instar nymphs under 17 47% relative humidity. However, relative humidity l evels between 77 and about 98% allowed 3rd 4th instar nymphs to live longer than adults under the same starvation and water deprivation conditions. The difference in longevity may be due to uric acid and urate salts replacing lipid reserves in the fat body (Tucker 1977, Park et al. 2013). No significant difference in longevity was found for the adults between 15 and 30% wood moisture levels, or 90 to 98% relative humidity. This suggests that this high range of wood moisture and accompanying relative humidit y is optimal for the survival of adult American cockroaches. While provided with food and water, cockroaches will produce fecal material as a part of the digestive process. Without food, feces production should cease. The cockroaches in this study were de nied food and available drinking water, yet were observed to be producing fecal pellets throughout the experiment, with the exception of 1st instar nymphs. These pellets were analyzed microscopically and discovered to be composed of wood fragments. By asso ciation, it is clear that the 3rd 4th instar nymphs and adults were consuming wood. The 1st instar nymphs may have failed to consume wood due to a lack of cellulose digesting endosymbionts, which would necessarily be acquired through coprophagy (Cruden and Markovetz 1984, Watanabe and Tokuda 2010) and they were never exposed to older cockroaches (see Materials and Methods). Alternatively, the wood available could have been too difficult for very small nymphs to
40 bite through, though no work has been done to ascertain the bite force of young cockroaches (Weihmann et al. 2015). The 3rd 4th instar nymphs and adults in this study were chewing wood and ingesting it instead of leaving chewed fragments behind. Carpenter ants are known to chew wood for the sake of e xcavating galleries, but this activity does not involve the ingestion of wood. The wood particles removed are discarded instead because wood is nutritive food item for A merican cockroaches ( Scrivener et al. 1998 ). The cockroaches chewing the wood in which they harbored could be an attempt to escape. If this were the case, leaving the chewed wood fragments behind, could be expected. However, cockroaches are known to chew a nd ingest several items that may be considered non food including clothes, boots, paper, hair, books (Nigam 1933) and wire insulation (Appel 1995). No work has been done on the ingestion of raw wood by American cockroaches. It is known that American cockro aches possess enzymes necessar y to break down cellulose. S ome argue these cellulases are endogenous (Wharton et al. 1965, Slaytor 1992, Genta et al. 2003). The well developed foregut and midgut of the American cockroach could indicate that cellulose digest ion takes place via endogenous cellulases, however, the species does not have a hindgut as well developed as Panesthia spp. (wood feeders), indicating that these enzymes for cellulose degradation could be endogenous (Watanabe and Tokuda 2009). Regardles s o f potential cellulase sources, cockroaches in this study los t more body weight before death the longer they lived, indicating that the cockroaches were not
41 able to convert the cellulose from the wood they consumed into enough useable energy, if any at all ( Figure 3 5 ) Gijzen et al. (1994) conclude that, based on endogenous FPase (an enzyme that degrades filter paper) activity in the hind gut of P. americana, adults of this species could digest about 2 mg of cellulose per day. White pine, as used for harbor ages in this experiment, contains approximately 60% cellulose (Mahood and Cable 1922). Dividing the dry weight of wood fecal pellets by the number of days lived in the wood harborages, it is evident that the cockroaches in this study consumed on average ju st less than 2 mg of cellulose per day. It is unknown if this amount of cellulose digestion would be sufficient for daily nutritional needs. If cockroaches consume sufficient nutritive material, it is expected that their body weight will be at least mainta ined. Throughout the test period, adult and 3rd 4th instar nymphs continuously lost weight the longer they lived, despite consuming wood from their harborages continuously. The fecal pellets produced from the consumption of wood appeared to contain whole, undigested fragments of chewed wood ( Figure 3 2 ). Wharton et al. (1 965b) showed that adult female American cockroaches chewed filter paper, especially before producing oothecae, and that some of the paper ended up shredded on the floor of the cage while m uch of it was ingested. This took place despite available Purina Laboratory Chow, chicken eggs and carrots. Even though adult males were never observed chewing the filter paper, they excreted more cellulase in their feces than the adult females In the pr esent study, males were found to produce more wood fecal pellets than females relative to the amount of time they lived in their wood harborages, indicating that males ate wood more readily than females ( Figure 3 6 ) It is important to note that while the cockroaches in this study were deprived of food and
42 water, the cockroaches in the Wharton et al. (1965b) study were not. There are likely different reasons for each sex of the adult American cockroach to chew wood or paper, though it is not possible to dis cuss with certainty any reasons within the context of this research, indicating a need for additional research on the subject. Relative humidity as determined by wood moisture level in a harborage is important for cockroach survival. This study identified wood moisture levels that are optimum and suboptimum for American cockroach survival at various life stages. It was also discovered that the longer the cockroaches could survive without alternative food sources in a wood void, the more wood they would con sume. At higher wood moisture levels, cockroaches could live longer and consume more wood. According to the results of this work, American cockroach population increase would not be likely inside of a wood harborage, such as a wall void, when wood moisture is below 15%. Importantly, this wood moisture level is within the range conducive to termite infestation (12 20%). It is recommended that wood moisture levels in walls be kept below this range for the sake of termite management (BASF 2004, Orkin 2017), th erefore appropriate low wood moisture levels in wall voids will help in the management of both termites and cockroaches.
43 Table 3 1. Days to mortality for starved and water deprived 1st instar nymphs 3rd 4th instar nymphs and adult American cockroaches at 0 30% wood moisture and resulting relative humidities. Days to Mortality % Wood Moisture % Relative Humidity + SE Range Median 1st instar Nymphs 0 15.0 + 0.9 1 1 5 41.5 + 1.1 1 1 10 72.8 + 1.1 3 14 3 15 89.0 + 1.6 3 8 7 20 95.3 + 0.9 10 15 13 25 97.8 + 1.2 9 25 18 30 98.0 + 1.9 15 24 16 3rd 4th instar Nymphs 0 15.1 + 0.9 2 6 6 5 42.2 + 1.3 4 30 6 10 73.1 + 1.1 7 40 30 15 89.3 + 1.7 27 56 39 20 96.0 + 1.4 41 89 57 25 97.9 + 1.0 32 104 63 30 98.1 + 1.9 42 93 71 Adults 0 17.7 + 2.9 2 9 4 5 47.0 + 1.8 4 17 1 4 10 77.5 + 1.3 4 36 17 15 90.3 + 1.3 17 32 22 20 96.7 + 1.4 15 27 21 25 97.0 + 1.4 24 53 29 30 97.8 + 1.9 8 38 22 All individuals died within the first day
44 Figure 3 1. Wood block harborage with acetate paper circle stapled over the top and a 1st i nstar nymph inside Four holes were used as wells for increasing wood moisture Photo by Dallin Ashby F igure 3 2 F ecal pellets of an adult American cockroach, derived from standard cockroach diet (left) and white pine ( collected from the wood harborage in whi ch it lived while deprived of food and water. Fecal pellets composed of wood were much lighter in color than pellets derived from standard cockroach diet. They also contained visible wood fragments throughout. Photo by Dallin Ashby. Harborage Well Standard Diet White Pine
45 Figure 3 3 Mean long evity in days of 1st instar nymphs (A) 3rd 4th instar nymphs (B) and adults (C) of American cockroach es living in wood harborages at different moisture levels. Means within each life stage group followed by the same letter are not significantly different (p < test, JMP 12.1.0, 2015) A B C
46 Figure 3 4. Longevity of 1st instar nymphs (A), 3rd 4th instar nymphs (B), and adults (C) of the American cockroach while starved and water deprived in wood harborages of various wood moisture levels. A B C
47 Y=0.706+0.207 7 *X R 2 =0.486 Y=61.96 0.4441*X R 2 =0.456 Y=199.1 2.466*X R 2 =0.391 Y=6.569+0.4839*X R 2 =0.152 A B
48 F igure 3 5 Linear fit of fecal pellet (composed of wood) and body weight s post mortem, of starved and water deprived 3rd 4th instar nymphs (A) and adults (B) of the American cockroach Figure 3 6 Mean weight of wood composed fecal pellet s (feces weight at mortality/days lived) produced by starved, water deprived male (M) and female (F) American cockroaches (t=2.49, p=0.0202, t test, JMP version 12.1.0, 2015). 0.18 0.42
49 CHAPTER 4 EFFICACY OF POSSIBLE PRECONSTRUCTION WALL VOID TREATMENTS AGAINST AMERICAN COCKROACHES, SILVERFISH AND FLORIDA CARPENTER ANTS The ability of American cockroaches to access and infest wall voids has bee n established (Owens and Bennett 1982 ). O ther insects are also known to infest wall voids including c arpenter ants and silverfish Flori da carpenter ants can access wall voids during active f oraging ( Ebeling et al. 1969 ) and nests can be found inside of wall voids (Fowler 1986 ). Though carpenter ants do not consume the wood in which they harbor, they can nevertheless exa cerbate dama ge already done by fungus or other insects ( Warner and Scheffrahn 2002 ). Silverfish may access wall voids, seeking shelter (Ebeling et al. 1969 ) and potentially food, feeding on the paper (Morita 1926 ) on the drywall that is exposed within wall voids of wo od frame structures ( Ferguson 2012 ). Also, an association of an unknown species of silverfish with Florida carpenter ants has been documented (Davis and Jouvenaz 1990). Appel (1997) suggested that cockroach wall voi d infestations are avoidable by making s uch harborages unsuitable for habitation. The author also pointed out that post construction treatments such as foam applications to wall voids can be expensive and may not be cost effective. Preconstruction treatments against wall void infestations shou ld ideally remain effective for up to five years, equal to the requirements in place for preconstruction termiticide treatments ( Florida Bureau of Entomology and Pest Control 2013 ). Ebeling et al. (1967) indicate d that dusting wall voids could lead to long term control due to the inert nature of desiccant dusts The application of desiccant dusts as spray formulations during building construction is possible, though studies indicate that
50 knockdown of cockroaches might take more time after exposure to a dust that has been applied wet vs. a dust that was applied dry (Tarshis 1959) With wood being a common building material in wa ll voids (Understand Building Construction 2017) and Am erican cockroaches, silverfish and Florida carpenter ants being known to inf est wall voids, the present study aimed to test the efficacy of potential pre construction treatment s to wood framed houses against these insects Three research objectives in two experiments addressed this goal: a) determine the relative efficacy of Arilo n Phantom applied as a spray to wood, either as stand alone treatments or in combination with against silverfish, Florida carpenter ants and/or American cockroaches, b) determine the effect of the addition of on the longevity of Arilon Phantom and c) discover differential effects of the treatments listed on the three species listed. Materials and Methods Insects Ameri can cockroach 3rd 4th instar nymphs were collected from la bora tory colonies for two independent studies as described throughout this chapter All cockroaches had been maintained in the Urban Entomology laboratory located at the University of Florida in Gainesville, Florida. Cultures of American cockroaches have been provided these cockroaches. Laboratory colonies remained in the rearing room under the following controlled conditions: approximately 26 o C, 55%RH and 12:12 h (L:D) photoperio d. Colonies were kept in large glass jars (25 cm height by 22.5 cm diameter) covered with a cloth lid secured by an elastic band. The cockroaches could seek refuge
51 within various cardboard harborages, were fed dry dog food (Pedigree(R) Puppy, Mars Inc., Mc Lean, VA), and provided with water. Silverfish ( Lepisma saccharina ) were coll ected from lab raised colonies. Colonies have been maintained in the Urban Entomology laboratory located at the University of Florida in Gainesville, Florida under controlled co nditions: approximately 26 o C, 55% RH and 12:12 h (L:D) photoperiod Stock cultures originally obtained from the USDA have within the laboratory storage room. Silverfish were reared in clear Sterilite TM totes (part number 18468010) measuring approximately 59 cm long x 43 cm wide x 16 cm deep with white lids. The sides of the totes were lined with petroleum jelly, on the inside and outside, to prevent escape as well as entrance by ant s or other insects. The entire bottom of each tote was lined with paper towe ls to provide traction Flat pieces of cardboard of various dimensions were stacked from 12 to 15 pieces high in the middle of each tote. T ongue depressors were used within the hig hest half of the cardboard stack to provide space between individual pieces of cardboard A bout 12 cardb oard tubes of various lengths, with diameters ranging from 1.5 to 4 cm, were also provided as harborage along the length s of the totes. Food consisted o f chicken pellets and egg noodle dry pasta, though paper and cardboard consumption was common. Chicken pellets (Purina Layena Pellets, Purina Animal Nutrition LLC, Shoreview, MN) were offered whole and ground. Similarly, egg noodle pasta (Publix wide egg noodle pasta, Publix Asset Management Company, Lakeland, FL) was offered in fragments sieved to size #12 or ground. Dry food was placed on paper towels one teaspoon per food type in each end of the tot e, making two teaspoons of each food type placed every two weeks. Water was provided
52 by placing two water filled vials with cotton stoppers into each tote. Water was only provided between December and May of each year to prevent excess moisture within the totes during summers. Small and mid sized individuals w ere not taken for this experiment, only large individuals. Silverfish were harvested by tapping parts of their cardboard ha rborages over plastic deli cups so that forceps were not needed. Florida Carpenter Ants ( Camponotus floridanus ) were collected fro m lab raised colonies that had been maintained at the University of Florida in the Urban Entomology laboratory since July of 2015. The colony was maintained in plastic bins (Panel Controls Corp., Detroit, MI) (41 cm long x 38 cm wide x 11.5 cm high) lined wi th Fluon (BioQiop Products, Rancho Dominguez, CA). Cells used for harborages were made of plastic Petri dishes interiorly lined with dental stone (Castone, DENTSPLY International Inc., York, PA) and topped with red cellophane to reduce light intensity. Th e ants were provided the three major macronutirents, lipids, proteins, and carbohydrates, in various food sources. Once a week, food trays were refilled with fruit, eggs, jelly, honey and dead insects, which typically comprised of cockroaches or crickets r eared on site. Ants were also supplied both tap and sugar water and were maintained at approximately 25 o C, 50% RH, and on a 12:12 H (L:D) cycle. Ants were harvested for use in this experiment with featherweight forceps to reduce potential harm to the insec ts. Wood Blocks Wood blocks were created using untreated white (Home Depot model# 687642). These were cut to the dimensions of 9 cm by 9 cm by 1.8 cm each. Sixty milliliter deli cups (Dart Conex clear portion containers, s tock number 400PC, Dart Corp., Mason, MI) were used to contain the insects on the treated wood surfaces. Deli cups were secured in place by rubber bands. The cups for the
53 surface treatment experiment ( Arilon Phantom alone and in combination with ) received a sin gle centrifuge tube (part number 3440, Thermo ScientificTM, Waltham, MA ), with the cap removed, filled with water and stoppered with cotton, and adhered to the inside edge of the cup with hot glue ( Figure 4 1 ). The cups for the wood treatment experiment ( alone and in combination with ) were not supplied with water. Treatments Surface treatment experiment The following chemicals were used in this experiment: 100% amorphous silica (Rockwell Labs Ltd., Kansas City, MO), Phantom Termiticide Insecticide 21.45% Chlorfenapyr (BASF Corporation, Research Tri Insecticide 20% Indoxacarb (E. I. du Pont de Nemours and Company, Wilmington, DE), and 7.9% Bifenthrin (FM C Corporation, Philadelphia PA) Arilon Phantom and are each broad spectrum insecticides. The pesticide label for Arilon includes cockroaches and ants (broadly) as target organisms. The labels for Phantom and include American cockroaches, carpenter ants and silverfish as target organisms. The pesticide label for CimeXa includes ants, cockroaches and silverfish (broadly). Wood treatment experiment and Wood Treatment 23.4% Bifenthrin (FMC Corporation, Philad elp hia, PA) were tested in the wood treatment experiment is labeled only for treatment of wood against wood destroying organisms. Formulations. Of the treatments used in experiments 1 and 2, f our were pesticide mixtures combining the four toxicants : Arilon Phantom ( surface treatment experiment ) ( the wood treatment
54 experiment ) T hese four toxicants were also diluted alone to act as four stand alone treatments in the same respective experiments A ninth treatment was alone which was used in both experiments The control used in both experiments was distilled water. Formula c rate of 1.438 g of powder into 12 mL of water. Totality mixed at the label rate of 0.03 mL of concentrate into 11.97 at the high label rate of 0.05 mL into 12 mL of water. Phantom was mixed at the high label rate of 0.29 m L into 12 mL of water. Arilon was mix ed at the high label rate of 59 mg into 12 concentrates into a single 12 mL volume of water. An airbrush (P aasche H#3 airbrush with A 1/8 6 hose Paasche Airbrush Company, Chicago, IL ), set to 25 PSI, was used to apply ea ch treatment to one face of the prepared wood block s at the rate of 0.35 mL/M 2 which is the point of surface saturation. Accelerated A ging In experiments 1 and 2, t reatments on wood blocks were artificially aged us ing the oven heating method described by the EPA (2012) wherein two weeks in an oven at 54 o C + 2 o C was equivalent to one year of chemical degradation. This protocol wa s based on the Arrhenius equation, k=Ae Ea/RT where k is the constant representing the ra te of reaction T is the absolute temperature in Kelvins under which the reaction occurs, A is the prefactor, Ea is the activation energy, and R is the universal gas constant ( Laidler 1984 ). All treated blocks to be artificially aged were placed in an oven together while those to be used at one day post treatment were kept out Blocks were placed into the oven the same day as treatments were applied to them. Those to be
55 used for testing 1 year of chemical degradation remained in the oven for 2 weeks. Simil arly, those to be used for testing 2 years of chemical degradation remained in the oven for 4 weeks, and those to be used for testing 5 years of degradation remained in the oven for 10 weeks. Therefore, accelerated aging times were 0 days (used at day 1, w ithout placement in the oven), 2 weeks 4 weeks and 10 weeks. Bioassays Surface treatment experiment American cockroach 3rd 4th instar nymphs silve rfish and Florida carpenter ant majors we re subjected t o all seven treatments and the control after the fo ur accelerated aging times just described had been accomplished Mortality was assessed at 24 hours, 48 hours and 7 days after the initiation of exposure. T hree replicates of each treatment were used against each insect type with five insects per rep, for a total of 96 experimental units and 480 each of cockroaches, silve rfish and carpenter ants between all four accelerated aging times Wood treatment experiment American cockroach 3rd 4th instar nymphs were subjected to all three treatments and the contr ol after the four accelerated aging times had been accomplished Mortality was assessed at 24 hours. F ive replicates were used per treatment with five cockroache s in each replicate for a total of 80 experimental units and 400 cockroaches used between all four accelerated aging times For both experiments, m ortality was defined as the inability of the insects to hold on to the wood surface upon which they rested when oriented upside down. Analysis Both the surface treatment and wood treatment experiments were random block design. Some mortality occurred in the control groups in the surface treatment experiment, therefore mortality rates were corrected
56 1925). To compare the efficacy of the treatments in the surface treatment experiment (Arilon Phantom ), within each accelerated aging time an ANOVA was conducted per accelerated aging time with %mortality as te sts were used to separate the means ( Figure 4 2 ). To determine the efficacy of and/or against American cockroach 3rd 4th instar nymphs in the wood treatment experiment a 2 way ANOVA was conducted fo r each treatment with %mortality as the was part of the treatment or not) and accelerated aging time as the independent variables. tests were used to identify significance between levels ( Figure 4 3 ) To determine the effects of Phantom , and Arilon with or without on the mortality rates of American cockroaches, silverfish and Florida carpenter ants, a 2 way ANOVA was conducted for each insect species involved and each toxicant combination, with % mortality as the dependent variable and was part of the treatment or not) and accelerated aging time as the independent variables tests were used to identify significant differences between levels ( Figures 4 4, 4 5, and 4 6 ) For all analyses, p values 0.05 were considered significant Analyses were completed using JMP version 12.1.0. 2015 SAS Institute Inc. Results In the surface treatment experiment, p ercent mortality in the control groups varied by insect and amount of accelerated aging as foll ows. For 0 days of accelerated aging, 40%, 33.3% and 6.7% of carpenter ants, cockroaches and silverfish respectively had di ed during the experiment. For 2 weeks of accelerated aging, 66.6%, 0% and 0%
57 of carpenter ants, cockroaches and silverfish respective ly had died during the experiment. For 4 weeks of accelerated aging, 80%, 6.7% and 0% of carpenter ants, cockroaches and silverfish respectively had died during the experiment. For 10 weeks of accelerated aging, 73.3%, 0% and 6.7% of carpenter ants, cockro aches and silverfish respectively died during the experiment. Mo rtality rates between treatments in the surface treatment experiment were significantly different for 0 day s (f=4.5 019; df=6; p=0.0004), 2 weeks (f=5.0 964; df=6; p=0.0001), 4 weeks (f=14.7196 ; df=6; p<0.0001), and 10 weeks (f=25.5069; df=6; p<0.0001) of accelerated aging tests separated the means of the mortality rates as shown in Figure 4 2 Mortality rates in the wood treatment experiment were not significantly different betw een treatments at 0 day s accelerated aging (f=2.250; df= 2; p=0.1480) but were significantly different at 2 weeks (f =576.0; df=2; p<0.0001), 4 weeks (f=12 1.0; df=2; p<0.0001) and10 weeks (f=35.6296; df=2; p<0.0001) of accelerated aging The efficacy of CimeXa the wood treatment experiment was significantly different across all four accelerated aging times (f=4.1143; df=3; p=0.0243). See Figure 4 3 for separation of means. For the surface treatment experiment significant differences in mortality rate s between treatments were found within Florida carpenter ants (f=5.8350; df=6; p<0.0001), American cockroaches (f=27.9137; df=6; p<0.0001), and silverfi sh (f=15.4433; df=6; p<0.0001). Accelerated aging had a significant impact on treatments in experiments 1 (f=4.9757; df=18; p=<0.0001) and 2 (f=27.8963; df=9; p=<0.0001). The difference in mortality rates between mixed with and alone were not significantly different ( t= 1.551; df=76; p=0.1251 ) over the four accelerated aging times i n the wood
58 treatment experiment Interactions were discovered in the surface treatment experiment between accelerated aging time and treatment (f=14.2735; df=6; p<0.0001) as well as insect and treatment (f=7.9492; df=12; p<0.0001). No int eraction was found between accelerated aging time and insect (f=2.6822; df=2; p=0.0696). Discussion Insecticide treatments to wood frame members of walls c an remain effective for about five years, providing protection against some common insects that a re known to infest wal l voids. Various i nsecticide formulation treatments do not have the same levels of e fficacy either one day after application or over the equivalent of several years post application depending on formulation This is especially true relative to the presenc e or absence of amorphous silica gel in the formulation. Of the insecticides tested in this study, most retained significantly longer efficacy when m ixed with Ebeling (1971) found that five chlorinated hydrocarbon insecticides applied to wooden b locks had longer lasting insecticidal effects (aged in an attic for 17 months) on drywood termites when the pesticides had been diluted in various dusts as compared to those not diluted in dusts It was also found that the more sorptive the dust diluent wa s, the more insecticidal the residue was. In the present study, the highly desiccant dust, amorphous silica gel ( ) was found to provide a similar effect on pesticide longevity when in combination with pesticides in use today, namely Arilon Phantom and Arilon Phantom and are broad spectrum insecticides with multiple pest species indicated on their respective labels. With their differing formulations, including active ingredients (BASF 2017, DuPont 2017, FMC 2017a) mor tality rates of various insects were expected to be different across the artificial aging
5 9 intervals tested. Indeed, Phantom accelerated aging intervals while Arilon maintained its insecticidal capacity. Wit h the icantly over the four aging intervals specific pesticide (FMC 2017), the efficacy of this treatment may differ from that of broad spectrum insecticides when also applied to wood. 4th instar nymphs after 24 hours of exposure to the one day old residue. Mortality rates for this formulation were never above 25% after ju st two w eeks in the oven (one year of accelerated aging ) provided 100% mortality over the remaining aging intervals tested in this study. Differences in insecticide efficacy also existed between the insect species tested More Florida carpenter ants died in the control groups than the other two insects. O nly one insecticide ( Phantom ) caused mortality rates significantly lower than 100% for the species Regardless of treatment most ants were de ad by day two of each sampl ing interval. In contrast, American cockroaches and silverfish shared similar trends in mortality rates with Phantom efficacy against these insects over accelerated aging The mean mortality rate for Cime silverfish in the surface treatment experiment never reached greater than 80%, whereas the mortality rate against Florida carpenter ants reached 100 % consistently across aging intervals Faulde et al. (2006) found that total population eradication of American cockroaches (50 nymphs and 50 adults) could be achieved in eight days, even with food
60 and water available, when the insects were exposed to a hydrophobised diatomaceous earth (addition of 1,1,1 trimethyl N tri methylsilane), which is composed primarily of silica. Similarly, complete population (100 adults) eradication of silverfish was accomplished in nine days with the same treatment. While the American cockroach nymphs expose alone in the surface treatment experiment never suffered mortality rates above 80%, those nymphs in the wood treatment experiment experienced mortality rates as high as 100%. This disparity may be explained by the lack of available water in the wood tr eatment experiment whereas those in the surface treatment experiment had drinking water available (see Materials and Methods). caused about 100% mortality for all three insect species tested across al l a ging intervals These two broad spectrum formulations could be considered as candidates for preconstruction treatment s against wall void infestation by American cockroaches, silverfish and Florida carpenter ants. The combination of C ca used 100% mortality against A merican cockroach nymphs. T hough is a wood treatment specific insecticide this combination could also be a candidate as a preconstruction tr eatment for wall studs against cockroaches and potentially other insect s Wh ether or not the apparently allowed some of the toxicant s mixed with it to stay available o n the surface, as evidenced by the decrease in efficacy over time of toxicants not mixed with CimeXa but no decrease in efficacy over time when mixed with CimeXa F urther
61 testing should be done to determine the effect of the combination on wood destroyin g organisms as these are the targeted organisms on the label These three treatments, Arilon when mixed with CimeXa c ould provide protection for abou t five years. It is important to note that all pesticide application s and mixtures should be accomplished in accordance with label restricti ons and state and federal laws.
62 Figure 4 1. Experimental unit used to test the efficacy of insecticide treatments on wood against cockroaches, silverfish and carpenter ants. A 60 mL deli cup was secured to the treated surface of white pine with elastic bands. Photo by Dallin Ashby.
63 Figure 4 2 ortality rates of 3rd 4th instar American cockroaches, silverfish and Florida carpenter ants combined, after seven da ys of exposure to seven pesticide treatme nts on wood : Ar+Ci ( Arilon with ), Arilon Ph+Ci ( Phantom with ), Phantom Ta+Ci ( with ), and Exp osure to treatments took place after 0 day s (A), 2 weeks (B ), 4 weeks (C) and 10 weeks (D) of accelerated aging in an oven. Bars within each graph not sharing letters were significantly different. A B C D
64 Figure 4 3 M ortality rates of 3rd 4th instar American cockroaches after 24 hours of exposure to (A), Total or a combination of and (B), at 0 days, 2 weeks, 4 weeks and 10 weeks of accelerated aging in an oven. Bar pairs not sharing letters were significantly different. A B
65 Figur e 4 4 ortality rates of 3rd 4th instar A merican cockroaches a fter 7 days of exposure to alone (A), Arilon (B), Phantom (C), or (D) at 0 days, 2 weeks, 4 weeks and 10 weeks of accelerated aging in an oven. Pairs of bars not sharing letters were significantly different Graph s without letters had no significant differences. A B C D
66 Figure 4 5 ortality rates of silverfish after 7 days of exposure to alone (A), mixed with: Arilon (B), Phantom (C), or (D), at 0 days, 2 weeks, 4 weeks and 10 weeks of accelerated aging in an oven Pairs of bars not sharing letters were significantly different. Graphs without letters had no significant differences. A B C D
67 Figure 4 6 ortality rates of Florida carpenter ants a fter 7 days of exposure to alone (A), mixed with: Arilon (B), Phantom (C), or (D), at 0 days, 2 weeks, 4 weeks and 10 weeks of accelerated aging in an oven. Pairs of bars not sharing letters were significantly different. Graph s without letters had no significant differences. A B C D
68 CHAPTER 5 CONCLUSIONS This is the first study to measure the longevity of starved, water deprived American cockroaches in wood harborages and specifically measure the longevity of 1st instar ny mphs of the species under these conditio ns. Longevity was found to be correlated with wood moisture content and the resulting relative humidity levels. The highest three wood moisture le vels (20 30%) produced nearly equivalent relative humidity levels. As expected, t hose cockroaches in blocks at higher wood moisture levels and consequently higher relative humidity survived the longest. It is apparent that atmospheric moisture is an important determining factor for the longevity of American cockroaches while starved an d water deprived. Controlling the moisture levels inside of wall voids should allow for limitation of wall void infestations by cockroaches. Specifically, relative humidity levels less than 15% will not allow water deprived 1st instar nymphs and adults of the American cockroach to live beyond about two weeks. Mid instar nymphs may live 50 or more days under 15% relative humidity when water deprived. Feeding on celluslosic material by American cockroaches will also therefore decrease with lower wood moisture and consequent relative humidity. B oth 3rd 4th instar nymphs and adults consumed some of the wood in which they were kept during this research After comparing dry wood fecal pellets produced during the experiment to the longevity of the cockroaches as w ell as dry body weight at mortality, it was determined that the consumption of wood did not allow these otherwise starving cock roaches to thr ive under the aforementioned conditions. Therefore, though
69 wood feeding activity may be prolonged by high wood mois ture in a wall void, the feeding will not sustain individuals or populations. Willis and Lewis (1957) found that when cockroaches were provided food but not water, they only lived as longs as those that had no food or water. Further testing should be done to determine if cockroaches under the same conditions as in this study, which ate wood but failed to thrive, could have thrived (i.e. molt thro ugh successive life stages) if water were provided. This is of special consideration given the amount of cellulo se that Gijzen et al. (1994) calculated could be digested per day by an American cockroach, though the cellulose in that study was in the form of paper, not raw wood as in the present study. The wood used in both the longevity study at various wood moistur es and the preconstruction treat ment efficacy study was white pine though cut to different dimensions. This wood was chosen because of its common use as wall framing material ( NELMA 2005 ) In a wall void, cockroaches and other insects may be able to take advantage of warm, humid conditions for harborage, especially if there are structural problems associated that cause excessive moisture (Benson 1987). Wood in these wall voids is a major moisture sink, allowing relative humidity to stay somewhat stable (Dr oin et al. 1988). Inasmuch as wall void humidity may not always be controllable within suboptimal levels for cockroach survival pesticide application s to wall void members should be considered. The application of desiccant dusts to wall frame members cou ld help prevent infestation of wall voids by cockroaches and other insects (Ebeling et al. 1969). The present body of work has s hown that wood treated with the desiccant dust
70 three different insects known to infest wall voids, even when pr ovided with water, though mortality rates never exceeded 80% after seven days of exposure in two of three insects. Phantom and time, but w hen mixed with their efficacy wa s maintained over at least f ive years never dropping significantly below 100% mortality It is possible that this is due to acting as a matrix. It is also possible that incr eases ity to the toxicants causing prolonged efficacy though these two possible causes are not mutually exclusive. In an experiment by Ebeling et al. (1966), German cockroaches avoided mock wall voids that were treated with silica gel, but not mock wall voids treated with boric acid. Cockroaches can be repelled by desiccant dusts, which could limit the amount of exposure they have to toxicants, but the repellency of desiccant dusts could fulfill the role of making a wall void uninhabitable by insects, even if the interactions of and toxicants are mutually exclusive. The concept behind using as a termiticide is that the treatment will (up to 6 mm) and remain available fo r attacking termites for at least six years (F MC 2017). When and are combined it is not certain that enough of the will penetrate the wood to act as a termiticide while the remainder stays on the w spectrum insecticide. Further research shoul d be do ne to determine any effect might have on the usability of as a termiticide
71 Of the toxicants tested in this research, only is currently labeled as a termiticide that can be applied to wood framing. Therein lies the advan tage of mixing with The / combination was shown to be highly effective against American cockroaches, even after five years of accelerated aging. With already suitable for treatment of wood framing, the addition of to preconstruction treatments with it would help save resources, as post construction wall void treatments should be unnecessary within at least the first five years. Though the other pesticides tested ( Arilon Phantom and ) are n ot currently labeled for use as termiticides applied to wood framing, the concept of tank mixing with for improved longevity remains the same for at least Phantom and The label for Arilon indicates that it is not to be used for long t erm control of termites, but its efficacy remained high against the three insects on the the incorpor ation of
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82 BIOGRAPHICAL SKETCH Dallin Myles Ashby is the fourth of six children born to Warren and Nancy Ashby. He was born and raised in Woods Cross, Utah, where he graduated from Woods Cross High School in 2001. Shortly after graduating from high school, Dallin served a two year mission for his church to the people of the Philippine islands. Upon returning home, D allin married and began his own family, and then graduated from Salt Lake Community College with an Associate of Science degree in biology. After earning a Bachelor of Science degree in biology from the University of Utah, Dallin worked in the pest control industry as a pest control operator in Salt Lake City for about four years. Looking for new opportunities and growth, he brought his family to the University of Florida to wo rk on his Master of Science degree in entomology and nematology under the direction of Drs. Philip Koehler, Rebecca Baldwin and Roberto Pereira. While studying at the University of Florida, Dallin served as president of the Urban Entomological Society for one year, was awarded the 2016 Insect IQ scholarship and wrote an article for PestPro magazine on occasional invaders. Upon graduation from the University of Florida, Dallin immediately re entered the pest management industry to s.