Adult Male German Cockroaches Research Articles

The effectiveness of commercial gel baits against German cockroach Blattella germanica (Linnaeus, 1767) in Indonesia

Gel baits product sold commercially to the public has long been used to control German cockroach populations in urban areas. The effectiveness and resistance level of gel bait products need to be known for the successful control of German cockroaches in the field. However, there have been no reports of resistance in Indonesia. This study used toxicity tests of six gel bait products (MF, CBG, SPB, OTG, BTX, and UBA) against two populations of adult male German cockroaches (VCRU-WHO and RKMN-BKT). Fipronil, boric acid and emamectin benzoate containing gel baits were effective to knock down and kill the German cockroaches. In contrast, gel bait with imidacloprid as an active ingredient was only useful to knock down the German cockroaches. Commercial gel bait product in Indonesia are still useful in controlling German cockroaches’ populations with a time of effectiveness to cause mortality between three to four weeks after being exposed in the field and the level of cockroach resistance to gel bait are susceptible until low resistance.

Antennal grooming facilitates courtship performance in a group-living insect, the German cockroach Blattella germanica

The antennae of adult male German cockroaches detect a contact sex pheromone embedded in the female’s cuticular lipids. The female pheromone stimulates courtship behavior in males, notably a wing-raising (WR) display. Within aggregations, however, cuticular lipids are disseminated by contact among group members, including nymphs and adults of both sexes, and “contamination” of cockroaches with the cuticular lipids of another stage or sex may interfere with sex discrimination and disrupt courtship. We used behavioral observations, bioassays and chemical analysis to determine how males maintain their sensitivity to sex pheromone in aggregations. Males contaminated with female pheromone displayed lower courtship, because residual female pheromone on their antennae adapted their peripheral sensilla and habituated the central nervous system. Female pheromone that contaminated the male’s antennae also elicited courtship from other non-contaminated males, disrupting their sex discrimination in the group. However, antennal grooming effectively removed female pheromone from males’ antennae and maintained their chemosensory acuity and sexual discrimination among group members. Thus, grooming of the antennae and other sensory appendages is an important strategy to enhance sensory acuity, especially in group-living insects like the German cockroach.

Insecticidal and acetylcholine esterase inhibition activity of Asteraceae plant essential oils and their constituents against adults of the German cockroach (Blattella germanica).

The fumigant and contact toxicities of 16 Asteraceae plant essential oils and their constituents against adult male and female Blattella germanica were examined. In a fumigant toxicity test, tarragon oil exhibited 100% and 90% fumigant toxicity against adult male German cockroaches at 5 and 2.5 mg/filter paper, respectively. Fumigant toxicities of Artemisia arborescens and santolina oils against adult male German cockroaches were 100% at 20 mg/filter paper, but were reduced to 60% and 22.5% at 10 mg/filter paper, respectively. In contact toxicity tests, tarragon and santolina oils showed potent insecticidal activity against adult male German cockroaches. Components of active oils were analyzed using gas chromatography, gas chromatography-mass spectrometry, or nuclear magnetic resonance spectrometer. Among the identified compounds from active essential oils, estragole demonstrated potent fumigant and contact toxicity against adult German cockroaches. β-Phellandrene exhibited inhibition of male and female German cockroach acetylcholinesterase activity with IC50 values of 0.30 and 0.28 mg/mL, respectively.

Fumigant and contact toxicity of Myrtaceae plant essential oils and blends of their constituents against adults of German cockroach (Blattella germanica) and their acetylcholinesterase inhibitory activity

Fumigant and contact toxicities of 11 Myrtaceae plant essential oils and their constituents against adult male and female Blattella germanica were evaluated. Of 11 Myrtaceae plant essential oils, Eucalyptus polybractea, Eucalyptussmithii, Eucalyptusradiata, Eucalyptusdives, Eucalyptusglobulus, and Melaleuca uncinata, showed 100% fumigant toxicity against adult male German cockroaches at a concentration of 7.5mg/liter air concentration. In contact toxicity tests, E. polybractea, E. smithii, E. radiata, E. dives, E. globulus, Melaleucadissitiflora, and M. uncinata produced strong insecticidal activity against adult male and female German cockroaches. Of the essential oil constituents, terpinolene, α-terpinene, and terpinen-4-ol demonstrated strong fumigant toxicity against adult male and female B. germanica. Eugenol, isoeugenol, methyl eugenol, and terpinen-4-ol showed strong contact toxicity against adult male B. germanica. The toxicity of the constituent blends identified from M. dissitiflora essential oils indicated that terpinen-4-ol were major contributor to the fumigant activity or contact toxicity of the artificial blend. Only isoeugenol exhibited inhibition activity against male acetylcholinesterase. IC50 values of isoeugenol were 0.22mg/mL against male acetylcholinesterase.

Insecticidal and Acetylcholine Esterase Inhibition Activity of Apiaceae Plant Essential Oils and Their Constituents against Adults of German Cockroach (Blattella germanica)

We evaluated the insecticidal and acetylcholine esterase (AChE) inhibition activity of 11 Apiaceae plant essential oils and their constituents in adult male and female Blattella germanica. Of the 11 Apiaceae plant essential oils tested, dill (Anethum graveolens), carvi (Carum carvi), and cumin (Cuminum cyminum) demonstrated >90% fumigant toxicity against adult male German cockroaches at a concentration of 5 mg/filter paper. In a contact toxicity test, dill (Anethum graveolens), carvi (Carum carvi), cumin (Cuminum cyminum), and ajowan (Trachyspermum ammi) produced strong insecticidal activity against adult male and female German cockroaches. Among the test compounds, (S)-(+)-carvone, 1,8-cineole, trans-dihydrocarvone, cuminaldehyde, trans-anethole, p-cymene, and γ-terpinene demonstrated strong fumigant toxicity against adult male and female B. germanica. In a contact toxicity test, carveol, cuminaldehyde, (S)-(+)-carvone, trans-anethole, thymol, and p-cymene showed strong contact toxicity against adult male and female B. germanica. IC(50) values of α-pinene, carvacrol, and dihydrocarvone against female AChE were 0.28, 0.17, and 0.78 mg/mL, respectively. The toxicity of the blends of constituents identified in 4 active oils indicated that carvone, cuminaldehyde, and thymol were major contributors to the fumigant activity or contact toxicity of the artificial blend.

Toxicity of novel aromatic and aliphatic organic acid and ester analogs of trypsin modulating oostatic factor to larvae of the northern house mosquito, Culex pipiens complex, and the tobacco hornworm, Manduca sexta

Eight non-peptidic chemical analogs of trypsin modulating oostatic factor (TMOF, NH 2-YDPAP 6), an insect hormone inhibiting trypsin biosynthesis in mosquitoes, were synthesized based on the structure of the native peptide. The median lethal concentration (LC 50) for the chemical analogs, TMOF and FDPAP (a peptidic analog of TMOF) was estimated for larvae of the northern house mosquito, the Culex pipiens complex, using a static 5-day bioassay. Four of these compounds demonstrated the same larvicidal activity as TMOF, while three of these compounds were 1.2–2.5-fold more active than TMOF. The compounds introduced by injection were toxic to fourth instars of the tobacco hornworm, Manduca sexta, except for TMOF, FDPAP, and PPHEN. Injection of TMOF and FDPAP into fourth stadium and TMOF into second stadium M. sexta had no effect on trypsin activity, growth, or mortality. Apparently the mosquito hormone is inactive in the tobacco hornworm at the developmental stages examined. Three TMOF analogs (CHEA, PHEA, and PHA) demonstrating the highest activity by injection in M. sexta were also found to be toxic by injection in fourth instars of the tobacco budworm, Heliothis virescens, and the cotton bollworm, Helicoverpa zea, as well as adult male German cockroaches, Blattela germanica. A two-choice feeding bioassay with H. virescens indicated that at least one of the TMOF analogs, PHEA, has anti-feeding properties.

Effects of moisture on the toxicity of inorganic and organic insecticidal dust formulations to German cockroaches (Blattodea: Blattellidae).

Toxicity of boric acid (40-99% [AI]), silica gel, eugenol, and deltamethrin dust formulations to adult male German cockroaches, Blattella germanica (L.), was evaluated at five different relative humidities ranging from 0 to 100% and in the presence of 0 to 1 ml of water. Victor boric acid dust was generally the most toxic boric acid formulation at all relative humidities, despite having the lowest percentage (40%) of boric acid; however, this was the only formulation to have sucrose and other edible ingredients. There was no consistent effect of relative humidity on dust toxicity; LT50 values of Roach Prufe (98% boric acid), Victor, and Drione (silica gel and synergized pyrethrins) increased significantly linearly with relative humidity, whereas other formulations were unaffected. The LT50 values of all boric acid-based dust formulations declined exponentially when wetted with increasing volumes of water. Water did not affect the toxicity of deltamethrin and eugenol dusts, but it caused a linear decline in toxicity of silica gel (Dri-Die). The toxicity of a formulation containing silica gel and synergized pyrethrins (Drione) increased exponentially with increasing amounts of water. Moisture in the form of relative humidity does not strongly affect the toxicity of most insecticidal dust formulations. Presence of water, however, increases the toxicity of boric acid dusts and Drione. Toxicity of the hydrophobic deltamethrin (DeltaDust) and eugenol (EcoPCO D) dusts were unaffected by water.

Behavioral activity of catnip (Lamiaceae) essential oil components to the German cockroach (Blattodea: Blattellidae).

The essential oil of catnip, Nepeta cataria L., contains two isomers of nepetalactone, E,Z-and Z,E-nepetalactone, and was tested for repellent activity to adult male German cockroaches, Blattella germanica (L.), in a choice-test arena. The two isomers of nepetalactone were purified by using preparative thin-layer chromatography and tested for behavioral activity in the choice-test arena. Significant differences due to concentration were detected by analysis of variance, and the responses were compared by least-squared means analysis. The activities of the essential oil and purified isomers were compared with N,NA-diethyl-3-methylbenzamide (DEET) by a paired t-test. E,Z-Nepetalactone was the most active of the compounds tested, being significantly more active to this species than equivalent doses of DEET, the essential oil, or Z,E-nepetalactone. Antennectomized insects showed no response to concentrations that were active against intact insects.

Effects of the synergists piperonyl butoxide and S,S,S-tributyl phosphorotrithioate on propoxur pharmacokinetics in Blattella germanica (Blattodea: Blattellidae).

Effects of the synergists piperonyl butoxide (PBO) and S,S,S-tributyl phosphorotrithioate (DEF) on propoxur pharmacokinetics were examined in the German cockroach, Blattella germanica (L.). Treatment of adult male German cockroaches with the cytochrome P450 monooxygenase inhibitor, PBO, or the esterase inhibitor, DEF, increased propoxur toxicity by 2- and 6.8-fold, respectively, implicating hydrolysis as a major detoxification route of propoxur in the German cockroach. However, significant hydrolytic metabolism could not be demonstrated conclusively in vitro resulting in a conflict between in situ bioassay data and in vitro metabolic studies. In vitro propoxur metabolism with NADPH-fortified microsomes produced at least nine metabolites. Formation of metabolites was NADPH-dependent; no quantifiable metabolism was detected with cytosolic fractions. However, microsomal fractions lacking an NADPH source did produce a low, but detectable, quantity of metabolites (1.6 pmol). PBO inhibited NADPH-dependent propoxur metabolism in a dose-dependent fashion, implicating cytochrome P450 monooxygenases as the enzyme system responsible for the metabolism. Interestingly, DEF also inhibited the NADPH-dependent metabolism of propoxur, albeit to a lower extent. Treatment with PBO or DEF also caused a significant reduction in the cuticular penetration rate of propoxur. The data demonstrate that unanticipated effects are possible with synergists and that caution must be exercised when interpreting synergist results.

A Microsomal Esterase Involved in Cypermethrin Resistance in the German Cockroach, Blattella germanica

Abstract Adult male German cockroaches of the Marietta strain exhibited 5-fold resistance to cypermethrin compared with the insecticide-susceptible Orlando strain. The cypermethrin resistance level decreased to 2.9-fold when cockroaches were pretreated with S , S , S -tributylphosphorotrithioate, indicating that esterases played a role in the resistance. Cypermethrin was metabolized faster by microsomal esterases from the Marietta strain (15.4 ± 1.1 pmol/h/mg) than by those from the Orlando strain (12.5 ± 0.2 pmol/h/mg). Partial purification of microsomal esterases from the Marietta and Orlando strains was accomplished by anion exchange and hydrophobic interaction chromatography (HIC) and native-PAGE. HIC partitioned the single anion exchange peak of α-naphthyl acetate esterase activity into three fractions, HIC I, HIC II, and HIC III. All three HIC fractions metabolized cypermethrin significantly faster than microsomes. Native-PAGE analysis of each of these fractions revealed a unique band in Marietta HIC II and III which was referred to as microsomal esterase Marietta (ME mar ). ME mar was isolated by native-PAGE and found to hydrolyze α-naphthyl acetate at a rate of 25.5 μmol/min/mg protein, representing a purification of 54-fold over that of microsomes. Furthermore, Marietta strain HIC II and III fractions (which contained ME mar ) metabolized cypermethrin significantly faster than the corresponding fractions from the Orlando strain. ME mar metabolized cypermethrin at 3461 pmol/min/mg protein, representing a 225-fold increase over that of microsomes. ME mar was found to exhibit a molecular weight of 57 kDa by SDS-PAGE and 64 kDa by gel filtration chromatography, indicating that the esterase was a monomer. Also, the ME mar isozyme was inhibited by paraoxon and phenylmethylsulfonyl fluoride, indicating that the esterase was a “B”-type serine esterase. Finally, none of the isozymes in the HIC III fraction, including the ME mar isozyme, bound to concanavalin A, indicating that the HIC III isozymes were not glycosylated.

Method of insecticide delivery affects horizontal transfer of fipronil in the German cockroach (Dictyoptera: Blattellidae).

Horizontal transmission of insecticide occurs when foragers contact or ingest an insecticide, return to the aggregation or nest, and translocate the insecticide to the shelter and its vicinity. Relatively more sedentary members of the population then contact or eat the translocated insecticide and die. We evaluated three different methods of delivering fipronil to adult male German cockroaches, Blattella germanica (L.), for their potential to cause such secondary mortality in various developmental stages of the cockroach. Adult males topically treated with 5 ng of fipronil (approximately LD99) caused low mortality in untreated nymphs and no mortality in untreated adults within the same aggregation. Males exposed to residual fipronil on a glass surface translocated more insecticide, resulting in higher mortality of cockroaches they contacted, but only early instars were affected and no adult mortality was observed. Ingested fipronil bait, however, was most effectively translocated, and caused high mortality of untreated adults and nymphs. Ingestion of fipronil also caused greater secondary kill compared with a topical application of 25 ng, approximately the same amount recovered from the exterior of males that ingested 1 mg of 0.05% fipronil bait. Secondary mortality in the untreated population was significantly affected by the duration of contact between the treated and untreated cockroaches, the quantity and freshness of excretions from the treated insects, and the accessibility of the secretions to untreated cockroaches. The mechanisms that cause secondary kill may include ingestion of excreted fipronil residues, cannibalism of bait-fed cockroaches, as well as contact with fipronil-contaminated substrates.

Cytochrome P450 CYP6L1 is specifically expressed in the reproductive tissues of adult male German cockroaches, Blattella germanica (L.)

A full-length cDNA encoding a new cytochrome P450, CYP6L1, was cloned from German cockroaches, Blattella germanica. CYP6L1 has an open reading frame of 1509 nucleotides with a deduced protein of 503 amino acids and molecular mass of 57 Kd. CYP6L1 is most similar to CYP6H1, a putative ecdysone 20-hydroxylase from Locusta migratoria. CYP6L1 mRNA was not detected in embryos nor nymphs, nor in adult females. CYP6L1 mRNA was detected only in the testes and accessory glands of male adult German cockroaches. Given that the testes and accessory glands are the most important components of the reproductive system in male insects, the expression of CYP6L1 mRNA exclusively in these tissues strongly suggests that CYP6L1 has a role in reproduction. Possible substrates for CYP6L1 are discussed.

Secondary Kill of Adult Male German Cockroaches (Dictyoptera: Blattellidae) Via Cannibalism of Nymphs Fed Toxic Baits

Five commercially available bait formulations were evaluated for primary kill of 1st-and 2nd-instar German cockroaches, Blattella germanica (L.), and secondary kill of adult male German cockroaches via cannibalism of bait-fed nymphs. Chlorpyrifos and fipronil baits killed 1stand 2nd-instar cockroaches significantly faster than hydramethylnon, boric acid, or abamectin baits. Secondary kill was observed for all baits tested. Adults that consumed bait-treated nymphs had significantly higher mortality than those fed untreated nymphs. The LT 50 values calculated for secondary kill of adult male cockroaches were 1.84 d for adults consuming fipronil-fed nymphs, 6.69 d for hydramethylnon-fed nymphs, 7.21 d for boric acid-fed nymphs, 7.94 d for abamectin-fed nymphs, and 8.48 d for chlorpyrifos-fed nymphs. Adult LT 50 values for boric acid, abamectin, and chlorpyrifos were not significantly different. Because secondary kill was observed for all bait formulations tested, it is possible that the importance of toxicant transmission via cannibalism has been underestimated in laboratory and field evaluations.

Influence of carbon dioxide anesthesia on chlorpyrifos toxicity in the German cockroach (Dictyoptera: Blattellidae).

Insecticide-susceptible (Orlando normal) and multi-insecticide-resistant (Village Green) adult male German cockroaches, Blattella germanica (L.), were exposed to carbon dioxide (CO2) gas in either varying durations or multiple exposures of fixed duration followed by topical treatment with acetone or chlorpyrifos (LD25) to evaluate the effect of CO2 anesthesia on chlorpyrifos toxicity. CO2 anesthesia did not increase chlorpyrifos toxicity in either strain regardless of exposure duration up to 1 h. However, multiple CO2-induced knockdowns alone caused mortality and increased chlorpyrifos toxicity. Twenty-four-hour weight loss was independent of CO2 duration exposure by strain. Village Green and Orlando cockroaches lost 5.3 and 7.6% of their weight in 24 h when treated with acetone and 10.5 and 12.8% when treated with chlorpyrifos, respectively. Conversely, 0- and 24-h weight loss increased with increasing CO2-induced knockdowns regardless of strain or topical treatment. Based on these results, CO2 used either once of limited duration (< or = 15 min) or multiple times of short duration, not to exceed four total knockdowns, does not increase chlorpyrifos toxicity in the adult male German cockroach.

Laboratory Residual Studies for German Cockroach Control, 1990

Abstract The residual activity of two concentrations, 0.25% and 0.50%, of Dursban LO and the experimental compound XRM-5184 were tested on three surfaces, masonite, painted plywood and stainless steel for efficacy in controlling German cockroaches. The test surfaces were 16 inches2 marked into quadrants 8 inches2 so that each of the four exposures could be done on a previously unused surface. The 1/4 inch plywood was painted with 2 coats of white, flat latex paint and allowed to dry 32 d prior to treatment. The Vi inch masonite surfaces were unpainted and the 1/8 inch stainless steel surfaces were unpainted but washed, thoroughly rinsed, and dried prior to treatment. Each treatment was replicated 4 times. Thus 4 panels of each surface material were sprayed with each insecticide at each rate and a control set was sprayed with water. The experimental design was a complete randomized block with 4 treatments, 2 insecticides at 2 rates, on 3 types of surfaces with each surface replicated 4 times for each treatment. Residual activity of these treatments was determined by exposing cockroaches at 24 h, 7, and 14 DAT. The insecticide application system was a modified B&amp;G sprayer, model 104-S, equipped with a teejet fan nozzle #800067 attached to a mobile nozzle stand. The nozzle stand was attached to a motorized track, powered by a zero max 0-400 electric motor, that moved the nozzle stand at a rate of 2.5 ft/s. The nozzle was set at a height of 12 inches over the target surfaces. The compressed air source was set at 20 psi to deliver a finished spray concentration of 2.2 oz/100 ft2 as the nozzle moved over the 4 target panels. The sprayer design, speed of delivery and application rate were set to simulate field application rates. Treated surfaces were allowed to air dry for 24 h before cockroaches were exposed to the treated surfaces. Cockroaches were confined to the treated surfaces in cages made from white PVC couplers that were 6.5 inches in diameter × 8 inches tall. A petroleum jelly-mineral oil mixture was applied to the inside wall 0.5 inches from the exposure surface to keep the cockroaches on treated surfaces. The top of the cages were covered with a nylon mesh fabric to prevent any escapes of cockroaches that crossed the sticky barrier. Ten adult male and/or nongravid female German cockroaches were exposed to the treated surfaces and the control surface. Cockroaches were exposed to each surface for 24 h during which mortality counts were made at 4, 8 and 24 h. After the 24 h count, the treated surfaces were removed. The cages were inverted and the cockroaches were knocked down to the nylon mesh top of the cages. The cages were left standing with the nylon screen in contact with untreated surfaces and the open end of the cages was covered with clear saran wrap to prevent escapes. A final mortality count was made 24 h later which was 48 h after the initial exposure. Cockroaches were exposed to the treated surfaces following the same procedure at 7 and 14 DAT.

Residual Efficacy of Chlorpyrifos and Diazinon Formulations for German Cockroaches (Orthoptera: Blattellidae) on Panels Placed in Commercial Food Preparation Areas2

Ceramic and stainless steel panels were treated with chlorpyrifos (Dursban LO or ME) or diazinon (Knox Out 2FM) and aged in a commercial kitchen. Type of surface (ceramic tile or stainless steel) did not significantly affect residual performance of formulations used for control of adult male German cockroaches, Blattella germanica (L.). Microencapsulation stabilized the residues of both chlorpyrifos and diazinon and caused 100% mortality of susceptible German cockroaches for 8 weeks and resistant cockroaches for 4 weeks. The emulsifiable formulation provided only 0–67% mortality after 1–2 weeks.

Evaluation of Experimental Propoxur Baits, 1988

Abstract Three experimental baits were prepared using peanut butter, flour, Propoxur, and boric acid. Effectiveness of the experimental baits on susceptible and resistant cockroaches was compared to commercial Combat bait stations containing 1.65% hydramethylnon. The experimental baits tested were 2% Propoxur in peanut butter, 2% Propoxur + 25% flour in peanut butter, and 2% Propoxur + 40% boric acid in peanut butter. Fifty susceptible or Propoxur-resistant adult male German cockroaches were introduced into 22- by 12- by 8-inch clear plastic cages with water, harborage, dog food, and experimental bait that had been placed in a sealed plastic bait tray. Experimental conditions were maintained at 25°C with a photoperiod of 12:12 (L:D). Insects were considered dead if they did not move when gently prodded with forceps. Mortality readings were taken hourly for the first 8 h, and daily thereafter for 1 wk. Probit analyses generated LT25, LT50, LT95 values in h, and 95% fiducial limits for each treatment.

Differences in Repellency of Substances Secreted by Blattella germanica (Dictyoptera: Blattellidae) Females during the First Week Postecdysis

The response of adult male German cockroaches to substances secreted by crowded adult females varied with female age and intensity of crowding. Secretions by moderately crowded females tended to become progressively more attractive during the first 5 d postecdysis. Those from 6- to 7-d-old females were strongly repellent, which indicates secretion of the dispersant pheromone. Under extremely crowded conditions, 3-d-old females also secreted the dispersant, but repellency was less than that of similarly crowded 7-d-old females.

Repellency and Toxicity of Eastern Red Cedar to Cockroaches and the Firebrat, 1986

Abstract Freshly made, 7 mm thick, 100% cedar particle board was evaluated for repellency in standard Ebeling choice boxes and for toxicity by continuous exposure. Three surface areas of particle board were evaluated: 250, 400, and 469 cm2, as well as untreated control (masonite panel). Each treatment was replicated 6 times. Water and food (Purina Dog Chow) was provided ad libitum only in the light side of the choice box. Twenty adult male German cockroaches, (American Cyanamid Co., Clifton, NJ, susceptible strain), brownbanded cockroaches, American cockroaches, smokybrown cockroaches, or firebrats, were placed into the light side of each box. The insects were allowed access to the treated side after 2 h. Position and mortality were recorded daily for 14 days. Toxicity of cedar paneling was accessed by confining 5 groups of 6 males of each cockroach species or large firebrats to the paneling. The insects were confined under inverted 9 cmdiam petri dish bottoms that had been lightly coated on the vertical sides with petroleum jelly. No food or water was provided and mortality was recorded daily. Control mortality was determined for each species by confinement to masonite paneling.

Behavioral responses of the German cockroach, Blatella germanica (L.) (Orthoptera: Blatellidae), to a propoxur formulation.

Exposure to vapors from a formulation of 1% propoxur in oil caused an increase in movement and antennal and tarsal grooming in adult male German cockroaches, Blattella germanica (L.). Increased movement was the most immediate response, followed by increased antennal grooming. Increased tarsal grooming was the last response and was most likely a secondary response to other factors. Adult males of a resistant field strain were more active than those of a susceptible laboratory strain in control studies. However, susceptible males displayed greater responses to the controls than did resistant males after exposure to the insecticide.