Cockroach Mortality Research Articles

Pathogenic fungi synergistically cooperate with Serratia marcescens to increase cockroach mortality

The abuse of chemical insecticides has led to strong resistance in cockroaches, and biopesticides with active ingredients based on insect pathogens have good development prospects; however, their slow effect has limited their practical application, and improving their effectiveness has become an urgent problem. In this study, the interaction between Serratia marcescens and Metarhizium anisopliae enhanced their virulence against Blattella germanica and exhibited a synergistic effect. The combination of S. marcescens and M. anisopliae caused more severe tissue damage and accelerated the proliferation of the insect pathogen. The results of high-throughput sequencing demonstrated that the gut microbiota was dysbiotic, the abundance of the opportunistic pathogen Weissella cibaria increased, and entry into the hemocoel accelerated the death of the German cockroaches. In addition, the combination of these two agents strongly downregulated the expression of Imd and Akirin in the IMD pathway and ultimately inhibited the expression of antimicrobial peptides (AMPs). S. marcescens released prodigiosin to disrupted the gut homeostasis and structure, M. anisopliae released destruxin to damaged crucial organs, opportunistic pathogen Weissella cibaria overproliferated, broke the gut epithelium and entered the hemocoel, leading to the death of pests. These findings will allow us to optimize the use of insect pathogens for the management of pests and produce more effective biopesticides.

The Pengendalian lipas jerman (Blattella germanica Linnaeus) dengan menggunakan attractive toxic sugar baits

Penggunaan attractive toxic sugar baits (ATSB) merupakan hal baru dalam pengendalian vektor dan hama permukiman. Penelitian ini bertujuan untuk mengetahui konsentrasi umpan gula yang mampu menarik lipas jerman Blattella germanica Linnaeus dan mengetahui keefektifan berbagai jenis bahan toksik sebagai ATSB untuk mengendalikan lipas jerman. Metode ini didasarkan pada perilaku serangga dewasa yang memakan gula dari sumber yang mengandung bahan toksik yang dapat membunuh serangga tersebut. Jenis bahan toksik yang digunakan dalam penelitian ini adalah insektisida anorganik (asam borat), pirol (klorefenapir), neonikotinoid (dinotefuran), dan piretroid (permetrin dan deltametrin). Hasil penelitian menunjukkan umpan gula yang menarik untuk lipas jerman adalah sukrosa 5%. ATSB dengan bahan toksik asam borat 25% menimbulkan kematian lipas sebesar 46,25%, dan dengan bahan toksik klorfenapir 0,12% menyebabkan kematian lipas 70% pada 24 jam pascaperlakukan. Selanjutnya, ATSB dengan bahan toksik dinetofuran 0,08% dan deltametrin dalam berbagai konsentrasi menyebabkan kematian lipas tertinggi (100%), sedangkan dengan permetrin menimbulkan kematian lipas yang lebih rendah daripada ATSB dengan bahan toksik lainnya pada jam pengamatan yang sama. Penelitian ini memberikan informasi dasar tentang pemanfaatan ATSB dan potensinya dalam pengendalian lipas jerman di Indonesia.

Optimizing the Loading Level of Boric Acid in a Particle Bait: A Preliminary Study with Periplaneta americana (Blattodea: Blattidae)

Optimizing the Loading Level of Boric Acid in a Particle Bait: A Preliminary Study with <i>Periplaneta americana</i> (Blattodea: Blattidae)

POTENSI AIR RENDAMAN DAUN TEMBAKAU (Nicotiana tabacum) SEBAGAI BIOINSEKTISIDA KECOA (Periplaneta americana)

Cockroaches are animals in residential areas that act as vectors of diseases, including cholera, typhus, dysentery and diarrhea, and are often found in a common public places. Tobacco (Nicotiana tabacum) contains nicotine so that it is a type of plant that can be used as a bio-insecticide to control insects. The experiment used a pretest-posttest control group design, with 9 replications. The test material used was tobacco leaf (Nicotiana tabacum) immersion water with immersion length variations of 2, 4, and 6 days. The cockroach being used was 810 Periplaneta americana obtained from residential areas. The data obtained were analyzed using the Oneway ANOVA test, Least Square Difference (LSD) and probit analysis. The results suggested that the highest percentage of cockroach (Periplaneta americana) mortality was in the use of 6 days immersed tobacco, by 32%. The results of the statistical analysis suggested a significant difference (p-Value = 0.000) in the treatment and control groups. However, there were no significant differences between treatment groups (p-value = 0.285). While the results of the probid analysis acquire the LD 50 at 2.925% concentration. Immersed Tobacco leaf (Nicotiana tabacum) can be used as an alternative to bio-insecticides in cockroach control (Periplaneta americana). Further research is necessary to obtain significant results, in terms of variations in treatment, variations in contact time, and homogeneous test materials.

Comparative Efficacy of Residual Insecticides against the Turkestan Cockroach, Blatta lateralis, (Blattodea: Blattidae) on Different Substrates.

The Turkestan cockroach, Blatta lateralis (Walker) is an invasive urban pest prevalent throughout the Southwestern United States. Despite the presence of this cockroach in peridomestic areas, there is limited information on strategies that can be utilized by pest management professionals (PMPs) to effectively manage populations of this pest. We evaluated the efficacy of dry residues of liquid insecticides commonly used for household and structural insect pest control: Tandem (0.10% thiamethoxam, 0.03% lambda-cyhalothrin), Transport GHP (0.05% acetamiprid, 0.06% bifenthrin), Temprid SC (0.10% imidacloprid, 0.05% beta-cyfluthrin), Demand CS (0.06% lambda-cyhalothrin), Talstar P (0.06% bifenthrin), and Phantom (0.5% chlorfenapyr) on three different substrates against Turkestan cockroach nymphs. Except for Phantom and Talstar P, all insecticide formulations killed 100% of the cockroaches on concrete, 89–100% on tile, and 77–100% on wood within 4 days. The rate of cockroach mortality varied according to the substrates to which they were exposed. Temprid SC and Transport GHP killed cockroaches faster on tile than wood. Tandem provided a faster mortality rate than Transport GHP and Temprid SC on concrete. Demand CS and Tandem killed cockroaches at similar rates on the three substrates. This study provides information to guide PMPs in their selection of insecticide formulations for the management of Turkestan cockroach infestations.

Development of New Boric Acid Gel Baits Against German Cockroaches, Blatella germanica L (Blattodea: Blattellidae)

The German cockroach, Blatella germanica, is a pest of human habitats distributed throughout the world. Boric acid (BA; H3BO3), in the form of powder, pellets, or blocks, has been used to control German cockroaches. Gel baits are also considered highly effective for controlling German cockroach populations. However, BA is not currently available as a gel bait. Thus, the present study was carried out to determine the best concentration of BA to formulate as a gel bait, and measure its direct effectiveness and the horizontal transfer of the active ingredient (AI) through cannibalism in adult German cockroaches (domino effect). Effectiveness of laboratory-prepared BA gel baits (lab baits) was analysed, and the efficacy and horizontal transfer of the most effective lab bait was compared to four commercial baits. Among three tested lab baits, the bait prepared with 40% BA (lab bait A) resulted in significantly greater cockroach mortality and a lower lethal time (LT50) value than other lab baits. When compared with commercial baits, there was no significant difference between lab bait A and BA baits in the amount of bait consumed and the detection time. Similarly, mortality of cockroaches caused by lab bait A was equal to mortality caused by the commercial BA bait. Percentage of bait unfed adult cockroaches killed by transferred BA from lab bait A fed and dead adult cockroaches (secondary mortality) was significantly greater than that caused by both commercial BA bait and fipronil bait.

Adipokinetic hormone promotes infection with entomopathogenic fungus Isaria fumosorosea in the cockroach Periplaneta americana

The adipokinetic hormones (AKHs) are known to be involved in insect immunity, thus their role in the cockroach Periplaneta americana infected with the entomopathogenic fungus Isaria fumosorosea was examined in this study. The application of I. fumosorosea resulted in a significant increase in both Akh gene expression and AKH peptide levels. Further, co-application of I. fumosorosea with Peram-CAH-II significantly enhanced cockroach mortality compared with the application of I. fumosorosea alone. The mechanism of AKH action could involve metabolic stimulation, which was indicated by a significant increase in carbon dioxide production; this effect can increase the turnover and thus efficacy of toxins produced by I. fumosorosea in the cockroach's body. I. fumosorosea treatment resulted in a significant decrease in haemolymph nutrients (carbohydrates and lipids), but co-application with Peram-CAH-II restored control level of lipids or even further increased the level of carbohydrates. Such nutritional abundance could enhance the growth and development of I. fumosorosea. Further, both I. fumosorosea and Peram-CAH-II probably affected oxidative stress: I. fumosorosea alone curbed the activity of catalase in the cockroach's gut, but co-application with Peram-CAH-II stimulated it. Interestingly, the hormone alone had no effect on catalase activity. Taken together, the results of the present study demonstrate the interactions between the fungus and AKH activity; understanding this relationship could provide insight into AKH action and may have practical implications for insect pest control in the future.

Repellancy and contact toxicity of clove bud oil and its constituents against German cockroaches, Blatella germanica (Dictyoptera: Blattellidae), under laboratory conditions

The German cockroach, Blattella germanica L. (Dictyoptera: Blattellidae), an invasive pest of human habitats, is distributed throughout the world, except in Antarctica. They have developed resistance against chemical pesticides used for the management of their populations. Numerous essential oils and their constituents have been tested; however, the insecticidal activities of clove bud powder, oil, and their constituents have not yet been tested against the German cockroaches. Thus, in this study, clove bud powder, oil, and their major constituents, eugenol and eugenol acetate, were evaluated for their contact toxicity and repellancy against adult German cockroaches under laboratory conditions. The clove bud powder applied at 30 mg/cm2 killed 92% of German cockroaches at 6 hours after treatment (HAT). Similarly, clove bud oil, eugenol and eugenol acetate applied at 4.00 ml/cm2 provided 95%, 85%, and 87% German cockroach mortality at 24, 6, and 24 HAT, respectively. At 2.0 ml/cm2, clove bud oil repelled 80% of German cockroaches within 30 min. In contrast, eugenol and eugenol acetate repelled 85% at 1.0 ml/cm2 and 2.5 ml/cm2, respectively, at 0.5 HAT. Based on this study, clove bud powder, oil, eugenol, and eugenol acetate could be environmentally friendly tools for the management of German cockroaches.

Efficacy Test on Some Entomopathogenic Bacterial Isolates of the Periplaneta americana and Blatella germanica Cockroaches (Orthoptera) at Laboratory Scale

Cockroach is one of insects which plays a role as a disease vector, causing negative impacts to human health. Controlling cockroach by using excessive insecticide adds residue to the environment and strengthens its resistance toward insecticides. The objective of this research was to implement and evaluate the alternative use of biological control agent, such as entomopathogenic bacteria against two types of cockroach. In this study, three entomopathogenic bacterial isolates derived from dead Spodoptera litura pupa and Bacillus thuringiensis were employed. The test was performed by administering spraying and baiting methods at cell concentration of 108 CFU/ml. The results showed that three entomopathogenic bacterial isolates used in this study affected cockroach mortality. The result of morphological observation and Postulate Koch test showed that cockroach mortality was caused by the bacterial isolates. The spraying method on BLSP4 bacterial isolate contributed to the highest mortality rate by 80% to the Blatella germanica. Meanwhile, in the baiting method, the isolate of B. thuringiensis caused the highest mortality to the Periplaneta americana by 10%. Based on the mortality period, it can be recognized that BLSP4 treatment with spraying method affected the mortality of B. germanica effectively within 2 hours 30 minutes 46 seconds. An important finding in this study was that BLSP4 bacteria has been known potential for controlling cockroach using spraying method. The result of this study provides insights that BLSP4 bacteria can be used as a new alternative for controlling cockroach and generally in pest management.

Efficacy of synergized and non-synergizedTagetes minutamethanol extract in controllingPeriplaneta americanawithin households

In this study, comparative analysis of Sesamum indicum L. oil synergized and non-synergized methanol extract of the T. minuta were assayed against P. americana collected from households within Maseno Division, Kenya. The mortality and LC50 for both synergized and non-synergized extracts were determined. The synergized extract had cockroach mortality of 60 (n = 60) (100%) while non-synergized showed mortality of 52 (n = 60) (86.1 ± 1.2%) at 22 μg/ml after 36 h using contact toxicity method. On the other hand, with fumigation method, 100% mortality of the pest was achieved within 30 h using synergized extract while the non-synergized extract afforded 84.0 ± 1.1% mortality at the same concentration after the same period of time. The LC50 for the synergized extract was observed to be 6.31 μg/ml while the non-synergized was found to be 8.91 μg/ml. Thus, T. minuta extract may be used alone or synergized with S. indicum oil for effective management of cockroaches within households.

Madagascar hissing cockroach mite, Gromphadorholaelaps schaeferi, prevents fungal infection in its cockroach host: evidence for a mutualistic symbiosis

In this study, we provide the first evidence that the mite Gromphadorholaelaps schaeferi is beneficial to the Madagascar hissing cockroach Gromphadorhina portentosa by participating in a cleaning symbiosis and thus prolonging the life of its host. Gromphadorholaelaps schaeferi is a permanent resident of the cockroach and reduces mould levels by removing the food debris from the cockroach that acts as a substrate for fungal growth. To investigate the mould clearance attributes of these mites, we determined the effectiveness of mite infestation for decreasing cockroach mortality from a topically applied entomopathogenic fungus Metarhizium anisopliae. We further determined the effects of regulating cockroach food levels on altering the mycoflora profile of the cockroaches, with and without mites. Results showed that the lifespan of the cockroaches is extended by approximately 9 months when infested with mites. When treated with M. anisopliae (107 conidia/ml), which is pathogenic to the cockroach but not to the mite, mite infestation increases cockroach longevity by 65% as compared to uninfested cockroaches. Also, the effects of limiting the food offered to the cockroaches synergize with the cleaning symbiosis relationship to further reduce cockroach surface moulds. As a side observation, limiting food input in the cockroach colony not only reduces total cockroach moulds, but also shifts the fungal competition to favour those strains that are less medically significant, that is, away from an otherwise heavy zygomycete load of Rhizopus spp. and Mucor spp. to mitosporic fungi. Maintaining a healthy mite population, and reducing the amount of food kept in the cages, when keeping the hissing cockroach in captivity can potentially reduce fungal load and therefore any associated (human) allergies.

Control of American cockroach (Periplaneta americana) and German cockroach (Blattella germanica) by entomopathogenic nematodes

Two local and three imported entomopathogenic nematodes (EPNs) were tested for control of the American cockroach (Periplaneta americana) and the German cockroach (Blattella germanica). Only two Steinernematidae caused substantial cockroach mortality; one was a local strain of Steinernema sp. (strain T1), and the other was an imported strain of S. carpocapsae. A homemade bait that contained cat food and attapulgite clay at a ratio of 3:7 (W:W, 10 g total per bait) and 1x106 Steinernema sp. (T1) per bait resulted in 48.0 ± 4.7% mortality of the American cockroach and 57.7 ± 8.0% mortality of the German cockroach. A similar bait containing S. carpocapsae caused 40.0 ± 3.3% mortality of the American cockroach and 86.7 ± 4.7% mortality of the German cockroach. The optimal concentration of Steinernema sp. (T1) and S. carpocapsae to control the American and German cockroach was 1x106 EPNs and 5.4x104 EPNs per bait, respectively. The most susceptible stage of the American cockroach to both EPNs was the last instar, but susceptibility of the German cockroach to both EPNs did not differ among cockroach stages.

Linear Alcohol Ethoxylates: Insecticidal and Synergistic Effects on German Cockroaches (Blattodea: Blattellidae) and Other Insects

Sixteen linear ethoxylated alcohol surfactants (AEOs) were studied to determine their contact insecticidal activity to adult German cockroaches, Blattella germanica (L.) (Blattodea: Blattellidae). Within groups of AEOs of equal carbon chain length, insecticidal activity, measured as LT50 values (in minutes) and 24-h mortality after treatment, was inversely related to the amount of ethoxylation. There was a highly significant negative relationship between the hydrophile-lipophile balance (HLB) value of the AEO and contact toxicity. The AEO with the lowest HLB value, Tomadol 23-1 (HLB = 3.7), produced the greatest 24-h cockroach mortality. The contact activity of Tomadol 23-1 was evaluated against a wide range of other insect species. Most species were killed within 24 h by direct exposure (1-4 microl of a 50% ethanol solution) to Tomadol 23-1 or by spray exposure to an aqueous solution. Tomadol 23-1, at a sublethal concentration, was tested in combination with representative members of the carbamate, nicotinoid, organophosphate, pyrethrum, pyrethroid, and pyrrole insecticide classes. Significant synergism was demonstrated in combinations of Tomadol 23-1 and chlorfenapyr, clothianidin, imidacloprid, thiamethoxam, and pyrethrum. Tomadol 23-1 significantly reduced the insecticidal activity of propoxur, suggesting antagonism. The insecticidal activity of Tomadol 23-1 was synergized by coapplication with a sublethal amount of piperonyl butoxide, indicating the involvement of cytochrome P450 microsomal monooxygenases in insect metabolism of AEO surfactants.

Improvement of German Cockroach (Dictyoptera: Blattellidae) Population Control by Fragmented Distribution of Gel Baits

The aim of this study was to test the efficiency of gels in relation to fragmentation of baits and population density against the German cockroach, Blattella germanica (L.). We hypothesized that the efficiency of cockroach control could be improved by fragmentation of gel baits, i.e., by distributing the same amount of bait in several small drops instead of one large one. Our results show that bait fragmentation increased the number of cockroaches gaining access to the gel. However, bait fragmentation increased cockroach mortality only at high population densities. Our results allow us to recommend modulation of bait application in relation to cockroach population density. At low population densities (42 individuals/m2), the recommended dose, one single 30-mg drop/m2, can be applied. At high population densities (≥208 individuals/m2), the same recommended dose would be more efficient if applied as several 3-mg drops.

Improvement of German cockroach (Dictyoptera: Blattellidae) population control by fragmented distribution of gel baits.

The aim of this study was to test the efficiency of gels in relation to fragmentation of baits and population density against the German cockroach, Blattella germanica (L.). We hypothesized that the efficiency of cockroach control could be improved by fragmentation of gel baits, i.e., by distributing the same amount of bait in several small drops instead of one large one. Our results show that bait fragmentation increased the number of cockroaches gaining access to the gel. However, bait fragmentation increased cockroach mortality only at high population densities. Our results allow us to recommend modulation of bait application in relation to cockroach population density. At low population densities (42 individuals/m2), the recommended dose, one single 30-mg drop/m2, can be applied. At high population densities (> or = 208 individuals/m2), the same recommended dose would be more efficient if applied as several 3-mg drops.

Synergism between Metarhizium anisopliae (Deuteromycota: Hyphomycetes) and Boric Acid against the German Cockroach (Dictyoptera: Blattellidae)

Mortality of German cockroaches, Blattella germanica (L.), caused by Metarhizium anisopliae (Metschnikoff) Sorokin strain AC-1 alone and in combination with different formulations of boric acid, was evaluated in laboratory bioassays. Topical application of M. anisopliae alone (8.96 × 109 conidia/m2) required 28 days to cause >92% cockroach mortality (LT50 = 10 days). In contrast, in combination with boric acid (topically applied as a dust or in drinking water), M. anisopliae killed cockroaches significantly faster than without boric acid. M. anisopliae conidial dust (8.96 × 108 conidia/m2) with either 12.5% (w/w) boric acid dust or 0.1% (w/v) boric acid in drinking water killed 100% of the cockroaches in only 8 days (LT50 = 5 days) and 10 days (LT50 = 6 days), respectively, without compromising the fungus emergence from cadavers. Replacement of M. anisopliae with flour dust or heat-killed M. anisopliae conidia eliminated this effect, demonstrating that it was not the consequence of greater boric acid ingestion due to more extensive cockroach grooming upon exposure to M. anisopliae conidia. Moreover, injections of a low dose of M. anisopliae, which caused only 30% mortality, together with sublethal concentrations of boric acid into the cockroach hemocoel resulted in a doubling of mortality. Statistical analysis demonstrated a synergistic interaction between these two insecticides.

In vivo study on combined toxicity of Metarhizium anisopliae (Deuteromycotina: Hyphomycetes) strain ESC-1 with sublethal doses of chlorpyrifos, propetamphos, and cyfluthrin against German cockroach (Dictyoptera: Blattellidae).

The effect of Metarhizium anisopliae (Metschnikoff) Sorokin strain ESC-1 alone and in combination with sublethal doses of commercial formulations of chlorpyrifos, propetamphos and cyfluthrin on mortality of CSMA strain of German cockroach, Blattella germanica (L.), was determined by conducting in vivo studies that included 3 bioassays. Spores of M. anisopliae cultured on SDAY media had germination of >90%. Based on bioassay 1, doses ranging from 0.5 to 300 ppm of chlorpyrifos and propetamphos, and 0.05 to 40 ppm of cyfluthrin were selected for bioassays 2 and 3. Cockroach mortality ranged from 5 to 20% for insecticides alone and 48 to 70% for insecticides + M. anisopliae in bioassay 2. In bioassay 3, mortality ranged from 15 to 60% for insecticides and 57.5 to 92.5% for insecticides + M. anisopliae. Percentage of cockroach mortality resulting from insecticide + M. anisopliae combinations was significantly higher than insecticide alone. Mortality was also significantly higher in certain insecticide + M. anisopliae combinations than M. anisopliae alone. There was no significant interaction between M. anisopliae and insecticides with their concentrations in bioassay 2, indicating an additive effect. But in bioassay 3, a significant interaction was observed when M. anisopliae was combined with multiple insecticide concentrations. The interaction indicated an additive effect for chlorpyrifos and cyfluthrin, and a synergistic effect for propetamphos. There were significant differences in LT50 among various treatment combinations. M. anisopliae alone or insecticide + M. anisopliae combinations did not affect body weight in treated German cockroaches.

Use of German Cockroach (Dictyoptera: Blattellidae) Fecal Extract To Enhance Toxic Bait Performance in the Presence of Alternative Food Sources

The ability of German cockroach, Blattella germanica (L.), fecal extract to enhance toxic bait performance was evaluated in tests where a toxic bait was housed adjacent to the extract in arenas containing 5 alternative food sources. In arenas containing fecal extract and hydramethylnon bait (0.3% [AI]), cockroach mortality was 60% after 5 d. This was significantly greater than the 30% mortality obtained in arenas with hydramethylnon bait but no fecal extract. Chlorpyrifos bait (0.5% [AI]) paired with fecal extract also resulted in significantly higher cockroach mortality (60%) after 7 d than chlorpyrifos bait alone (30%). The LT 50 value for arenas with the chlorpyrifos bait/extract combination was 5.7 d compared with 23.5 d for chlorpyrifos bait with no extract. These results indicate that the use of fecal extract in combination with toxic bait may increase the attractiveness of bait stations, decrease bait repellency, and enhance cockroach mortality in the presence of competing food sources.

Toxicity of Imidacloprid in the German Cockroach (Dictyoptera: Blattellidae), and the Synergism Between Imidacloprid and Metarhizium anisopliae (Imperfect Fungi: Hyphomycetes)

German cockroaches, Blattella germanica (L.), orally exposed to solid imidacloprid baits exhibited toxic symptoms rapidly (within 30 min). However, cockroaches recovered from this toxicity. The percentage of knockdown was positively correlated and the rate of recovery was negatively correlated with concentration. In the liquid bait tests, imidacloprid produced rapid moribundity (within minutes) in all exposed cockroaches, but this moribundity was transient. Topically applied imidacloprid also produced rapid but transient moribundity in both in the laboratory-snsceptible (JWax-S) and the field-collected resistant (Muncie'86) strains. In the topical application bioassay, recovery time was dependent on cockroach strain and presence of piperonyl butoxide (PBO). Resistant cockroaches recovered faster than susceptible cockroaches; cockroaches pretreated with PBO recovered faster than those not pretreated. The JWax and Lafayette (field-collected) strains were killed significantly faster with The entomopathogenic fungus, Metarhizium anisopliae alone, or Metarhizium + solid imidacloprid bait than imidacloprid bait alone in both the choice and no-choice bioassays. Combinations of direct contact to the conidia of Metarhizium and feeding on imidacloprid bait indicated synergy when compared with the activity of the individual components. We found no differences in mortality when the JWax cockroaches fed on either 500 or 1,000 ppm imidacloprid baits. The presence of alternate food slowed the lethal time for imidacloprid against the JWax and Lafayette strains. Both strains were killed significantly faster when cockroaches lind on imidacloprid after a topical application of spore suspensions of Metarhizium than when insects fed on imidacloprid bait alone, indicating possible synergistic interaction (i.e., greater than expected mortality) between imidacloprid bait and Metarhizium The mortality of cockroaches inoculated topically with spore suspensions of Metarhizium increased significantly with an increase in the number of fungal spores. No significant differences in daily cockroach mortality were detected among imidacloprid concentrations for each Metarhizium dose. Imidacloprid; d bait alone has a limited potential for use in controlling cockroaches, but it may have a potential if used in combination with a fungal pathogen such as Metarhizium.

Logistic Models Describing Effects of Temperature and Humidity on Residual Effectiveness of Chlorpyrifos and Cyfluthrin Formulations Against German Cockroaches (Dictyoptera: Blattellidae)

Multifactored logistic models were developed for chlorpyrifos and cyfluthrin formulations based on mortality data from laboratory studies with the German cockroach, Blattella germanica (L.). Insecticides were applied to stainless steel surfaces and aged at three different temperatures (23, 30, and 37 degrees C) and two levels of relative humidity (40 and 70%). After the insecticides dried, the treated panels were placed opposite plywood panels to simulate a crack and crevice application. At appropriate aging times, treated panels were removed from environmental chambers for bioassay. The combined effects of high temperature, high humidity, and aging of residues caused the greatest decline in cockroach mortality for chlorpyrifos. Increasing temperature and aging of residues resulted in decreased cockroach mortality for cyfluthrin formulations; however, mortality was greater than 87% for all formulations through 84 d. Information from this study can be incorporated into integrated pest management programs for German cockroaches.