Lethal and sublethal heat-exposure of bed bugs (Cimex lectularius L.) causes alarm pheromone emission and elicits a movement response in nearby recipients.

Many gregarious insect species use aggregation and alarm pheromones. The bed bug, Cimex lectularius L., emits an alarm pheromone (AP), a 70/30 blend of (E)-2-hexenal and (E)-2-octenal, when threatened. Bed bugs avoid temperatures above 43 °C, which are lethal to bugs and used commercially as spatial heat treatments to manage infestations. However, the interaction of bed bug AP in heat avoidance has not been investigated. The goal of this research was to: 1) determine if bed bugs emit AP as an alarm response to heat exposure, and 2) quantify the behavioral responses of conspecifics to AP emitted by heat-exposed bed bugs. Using a selected ion flow tube mass spectrometer, we found that bed bugs responded to lethal and sublethal heat exposure by emitting AP. The Harlan laboratory population emitted more pheromone than a laboratory adapted field population from Florida (McCall). Harlan females emitted the most AP, followed by Harlan males, McCall females and males. In separate behavioral experiments, we showed that conspecifics (i.e., recipients) reacted to AP released by heat exposed bed bugs (i.e., emitters) by frantically moving within 50 mm and 100 mm test arenas. The Harlan recipients reacted to AP in 100 mm areas, whereas the McCall strain did not, indicating a short area of effectiveness of the AP. Synthetic AP components tested in behavioral experiments caused identical effects as the natural AP blend released by heat-exposed bed bugs.

The Emergence and Sustainability of Urban Entomology.

Urban entomology is the study of arthropod and other pests of the urban environment. It has gained worldwide recognition as a distinct discipline. Its origin is associated with Walter Ebeling's publication Urban Entomology in 1975. Urbanization, invasive pests, increased demand for pest management services, and changes in legislation collided in the 1970s to create a need for research and extension activities worldwide. This resulted in urban entomology as a discipline and, within two decades, its national and international recognition. In this review, we present the factors that led to the development of urban entomology and how they have shaped its current meaning. As urbanization intensifies and the global economy increases, the demands for urban pest management will continue to grow. We discuss how these future challenges may shape and alter the discipline.

Expression profiles of an inactive aspartic protease (Bla g 2 allergen) in different tissues and developmental stages of the German cockroach (Blattella germanica).

Tergal glands are found in many insect species and contain constituents such as pheromones, sugars, proteins, and so forth. Preliminary studies have revealed that tergal gland secretions in the German cockroach (Blattella germanica L.) contain the human allergen Bla g 2 (B. germanica allergen 2), an inactive aspartic protease. Although Bla g 2 protein expression has been detected previously in various German cockroach body parts, including male tergal glands, studies that link protein expression in various life stages and tissues with mRNA and protein abundance have not been conducted. Therefore, the goal of this study was to measure the relative abundances of Bla g 2 protein and mRNA in different tissues and life stages of B. germanica using immunoblotting, quantitative PCR, and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based quantitative profiling. We found that Bla g 2 protein was detected in every sampled tissue, including the male tergal glands. Protein abundance was relatively high in adult males and their tergal glands in comparison to nymphs and virgin females. Similarly, Bla g 2 mRNA transcript levels were also comparatively higher in male tergal glands and adult males. In conclusion, this study provides new information on the relative abundance and distribution of Bla g 2 allergen, a medically significant protein, in different tissues and developmental stages of the German cockroach and lays the foundation for future studies that aim to determine the function of this protein in B. germanica development.

Characterization of heat exposure-associated escape behaviors and HSP gene expression in bed bugs (Cimex lectularius L.).

BACKGROUND: Heat can be effective for bed bug elimination. However, in some cases bed bugs survive heat treatments. The objectives of this study were to determine the behavioral responses of bed bugs to rising harborage temperatures (23.0-49.0 °C) and identify which heat shock protein (HSP) genes are expressed after heat exposure. First, a custom-made copper arena and harborage were used to determine the escape behaviors of six bed bug populations. Next, HSP gene expression responses of select populations were determined after heat exposure using real time quantitative polymerase chain reaction (RT-qPCR). RESULTS: Analysis of the 25 min behavioral experiment data found that harborage top temperatures associated with 25%, 50% and 75% probabilities of bed bugs to flee the harborage did not differ significantly between populations. Also, the percentage of insects that escaped from heated areas and survived (4.0-12.0%) was not different between populations. However, when specific temperatures at which successful escapes occurred were statistically compared, the Poultry House population was found to flee the harborage at statistically higher temperatures (43.6 ± 0.5 °C) than others (40.5 ± 0.6-42.0 ± 0.7 °C). The RT-qPCR experiments revealed that the HSP70.1, HSP70.3, and Putative Small HSP genes were significantly up-regulated 15 min, 2, and 4 h post-heat exposure and decreased back to baseline levels by 24 h. CONCLUSIONS: This study shows that when harborage top temperatures approach 40.0-43.0 °C, bed bugs will disperse in search for cooler areas. This work implicates the HSP70.1, HSP70.3, and Putative Small HSP genes in heat induced stress recovery of bed bugs. © 2021 Society of Chemical Industry.

Bed bugs (Cimex lectularius L.) exhibit limited ability to develop heat resistance.

The global population growth of the bed bug, Cimex lectularius (L.), is attributed to their cryptic behavior, diverse insecticide resistance mechanisms, and lack of public awareness. Bed bug control can be challenging and typically requires chemical and non-chemical treatments. One common non-chemical method for bed bug management is thermal remediation. However, in certain instances, bed bugs are known to survive heat treatments. Bed bugs may be present after a heat treatment due to (i) abiotic factors associated with the inability to achieve lethal temperatures in harborage areas for a sufficient time period, (ii) re-infestation from insects that escaped to cooler areas during a heat treatment or (iii) development of physiological resistance that allows them to survive heat exposure. Previous research has investigated the optimal temperature and exposure time required for either achieving complete mortality or sublethally affecting their growth and development. However, no research has examined bed bug populations for their ability to develop resistance to heat exposure and variation in thermo-tolerance between different bed bug strains. The goals of this study were: i) to determine if bed bugs could be selected for heat resistance under a laboratory selection regime, and ii) to determine if bed bug populations with various heat exposure histories, insecticide resistance profiles, and geographic origins have differential temperature tolerances using two heat exposure techniques (step-function and ramp-function). Selection experiments found an initial increase in bed bug survivorship; however, survivorship did not increase past the fourth generation. Sublethal exposure to heat significantly reduced bed bug feeding and, in some cases, inhibited development. The step-function exposure technique revealed non-significant variation in heat tolerance between populations and the ramp-function exposure technique provided similar results. Based on these study outcomes, the ability of bed bugs to develop heat resistance appears to be limited.

Detection of Reduced Susceptibility to Chlorfenapyr- and Bifenthrin-Containing Products in Field Populations of the Bed Bug (Hemiptera: Cimicidae).

Insecticide resistance is a major impediment for effective control of Cimex lectularius L. Previous resistance detection studies with bed bugs have focused on certain pyrethroid, neonicotinoid, organochlorine, organophosphate, and carbamate insecticides. Within the pyrethroid class, resistance studies have mostly been limited to deltamethrin, lambda-cyhalothrin, and alpha- and beta-cyfluthrin. The goal of this study was to develop diagnostic concentration bioassays for assessing bed bug susceptibility levels to chlorfenapyr- and bifenthrin-containing products. First, glass vial and filter paper bioassay methods were compared for their utility in susceptibility monitoring. Statistical comparison of toxicity data between bioassays indicated that the vial assay was less confounded by assay susbtrate effects, required less insecticide, and was faster, especially for chlorfenapyr. Next, using vial diagnostic concentrations (LC99) for each insecticide, 10 laboratory-adapted field strains and the Harlan lab-susceptible strain were screened for susceptibility to chlorfenapyr and bifenthrin. The results of this study reveal recent bed bug susceptibility levels to certain chlorfenapyr- and bifenthrin-containing products. Reduced susceptibility was detected in three and five field strains to chlorfenapyr and bifenthrin, respectively. Detection of reduced susceptibility suggests that certain strains may be segregating toward greater chlorfenapyr and bifenthrin resistance. These results merit continuous resistance monitoring efforts to detect chlorfenapyr and bifenthrin susceptibility shifts. Additionally, to reduce insecticide selection pressures and delay resistance development, adoption of integrated bed bug control strategies that combine chemical and nonchemical methods is recommended.

Using research and education to implement practical bed bug control programs in multifamily housing.

Multifamily housing facilities serving low-income populations have been at the forefront of bed bug outbreaks. Research conducted in the past 8 years has consistently proven that integrated pest management (IPM) is the best approach for successful suppression of bed bug infestations. Bed bug IPM in multifamily settings is especially dependent upon a collaborative community or building-wide effort involving residents, building staff and pest control technicians. Other components of a bed bug IPM program include regular monitoring to detect early-stage bed bug infestations and combined use of non-chemical and chemical interventions. Lastly, to reduce reinfestation rates and costs associated with bed bug control, it is critical to continue periodic monitoring and implement preventive control measures even after successful elimination of bed bugs has been achieved.

Odorous house ants (Tapinoma sessile) as back-seat drivers of localized ant decline in urban habitats.

Invasive species and habitat disturbance threaten biodiversity worldwide by modifying ecosystem performance and displacing native organisms. Similar homogenization impacts manifest locally when urbanization forces native species to relocate or reinvade perpetually altered habitat. This study investigated correlations between ant richness and abundance in response to urbanization and the nearby presence of invasive ant species, odorous house ants (Tapinoma sessile), within its native region. Surveying localized ant composition within natural, semi-natural, and urban habitat supported efforts to determine whether T. sessile appear to be primary (drivers) threats as instigators or secondary (passengers) threats as inheritors of indigenous ant decline. Sampling 180 sites, evenly split between all habitats with and without T. sessile present, yielded 45 total species. Although urbanization and T. sessile presence factors were significantly linked to ant decline, their interaction correlated to the greatest reduction of total ant richness (74%) and abundance (81%). Total richness appeared to decrease from 27 species to 18 when natural habitat is urbanized and from 18 species to 7 with T. sessile present in urban plots. Odorous house ant presence minimally influenced ant communities within natural and semi-natural habitat, highlighting the importance of habitat alteration and T. sessile presence interactions. Results suggest urbanization releases T. sessile from unknown constraints by decreasing ant richness and competition. Within urban environment, T. sessile are pre-adapted to quickly exploit new resources and grow to supercolony strength wherein T. sessile drive adjacent biodiversity loss. Odorous house ants act as passengers and drivers of ecological change throughout different phases of urban 'invasion'. This progression through surviving habitat alteration, exploiting new resources, thriving, and further reducing interspecific competition supports a "back-seat driver" role and affects pest management strategies. As demonstrated by T. sessile, this article concludes native species can become back-seat drivers of biodiversity loss and potentially thrive as "metro-invasive" species.

A novel gene from the takeout family involved in termite trail-following behavior.

This study investigated physiological and behavioral functions of a novel gene identified from the termite Reticulitermes flavipes. The gene, named deviate, encodes an apparent ligand binding protein from the takeout-homologous family. Initial studies were conducted to investigate deviate mRNA expression among termite castes and body regions, and changes in response to light-dark conditions, starvation, temperature, and juvenile hormone (JH). Deviate has ubiquitous caste and tissue expression, including antennal expression. Consistent with characteristics of other takeout family members, deviate expression is responsive to photophase conditions (p<0.1), and feeding, temperature, and JH (p<0.05). Using RNA-interference (RNAi) techniques, short-interfering RNAs (siRNAs) homologous to the deviate gene were synthesized and injected into worker termites, which were then subjected to bioassays designed to (1) induce caste differentiation or (2) measure various behavioral aspects of foraging and trail following. No impacts on JH-dependent caste differentiation were observable. However, trail following accuracy was significantly reduced in termites that received deviate siRNA injections, and this pattern generally mirrored deviate mRNA attenuation and recovery after RNAi. In a subsequent distance foraging bioassay, deviate-silenced termites exhibited equal feeding levels to controls, suggesting the deviate gene is not linked to general vigor or the ability/motivation of termites to move and forage. These findings are among the first linking the expression of a termite gene with eusocial behavior; they illustrate the connection between deviate expression and trailing behavior, which is a key evolutionary adaptation vital to subterranean social insects such as termites and ants.

Characteristics of Cimex lectularius (Hemiptera: Cimicidae), infestation and dispersal in a high-rise apartment building.

Bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae), are a fast-growing urban pest of significant public health importance in the United States and many other countries. Yet, there is very little field research on the ecology of this pest due to its near absence in the United States and most developed nations for several decades. We investigated characteristics of the bed bug infestation and dispersal in a 223-unit high-rise apartment building through visual inspections, intercepting devices, and resident and staff interviews between December 2008 and April 2009. The following results were obtained: 1) 101 apartments (45% of the high-rise building complex) experienced bed bug infestations (within 41 mo of the first confirmed introduction), 2) 78% of the bed bugs trapped were nymphs, 3) an average of six bed bugs were detected dispersing through apartment entry doors every 4 wk, 4) adult bed bugs were 9 times more likely to disperse than nymphs, 5) 53% of apartments adjacent to infested apartments also were infested, and 6) 50% of the interviewed residents who had infestations were unaware of the bed bugs in their apartments. In addition to active dispersal, several passive bed bug dispersal mechanisms were observed: bringing bed bug-infested furniture into the building, travel, resident turnover, resident visits, and use of a bed bug-infested wheelchair in building common areas. These findings validate an urgent need for public education, early detection, and adoption of more effective bed bug monitoring and intervention programs to curb the exploding problem of bed bug infestations.

Bed bug (Heteroptera: Cimicidae) attraction to pitfall traps baited with carbon dioxide, heat, and chemical lure.

Carbon dioxide (CO2), heat, and chemical lure (1-octen-3-ol and L-lactic acid) were tested as attractants for bed bugs, Cimex lectularius L. (Heteroptera: Cimicidae), by using pitfall traps. Both CO2 and heat were attractive to bed bugs. CO2 was significantly more attractive to bed bugs than heat. Traps baited with chemical lure attracted more bed bugs but at a statistically nonsignificant level. In small arena studies (56 by 44 cm), pitfall traps baited with CO2 or heat trapped 79.8 +/- 6.7 and 51.6 +/- 0.9% (mean +/- SEM) of the bed bugs after 6 h, respectively. Traps baited with CO2 + heat, CO, + chemical lure, or CO2 + heat + chemical lure captured > or = 86.7% of the bed bugs after 6 h, indicating baited pitfall traps were highly effective in attracting and capturing bed bugs from a short distance. In 3.1- by 1.8-m environmental chambers, a pitfall trap baited with CO, + heat + chemical lure trapped 57.3 +/- 6.4% of the bed bugs overnight. The pitfall trap was further tested in four bed bug-infested apartments to determine its efficacy in detecting light bed bug infestations. Visual inspections found an average of 12.0 +/- 5.4 bed bugs per apartment. The bed bugs that were found by visual inspections were hand-removed during inspections. A pitfall trap baited with CO2 and chemical lure was subsequently placed in each apartment with an average of 15.0 +/- 6.4 bed bugs collected per trap by the next morning. We conclude that baited pitfall traps are potentially effective tools for evaluating bed bug control programs and detecting early bed bug infestations.

Cost and effectiveness of community-wide integrated pest management for German cockroach, cockroach allergen, and insecticide use reduction in low-income housing.

Many low-income housing units in the United States continue to have chronic German cockroach, Blattella germanica (L.), infestations and high prevalence of cockroach allergens despite the availability of highly effective cockroach control products. Several studies have demonstrated the greater effectiveness of integrated pest management (IPM) compared with routine chemical interventions in apartment buildings and the benefit of cockroach allergen reduction using IPM. Yet, there has been little information on the cost and benefit of community-wide cockroach IPM, which is critical for voluntary adoption of IPM programs. We evaluated a community-wide IPM program in two low-income apartment complexes in Gary, IN. The program included education of staff and residents, monthly monitoring, and nonchemical (laying sticky traps) and chemical treatment based on monitoring results. One complex of 191 apartments was treated with cockroach gel bait, boric acid dust, and sticky traps by state licensed entomologists from Purdue University (E-IPM group). The other complex of 251 apartments was treated by pest management professionals (PMPs) from a contractor (C-IPM group) following the same protocol as the E-IPM group. Purdue University researchers trained Gary Housing Authority (GHA) staff on cockroach biology and management and cockroach allergen reduction techniques. GHA staff educated all residents in the two complexes on cockroach control and allergen reduction through printed materials, demonstrations, or both. Purdue University entomologists conducted the initial and monthly monitoring in both complexes (laying six sticky traps per apartment and retrieving them the next day) with the assistance from GHA to evaluate program effectiveness, guide insecticide applications, and identify apartments with poor sanitation conditions. Dust samples were collected from kitchen floors of 72 cockroach-infested apartments at the beginning, and again at 6 and 12 mo to evaluate changes in cockroach allergen Bla g 1 concentration. E-IPM resulted in significantly faster cockroach trap count reduction than C-IPM. At 12 mo, the number of cockroach-infested apartments decreased by 74% in both treatment groups. Geometric mean cockroach trap counts decreased from 99.7 at baseline to 0.4 (99.6% reduction) by E-IPM and from 76.0 at baseline to 1.3 (98.3% reduction) by C-IPM. From the first quarter to the fourth quarter, cockroach bait use decreased by 88.5 and 92.7% for E-IPM and C-IPM group, respectively. From month 0 to month 12, geometric mean Bla g 1 concentrations decreased from 27.8 to 2.2 U per gram of dust (U/g) in the E-IPM group and from 5.8 to 2.4 U/g in the C-IPM group. Assuming salary rates at $60/h for PMPs and $19/h for housing authority staff, the mean monthly cockroach management (material and labor expenses) cost was $7.5 USD/apartment for both groups excluding education cost. The cost for subsequent years service is expected to be lower due to reduced cockroach infestations. The effectiveness of both IPM programs was affected by the lack of assistance from housing authority with periodic inspections of the apartments, lack of proper maintenance of the properties, and inadequate cooperation from residents.

Evaluation of two least toxic integrated pest management programs for managing bed bugs (Heteroptera: Cimicidae) with discussion of a bed bug intercepting device.

The cost and effectiveness of two bed bug (Cimex lectularius L.) integrated pest management (IPM) programs were evaluated for 10 wk. Sixteen bed bug-infested apartments were chosen from a high-rise low-income apartment building. The apartments were randomly divided into two treatment groups: diatomaceous earth dust-based IPM (D-IPM) and chlorfenapyr spray-based IPM (S-IPM). The initial median (minimum, maximum) bed bug counts (by visual inspection) of the two treatment groups were 73.5 (10, 352) and 77 (18, 3025), respectively. A seminar and an educational brochure were delivered to residents and staff. It was followed by installing encasements on mattresses and box springs and applying hot steam to bed bug-infested areas in all 16 apartments. Diatomaceous earth dust (Mother Earth-D) was applied in the D-IPM group 2 d after steaming. In addition, bed bug-intercepting devices were installed under legs of infested beds or sofas or chairs to intercept bed bugs. The S-IPM group only received 0.5% chlorfenapyr spray (Phantom) after the nonchemical treatments. All apartments were monitored bi-weekly and retreated when necessary. After 10 wk, bed bugs were eradicated from 50% of the apartments in each group. Bed bug count reduction (mean +/- SEM) was 97.6 +/- 1.6 and 89.7 +/- 7.3% in the D-IPM and S-IPM groups, respectively. Mean treatment costs in the 10-wk period were $463 and $482 per apartment in the D-IPM and S-IPM groups, respectively. Bed bug interceptors trapped an average of 219 +/- 135 bed bugs per apartment in 10 wk. The interceptors contributed to the IPM program efficacy and were much more effective than visual inspections in estimating bed bug numbers and determining the existence of bed bug infestations.

Horizontal transfer of bait in the German cockroach: indoxacarb causes secondary and tertiary mortality.

Horizontal transfer of indoxacarb in the German cockroach, Blattella germanica (L.), was examined under laboratory conditions. Results show that a single bait-fed adult cockroach (i.e., the donor) transferred indoxacarb to numerous primary recipients (secondary mortality),which then became secondary donors. These recipients subsequently became donors to other cockroaches and caused significant mortality in other members of the aggregation, resulting in tertiary kill. Indoxacarb was effectively transferred among adult cockroaches and resulted in significant secondary mortality. When adult males served as donors and vectored the insecticide to adult males, the donor:recipient ratio affected the mortality of the recipients and the rate of secondary mortality increased with increasing the ratio of donors to recipients. Furthermore, secondary mortality in the untreated cockroaches was significantly affected by the freshness of excretions from the donors, the presence of alternative food, and the duration of contact between the donors and the recipients. Ingested indoxacarb was most effectively translocated when the recipients interacted with freshly symptomatic donors in the absence of alternative food. The transfer of indoxacarb continued beyond secondary mortality and resulted in significant tertiary mortality. Excretions from a single bait-fed adult killed 38/50 (76%) nymphs within 72 h. The dead nymphs then vectored indoxacarb to 20 adult males and killed 16/20 (81%) recipients within 72 h. Behavioral mechanisms involved in the horizontal transfer of indoxacarb may include: contact with excretions, necrophagy, emetophagy, and ingestion of other excretions that originate from the donors.

Detrimental effects of highly efficient interference competition: invasive Argentine ants outcompete native ants at toxic baits.

The Argentine ant (Linepithema humile) is an invasive species that disrupts the balance of natural ecosystems by displacing indigenous ant species throughout its introduced range. Previous studies that examined the mechanisms by which Argentine ants attain ecological dominance showed that superior interference and exploitation competition are key to the successful displacement of native ant species. The objective of this research was to test the hypothesis that effective interference competition by Argentine ants may also be detrimental to the survival of Argentine ant colonies where Argentine ants and native ants compete at toxic baits used to slow the spread of Argentine ants. To study this hypothesis, we examined the competitive interactions between Argentine ants and native odorous house ants, Tapinoma sessile, in the presence and absence of toxic baits. Results showed that Argentine ants aggressively outcompete T. sessile from toxic baits through efficient interference competition and monopolize bait resources. This has severe negative consequences for the survival of Argentine ants as colonies succumb to the toxic effects of the bait. In turn, T. sessile avoid areas occupied by Argentine ants, give up baits, and consequently suffer minimal mortality. Our results provide experimental evidence that highly efficient interference competition may have negative consequences for Argentine ants in areas where toxic baits are used and may provide a basis for designing innovative management programs for Argentine ants. Such programs would have the double benefit of selectively eliminating the invasive species while simultaneously protecting native ants from the toxic effects of baits.

Survey of pest infestation, asthma, and allergy in low-income housing.

Low-income housing often has multiple indoor health risks. Among them, pest infestation, pesticide use, and pest allergens are recognized as common risks which affect residents' health. Cockroach and rodent allergens are associated with morbidity and mortality of asthmatics. To characterize the levels of pest infestation, residents' attitudes toward pest control, and the relationships among cockroaches, mice, cockroach allergen level, asthma and allergy rate in public housing, we interviewed residents from 358 randomly selected apartments in Gary, Indiana and assessed the environmental conditions. Dust samples were collected from 101 apartment kitchen floors to analyze for cockroach allergen (Bla g 1 and Bla g 2) levels. Eighty one percent of the apartments were found infested by cockroaches, mice, ants, spiders, or flies. In the 101 apartments evaluated, 98% of the kitchen dust samples had detectable levels of Bla g 1 allergen (>or=0.4 U/g), 52% had >or=2 U/g, and 33% had >or=8 U/g of Bla g 1. Among the 1,173 residents, 13% and 9% had physician-diagnosed asthma and allergy, respectively. Existence of diagnosed asthmatic was positively correlated with mouse infestations.

Correlation of cellulase gene expression and cellulolytic activity throughout the gut of the termite Reticulitermes flavipes.

Termites have developed cellulose digestion capabilities that allow them to obtain energy and nutrition from nutritionally poor food sources, such as lignocellulosic plant material and residues derived from it (e.g., wood and humus). Lower termites, which are equipped with both endogenous (i.e., of termite origin) and symbiotic cellulases, feed primarily on wood and wood-related materials. This study investigated cellulase gene diversity, structure, and activity in the lower termite, Reticulitermes flavipes (Kollar). We initially used a metagenomics approach to identify four genes encoding one endogenous and three symbiotic cellulases, which we refer to as Cell-1, -2, -3 and -4. These four genes encode proteins that share significant sequence similarity with known endoglucanases, exoglucanases and xylanases. Phylogenetic analyses further supported these inferred relationships by showing that each of the four cellulase proteins clusters tightly with respective termite, protozoan or fungal cellulases. Gene structure studies revealed that Cell-1, -3 and -4 are intron-free, while Cell-2 contains the first intron sequence to be identified from a termite symbiont cellulase. Quantitative real-time PCR (qRT-PCR) revealed that the endogenous Cell-1 gene is expressed exclusively in the salivary gland/foregut, whereas symbiotic Cell-2, -3, and -4 are highly expressed in the hindgut (where cellulolytic protists are harbored). Cellulase activity assays mapped the distribution pattern of endoglucanase, exoglucanase and xylanase activity throughout the R. flavipes digestive tract. Cellulase gene expression correlated well with the specific types of cellulolytic activities observed in each gut region (foregut+salivary gland, midgut and hindgut). These results suggest the presence of a single unified cellulose digestion system, whereby endogenous and symbiotic cellulases work sequentially and collaboratively across the entire digestive tract of R. flavipes.

Genetic basis for resistance to gel baits, fipronil, and sugar-based attractants in German cockroaches (Dictyoptera: blattellidae).

A gel bait-resistant Blattella germanica (L.) strain (Cincy) was collected in Cincinnati, OH, in 2003. This strain exhibited strong behavioral resistance to Avert (0.05% abamectin), Maxforce FC (0.01% fipronil), and Pre-Empt (2.15% imidacloprid) gel baits. Reciprocal mass crosses and back crosses between the Cincy strain and a susceptible strain (Jwax) were made and tested for their inheritance of resistance to Avert, Maxforce FC, and Pre-Empt gel baits. Topical assays comparing the parental and reciprocal-heterozygous strains indicated the resistance to fipronil was incompletely recessive. LD50 and LD50 values of the Jwax male x Cincy female strain were not significantly different from he Jwax female x Cincy male strain, suggesting no sex linkage in physiological fipronil resistance. Feeding assays revealed that F1 reciprocal crosses were significantly less responsive to blank Avert and Maxforce FC baits (without active ingredients) than the susceptible strain. The Jwax female x Cincy male strain did not display significantly greater consumption of blank Avert and Maxforce FC baits relative to the Jwax male x Cincy female strain. In feeding assays with agar containing D-fructose, D-galactose, D-glucose, D-lactose, D-maltose, and D-sucrose, the crosses showed an intermediate feeding response to glucose compared with the Cincy and Jwax strains, and a similar response to other sugars compared with the Jwax strain. The Jwax male x Cincy female strain was significantly less responsive to glucose than the Jwax female x Cincy male strain. Mortality induced by Avert, Maxforce FC, and Pre-Empt gel baits against the F6 Jwax male x Cincy femaale strain was 44.2 +/- 6.8, 92.9 +/- 2.1, and 78.7 +/- 5.2%, respectively, indicating the resistance to Avert and Pre-Empt gel baits inherited by Cincy females was extremely stable. The F6 Jwax male x Cincy female strain was significantly more resistant to Avert, Maxforce FC, and Pre-Empt than the F6 Jwax female x Cincy male strain. These findings suggest that behavioral resistance to gel baits has weak sex-linkage, with a greater degree of the resistance trait being inherited by female cockroaches. Alternatively, physiological resistance to fipronil has no sex-linkage, but it is nonetheless important to the complete resistance phenotype.

Comparative study of integrated pest management and baiting for German cockroach management in public housing.

This study assessed the cost and effectiveness of a building-wide cockroach integrated pest management (IPM) program compared with bait alone treatment in public housing. In total, 12 buildings (66 apartments) were treated and monitored for cockroach infestations over 7 mo. The buildings were divided into two groups: bait treatment and IPM. Apartments in the bait alone group were treated with Maxforce FC Select (0.01% fipronil) during the first 12 wk and Maxforce Roach Killer Bait Gel (2.15% hydramethylnon) from 16 wk when necessary. For the IPM group, cockroaches were flushed and vacuumed at the beginning of the study; sticky traps were placed in all apartments to monitor and reduce cockroach numbers; educational materials were delivered to the residents; and Maxforce FC Select and Maxforce Roach Killer Bait Gel were applied to kill cockroaches. Two seminars were presented to the manger, and Community Service Program staff of the Gary Housing Authority to help gain tenant cooperation in the program. Effects of the treatments were monitored using sticky traps (six per apartment) at 2, 4, 8, 12, 16, and 29 wk after treatment. More treatments were applied during each monitoring visit when necessary. Those apartments with high levels of infestations (> or =12 cockroaches in six traps) before treatment were used to compare the IPM and bait only treatments. IPM resulted in significantly greater trap catch reduction than the bait treatment. The IPM (n=12) and bait only treatment (n=11) resulted in 100.0 and 94.6%, respectively, reduction in trap catch after 16 wk. At 29 wk, only one apartment in the IPM group had a high level (>12 cockroaches) of cockroach infestation. In contrast, five apartments in the bait treatment group had high level infestations at 29 wk based on overnight trapping counts; thus, IPM is a more sustainable method of population reduction. Sanitation levels in the IPM group significantly improved at 29 wk (n=11) compared with that at the beginning of the study. The sanitation levels in the bait treatment group remained similar throughout the experiment (n=9). The cumulative cost of IPM was significantly higher than that of the bait treatment. The median costs per apartment during 29 wk were 64.8 dollars and 35.0 dollars for the IPM and bait treatment, respectively. The median amount of bait used per apartment in the IPM and bait treatment was 45.0 and 50.0 g, respectively. The cost of the IPM group for the 29 wk service was similar to that of the bait treatment group. We expect that IPM will provide better control at similar cost compared with bait treatment beyond 29 wk.

Efficacy of noviflumuron gel bait for control of the German cockroach, Blattella germanica (Dictyoptera: Blattellidae)-laboratory studies.

The insecticidal activity of a cockroach gel bait containing a chitin synthesis inhibitor, noviflumuron, was evaluated using laboratory and field strains of the German cockroach, Blattella germanica (L.). Noviflumuron gel bait (0.01-5 mg g(-1)) caused > or = 90% nymphal mortality to laboratory and field strains of B. germanica in choice tests after 11 and 19 days of continuous exposure respectively. In 1 m x 1 m bioassay arenas, laboratory strain B. germanica population levels exposed to 5 mg g(-1) noviflumuron bait or 0.1 mg g(-1) fipronil gel bait were significantly lower than untreated population levels after 3 weeks and 1 week of exposure respectively. Various noviflumuron bait exposure periods (2, 4 and 7 weeks) caused similar population reductions, with a mean of 99.3 (+/- 0.3)% at 7 weeks. Fipronil gel bait caused 100% population reduction at 2 weeks post-exposure. The control population increased 89.0% at 7 weeks. In a simulated kitchen experiment with mixed stage laboratory populations, cockroach trap catches decreased 96.8 (+/- 2.0)% at 8 weeks in the 0.5 mg g(-1) noviflumuron bait treatment. The trap catches in the control increased 506.5 (+/- 493.7)% during the same period. Trap catch reduction by 0.1 mg g(-1) fipronil gel bait reached 100% at 4 weeks. Noviflumuron bait caused significantly lower nymph/total ratios to B. germanica populations in bioassay arenas from 2 weeks after exposure, demonstrating its effectiveness as a control agent for B. germanica with a pattern of activity similar to that expected from a chitin synthesis inhibitor.