Gary W. Bennett

Caste- and development-associated gene expression in a lower termite

BackgroundSocial insects such as termites express dramatic polyphenism (the occurrence of multiple forms in a species on the basis of differential gene expression) both in association with caste differentiation and between castes after differentiation. We have used cDNA macroarrays to compare gene expression between polyphenic castes and intermediary developmental stages of the termite Reticulitermes flavipes.ResultsWe identified differentially expressed genes from nine ontogenic categories. Quantitative PCR was used to quantify precise differences in gene expression between castes and between intermediary developmental stages. We found worker and nymph-biased expression of transcripts encoding termite and endosymbiont cellulases; presoldier-biased expression of transcripts encoding the storage/hormone-binding protein vitellogenin; and soldier-biased expression of gene transcripts encoding two transcription/translation factors, two signal transduction factors and four cytoskeletal/muscle proteins. The two transcription/translation factors showed significant homology to the bicaudal and bric-a-brac developmental genes of Drosophila.ConclusionsOur results show differential expression of regulatory, structural and enzyme-coding genes in association with termite castes and their developmental precursor stages. They also provide the first glimpse into how insect endosymbiont cellulase gene expression can vary in association with the caste of a host. These findings shed light on molecular processes associated with termite biology, polyphenism, caste differentiation and development and highlight potentially interesting variations in developmental themes between termites, other insects, and higher animals.

Gene expression profiles among immature and adult reproductive castes of the termite Reticulitermes flavipes

Array‐based genomic studies were conducted with the goal of identifying immature (i.e. nymph) and adult reproductive caste‐biased gene expression in the termite Reticulitermes flavipes. Using cDNA macro‐arrays, we identified thirty‐four nymph‐biased genes falling into eight ontogenic categories. Based on gene expression profiles among diverse castes and developmental stages (determined by quantitative PCR), several important trends emerged. These findings highlight the importance of several developmental and survival‐based factors among immature and adult termite reproductives, including: vitellogenesis, nutrient storage, juvenile hormone sequestration, ribosomal translational and filtering mechanisms, fatty acid biosynthesis, apoptosis inhibition, and both endogenous and symbiont cellulase‐assisted nutrition. These findings are highly significant as they are the first to elucidate the molecular biology underlying termite reproductive caste differentiation and reproductive caste‐specific biology. Other gene expression results are in agreement with previous findings that suggest roles for vitellogenin‐like haemolymph proteins in soldier caste differentiation.

Evaluation of Two Least Toxic Integrated Pest Management Programs for Managing Bed Bugs (Heteroptera: Cimicidae) With Discussion of a Bed Bug Intercepting Device

ABSTRACT 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

Characteristics of Cimex lectularius (Hemiptera: Cimicidae), Infestation and Dispersal in a High-Rise Apartment Building

463 and

Bed Bug (Heteroptera: Cimicidae) Attraction to Pitfall Traps Baited with Carbon Dioxide, Heat, and Chemical Lure

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.

Caste differentiation responses of two sympatric Reticulitermes termite species to juvenile hormone homologs and synthetic juvenoids in two laboratory assays

ABSTRACT 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.

Genome-wide analysis of phenobarbital-inducible genes in Drosophila melanogaster

ABSTRACT 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, CO2 + chemical lure, or CO2 + heat + chemical lure captured ≤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, apitfall trap baited with CO2 + 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.

Comparative Study of Integrated Pest Management and Baiting for German Cockroach Management in Public Housing

SummaryWe report on our investigations comparing three juvenile hormone (JH) homologs and two synthetic juvenoids to induce caste differentiation in laboratory colonies of Reticulitermes flavipes and R. tibialis. Two laboratory assays were evaluated as model systems for inducing caste differentiation: (1) shorter-term dish assays on groups of 20 individuals and (2) longer-term feeding assays on groups of 500 individuals. Each assay possessed attributes that can be considered advantageous under certain conditions. Specifically, dish assays were most suitable for presoldier and soldier induction, while jar assays provided for the induction of nymphs, presoldiers, soldiers, neotenic reproductives, and intercastes. Differences in response to the JH homologs and synthetic juvenoids were noted between species, suggesting differences in JH physiology may exist between R. flavipes and R. tibialis. Substantial morpholo-gical impacts were noted in association with some treatments, including (1) juvenoid-induced mandibular mal-formation in presoldiers, (2) JH II-induced abdominal elongation in R. flavipes soldiers and workers (associated with a presence of internal reproductive anatomy that is consistent with what would be expected to occur in pseudergates), and (3) JH II-induced soldier-nymph intercastes in R. tibialis that were able to further molt into soldier-alate intercastes. Findings are discussed in relation to the potential differences in JH-related physiology between R. flavipes and R. tibialis, and the use of model systems to induce rare castes and intercastes for molecular investigations of caste differentiation.

Seasonal polydomy in a polygynous supercolony of the odorous house ant, Tapinoma sessile

An oligoarray analysis was conducted to determine the differential expression of genes due to phenobarbital exposure in Drosophila melanogaster (w1118 strain) third instar larvae. Seventeen genes were observed to be induced with increased expression by a statistical analysis of microarrays approach with a q ≤ 0.05. At q ≤ 0.12, four more genes (Cyp12d1, DmGstd4, and two genes with unknown function) were found to be up‐regulated, and 11 genes with unknown function were found to be down‐regulated. Fifteen of these genes, Cyp4d14, Cyp6a2, Cyp6a8, Cyp12d1, Cyp6d5, Cyp6w1, CG2065, DmGstd6, DmGstd7, Amy‐p/Amy‐d, Ugt86Dd, GC5724, Jheh1, Jheh2 and CG11893, were verified using quantitative real time polymerase chain reaction. Some of these genes have been shown to be over‐transcribed in metabolically DDT‐resistant Drosophila strains.

Impacts of Soil Moisture Level on Consumption and Movement of Three Sympatric Subterranean Termites (Isoptera: Rhinotermitidae) in a Laboratory Assay

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.