Adult Bugs Research Articles

Food Habits of Invasive Bullfrogs and Native Thin-Toed Frogs Occurring in Sympatry in Southeastern Brazil

Abstract. Although the feeding ecology of sympatric anurans has been studied, less is known about the food habits of co-occurring invasive and native frog species, particularly in the Neotropics. We compared the food habits of invasive bullfrogs (Lithobates catesbeianus) and native thin-toed frogs (Leptodactylus cf. latrans) in a locality of Southeastern Brazil. Monthly field surveys and stomach content analyses were performed between September 2008–April 2009 and September–November 2009. Prey items were identified to the lowest taxonomic level and diet overlap was estimated. Juveniles of both species had similar body sizes, but adult thin-toed frogs were smaller than adult bullfrogs. Insects and spiders dominated the diets of juveniles of both species and of adult thin-toed frogs, whereas anurans and water bugs predominated in adult bullfrog diets. Thin-toed frogs consumed a larger number of prey items than bullfrogs, which in turn consumed more voluminous prey items. Aquatic and amphibious prey items we...

Tamanho de amostra para avaliar a densidade populacional de percevejos em lavouras de soja

RESUMO: O objetivo deste trabalho foi estimar o tamanho de amostra para medir a densidade populacional de espécies de percevejos, variando métodos de coleta, altitude e cultivares de soja. Foram utilizadas 100 lavouras de soja, distribuídas em nove municípios da região central do Rio Grande do Sul, em três safras agrícolas (2010/2011, 2011/2012, 2012/2013). Em cada lavoura, foram demarcados 30 pontos distantes em 20 metros entre si. Em cada ponto, foram coletados percevejos (adultos + ninfas) das espécies Dichelops sp., Piezodorus guildinii e Euchistus heros, por meio dos métodos pano-de-batida largo e rede entomológica, totalizando 6.000 coletas. Para cada lavoura, método de coleta e espéciede percevejo, foram estimadas a média da densidade populacional e o tamanho de amostra por meio de reamostragem. O tamanho de amostra (número de pontos) para determinar a densidade populacional de percevejos varia com o método de coleta e a densidade populacional. Usando o pano-de-batida largo para a coleta de percevejos em soja, para um erro de estimação (amplitude do intervalo de credibilidade) igual a dois percevejos e densidade populacional na classe de 1,5 a 2,0 percevejos m-2, o tamanho de amostra é 13, 77 e 15, respectivamente, para as espécies Dichelops sp., P. guildinii e E. heros.

Rearing Orius strigicollis (Hemiptera: Anthocoridae) on an alternative diet of brine shrimp, Artemia salina (Anostraca: Artemiidae)

We investigated the use of cysts of the brine shrimp Artemia salina Linnaeus as an alternative diet to eggs of the Mediterranean flour moth, Ephestia kuehniella Zeller, in rearing the biological control agent Orius strigicollis (Poppius). Although 3rd- and 4th-instar nymphs and 1st to 5th-instar nymphs took longer to develop when fed on brine shrimp cysts with shells than on E. kuehniella eggs, the difference was within or approximately 1 day. The nymphal survival and development were considered to be similar in O. strigicollis fed the two diets. In reproductive characteristics, adult female bugs fed eggs of E. kuehniella or brine shrimp cysts with shells performed better than those fed brine shrimp cysts without shells. Brine shrimp cysts with shells would, thus, be useful for reliably and economically rearing O. strigicollis. This rearing method may also prove useful as part of the quality assurance for commercially produced O. strigicollis.

Efficacy of diatomaceous earth and a DE-aerosol formulation against the common bed bug, Cimex lectularius Linnaeus in the laboratory

Wehaveinvestigatedefficacyofadiatomaceous earth(DE)andanaerosolformulationthereofforcontactand residual effects against the common bed bug, Cimex lectu- larius L. Efficacy of commercially available DE dust sam- ples varied with the product. DX13 TM and MotherEarth � dusts were significantly more effective than other DE dusts based on their lower lethal doses to kill 50 % of the insects, LD50 values (LD50s = 0.17 and 0.18 g m -2 , respectively), in contact bioassays with adult bugs. DX13 TM -aerosol demonstrated residual effect in both plastic box and the Petri dishmethods.Inlargeplasticboxesmortalityofthebedbugs due to residual effect of the aerosol was 98 % at 24 h. The residual effect of DX13 TM -aerosol in Petri dishes persisted for 21 days. Time to kill 50 % of the insects, LT50 value, increased from 10.2 h for freshly applied DE dust to 46.1 h fordustaged for21 days in Petri dishes. Mortalityof thebed bugsinthePetridisheswas(97 %at72 h,notonlyforfresh DX13 TM -aerosol residue, but also for residues aged up to 14 days. Mortality was 81 % at 72 h for DX13 TM -aerosol residueagedfor21 days.Mortalityofbedbugsconfinedona DX13 TM -incorporated mattress was 100 % at 48 and 72 h for bugs introduced on the mattress 3 and 32 weeks after manufacture, respectively. We also observed horizontal transfer of DX13 TM -dust between dead bugs collected from the DX13 TM -incorporated mattress to untreated ones. We discuss potential use of DX13 TM for the management of bed

Density and Egg Parasitism of Stink Bugs (Hemiptera: Pentatomidae) in Elderberry and Dispersal Into Crops.

Chinavia hilaris (Say), Euschistus servus (Say), Euschistus tristigmus (Say), and Thyanta custator custator (F.) (Hemiptera: Pentatomidae) are serious pests of crops in the southeastern United States but little is known concerning their dispersal from noncrop hosts in woodlands into crops. This 2-yr study was conducted to investigate whether elderberry [Sambucus nigra subsp. canadensis (L.) R. Bolli] in woodlands serves as a source of stink bugs dispersing into adjacent crops and to examine parasitism of C. hilaris and E. servus eggs on this plant. Elderberry was a reproductive host for each of the four stink bug species; females oviposited on plants with subsequent nymphs feeding on elderberry and developing into adults. Anastatus mirabilis (Walsh & Riley) (Hymenoptera: Eupelmidae), Anastatus reduvii (Howard), and Trissolcus edessae Fouts (Hymenoptera: Scelionidae) were prevalent egg parasitoids of C. hilaris but A. reduvii was the prevalent parasitoid of E. servus. Newly developed stink bug adults were first detected on elderberry around mid-July. Then in late July and early August, as elderberry fruit senesced and cotton bolls became available, stink bugs began dispersing from elderberry into cotton based on recapture of stink bugs on cotton that had previously been marked on elderberry. In addition, in 2015, density of C. hilaris, E. servus, and E. tristigmus was higher in cotton with elderberry than in cotton without it. Over the study, economic threshold was reached for four of seven cotton fields. Elimination of elderberry in woodlands adjacent to cotton may be a viable management tactic for control of stink bugs in cotton.

Insecticidal Control of Fall Armyworm and Sugarcane Borer, 2012: Table 1

Selected insecticides were evaluated for control of fall armyworm and sugarcane borer. The impact of insecticide treatments on pirate bug adults was also evaluated. The trial was conducted at the Experimental Station ‘Las Huastecas’, of the Instituto de Investigaciones Forestales, Agricolas y Pecuarias (INIFAP), located in Villa Cuauhtemoc, Tamaulipas, Mexico (N 22° 21' 12.24” , W 101° 01' 58.77”). Corn (A-7573, Asgrow) was planted on 16 Mar 2012, in a 0.25 ha field on double rows on beds (1.70 m wide by 45 m long) with drip irrigation at a …

Risk factors associated with Trypanosoma cruzi exposure in domestic dogs from a rural community in Panama.

Chagas disease, caused by Trypanosoma cruzi infection, is a zoonosis of humans, wild and domestic mammals, including dogs. In Panama, the main T. cruzi vector is hodnius pallescens, a triatomine bug whose main natural habitat is the royal palm, Attalea butyracea. In this paper, we present results from three T. cruzi serological tests (immunochromatographic dipstick, indirect immunofluorescence and ELISA) performed in 51 dogs from 24 houses in Trinidad de Las Minas, western Panama. We found that nine dogs were seropositive (17.6% prevalence). Dogs were 1.6 times more likely to become T. cruzi seropositive with each year of age and 11.6 times if royal palms where present in the peridomiciliary area of the dog's household or its two nearest neighbours. Mouse-baited-adhesive traps were employed to evaluate 12 peridomestic royal palms. All palms were found infested with R. pallescens with an average of 25.50 triatomines captured per palm. Of 35 adult bugs analysed, 88.6% showed protozoa flagellates in their intestinal contents. In addition, dogs were five times more likely to be infected by the presence of an additional domestic animal species in the dog's peridomiciliary environment. Our results suggest that interventions focused on royal palms might reduce the exposure to T. cruzi infection.

Identification of the Alarm Pheromone of Hygia lativentris and Changes in Composition during Development.

Heteropteran insects produce a series of volatile compounds from their scent glands that protect them from predators and parasites. These compounds also play roles in chemical communication that elicit aggregation, dispersal, and mating behaviors. Hygia lativentris (Coreidae) adults frequently aggregate on host plants. When disturbed, they quickly disperse with the release of a sour smell, suggesting that these bugs possess an alarm pheromone in their secretions. This adult secretion-induced dispersal has been examined with a laboratory assay. Hexanal, the predominant component of the adult secretion was identified as a component of the alarm pheromone by evaluation of the adult bug's response time and escape distance from the chemical source. Physicochemical analyses with gas chromatography/mass spectrometry and nuclear magnetic resonance spectroscopy revealed that secretory components differed between nymphs and adults, and also during adult aging. Nymphs produced two unsaturated compounds, (E)-2-hexenal and (E)-4-oxo-2-hexenal, together with hexanal and 1-hexanol, which were found in all developmental stages. In adults, hexyl acetate was the major component of secretions within 3 days of emerging, while the amount of this ester decreased and those of hexanal, hexanoic acid, and hexanal trimer increased with aging. The decomposition of hexyl acetate into hexanal via 1-hexanol was attributed to the presence of esterases and alcohol dehydrogenases specifically found in adult secretory glands. In contrast, the formation of a hexanal trimer may be due to a non-enzymatic reaction under acidic conditions.

Trap Cropping Systems and a Physical Barrier for Suppression of Stink Bugs (Hemiptera: Pentatomidae) in Cotton.

Euschistus servus (Say), Nezara viridula (L.), and Chinavia hilaris (Say) (Hemiptera: Pentatomidae) are economic pests of cotton in the coastal plain of the southeastern United States. The objective of this 2-yr study was to determine the ability of trap cropping systems, pheromone-baited stink bug traps, and a synthetic physical barrier at the peanut-to-cotton interface to manage stink bugs in cotton. The physical barrier was the most effective management tactic. Stink bug density in cotton was lowest for this treatment. In 2010, boll injury was lower for the physical barrier compared to the other treatments except for soybean with stink bug traps. In 2011, boll injury was lower for this treatment compared to the control. Soybean was an effective trap crop, reducing both stink bug density in cotton and boll injury regardless if used alone or in combination with either stink bug traps or buckwheat. Incorporation of buckwheat in soybean enhanced parasitism of E. servus egg masses by Telenomus podisi Ashmead in cotton. The insertion of eyelets in the lid of the insect-collecting device of a stink bug trap allowed adult stink bug parasitoids, but not E. servus, to escape. Stand-alone stink bug traps were not very effective in deterring colonization of cotton by stink bugs or reducing boll injury. The paucity of effective alternative control measures available for stink bug management justifies further full-scale evaluations into these management tactics for control of these pests in crops.

Influences of food sources on reproduction and aggregation pheromone production of Riptortus pedestris (Hemiptera: Alydidae) in its adult stage

AbstractThe dietary importance of sweet persimmon fruit (SPF) was determined in adult bean bug, Riptortus pedestris, by investigating the effect of feeding SPF and soybean seeds and peanut on longevity, weight change, fecundity and ability for pheromone production in the bean bug. Adult female R. pedestris fed on SPF had significantly shorter lifespans than those fed on soybean, while in males there was no significant difference. Males and females fed on SPF were significantly lighter than those fed on soybean seeds. Females fed on SPF did not lay eggs at all, but those fed on soybean laid 155.8 eggs, and those fed on soybean seed complemented with peanut seed laid 120.8 eggs in 50 days. The amount of pheromone components (E)‐2‐hexenyl (E)‐2‐hexenoate and (E)‐2‐hexenyl (Z)‐2‐hexenoate produced by male R. pedestris fed on SPF was significantly less than that produced by males fed on soybean. Other pheromone components, tetradecyl isobutyrate and octadecyl isobutyrate, were not produced by adult males fed on SPF. This difference was apparent at one week after emergence and was more at three weeks after emergence. In the present study, we demonstrated that SPF had adverse effect on female survivorship, reproduction of female adults and production of the aggregation pheromone by adult males, compared to soybean food. These results suggested that SPF is unsuitable for adult R. pedestris. Management of nearby vegetation of fruit orchards may play an important role in reducing damage by adult R. pedestris.

Molecular basis of peripheral olfactory plasticity in Rhodnius prolixus, a Chagas disease vector

Olfaction is fundamental for most animals and critical for different aspects of triatomine biology, including host-seeking, reproduction, avoidance of predators, and aggregation in shelters. Ethological and physiological aspects of these olfactory-mediated behaviors are well understood, but their molecular bases are still largely unknown. Here we investigated changes in molecular mechanisms at the peripheral olfactory level in response to different physiological and developmental conditions. For this, the antennal expression levels of the odorant (Orco) and ionotropic (IR8a, IR25a and IR76b) coreceptor genes were determined in Rhodnius prolixus by means of quantitative real-time PCR (qRT-PCR) analysis. Gene expression changes were analyzed to test the effect of feeding and imaginal molt for both sexes. Moreover, we analyzed whether expression of these genes changed during the early life of adult bugs. Under these conditions bugs display distinct behavioral responses to diverse chemical stimuli. A significantly decreased expression was induced by blood feeding on all coreceptor genes. The expression of all genes was significantly increased following the imaginal molt. These results show that olfactory coreceptor genes have their expression altered as a response to physiological or developmental changes. Our study suggests that olfactory coreceptor genes confer adaptability to the peripheral olfactory function, probably underlying the known plasticity of triatomine olfactory-mediated behavior.

Seasonality and Distribution Pattern of Brown Marmorated Stink Bug (Hemiptera: Pentatomidae) in Virginia Vineyards.

Brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a highly polyphagous invasive insect pest from eastern Asia that feeds on numerous fruit, vegetable, and field crops. Four commercial vineyards in Virginia were sampled in 2012 and 2013 to study the basic biology, seasonality, and distribution pattern of H. halys in vineyards. At each vineyard, two blocks were selected. Weekly 3-min timed count visual samplings were performed in border and interior sections from late May until mid-September. Overwintering adult bugs were first detected in vineyards in May; however, the timing of first detection differed among vineyards. Egg masses were found primarily in June and July, and were usually found on the lower surface of grape leaves, although they were occasionally on the upper leaf surface, on the berry, or on the rachis. All developmental stages of H. halys were found in vineyards, suggesting that grape can serve as a reproductive host for H. halys. Substantial variation in H. halys densities was found among vineyards and throughout the growing season. The first instars were found on egg masses and after molting, dispersed throughout the grape vines. The date on which the first egg mass was collected was considered as a biofix. Based on a degree-day model, there were sufficient degree-days for completion of a generation in Virginia vineyards. Significantly higher numbers of H. halys were collected in border sections compared with interior sections. These results are discussed in relation to the potential pest status of H. halys in vineyards and implications for possible control strategies.

Mortality, temporary sterilization, and maternal effects of sublethal heat in bed bugs.

Adult bed bugs were exposed to the sublethal temperatures 34.0°C, 35.5°C, 37.0°C, 38.5°C, or 40.0°C for 3, 6, or 9 days. The two uppermost temperatures induced 100% mortality within 9 and 2 days, respectively, whereas 34.0°C had no observable effect. The intermediate temperatures interacted with time to induce a limited level of mortality but had distinct effects on fecundity, reflected by decreases in the number of eggs produced and hatching success. Adult fecundity remained low for up to 40 days after heat exposure, and the time until fertility was restored correlated with the temperature-sum experienced during heat exposure. Three or 6 days of parental exposure to 38.5°C significantly lowered their offspring’s feeding and moulting ability, which consequently led to a failure to continue beyond the third instar. Eggs that were deposited at 22.0°C before being exposed to 37.0°C for 3 or 6 days died, whereas eggs that were exposed to lower temperatures were not significantly affected. Eggs that were deposited during heat treatment exhibited high levels of mortality also at 34.0°C and 35.5°C. The observed negative effects of temperatures between 34.0°C and 40.0°C may be utilized in pest management, and sublethal temperature exposure ought to be further investigated as an additional tool to decimate or potentially eradicate bed bug populations. The effect of parental heat exposure on progeny demonstrates the importance of including maternal considerations when studying bed bug environmental stress reactions.

Patterns of expression of odorant receptor genes in a Chagas disease vector

Rhodnius prolixus is a triatomine bug acting as a relevant vector of Chagas disease for which the genome sequence has been recently made available. Based on this information, a set of olfactory (ORs) and ionotropic receptor (IRs) genes potentially related to olfactory processes was characterized, and the expression patterns along bug development and in different structures potentially involved in promoting chemosensory-mediated behaviors were studied. For this, diverse bioinformatic procedures were used to validate gene models analyzing their structural and functional features and designing specific primers. Evolutionary relationships among R. prolixus olfactory coreceptors (RproOrco, RproIR25a, RproIR8a and RproIR76b) and their orthologues from other insects were shown to have mostly good bootstrap support values in phylogenetic trees. Moreover, antennal expression was confirmed for most genes included in the study. Both ORs and IRs showed antennal expression along the whole development of bugs of this species, with few exceptional receptors showing gradually increasing expression or expression restricted to the antennae of adult bugs. Finally, the expression of most of the selected genes was confirmed in other structures, such as rostri, tarsi, tibial pads and genitalia, which are potentially involved in promoting chemosensory-mediated behaviors. These results are discussed in terms of their relevance to advance in the understanding of the molecular bases of triatomine behavior.

Impact of Oebalus pugnax (Hemiptera: Pentatomidae) Infestation Timing on Rice Yields and Quality.

Sleeve and large field cage experiments were conducted in Stoneville, MS, in 2010 and 2011 to assess adult rice stink bug, Oebalus pugnax (F.), injury in rice. ‘Cocodrie’ and ‘Wells’ were infested at bloom, milk, and soft dough stages of panicle development. Twenty rice panicles were infested individually in the sleeve cage experiment as replicates with 0, 1, or 2 O. pugnax in a split-plot, completely randomized design. The large cage experiment had four replications infested with 9 or 18 O. pugnax per square meter over multiple rice panicles in a split-plot, randomized complete block design per cultivar. Caged uninfested controls were included in each experiment. Rough rice yield and percentage of clean, damaged, and blank kernels were evaluated. In both experiments, stage of panicle development impacted grain yield and quality. Yield loss was greatest during the bloom stage, while kernel damage was greatest during the milk and soft dough stages. Rice yield decreased with increased infestation density. Kernel damage increased with increased infestation density. Blank kernels affect yield, while kernel damage affects grain quality. While grain yield is the bottom line, grain quality affects marketability, which directly affects yield profitability. Based on these results, this study considers O. pugnax injury significant in all three stages of panicle development and concludes that a more aggressive threshold is recommended from panicle emergence through soft dough. More research is needed to determine the specific threshold, but it appears to be lower than the current threshold of 5 per 10 sweeps.

Frequent house invasion of Trypanosoma cruzi-infected triatomines in a suburban area of Brazil.

BackgroundThe demographic transition of populations from rural areas to large urban centers often results in a disordered occupation of forest remnants and increased economic pressure to develop high-income buildings in these areas. Ecological and socioeconomic factors associated with these urban transitions create conditions for the potential transmission of infectious diseases, which was demonstrated for Chagas disease.Methodology/Principal FindingsWe analyzed 930 triatomines, mainly Triatoma tibiamaculata, collected in artificial and sylvatic environments (forests near houses) of a suburban area of the city of Salvador, Bahia State, Brazil between 2007 and 2011. Most triatomines were captured at peridomiciles. Adult bugs predominated in all studied environments, and nymphs were scarce inside houses. Molecular analyses of a randomly selected sub-sample (n=212) of triatomines showed Trypanosoma cruzi infection rates of 65%, 50% and 56% in intradomestic, peridomestic and sylvatic environments, respectively. We detected the T. cruzi lineages I and II and mixed infections. We also showed that T. tibiamaculata fed on blood from birds (50%), marsupials (38%), ruminants (7%) and rodents (5%). The probability of T. cruzi infection was higher in triatomines that fed on marsupial blood (odds ratio (OR) = 1.95, 95% confidence interval (CI) = 1.22-3.11). Moreover, we observed a protective effect against infection in bugs that fed on bird blood (OR = 0.43, 95% CI = 0.30-0.73).Conclusions/SignificanceThe frequent invasion of houses by infected triatomines indicates a potential risk of T. cruzi transmission to inhabitants in this area. Our results reinforce that continuous epidemiological surveillance should be performed in areas where domestic transmission is controlled but enzootic transmission persists.

Sublethal Effects of ActiveGuard Exposure on Feeding Behavior and Fecundity of the Bed Bug (Hemiptera: Cimicidae)

Sublethal exposure to pesticides can alter insect behavior with potential for population-level consequences. We investigated sublethal effects of ActiveGuard, a permethrin-impregnated fabric, on feeding behavior and fecundity of bed bugs (Cimex lectularius L.) from five populations that ranged from susceptible to highly pyrethroid resistant. After exposure to ActiveGuard fabric or untreated fabric for 1 or 10 min, adult virgin female bed bugs were individually observed when offered a blood meal to determine feeding attempts and weight gain. Because bed bug feeding behavior is tightly coupled with its fecundity, all females were then mated, and the number of eggs laid and egg hatch rate were used as fecundity measures. We observed that pyrethroid-resistant and -susceptible bugs were not significantly different for all feeding and fecundity parameters. Bed bugs exposed to ActiveGuard for 10 min were significantly less likely to attempt to feed or successfully feed, and their average blood meal size was significantly smaller compared with individuals in all other groups. Independent of whether or not feeding occurred, females exposed to ActiveGuard for 10 min were significantly more likely to lay no eggs. Only a single female exposed to ActiveGuard for 10 min laid any eggs. Among the other fabric treatment-exposure time groups, there were no observable differences in egg numbers or hatch rates. Brief exposure of 10 min to ActiveGuard fabric appeared to decrease feeding and fecundity of pyrethroid-resistant and susceptible bed bugs, suggesting the potentially important role of sublethal exposure for the control of this ectoparasitic insect.

Comparison of the Effects of Neonicotinoids and Pyrethroids AgainstOebalus pugnax(Hemiptera: Pentatomidae) in Rice

The rice stink bug, Oebalus pugnax (F.) (Hemiptera: Pentatomidae), is an economically important late-season pest of rice in the southern United States. Stink bug feeding results in yield reduction and discounted purchase price due to broken or discolored (“pecky”) rice grains. The primary tactic for O. pugnax management is the application of insecticides once adults reach an action threshold. Recent surveys show that pyrethroids are preferred by southern U.S. rice farmers over all other insecticides to reduce O. pugnax densities. However, preliminary tests in 2009 suggested resistance to pyrethroids may be developing in an O. pugnax population in Texas, where applications are more frequent than in other rice-growing areas. This study compared the effects of pyrethroids and neonicotinoids on O. pugnax behavior and mortality in the laboratory and in a number of field experiments conducted between 2011 and 2014. Results from these experiments showed that control of O. pugnax given by the neonicotinoid, dinotefuran, was similar to that given by pyrethroids in the laboratory and field. Results from small-plot field studies were influenced by movement of adult rice stink bugs from surrounding untreated plots, and the data from commercial-scale trials and from sampling of nymphs in small plots may provide more useful information on the efficacies of insecticides. Two experiments provided limited evidence for longer residual activity of dinotefuran compared to the pyrethroid λ-cyhalothrin, and a laboratory study showed that both insecticides reduced feeding activity of rice stink bugs. Tests also confirmed the increased tolerance of a Texas population of rice stink bugs to λ-cyhalothrin, suggesting the need for insecticides with different modes of action in the O. pugnax management program.

Effects of Starvation on Deltamethrin Tolerance in Bed Bugs, Cimex lectularius L. (Hemiptera: Cimicidae).

Bed bugs, Cimex lectularius L., are a major pest in the urban environment. Their presence often results in physical, psychological, and financial distress of homeowners and apartment dwellers. Although many insecticide bioassays have been performed on this pest, little attention has been paid to bed bug feeding status, which is closely linked to metabolism, molting, and mass. Therefore, we evaluated the toxicity of topically applied deltamethrin on insecticide susceptible adult male bed bugs fed 2 d, 9 d, and 21 d prior to testing. When toxicity was evaluated on a “per-bug” basis, there was no difference between 2 d [LD50 = 0.498 (0.316 − 0.692) ng·bug−1] and 9 d [LD50 = 0.572 (0.436 − 0.724) ng·bug−1] starved bugs, while 21 d starved bugs had a significantly lower LD50 [0.221 (0.075 − 0.386) ng·bug−1]. When toxicity was evaluated in terms of body mass, 9 d starved bugs had the highest LD50 values [0.138 (0.102 − 0.176) ng·mg−1], followed by 2 d starved bugs [0.095 (0.060 − 0.134) ng·mg−1], and then 21 d starved bugs [0.058 (0.019–0.102) ng·mg−1]; the LD50 values of 2 d and 9 d starved bugs were significantly different from 21 d starved bugs. These results indicate that feeding status plays an important role in the toxicity of deltamethrin. In addition, the lack of differences between 2 d and 9 d starved bugs indicate that the blood meal itself has little impact on tolerance, but rather it is some physiological change following feeding that confers increased tolerance to bed bugs.

Effects of Ibuprofen and Caffeine Concentrations on the Common Bed Bug (Cimex lectulatius L.) Feeding and Fecundity

Bed bugs are ectoparasites of humans and require a blood meal for their growth and reproduction. Since humans consume Ibuprofen as pain medication and drink coffee (caffeine), bed bugs are likely to acquire these drugs through blood feeding. In this study, we determined the biological effects of Ibuprofen and caffeine on bed bug feeding, fecundity and egg hatch. Five concentrations of Ibuprofen and caffeine were incorporated into reconstituted human blood (RHB). Control treatment had no Ibuprofen or caffeine. Each treatment had six replications. Groups of 20 adult bed bugs (10 males: 10 females)/treatment/replication were pre-weighed, allowed to feed for 45 minutes, and then reweighed. After feeding, bed bugs were transferred into a glass jar equipped with harborage and all the jars were placed in an environmental chamber undisturbed for three 7-day intervals to determine fecundity and nymph emergence. Ibuprofen data showed that the mean mass of the 20 adult bed bugs increased by 0.1074 g (125.65%) in the control but by 0.1336 g (157.30%) at 200 ppm after feeding. After 7 days, 306 and 146 eggs were laid by the 60 female bed bugs fed on 0 and 200 ppm Ibuprofen, respectively. After 2 weeks, 94% eggs hatched with no significant differences amongst treatments. In the caffeine experiments, the bed bug mean mass increases were 0.1219 g (163.90%) in control and 0.0790 g (104.62%) at 50 ppm caffeine. After 7 days, 264 eggs were laid by 60 female bed bugs in control but only 81 eggs were laid at the 50 ppm. Nymph emergence was >80% for all caffeine concentrations after 2 weeks. These results demonstrated that increasing Ibuprofen concentrations had positive effects on mass gain but negative effects on egg laying capacity of bed bugs. Caffeine concentrations had negative effects on bed bug feeding, fecundity and egg hatch.