2019
Ridge, G. E., W. Elmer, S. Gaines, X. Li, D. Schlatzer, K. McClure-Brinton, and J. Scheele. 2019. Xenointoxication of a rabbit for the control of the common bed bug Cimex lectularius using ivermecting. Scientifica. doi: 10.1155/2019/4793569
“Human bed bug infestations have undergone a recent global resurgence. The human antiparasitic drug ivermectin has been proposed as a strategy to help control bed bug infestations, but in vivo data are lacking. We allowed separate populations of the common bed bug, Cimex lectularius L., to feed once on a rabbit before and after it was injected subcutaneously with 0.3 mg/kg of ivermectin, and bed bug morbidity and mortality were recorded. Ivermectin levels in the rabbit were measured using high-performance liquid chromatography and mass spectroscopy. Ivermectin blood levels of ∼2 ng/mL caused reductions in bed bug fecundity, and levels of >8 ng/mL caused bed bug death and long-term morbidity including reductions in refeeding, mobility, reproduction, and molting. Gut bacterial cultures from the fed bed bugs showed that ivermectin altered the bed bug gut microbiome.”
2018
Sierras, A., A. Wada-Katsumata, and C. Schal. 2018. Effectiveness of boric acid by ingestion, but not by contact, against the common bed bug (Hemiptera: Cimicidae). J Econ Entomol. 111(6):2772-2781 doi: 10.1093/jee/toy260
“Boric acid has been used as an insecticide in the successful control of agricultural, public health and urban pests long before the advent of synthetic organic pesticides. Boric acid products, formulated as dusts, sprays, granular baits, pastes, gels, and liquids, are widely available to consumers and pest management professionals, especially to control pest infestations within homes. Boric acid dust is commonly used against bed bugs (Cimex lectularius L. [Hemiptera: Cimicidae]), but its efficacy has not been demonstrated. We evaluated the efficacy of boric acid as an ingestible and residual contact insecticide on bed bugs, and compared its efficacy on the German cockroach (Blattella germanica L. [Blattodea: Ectobiidae]) which is known to be susceptible to boric acid by both routes. Dose–response studies of 0–5% boric acid in blood demonstrated that ingested boric acid caused rapid mortality at concentrations of ≥2%, and even 0.5% and 1% boric acid caused 100% mortality, albeit at a slower time course. In contrast, bed bugs survived contact with high concentrations of boric acid dust. Smaller boric acid particles did not increase mortality of either unfed or recently fed bed bugs. The same boric acid products were effective at causing mortality of German cockroaches by both contact and ingestion. We thus conclude that although boric acid is an excellent candidate active ingredient for an ingestible bait formulation, residual applications of dust or spray would be ineffective in bed bug interventions.”
2017
Matos, Y. K., A. Sierras, and C. Schal. 2017. Evaluation of the potential for secondary kill for ingested insecticides in the common bed bug (Hemiptera: Cimicidae). Journal of Economic Entomology. 110(3): 1218–1225. doi: 10.1093/jee/tox082
“Baits are a preferred method of urban pest management. Baits enable more targeted insecticide applications with a fraction of the active ingredient used in residual sprays. Bait translocation by foragers, and consequent secondary kill of nonforagers, enhances bait effectiveness in social insects, and in other group-living species like German cockroaches (Blattella germanica L.). We investigated the potential for secondary kill in bed bugs (Cimex lectularius L.), another gregarious species, using a liquid bait. We first investigated whether blood-fed adults enhance nymph survivorship within aggregations by increasing the local relative humidity (RH) and providing fecal nutrients. Higher RH (50% and 95%) resulted in greater survivorship of first instars compared with 0% RH. Therefore, in subsequent experiments, we controlled RH to decouple its effect on nymph survivorship from effects of fecal nutrients. The presence of fed or unfed adults did not increase unfed first instar survivorship, suggesting that if nymphs ingested feces, its nutritional benefits were minimal. Nymph survivorship was unaffected by the presence of adult males fed fipronil or clothianidin, suggesting that unlike in cockroaches, highly effective insecticides might not be effective as secondary kill toxicants in bed bugs. To directly compare secondary kill in first-instar bed bugs and B. germanica, we exposed both to insecticide-laden adult B. germanica feces. Whereas first-instar B. germanica died in the presence of insecticide-laden feces, bed bugs did not. We, therefore, conclude that secondary kill with neuroactive insecticides will likely not be a significant factor in bed bug population suppression.”
Sheele, J. M., G. E. Ridge, W. Du, N. Mallipeddi, and M. Vallabhaneni. 2017. A screen of pharmaceutical drugs for their ability to cause short-term morbidity and mortality in the common bed bug, Cimex lectularius L. Parasitology Research. 116(10): 2619-2626. doi: 10.1007/s00436-017-5565-0
“The common bed bug, Cimex lectularius L., is a hematophagous ectoparasite that preferentially feeds on humans. Pharmaceuticals present in a person’s blood may adversely affect C. lectularius when it feeds. We fed >10,000 C. lectularius on blood samples containing more than 400 different drug doses and drug combinations using an in vitro feeding system to determine insect mortality. The majority of drug doses approximated the peak plasma concentration in humans taking those drugs. Twenty-one drugs were found to cause >17% 12–14-day mortality compared to 8.5% mortality in the control (p < 0.05), but postliminary testing of three of the drugs, famotidine, ethambutol, and primaquine, did not demonstrate an increase in C. lectularius mortality. We also tested 23 drugs for their effects on C. lectularius fecundity. The results may have implications for understanding C. lectularius population dynamics in an infestation.”
Zha, C., C. Wang, and J. M. Sheele. 2017. Effect of moxidectin on bed bug feeding, development, fecundity, and survivorship. Insects. 8(4): 106. doi: 10.3390/insects8040106
“The common bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), is a blood-feeding ectoparasite which experienced world-wide resurgence during recent decades. The control of bed bugs is often challenging, due to their cryptic nature and resistance to commonly used insecticides. In this study, we evaluated the effect of the antiparasitic drug moxidectin on bed bug survival, reproduction, and development. The LC50 (lethal concentration to kill half the members of a tested population) of moxidectin against bed bug male adults, female adults, and large nymphs were 52.7 (95% CI (confidence interval): 39.5–70.8), 29.3 (95% CI: 20.7–40.5), and 29.1 ng/mL (95% CI: 23.3–35.3), respectively. Moxidectin (≥ 25 ng/mL) reduced egg laying of bed bug females, but showed no significant effect on egg hatching. One time feeding on rabbit blood containing 20 and 40 ng/mL moxidectin showed no negative effects in bed bug feeding and blood meal ingestion, but significantly reduced digestion rates and nymph molting rates. Although moxidectin at concentrations of 20 and 40 ng/mL only caused moderate mortality in bed bugs, it significantly interrupted digestion, development, and oviposition of survived bed bugs for at least one week after feeding. Moxidectin is a promising supplement of the existing bed bug control materials if its use on humans can be approved in the future.”
2016
Sheele, J. M., and G. E. Ridge. 2016. Toxicity and potential utility of ivermectin and moxidectin as xenointoxicants against the common bed bug, Cimex lectularius L. Parasitology Research. 115(8): 3071–3081. doi: 10.1007/s00436-016-5062-x
“The recent resurgence of the common bed bug Cimex lectularius L. throughout western industrialized nations has been facilitated in part by the insect becoming pesticide-resistant. Novel control strategies, including xenointoxication, should be considered to combat C. lectularius. Ivermectin, a U.S. Food and Drug Administration (FDA)-approved treatment for several human parasites, and the antiparasitic drug moxidectin, currently being explored in human clinical trials, were evaluated for efficacy against C. lectularius. Results showed that C. lectularius fed on ivermectin or moxidectin blood concentrations of >25 ng/mL and had significantly higher mortality (50–100%) than controls (0–6%) by day 13. Bed bugs that survived a blood meal containing >2.5 ng/mL of ivermectin suffered long-term sequelae including reduced fecundity, feeding difficulty, and incomplete ecdysis. Some insects that survived a blood meal containing ≤75 ng/mL moxidectin were able to feed and reproduce.”
Sierras, A., and C. Schal. 2016. Comparison of ingestion and topical application of insecticides against the common bed bug, Cimex lectularius (Hemiptera: Cimicidae): Ingestible insecticides for bed bug control. Pest Management Science. 73(3): 521–527. doi: 10.1002/ps.4464
“The global prevalence of Cimex lectularius infestations has challenged current intervention efforts, as pyrethroid resistance has become ubiquitous, availability of labeled insecticides for bed bugs is limited, and non-chemical treatment options, such as heat, are often unaffordable. We evaluated representative insecticides toward the goal of developing a novel, ingestible liquid bait for hematophagous arthropods. LC50 values were estimated for adult males and first instar nymphs of an insecticide-susceptible strain for abamectin, clothianidin, fipronil and indoxacarb, after ingestion from an artificial feeder. LD50 values were calculated based on the ingested blood volume. Ingested abamectin, clothianidin and fipronil caused rapid mortality in both life stages. Fipronil was ∼43-fold more effective by ingestion than by topical application. Indoxacarb and its bioactive metabolite decarbomethoxylated JW062 (DCJW) were ineffective at causing bed bug mortality even at concentrations as high as 1000 ng mL−1 blood. Fipronil, clothianidin and abamectin have potential for being incorporated into a liquid bait for bed bug control; indoxacarb and DCJW were not effective. Bed bugs are a good candidate for an ingestible liquid bait because systemic formulations generally require less active ingredient than residual sprays, they remain contained and more effectively target hematophagous arthropods.”