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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

BACKGROUND 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. RESULTS 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. CONCLUSIONS 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. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]