Insecticide resistance and diminished secondary kill performance of bait formulations against German cockroaches (Dictyoptera: Blattellidae)

Abstract

BACKGROUND Bait formulations are considered the most effective method for reducing German cockroach infestations. An important property of some bait formulations is secondary kill, whereby active ingredient is translocated in insect-produced residues throughout the cockroach population, especially affecting relatively sedentary early instar nymphs. RESULTS Blattella germanica was collected from a location where baits containing hydramethylnon, fipronil, or indoxacarb became ineffective, and these AIs were topically applied to adult males. Results revealed the first evidence for hydramethylnon resistance, moderate resistance to fipronil and extremely high resistance to indoxacarb. Insecticide residues excreted by field-collected males that ingested commercial baits effectively killed nymphs of an insecticide-susceptible laboratory strain of B. germanica but failed to kill most nymphs of the field-collected strain. CONCLUSIONS We report three novel findings: 1) The first evidence for hydramethylnon resistance in any insect; 2) extremely high levels of indoxacarb resistance in a field population; and 3) reduced secondary mortality in an insecticide-resistant field-collected strain of B. germanica. We suggest that while secondary mortality is considered to be advantageous in cockroach interventions, the ingestion of sublethal doses of AI by nymphs may select for high insecticide resistance by increasing the frequency of AI resistance alleles within the population.

Development of Diagnostic Insecticide Concentrations and Assessment of Insecticide Susceptibility in German Cockroach (Dictyoptera: Blattellidae) Field Strains Collected From Public Housing

“…Our findings are consistent with other studies showing significant indoxacarb (Gondhalekar et al 2013, Ko et al 2016a) and fipronil (Holbrook et al 2003, Chai and Lee 2010, Gondhalekar et al 2011) resistance in German cockroaches. Resistance to indoxacarb and fipronil in the I-IN and D-IL strains are likely the result of prior selection pressure.…”

Diet quality affects bait performance in German cockroaches (Dictyoptera: Blattellidae)

“…Sensory mechanisms (olfaction and taste) and insecticide resistance are two factors that play prominent roles in the efficacy of cockroach baits. This study, and a related investigation, have shown that the efficacy of baits can be compromised, resulting in sublethal doses of AI being received by foraging cockroaches and coprophagous nymphs, potentially hastening the evolution of insecticide resistance …”

“…D, green line). Thus, the secondary kill properties of bait formulations are considerably affected by available alternative foods, the palatability of food and bait and insecticide resistance, which affect the ingestion of bait by foraging insects, their survival and the amount of feces they deliver to aggregation sites.…”

“…The effects of sensory mechanisms on the interaction of cockroach nymphs with adult feces are most readily seen in T164 nymphs; these nymphs ingested less feces produced from glucose‐rich baits, thus not only reducing the efficacy of baits but also exposing cockroaches to sublethal doses of AI. Insecticide resistance has also been shown to result in sublethal doses of AI delivered to coprophagous nymphs, suggesting that the presence of alternative foods may influence the development of resistance in a similar manner …”

Efficacy of Maxforce and Avion gel baits containing fipronil, clothianidin, and indoxacarb against the German cockroach (Blattella germanica)

“…; Ko et al . ), there is little information available regarding the efficacy of gel bait formulations against German cockroaches in Iran. The present study was designed to evaluate the efficacy of selected commercial insecticide gel bait formulations against German cockroaches.…”