Cockroaches as Trojan Horses for Control of Cockroach Aggregations With Baits.

Jamora A Hamilton, Ayako Wada-Katsumata, Coby Schal

Journal of economic entomology 2023 Apr 24

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Gel bait formulations of insecticides have been shown to be highly effective in managing German cockroach (Blattella germanica L. [Blattodea: Ectobiidae]) populations. Three potential reasons for this are high palatability of baits, the use of slow-acting insecticides, and their horizontal transfer within aggregations, a phenomenon known as 'secondary mortality'. Our objective was to determine whether horizontal transfer can go beyond secondary, to tertiary and quaternary effects, and to compare various gel baits with different active ingredients. We fed adult females a bait and recorded their bait consumption, moribundity, and mortality. Groups of first instars were then exposed to the dead females and their feces, secondary mortality was quantified, and a new cohort of nymphs was then exposed to the feces and dead nymphs (for tertiary mortality); this process was repeated for quaternary mortality. This design did not distinguish among the major mechanisms of horizontal transfer of insecticides, namely coprophagy and contact with feces, exposure to regurgitated fluids, and cannibalism and necrophagy of nymphs. All the tested baits caused 100% mortality of the adult females that directly fed on the bait and high secondary mortality (average of >85%) within 48 hr. Baits containing either dinotefuran, emamectin benzoate, fipronil, or indoxacarb caused tertiary mortality (average of 15-70%), but only the fipronil and indoxacarb baits caused some quaternary mortality. The relative importance of secondary, tertiary, and quaternary transfer of the active ingredient remains to be determined in field populations of the German cockroach. © The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Citation

Jamora A Hamilton, Ayako Wada-Katsumata, Coby Schal. Cockroaches as Trojan Horses for Control of Cockroach Aggregations With Baits. Journal of economic entomology. 2023 Apr 24;116(2):529-537