Conspecific transmission of insecticidal adhesive powder through mating in the Mediterranean fruit fly, Ceratitis capitata

The Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) (medfly) is a polyphagous pest of global economic importance. This study tested the suitability of two different adhesive powders, Entostat(TM) and an adhesive metal powder, as insecticide carriers for use in a lure and kill pest control system, that would allow the auto-dissemination of insecticide from males to female conspecifics through sexual interactions. Lethal time to 50 % (LT50) irreversible knockdown was calculated for male and female medfly artificially contaminated by five different doses of spinosad insecticide, formulated with each adhesive carrier powder. The formulations with adhesive metal powder resulted in a rapid knockdown of medfly which was too fast for use in an auto-dissemination system. Entostat powder with 2 % spinosad gave the best performance, allowing sufficient time for transfer between conspecifics before knockdown and, therefore, allowing the most auto-dissemination (LT50 4 h). Knockdown through transfer of powder from males to females during mating was confirmed, with knockdown at 70-78 % for mated females, with a LT50 of < 40 h. These results indicate that Entostat powder is a suitable carrier powder for the development of an insecticidal auto-dissemination control system.