Emetophagy: Fipronil-Induced Regurgitation of Bait and Its Dissemination from German Cockroach Adults to Nymphs

Blattella germanica (L.) (Dictyoptera: Blattellidae) that were fed fipronil bait produced liquid excretions that were toxic to conspecifics. We have used a combination of analytical and behavioral assays to localize the source, to elucidate the time course, and to evaluate the role of these excretions in facilitation of secondary kill. Fipronil excretion coincided with the onset of the paralytic symptoms, and most of the excreted fipronil (79%) was eliminated during the first 12 h after ingestion of the bait. More than 74% of the total radioactivity excreted in 48 h from [14C]fipronil-fed females was recovered from their oral region, and time-lapse video analysis showed that first instars were highly attracted to these excretions. Moreover, first instars preferentially contacted the oral region of dying females and imbibed the liquid exudates. Emetophagy, the ingestion of insecticide-induced regurgitate, may constitute an important mechanism by which fast-acting, emetogenic insecticides are disseminated within cockroach populations