Insecticide resistance reduces secondary kill in German cockroaches (Blattella germanica)

Secondary kill is a characteristic of many modern bait formulations used in the control of German cockroaches.  This enables pest control operators to not only kill cockroaches directly feeding on the bait (primary kill), but also kill cockroaches that secondarily feed upon the excretions of dead affected cockroaches (secondary kill).  We present data demonstrating how insecticide resistance affects secondary kill.  We find that baits are largely effective against low active-ingredient resistant German cockroach adults in primary kill.  However, feces from these adults failed to kill conspecific nymphs in secondary kill, suggesting that bait formulations may be inadvertently selecting for greater levels of insecticide resistance if sublethal feces enable mildly resistant insects to live.