New Food Baits for Trapping German Cockroaches, Blattella germanica (L.) (Dictyoptera: Blattellidae).

German cockroaches (GCRs), Blattella germanica (L.) (Dictyoptera: Blattellidae), are attracted to those beer semiochemicals (e.g., ethanol) that formerly living and active yeasts have produced or otherwise formed in the brewing process. We predicted that an earlier step in the production of beer, where yeasts actively metabolize the sugar in malted barley powder (dry malt extract [DME]), is very attractive to GCRs. In laboratory experiments, a 3-component composition (3CC) comprising DME, water, and Brewer's yeast strongly attracted GCR nymphs, females, and males. Both Brewers' yeast and 'spoilage organisms' in the DME or water seem to add to the attractiveness of the 3CC, but there is no additive or synergistic effect between them. The 3CC becomes optimally attractive to GCRs after 12 h of fermentation and stays that attractive for at least 120 h. In field trapping experiments, the 3CC and-unexpectedly-also the DME each proved as effective for attracting and capturing GCRs as a commercial cockroach bait (Combat Roach Gel). Future studies will investigate lethal biocontrol agents that can be added to the 3CC, or the DME, and will explore the efficacy of such lethal baits for GCR control.