THE RESPONSE OF GERMAN COCKROACHES TO TOXIC BAITS - STRAIN DIFFERENCES AND THE EFFECTS OF SELECTION PRESSURE

Strain differences in the response of German cockroaches to toxic bait s and their potential to evolve resistance to them was evaluated in ch oice tests. Percentage bait consumption(amount of bait consumed divide d by total food consumed) was used to estimate relative attractancy/re pellency of the baits. One strain apparently had low level resistance to abamectin, but no evidence of resistance was found in other strains tested with either Roach Ender or a gel bait (abamectin-based baits). Incipient behavioral resistance occurred in two strains selected for three generations with Roach Ender; a stronger response in a strain se lected with the gel bait is attributed to the development of behaviora l resistance. Baygon bait was highly repellent. Low level resistance t o propoxur caused a large decrease in mortality compared with suscepti ble strains. Strong behavioral resistance developed in strains selecte d with Stapleton's Magnetic Roach Food.