- Volume 36 Issue 3
Bait formulations containing 50% micro-capsuled fenitrothion, 2.0% hydramethylnon or 0.8% chlorpyrifos were evaluated in an 8 week field experiment against German cockroach, Blattella germanica(L). In German cockroach infested 15 restaurants, micro-capsuled fenitrothion (avg. 82.8%) was more effective at reducing adult German cockroach populations than chlorpyrifos (avg. 68.4%), but was about equally as effective as hydramethylnon(avg. 86.1%). The baits of micro-capsuled fenitrothion (avg. 76.5%), hydramethylnon (avg. 82.8%) and chlorpyrifos (avg. 74.9%) almost equally reduced nymphal German cockroach populations in the field. Most baits remained in the bait stations at the heavily infested restaurants after the 8 week treatments. However, the contents of hydramethylnon baits had been subject to significantly greatest consumption (0.72g) and the remaining bait was on the average of 57% by German cockroaches. It was assumed that the previous phenomenon of extra consumption of bait was explained by the infesting cockroaches continuously taking these baits because of the mode of action, the bait food material and the population densities of German cockroaches.