Aggregation agents in German cockroach Blattella germanica: Examination ofefficacy

Aggregation behavior and reduced locomotory activity in the German cockroac h is known to be caused by chemical compounds in the feces. The attractive and/or arrestant efficacy of three relevant substances was tested in first instars by a two-choice aggregation test and in adults with a locomotion co mpensator apparatus that allows quantification of taste-directed orientatio n and walking speed as a function of antennal stimulation. The three substa nces tested were a feces crude extract; a mixture of six carboxylic acids ( mix G) out of a total of 29 that were identified in the feces extract and t ested as single compounds and in various combinations; and a steroid glucos ide denoted as blattellastanoside A, which has been suggested as an aggrega tion arrestant pheromone in Blattella germanica. With both of our test meth ods, feces extract and mix G proved to be very attractive, whereas the effe cts of blattellastanoside A were, if anything, very poor. Possible reasons for discrepancies are discussed.