Comparisons of toxic baits for controlling the cockroach, Blattella germanica: attractiveness and feeding stimulation

Female German cockroaches, Blattella germanica (L.) (Dictyoptera: Blattelli dae) and nymphs (stages 1, 3 and 6) were used to test the attractiveness an d the feeding stimulation of several commercial gel formulations of insecti cide food baits in laboratory binary choice tests. The four toxic gel baits tested were: 'Avert' (0.05% abamectin = avermectin B1), 'Drax' (33.3% bori c acid), 'Goliath' (0.05% fipronil) and 'Maxforce' (2.15% hydramethylnon). The attractiveness of a bait was estimated by the number of cockroaches tha t chose it first, and by their tendency to change to it secondarily. Feedin g stimulation was estimated by the mean duration of feeding bouts and total duration of food intake. Variability of these factors was assessed in rela tion to age of cockroaches and to age of baits. With a few exceptions, cock roach age did not affect performance in any of these tests. Attractiveness to B. germanica ranked 'Goliath' gel higher than 'Avert', 'Drax' and 'Maxfo rce' gels, whether or not the active ingredient fipronil was present in 'Go liath' gel. Feeding stimulation ranked 'Avert' and 'Maxforce' gels higher t han 'Goliath' gel, and 'Drax' gel was inferior. With ageing up to 3 months, the feeding stimulation power of 'Goliath' and 'Maxforce' gels increased, whereas that of 'Avert' fluctuated. Assuming that all types of bait effecti vely kill cockroaches once ingested, these results illustrate the importanc e of behavioural observations on bait efficiency and show that ranking of t hese different food baits varies in relation to the parameter analysed.