EVALUATION OF HYDROPRENE POINT SOURCE IN COMBINATION WITH HYDRAMETHYLNON GEL BAITS AGAINST THE GERMAN COCKROACH (BLATTELLA GERMANICA) IN SIMULATED DOMESTIC ENVIRONMENTS

Abstract:
Four simulated domestic environments were each infested with mixed populations (3,300 insects) of German cockroaches (Blattella germanica). The simulated domestic environments (containers) were maintained at 25°C and 45% r.h. and cockroaches were fed and watered ad lib. After an acclimation period of eight weeks, three of the containers were treated and one was left as an untreated control. One container was treated with four hydroprene point sources each containing 120mg technical grade S-hydroprene and 20% butylated hydroxy toluene. The point sources used were supplied by Sandoz Speciality Pest Control and were applied as indicated by the manufacturers proposed label instructions. One container was treated with hydramethylnon gel bait (Maxforce gel) at the manufacturers recommended rate. The final container was treated with both hydroprene and hydramethylnon at the above rates. All treatments were repeated at three monthly intervals. During the acclimation period, cockroach populations were monitored at weekly intervals using live catch Roatel traps. After treatment, populations were monitored at fortnightly intervals until the populations were eradicated. During each monitoring, effects on the population size, structure and reproduction were recorded. Numbers of deformed adults (twisted wings) were recorded at each monitoring since it has been shown in the literature that the percentage of deformed adults is directly related to inhibition of reproduction. Effects on reproduction were monitored at monthly intervals by isolating ten females from the containers in one litre glass jars until one ootheca had been produced and hatched. Numbers of nymphs hatching were then recorded before returning the insects to the appropriate container. In the environment treated with hydroprene alone, the cockroach population was eradicated after 18 months. Treatment of the environment with hydramethylnon gel on its own eradicated the cockroaches after four months. In the combined hydroprene hydramethylnon treatment cockroaches remained for up to seven months before eradication. The data presented suggest that the combination of hydroprene and hydramethylnon would be effective in the field. Combining these two treatments ensured that any residual infestation remaining after the bait treatment could not multiply. Furthermore, the use of the bait to reduce the initial population size also reduced the time taken to eradication compared to when hydroprene was used alone.