抄録
Feeding with various amount of food, "Oriental Rat Food MF powder", population equilibrium, age composition, and response of individuals to traps were investigated with experimental populations of the German cockroach, Blattella germanica L. at a constant temperature of 27±1℃ and 16 hours illumination per day (Fig. 1). When supplied with 4g, 8g or 16g of food every 30 days, or 3g every week, populations starting with 10 adult females with oothecae attained an equilibrium state within two months. The proportion of nymphs in populations in the equilibrium state was usually about 80% or more (Figs. 2,3 and 4). When an excess amount of food was given to the populations, the number of cockroaches increased almost two-fold in 10 days. The increase was largely due to that of 2nd to final-instar nymphs. Thus, the break of the equilibrium caused an increase of the nymphal proportion in the populations (Fig. 5). Catches of cockroaches in glass jar traps without bait showed a periodicity which was exactly parallel with that of the additions of new food. Peaks of the catches occurred just before the addition of new food, while the fewest catches just after it (Fig. 6). These results appear to indicate that, in controlling the German cockroach, the use of poisonous food baits may be more effective than to utilize sex pheromones which attract only adult insects.
