Submitted to: Entomologica Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/1995
Publication Date: N/A
Interpretive Summary: Baits are one of the most commonly used measures for control of German cockroaches. Field populations of German cockroaches are composed of adults and nymphs, with 80% of the population composed of nymphs. In order for baits to control cockroaches, the nymphs must consume the bait; however, there is little information about food consumption by the nymphal stages. Nymphs usually have 6 nymphal stages or stadia. In each stadium, the nymphs had a similar pattern of food consumption-- low to moderate at the beginning of the stadium, increasing to the maximum near the middle, and declining to no consumption near the end of the stadium. Cumulative consumption for the 6 nymphal stages was 68-85 mg of rat chow, depending on the stain of cockroach. Consumption also increased with each succeeding stage, and late stage female nymphs consumed more than males.
Technical Abstract: Food consumption was measured in an insecticide-susceptible (Orlando) and -resistant (Village Green) strain of German cockroach, Blattella germanica (Dictyoptera: Blattellidae), throughout each stadium. All instars exhibited a similar pattern of consumption over the course of the instar; consumption was low to moderate at the beginning of each instar, climbed steadily to a maximum near the middle, declined progressively from the midinstar maximum, and ceased or was minimal several days before the next molt. Consumption ceased or was minimal during the final two to four days of each instar. Cumulative consumption for the six instars was not significantly different between strains. Orlando nymphs consumed 85.3 + 14.8 mg of rat chow while Village Green nymphs consumed 68.8 + 5.4 mg. Total consumption by instar increased significantly with each successive instar in the Village Green strain. In addition, Village Green sixth instar females consumed significantly more food than sixth instar males. A similar trend was observed for the Orlando strain; consumption tended to increase in each successive instar. Relative consumption rate was highest in the first two instars and decreased in subsequent instars.