Laboratory Evaluation of Alsystin Against the German Cockroach (Orthoptera: Blattellidae): Effects on Immature Stages and Adult Sterility

Abstract

Diets containing alsystin (=BAY SIR 8514) were fed to nymphs and adult females of Blattella germanica (L.). The effects of the chemical were evaluated on the basis of nymphal mortality, adult sterility, and oothecal development. When six diet concentrations ranging from 0.0312 to 1.0% (AI) were fed to nymphs at ages 1, 7, 14, 21, and 28 days, and mortality was recorded weekly for 4 weeks, percent mortality increased over time, with a high degree of mortality (73 to 100%) occurring in nearly all age groups at all concentrations at 3 weeks post treatment. At 4 weeks post treatment, significant ( P = 0.05) mortality (80 to 100%) occurred in all age groups at all concentrations. Molting abnormalities were common among nymphs in all age groups; nymphs so affected eventually died. Alsystinat diet concentrations of 0.25, 0.5, and 1.0% (AI) were fed to newly eclosed adult female roaches to observe effects on fecundity and maturation of oothecae. Diets of 0.5 and 1.0% (AI) completely inhibited the hatch of nymphs from oothecae; total hatch from oothecae of females on the 0.25% diet was only 6.0%. In addition to inhibition of hatch, alsystin affected the appearance and normal development of oothecae. Most oothecae (70%) of roaches on the 1.0% diet were shriveled when first formed; deformities were negligible at lower concentrations. Discoloration of oothecae from the normal chestnut brown to black occurred in 50 and 70% of oothecae produced by females on the 0.25 and 0.5% (AI) diets, respectively.