Reproductive effects of a neonicotinoid insecticide (Imidacloprid) in the German Cockroaches Blattella germanica L. (Dictyoptera, Blattellidae)

Abstract

Imidacloprid a neonicotinoid insecticide was administrated by injection to newly emerged adults of the German cockroach Blattella germanica (Insecta, Dictyoptera) at 0.0002% and 0.0005% doses corresponding to the LD50 and LD90 respectively. The insecticidal effect of compound was investigated on ovarian growth during the first gonadotrophic cycle (0, 2, 4 and 6 days) under laboratory conditions. Results showed that imidacloprid reduced the number of oocytes per paired ovaries and the size of basal oocytes with a dose-response relationship. Furthermore, the compound was examined on ovarian biochemical composition. Biochemical analysis revealed that the insecticide at the two tested doses reduced significantly the contents of proteins, lipids and carbohydrates as compared with control series. The overall results suggest an interference of the compounds with the vitellogenesis.