Laboratory evaluation of azadirachtin against the oriental cockroach, Blatta orientalis L. (Dictyoptera, Blattellidae): Insecticidal activity and reproductive effects

In this work, the toxicity of azadirachtin applied topically at various doses (300, 600, 1200, 2400, 4800 and 9000 ng/insect) was evaluated against newly emerged adults of the oriental cockroach, Blatta orientalis L. (Dictyoptera, Blattellidae) under laboratory conditions. Results show that treated insects exhibited toxic symptoms with a dose-dependent mortality. In a second series of experiments, the compound applied topically at its LD sub(50)and LD sub(90) on newly emerged female adults was investigated on ovarian growth during the first gonadotrophic cycle (0, 2, 4 and 6 days). Azadirachtin was found to reduce the number of oocytes per paired ovaries and the size of basal oocytes. Furthermore, the compound was examined on ovarian biochemical components. Biochemical data revealed a significant reduction of ovarian contents of proteins, lipids and carbohydrates with the two tested doses. The overall results suggest an interference of the compounds with the vitellogenesis.