Evaluation of azadirachtin, a biopesticides, on growth, development and cuticle secretion of Mediterranean flour moth, Ephestia kuehniella Zeller

The current study examined the lethal and sublethal effects of azadirachtin on pest of stored food Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Firstly, several doses were tested by topical application on newly molted pupae and the doses of inhibition (ID) of adult emergence were determined then, two doses, 0.42 μg/pupa and 1.06 μg/pupa, corresponding to ID₂₅ and ID₅₀, the doses required for 25 and 50% inhibition of adult emergence, respectively. They were tested on different development parameters and cuticular thicknesses during metamorphosis. Results showed that azadirachtin significantly increased the duration of pupal development and decreased pupal weight. In addition, treatment disrupted metamorphosis and several morphogenetic types have been observed (malformed adults, partial molt and blocked molt). Lastly, azadirachtin also affected cuticular secretion by reducing the thickness of the old and the new cuticle at different ages during metamorphosis.