Antifeedent and toxic activity of endophytic Alternaria alternata against tobacco caterpillar Spodoptera litura

Fungal endophytes play a significant role in plant resistance to insects by altering the nutritional quality of plants or by production of various alkaloid-based defensive compounds. Ethyl acetate extract of endophytic Alternaria alternata isolated from Azadirachta indica A. Juss was tested for its bioactivity against Spodoptera litura (Fab.). Effect of different concentrations of ethyl acetate extract of A. alternata was assessed on growth and development of S. litura larvae. The results indicate higher larval mortality on diet supplemented with the fungal extract than control. Adverse effects of A. alternata were also observed on development of the insect. Ethyl acetate extract of the fungus also significantly reduced the adult emergence, longevity and reproductive potential of S. litura. Larvae feeding on diet supplemented with fungal extract showed significant reduction in relative growth and consumption rate, as well as efficiency of ingested and digested food. The antifeedant and toxic effects of A. alternata may be due to production of bioactive molecules by this fungus.