COMBINED EFFECT OF ENTOMOPATHOGENIC FUNGUS METARHIZIUM ANISOPLIAE (METSCHINKOFF) AND NOVEL INSECTICIDES ON THE CELLULAR AND HUMORAL IMMUNE MECHANISMS OF SPODOPTERA LITURA (FABRICIUS)

Combination of insect entomopathogenic fungi and microbial metabolites is a prospective method for highly polyphagous pest control.The effect of the entomopathogenic fungus, Metarhizium anisopliae (Metschinkoff) and Emamectin benzoate, Spinosad and Spinetoram on the cellular and humoral responses of Spodoptera litura (Fabricius) larvae {Cellular immune responses [Total haemocyte count (THC), Differential haemocyte count (DHC), phagocytosis, nodulation and encapsulation] and Humoral immune responses [lysozyme-like, phenoloxidase (PO) activities]} was studied.It is shown that the combination of these agents leads to a synergistic effect on S. litura mortality.Colonization of S. litura larvae by entomopathogenic fungus following inoculation with novel insecticides is shown.The larvae affected by combined treatments are characterized by a decrease in PO and lysozyme levels.In the initial stages of fungal infection and toxicosis (12 to 24 h posttreatment), increases in the activity of insect cellular and humoral responses, and these increases are suppressed later with time.A strong suppression of immune response of the larvae under combined treatment of M. anisoplae with Emamectin benzoate and mild response when combined with M. anisoplae and Spinosad, Spinotoram was observed, however the response was decreased after 24 hours of treatment.The changes in the response of immune system under combined treatment suggest the effect of synergism.