Enhanced activities of acetylcholinesterase, acid and alkaline phosphatases in Helicoverpa armigera after exposure to entomopathogenic fungi

Abstract

The toxicity of entomopathogenic fungi, Metarhizium anisopliae (isolates Ma-11.1 and Ma-4.1), Isaria fumosorosea (isolates If-02 and If-2.3) and Beauveria bassiana (isolates Bb-01 and Bb-08) to Helicoverpa armigera was assessed by measuring the activity of acetylcholinesterase (AChE) and acid/alkaline phosphatases after 48 h of exposure till 168 h. The results showed high AChE activity in the hemolymph, intestine and fat bodies samples of H. armigera exposed to higher concentrations of I. fumosorosea (If-02 and If-2.3), M. anisopliae (Ma-4.1), B. bassiana (Bb-08) between 72 -168h at 7×108 spores/mL concentration, while M. anisopliae (Ma-4.1) exhibited maximum acid phosphatases (ACP) activity at similar concentration in the hemolymph and intestine samples with similar duration of exposure. On the other hand, isolates If-2.3, Ma-4.1 and Bb-08 showed maximum ACP activity during the same exposure duration. The results showed similar high alkaline phosphatases (ALP) activity in all body samples of H. armigera when treated with Ma-4.1 (7×108 spores/mL), while, isolate Bb-08 at similar concentration showed maximum ALP activity after 72 and 120 h of exposure. The increased production of these detoxification enzymes in this economic insect pest can possibly lead to the development of resistance against entomopathogenic fungi.