Effect of artificial diets containing different maize hybrids powdered seeds on digestive proteolytic and amylolytic activities and nutritional responses of Helicoverpa armigera (Lep.: Noctuidae)

Digestive proteolytic and amylolytic activities and feeding responses of fifth instar Helicoverpa armigera on different maize hybrids (DC370, SC704, SC700, SC500 and SC260) incorporated into artificial diets were investigated under controlled conditions (25±1°C, 65±5% R.H. and a photoperiod of 16:8 (L:D) h). The highest total proteolytic activity was in the larvae reared on DC370 (7.954±0.543 U mg-1) and SC500 (7.965±0.171 U mg-1), whereas the lowest one was in the larvae fed on SC704 (5.878±0.160 U mg-1). The highest amylolytic activity was detected on DC370 (0.055±0.001 mU mg-1) and SC500 (0.047±0.007 mU mg-1) and the lowest activity was on SC704 (0.012±0.001 mU mg-1). Larval weight of fifth instar H. armigera demonstrated significant difference, being heaviest on SC704 (45.77±6.16 mg) and lightest on DC370 (18.14±1.61 mg). The highest and lowest values of food consumption were on SC500 219.56±11.4 mg/larva) and DC370 (155.05±10.3 mg/larva), respectively. The feces weight of H. armigera was the highest on SC704 50.74±8.2 mg/larva) and lowest on SC500 (27.51±4.21 mg/larva). According to the results, hybrid DC370 is unfavorable host for feeding fifth instar larvae of H. armigera.