Department of Zoology, University of Calicut, Calicut-673635, Kerala, (India).
*Address for correspondence: Thekke Thattupurackal, Kadakkarappally P.O., Cherthala, Alappuzha-688529, Kerala, (India).
The effects of azadirachtin, AZA (1 or 5 μg) injected into the final sixth instar larvae of Spodoptera mauritia Boisd. were studied on food consumption and utilization at 24 h intervals during the entire phagoperoid. AZA treatments adversely affected the amount of food consumed, faeces produced and weight gained by the treated larvae. Considerable decrease in various nutritional indices like consumption index, efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD) and growth rate (GR) were recorded. On the other hand, the approximate digestibility (AD) of treated larvae showed an increase when compared with controls. Reduction in ECI and ECD values but an increase of AD values suggest that the interference of AZA with nutritional metabolism occurred after digestion. The increase in AD values might reflect attempts by insect to compensate for reduced consumption of food in order to maintain the GR.
