Plant Health Clinic, Division of Entomology, Indian Agricultural Research Institute, New Delhi - 110 012, India.
Total life cycle of Z. bicolorata had a highly significant negative correlation with constant temperature while development of all the stages had a significant negative correlation. The egg period lasted for 12.65 days at 15°C and correlation coefficient of −0.97 with a regression equation Y1 = 18.80–0.46x. Both adults and larvae died within 24 hrs, when reared at 40°C. The optimum temperature for feeding, oviposition and hatchability ranged between 25°C to 30°C. Development of egg and larva was completely arrested when reared at 10°C. Maximum egg laying (17.8 ± 2.8/24hrs) and hatchability (89%) were observed at 25°C. Interestingly, fecundity had negative correlation as it decreased with the increase in temperature. Total leaf area consumed by one larva during its developmental period at 25°C was 22.92 ± 2.56 cm2. Rate of feeding was reduced markedly both by high (35°C) and low (15°C) temperatures. Similarly, the pupal mortality was very high (70.84%) at 15 and 35°C, whereas only 14 per cent of the pupa died at 25°C.
