Effect of temperature on the biology and fitness traits of papaya mealybug parasitoid Acerophagus papayae

Abstract

Effect of temperature on the parasitoid Acerophagus papayae of papaya mealy bug Paracoccus marginatus was studied. The results revealed that its parasitism drastically decreased with increase in temperature. Though parasitism was noticed at all temperatures, there was a strong negative correlation and % parasitism increased from 20 to 32°C. The peak in parasitism was at 32°C (52.7, 38.26 and 4.8%) with second, third nymphal and adult female stages, respectively. Thereafter the parasitism rate decreased with rise in temperature. The maximum parasitism was observed with the second instar nymph compared to the third instar and adult stages. Adult emergence increased with temperature till 32°C, thereafter a drastic drop was evident; emergence was maximum at 32°C with all host stages (76.8, 74.35 and 71.28% of 2nd, 3rdnymphal stages and adult female, respectively). The least emergence of adult parasitoid was at 20°C (60.9, 58.9 and 52.7% in respective host stages). The maximum developmental time (10.6 days) for A. papayae was found at 20°C; at 25 and 30°C it was observed to be same (7.15 and 7.0 days, respectively). The least developmental time of 5.0 days was observed at 35°C. More number of Male of A. papayae emerged from second instar of female P. marginatus at 30°C. The highest female to male sex ratio was noticed at 30°C (1: 1.74), followed by 25°C (1: 1.50).