PARASITISM OF THE CASTOR WHITEFLY, TRIALEURODES RICINI (HOMOPTERA, ALEYRODIDAE) BY ENCARSIA-FORMOSA (HYMENOPTERA, APHELINIDAE) - BIONOMICS IN RELATION TO TEMPERATURE

Selected life history characteristics of Encarsia formosa Gahan parasi tizing the castor whitefly, Trialeurades ricini (Misra) were studied a t three constant temperatures (20, 25 and 30 degrees C). Egg-to-adult developmental time decreased from 32 days at 20 degrees C to 13 days a t 30 degrees C An average of 241 day-degrees was required to complete development above the lower threshold temperature (12 degrees C). Juve nile mortality was 34, 40 and 47% at 20, 25 and 30 degrees C, respecti vely. Mean longevity of E. formosa ranged from 7.7 days at 20 degrees C, to 2.6 days at 30 degrees C. Mean total fecundity ranged from 18 to 36 eggs/female. Intrinsic rate of increase (r(m)) increased with temp erature from 0.065/day at 20 degrees C to 0.169/day at 30 degrees C. G eneration times decreased from 37 to 14.5 days with increasing tempera ture.