Biotic potential of aphid parasitoid, Diaeretiella rapae (Hymenoptera: Braconidae: Aphidiinae) at different temperature regimes

Abstract

The efficiency and development of the insect’s natural enemies affects greatly with changes in environmental conditions. Diaeretiella rapae M’Intosh (Hymenoptera: Aphidiidae) is one of the most common and successful parasitoids of the cabbage aphid Brevicoryne brassicae (L.) (Hemiptera: Aphididae). The biotic potential of D. rapae fed on B. brassicae was assessed in terms of parasitism rate, adult emergence, longevity and developmental period at different temperature regimes; 15, 20, 25, and 30 ºC. Results of the present research showed that maximum percent parasitism (41.16% ± 0.80) and adult emergence (75.43% ± 1.04) of D. rapae were observed at 25ºC and minimum at 15ºC of about 14.02% ± 0.97 and 36.72% ± 1.93 respectively. Total longevity and development period (egg-adult emergence) at higher temperature (30ºC) were observed about 6.33 ± 0.33 days and 7.67 ± 0.57 days respectively. Adult longevity of D. rapae was maximum at 25ºC of about 9.67 days ± 0.34. Development time of parasitoid was higher (17.33 days ± 1.16) at lower temperature regime (15ºC). The study indicates that development between 20-25oC was favorable for D. rapae parasitoid and it can tolerate to a higher temperature at 30oC. Therefore, it could be a preferable candidate for the biocontrol program for aphids in relatively warmer climates.