Biological Parameters of Aphidius Smithi Sharma and Subba Rao (hymenoptera: Aphidiinae), A Parasite of the Pea Aphid, Acyrthosiphon Pisum (homoptera: Aphididae) under Laboratory Conditions

Aphidius smithi (Aphidiinae: Hymenoptera) is an important endoparasitoid of pea aphid (Acyrthosiphon pisum) which has been utilized to determine the effectiveness of this agent in reducing pest damage. Biology of the A. smithi reared on A. pisum in the laboratory at 23 +/- 1 degrees C has been studied. The development cycle of A. smithi from larvae to adult was completed in about 11 days. The pre-mating period of males (n=10) varied between 5 and 8 min (mean: 4 min). Copulation time (n = 10 pairs) was between 33 and 55 sec (mean: 45.2 sec). Oviposition time (n = 10 females) was between 1 and 2 sec (mean: 1.5 sec). Female parasitoids lived longer (5.75 days) than male parasitoids (4 days) when offered honey and water as a food diet. Lifespan of adult male and females was shorter i.e. 2.25 and 2.75 days respectively when fed upon dissected aphid. When adult parasitoids were released on pea plant provided with pea aphid, mean period of life for male and female was 4.75 and 6 days respectively. Sex ratios of field collected mummies were female biased (60%). Two species of hyperparasitoids viz. Asaphes suspensus (68%) and Pachyneuron aphidis (54%) were involved. Examination for phenotypic polymorphism showed that field population of A. smithi contained both dark and light pigmentation pattern of abdominal segments while laboratory reared samples were only dark pigmented in both sexes. The findings of this study can help in defining strategies for the rearing to release this parasitoid in biological control programs against A. pisum in Pakistan.