Seasonal ecology of Aphidius nigripes (Hymenoptera: Aphidiidae), a parasitoid of Macrosiphum euphorbiae (Homoptera: Aphididae)
1994
Brodeur, J. | McNeil, J.N.
Aphidius nigripes Ashmead is the most common parasitoid attacking the potato aphid Macrosiphum euphorbiae (Thomas) in eastern North America. In field and insectary experiments, >87% of A. nigripes prepupae successfully overwintered. Spring emergence occurred from mid-April to mid-May, the period during which diapausing M. euphorbiae eggs are hatching on primary hosts. Data obtained from sticky traps indicate that both aphid and parasitoid enter the potato agroecosystem in early june, suggesting that one or several generations occur on primary host plants in the spring. The number of males captured in sticky traps containing virgin females indicated that the parasitoid is present in high numbers throughout the potato growing season. Diapause in A. nigripes was observed from mid-August, when aphids had migrated back to their primary host plants. Our results do not support the hypotheses that inability of the parasitoid to overwinter or host-parasitoid asyncrony explain why A. nigripes does not appear to have any major regulating effect on M. euphorbiae in the potato agroecosystem.
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