Measuring the field dispersal of Aphidius colemani (Hymenoptera: Braconidae)

The spatial and temporal dispersal of the aphid parasitoid Aphidius colemani (Hymenoptera: Braconidae) was studied in the field. Dispersal was determined on the basis of mummified Myzus persicae (Hemiptera: Aphididae) aphids on kohlrabi trap plants. Trap plants were arranged equidistantly in circles at distances of 1, 2, 4, 8 and 16 m from a central release point. Plants were replaced on day 1 and 3 after the release of A. colemani. The pattern of mummified aphids showed that parasitoids moved at least 16 m within 24 h after release. Mean numbers of A. colemani mummies per trap plant were low (3.0, 1.8 and 1.1 on days 1, 3 and 5 after release). In most cases dispersal was random with regard to compass direction. Prevailing light to moderate wind speed did not influence dispersal of parasitoids. Released A. colemani remained at the experimental site for at least 3 days.