G. it. Ent., 5 (25): 59-65
August 31, 1990
The area of discovery of Diaeretiella rapae (McIntosh)
(Hymenoptera: Aphidiidae), a parasitoid of
Lipaphis erysimi (Kalt.) (Homoptera: Aphididae)
by
KESHAV P. PANDEY, ARVIND KUMAR, C. P. M. TRIPATHI
Abstract - The area of discovery of the parasitoid decreases linearly, while the killing power (k value) increases significantly, with the increase of parasitoid density. However, when host density increases, both the area of discovery and k value increase up to 50 hosts, and thereafter decrease. The mutual interference among parasitoids at higher densities is suggested as a cause for this type of behavioural response, which is explained by the population model of Hassell & Varley (1969). For the suppression of host population a parasitoid/host ratio not exceeding 1:50 is suggested.
