Effects of parasitisation by the cereal aphid parasitoid Lysiphlebus delhiensis (Subba Rao and Sharma) (Hymenoptera, Aphidiidae) at its varying densities
1990
Mishra, S. (Gorakhpur Univ. (India). Aphid-Biocontral Lab. Dept. of Zoology) | Singh, R.
If 1, 2, 4, and 8 female parasitoids of Lysiphlebus delhiensis were released per cage on 200 hosts (Rhopalosiphum maidis) for 24 h, the number of hosts parasitised as well as of parasitoids emerged increased. However, the rate of multiplication (number of hosts parasitised/female) declined with the increase of parasitoid-host ratio. Increasing parasitoid density decreased the searching efficiency of the parasitoid. The fact that more parasitoids have lower rate of multiplication and search rate show the presence of mutual interference. Various aspects of the parasitoid's behaviour which could give rise to interference effects are discussed. Proportion of females in F(1) offspring decreased with increase of parasitoid-host ratio. The factors which could give rise such effect are explained. In relation to a given site, the data presented herein furnish an insight into the number of parasitoids needed to regulate the estimated aphid population. In insectary, they can be utilised for procuring maximum yield of progeny, particularly females, per unit of host material from a host-parasitoid culture
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