Fitness of potato aphid Macrosiphum euphorbiae and it’s parasitoid Aphidius
nigripes were studied when the host was reared on either of five potato lines
(transgenic-BT, transgenic-OCI, NYL 235-4 and two controls) with different
mechanisms of resistance to the Colorado Potato Beetle (CPB) Leptinotarsa
decemlineata. Results indicated that factors of potato resistance that are currently being developed mainly against the CPB affected the nontarget organisms in different ways. BT potatoes negatively affected fitness indices of M. euphorbiae and aphid parasitoid, whereas OCI-potatoes unexpectedly improved aphid and parasitoid performance. Aphids and parasitoids were larger on OCI and smaller on BT potatoes than in controls. This difference was reflected on aphid fecundity, which was lowest on BT, and highest on OCI. Parasitoid survival was significantly lower on the BT potatoes as compared to other lines. The parasitoid developed significantly faster on 'NYL 235-4' than on other lines. The results indicate that the performance of potato aphid as a secondary pest as well as it's parasitoid depends on the nature of the resistance factors; factors involved while developing specific resistance to primary pests.
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