Host selection by the generalist aphid Myzus persicae (Hemiptera: Aphididae) and its subspecies specialized on tobacco, after being reared on the same host.

Decision-making during host selection by phytophagous insects has proved to be related to host range, with specialists taking faster decisions than generalists; however, this pattern fails to materialize in some host selection studies performed with aphids. Differences found in testing designs point to rearing effects on aphid host selection. To test whether specialization patterns derive from the nature of the aphid or as a consequence of rearing environment, host selection behaviours were compared between the generalist Myzus persicae (Sulzer) s.s. and its subspecies specialized on tobacco when reared on a common host and offered the choice of an alternative host and a non-host plant. Pre-alighting (host finding and attraction towards host volatiles) and post-alighting (leaf surface exploration and probing) behaviours did not differ between the generalist and the tobacco-specialist, except in the allocation of time to probing behaviour; furthermore, all specialists chose the host on which they performed best. Thus, although the specialist was not faster than the generalist, it showed a higher level of commitment to its preferred host plant.