Formation of reproductive isolation barriers in the european corn borer, Ostrinia nubilalis: differences in host plant exploitation strategies
1994
Frolov, A.N.
Ethiological reproductive isolation barriers between populations feeding on corns (Ostrinia nubilalis, O. persica) and on dicotyledonous host plants (O. nubilalis, O. narynensis, O. nubilalis x narynensis, O. scapulalis) were tested in lab using pair mating analysis. The corn dwelling populations of O. nubilalis were shown to form two groups according to their ability to breed with dicotyledon dwellers. In one group, populations which crossbred freely were clustered; another group contained populations with lower fertility rate. Formation of the reproductive barriers was correlated with caterpillars adaptations to feed upon corn leaves at whorl stage, which is peculiar to northern populations. Contrary to this, in the south where caterpillars used to feed upon leaves after their tasseling, there was no sign of barriers. It is supposed that differentiation of the O. nubilalis populations is caused by their selecting one of two possible strategies of the fodder plants. One of these is species-generalized and ontogenetic stage-specialized strategy implying feeding on a wide score of plant species but at flowering stage only. Another is species-specialized and ontogenetic stage-generalized strategy, feeding occurring on few plant species but at different stages, including those when antibiotic mechanisms are in effect
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