Effect of Host Plants on the Viability of Black-veined White Aporia crataegi L. at Low Natural Population Density

Patterns of interaction of an oligophagous insect, black-veined white Aporia crataegi L., with host plants in years with a low density of its natural population are analyzed. In years with low A. crataegi population abundance in the south of Sverdlovsk region (Sysertsky district), the species composition of caterpillar host plants gradually decreases from several woody rosaceous species of the genera Padus, Sorbus, Malus, and Crataegus to one species (Padus avium Mill.). It is shown that the mortality rate is higher for fifth-instar caterpillars developing on mountain ash than for those developing on bird cherry. Adult A. crataegi developing on bird cherry are not only larger but also grow faster than those developing on mountain ash, which may be an additional factor responsible for the observed chronographic variation during the emergence of A. crataegi generation in nature.