The influence of density-dependent factors on larval development in native and invasive populations of Harmonia axyridis (Pall.) (Coleoptera, Coccinellidae)

摘要

AbstractEffects of the number of larvae per Petri dish (1, 5, and 10) on the preimaginal development of individuals of the native (Irkutsk, southern Siberia) and invasive (Sochi, the Northern Caucasus) populations of the multicolored Asian ladybirdHarmonia axyridiswere investigated in the laboratory. The experiments were conducted under short (12 h) and long (18 h) day conditions; the larvae were fed on the green peach aphidMyzus persicaeor on the eggs of the grain mothSitotroga cerealella. An increase in the number of larvae developed in one Petri dish resulted in a significant decrease in the rate of development in individuals from both populations which fed on aphids. Survival decreased with an increase in the number of larvae developed in one Petri dish fed on both prey species, but only in larvae from the invasive population ofH. axyridis. The weight of emerging adults decreased with the number of larvae per dish in individuals from both study populations, but only when fed on aphids. These data suggest that the influence of density-dependent factors on the development ofH. axyridisdepends significantly on larval prey species. In addition, larvae from the invasive population have somewhat more aggressive interactions with competitors, this possibly having been one of the prerequisites for invasion.]]>