Larval Starvation Resistance in Invasive and Native Populations of the Multicolored Asian Ladybird, Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae)

Resumo

Resistance of Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae) larvae to long-term (up to 8 days) starvation was studied under laboratory conditions. The experiments were conducted with individuals from the native population originating from Irkutsk (Siberia) and the invasive population originating from Sochi (the Caucasus). Before and after starvation, larvae fed either on the green peach aphid Myzus persicae (Sulz.) (Homoptera, Aphididae) or on eggs of the grain moth Sitotroga cerealella Oliv. (Lepidoptera, Gelechiidae). Starvation resistance of H. axyridis larvae increased with their weight. Larvae that fed on the grain moth eggs were significantly more resistant than those of the same weight fed on aphids. The lethal weight loss of larvae of different ages was about 50%. The 1st instar larvae survived without food for 2 days; the survival of the larvae of the late 3rd-early 4th instars after 8 days of starvation varied, depending on pre-test diet, from 50 to 100%. Most of the surviving larvae were able to continue feeding and produce adults, although the size and weight of emerging adults decreased with the starvation period. Male and female larvae were equally resistant to starvation. Larvae of the native and invasive populations did not differ in starvation resistance.