Habitus Diversity of Ladybirds (Coleoptera,Coccinellidae) in the Steppe Zone of the Southern Urals and the South of Western Siberia

In the ladybird fauna of the steppe zone of the Southern Urals and the south of Western Siberia, five variants, three forms, and two habitus types of adult beetles are distinguished, and their hierarchy is established. The habitus diversity of ladybirds is revealed using a new method of describing each form in a polar system of coordinates whose center coincides with the center of gravity of the insect body. The system of ladybird habitus reflects the main directions of trophic specialization in the family.     

Social feeding in ladybird beetles: adaptive significance and mechanism

Summary. Young larvae of Adalia bipunctata search an area more intensively when exposed to the odour from other larvae feeding on aphids than when exposed only to the odour of aphids. In an olfactometer young larvae were significantly attracted either to the odour of crushed aphids or larvae feeding on aphids, but not to that of aphids, larvae, larvae plus aphids or larvae feeding on an artificial diet. That is, the change in searching behaviour appears in response to a volatile released by aphids when attacked. The odour released by crushed aphids is made up entirely of aphid alarm pheromone, β-farnesene. It is likely that the adaptive significance of this response is that it increases the ability of larvae to locate larvae that have already caught prey. By sharing the aphid kill of another larva it is likely that a first instar ladybird larva greatly increases its probability of surviving to the next instar. It is suggested that this social feeding is facilitated by egg clustering, which also may additionally account for why aphidophagous ladybirds lay their eggs in clusters. Received 28 February 2000; accepted 24 March 2000