Risk of population extinction in moths: Effect of host plant characteristics

The relationship between the risk of population extinction and population size was inferred from the parameters of an incidence function model, fitted to data on island occupancy of moths in an archipelago in SW Finland. The extinction risk declined faster with increasing population size in moths feeding on coniferous than deciduous woody plants, on perennials than annuals, and on habitat generalist than habitat specialist plant species. Coniferous woody plants, perennials and habitat generalist plants represent more stable resources for moths than deciduous woody plants, annuals and habitat specialist plants, which appears to explain the observed pattern. The relationship between extinction risk and population size was not affected by the characteristics of the moths, with the possible exception of more rapidly declining extinction risk with increasing population size in polyphagous than monophagous species. These results suggest that patterns in the risk of extinction of herbivorous moths are significantly affected by the host plant characteristics rather than by the characteristics of the moths themselves.