Patterns of host use by the shoot-borer Hypsipyla robusta (Pyralidae: Lepidoptera) comparing five Meliaceae tree species in Asia and Australia

Larvae of moths in the genus Hypsipyla are specialist feeders on trees in the Swietenioideae sub-family of Meliaceae. It has been suggested that there is a pattern of preference for endemic hosts such that the Asian Hypsipyla robusta damages Asian swietenioid host species, but avoids American and African species in the same sub-family. However, this claim has never been tested in well replicated multi-species field trials. In this study we consider five swietenioid tree species: Toona ciliata and Chukrasia tabularis from the Asian/Australian region, Swietenia macrophylla and Cedrela odorata from tropical America and Khaya senegalensis from Africa. These species were included in trials planted in four widely dispersed sites in the Asian/Australian region (Thailand, Laos PDR, the Philippines and Australia). We found that all five tree species were attacked by H. robusta. The "preference for endemic hosts" hypothesis was however, supported in two ways. Firstly, T. ciliata, the only species endemic to the regions of all four field sites, was always more frequently attacked than the American and African species. Secondly, we observed that C. tabularis was frequently damaged in trials within the tree's native range (Thailand and Laos) and relatively less damaged when growing outside of its native range (the Philippines and Australia) reflecting geographic variation in the host use pattern of H. robusta.