Host-plant ranges and pest potential: habits of some thrips species in areas of southern Italy.

Data on host-plant ranges are scanty for several thrips species. Published records often refer to collecting sites of adults that have dispersed from their breeding sites. Thus there are difficulties in knowing the plants that are essential to population maintenance for most Thysanoptera species. Despite this, different patterns of host exploitation permit a distinction between monophagous, oligophagous and polyphagous species. Such biological differences can help in the identification of pest species, although some thrips species are known to exhibit remarkable host shifts, such that they became pests on plants unrelated to their “natural” hosts. In the present contribution, related to southern areas of Italy, the following species are reported: Neohydatothrips gracilicornis becoming a pest on Pinaceae, and Drepanothrips reuteri on Quercus, also the polyphagous species Heliothrips haemorrhoidalis, a pest on Citrus until a few years ago, has been supplanted by Pezothrips kellyanus in the intensive southern citrus orchards (Navel orange, lemon and bergamot). At present H. haemorrhoidalis is expanding as a pest in forest areas. For each thrips species, data on field observations and some aspects of their biology on the “new” hosts are provided and discussed.