Native fruit, cone and seed insects in the mediterranean basin
Résumé
Tree reproductive structures represent both an extremely rich source of food and breeding sites for many insect species, which are considered the most important seed predators during the pre-dispersal phase of seed development. In the Mediterranean Basin, a total of 99 native species, distributed among 47 genera, 21 families and 5 orders (Coleoptera, Diptera, Hemiptera, Hymenoptera and Lepidoptera), are currently known to colonize the fruiting structures of both angiosperms and gymnosperms. Such entomofauna displays a particularly high level of endemism. Species can be included in different guilds, depending on whether they feed or develop only in the fruit (including the seeds) or if they can also feed or develop in other habitats (e.g. foliage, shoots and twigs, cone-bearing shoots, bark) when fruits are unavailable. Specialist and generalist insect species have developed diverse ecological strategies to exploit this particular kind of resource, which, unlike other parts of the plant such as leaves, can display important spatio-temporal variations in abundance. Additionally to direct consumption, insect attacks can lead to fruit abortion or facilitated introduction of microbes and pathogens. Fruiting structure insects can have important impacts on both plant demography and evolution, which make them contribute to key ecological processes in Mediterranean forest ecosystems. Economic impacts of fruiting structure insects are related to reductions in the availability of high quality seeds for reforestation and afforestation programs, or by affecting supplies of non-wood forest products. This chapter provides the first synthesis on the diversity, the evolutionary ecology and the impacts of the insect fauna associated with fruits and seeds of forest trees in the Mediterranean Basin.