Biological control of exotic pests in Italy: recent experiences and perspectives1

Abstract

In Italy, successful application of classical biological control began in the 20th century, when Berlese released the predator Rodolia cardinalis in 1901 and the parasitoid Encarsia berlesei in 1906. Later, the ‘inoculative’ method was applied many times, limiting the misuse of insecticides and therefore achieving very positive effects for both the agricultural economy and environmental protection. When the establishment of new natural enemies failed, some exotic pests continued to damage important crops, sometimes disrupting any possibility of applying Integrated Pest Management (IPM). In other cases, new associations between exotic pests and native natural enemies occurred spontaneously and the importation of new species was not necessary: when no broad‐spectrum plant protection products are applied, some palaearctic parasitoids, such as Diglyphus isaea, naturally control the imported American leafminers Liriomyza trifolii and L. huidobrensis and some native predators (mainly Orius spp.) often control the exotic western flower thrips Frankliniella occidentalis. However, the introduction of natural enemies from the area of origin of the exotic pest is often the only alternative to chemical insecticides. Since its introduction in 1979, the American Flatid, Metcalfa pruinosa, has been spreading annually into new areas of the Mediterranean, causing severe damage to many crops because none of the indigenous natural enemies are sufficiently effective. Therefore, only the introduction of exotic natural enemies, such as the parasitoid Neodryinus typhlocybae, may reduce the outbreaks.