Exotic Insects in Japan

A total of 260 insect species has been introduced into Japan since 1868 (Meiji-era). The number of exotic species becoming established is increasing exponentially and more than half of them were Coleoptera and Hemiptera. On an average, 3 species per year have been invading Japan so far. They were accounted for 73, 22 and 5 per cent as pest, non-pest and beneficial insects, respectively. The southern islands encompass only 1.2% of Japanese land, but 40% of exotic species are first established in these islands. As a result of the secondary range extension between islands and mainland, 60% of exotic insects have become established in the southern islands. Both greenhouse and outdoor pests extended their distribution range exponentially with the same rate, enabling us to predict the extent to which an invasive insect or mite will occur in the future. It was shown that homogenization in insect and mite fauna is taking place worldwide in greenhouses.