Exotic Insects in Italy: An Overview on Their Environmental Impact

Abstract

Hundreds of alien arthropods, native to different continents or introduced from other parts of Europe, have been recorded in Italy in the last few decades (Jucker et al., 2009; Pellizzari & Dalla Monta, 1997; Pellizzari et al., 2005). Italy is at high risk of introduction of exotic insects, particularly because of the country’s climatic conditions, which support many subtropical species, and its position in the middle of the Mediterranean Sea, which makes Italy a commercial and tourist crossroad. Invasion is a normal ecological process, but it can be incentivized by human activities with processes far more rapid than those that occur in purely native systems. Biological invasion by exotic species is considered one of the main threats to the loss of biodiversity; it can cause enormous damage in terms of socio-economic costs, harm human health, and result in ecological losses (Kenis et al., 2009). The rise in economic costs can be attributed to yield losses, in agriculture and horticulture, or to increases in the production costs for pest management. The severe economic impact of these species is evident: the crudest estimate of the total known monetary impact of alien species in Europe is close to 10 billion euros annually (COM, 2008). Moreover, the damage to human health leads to major costs connected to control programs and public health measures. Damage is due to irritation and disease transmission by hematophagous species, or to allergies, and other maladies by other groups of insects. The introduction of a species affects the ecosystem of the new habitat in different ways: the invasive species can be a herbivore, predator, or parasitoid, and can compete with indigenous species via different interactions (competition, disease transmission, hybridization). The major pathways of arthropod migration are indeed accidental, represented by different means of transports, the trade in ornamental plants and other goods, and tourism; natural climatic events can also be responsible for the movement of arthropods. We likewise have to consider that sometimes the introduction of the invasive species is voluntary, and even if the insect itself is helpful, can become a serious threat to a country’s biodiversity. The deliberate introduction into the new environment can be for productive purposes or as a control agent (the classical biological control, based on importation of natural enemies from the country of origin of the exotic pest). Rodolia cardinalis (Mulsant), imported in California in the late 19th century to control cottony cushion scale, has ever since been a textbook example illustrating the accomplishments of biological control.