Management of the Invasions of Allochthonous Arthropods: Pathways of Introduction and Eto-ecological Aspects

The increased complexity of transport networks, the augmented demand of commodities, and the consequent enhanced goods flows worldwide intensify the likelihood of alien species invasions. Allochthonous invasive species are the second leading driver of species extinctions and pose serious threats to ecosystem services, economies, and human health and wellbeing. Terrestrial arthropods, and particularly insects, are a large part of the problems generated by alien species. To develop effective strategies to prevent and manage biological invasions, information regarding pathways of introduction and biology and behavior of introduced species should be gathered. In my thesis, I attempted to quantify the entomological allodiversity (i.e. the diversity of alien insects) in Tuscany: I compiled a dataset and compared my results with those from datasets of Italian and European allodiversity. During field surveys, Gonipterus scutellatus complex, a quarantine pest weevil damaging Eucalyptus spp., has been detected for the first time in Tuscany, along with other pests of eucalypts. Then, I focused my research on the study of the pathways of introduction, evaluating the risk of introduction on pests (e.g. Thrips palmi) as contaminants of fresh-cut flowers. Curculionidae (bark beetles and weevils) were the target species of my research. I assessed the role of nurseries and horticultural activity in introducing bark beetles, and investigated some behavioral aspects of the red palm weevil, Rhynchophorus ferrugineus, a pest of palm spreading in Tuscany. In particular, in R. ferrugineus I analyzed behaviors whose knowledge is necessary for the application of new management techniques, such as sterile insect technique and the biocontrol with microbial agents. I also investigated female oviposition preferences and male role in indicating a good site for laying eggs. The results show that Tuscany is particularly exposed, as the entire Italy, to biological invasions of arthropods. Notwithstanding this, knowledge of allochthonous species assemblages, such as eucalyptus species and the invertebrate they host, is scanty. The study of pathways is crucial to tackling invasions. Pests contaminating commodities are difficult to detect and information about their deliveries (e.g. origin, dimensions, and packaging procedures) are precious to better focus the inspection effort at political borders. The first report in Tuscany of Ambrosiodmus rubricollis confirms that ornamental nurseries and horticultural industry are gateways for allochthonous bark beetles, due to the their resistance to common phytosanitary treatments, which make nurseries uncomfortable for the survival of phytophagous and other insects occupying flowers, fronds, leaves, and external surfaces of plants. In conclusion, my results highlight the importance of biological and behavioral studies to develop and improve the available tools for the management of biological invasions. In fact, the model species R. ferrugineus shows a complex mating system, which is compatible with the use of new management techniques, despite the need of further studies before their application.