New associations between native parasitoids and exotic insects introduced in Italy and in Europe

The introduction of exotic species is one of the most important threats to biodiversity.This phenomenon may cause economic and environmental damage. To prevent these invasions there are institutions like EPPO. Nevertheless, the introduction of exotic pests is an increasing issue, difficult to control. Classic biological control, based on importation of natural enemies from the country of origin, has been successfully used for over 120 years, but it has also raised some criticism. My research work has focused on the study of the new associations occurring between indigenous parasitoids and three exotic pests introduced in Italy and Europe. The three target insects considered were: Cacyreus marshalli Butler (Lepidoptera: Lycaenidae), a pest of Geranium plants; Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae), a plague of Castanea sp. and Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). This ladybug has been introduced as a biological control agent, but since some years it considered as an invasive species. For C. marshalli I performed laboratory tests on acceptance and suitability of immature stages of this butterfly by Exorista larvarum (Diptera: Tachinidae) and Brachymeria tibialis (Hymenoptera: Chalcidicae). The experiments showed that these two parasitoids could be used to contain this pest. For D. kuriphilus I performed field samplings in an infested chestnut area, the samples were maintained in rearing chamber until gall wasp or parasitoids emergence. In the 3-year research many parasitoids of gall wasps were found; one of these, Torymus flavipes (Walker), was found in large number. For H. axyridis the research work included a first phase of field sampling, during which I searched indigenous parasitoids which had adapted to this new host; the only species found was Dinocampus coccinellae (Schrank) (Hymenoptera: Braconidae). Laboratory tests were performed on the wasp rearing, biology and capacity to contain H. axyridis.

Towards a more sustainable aquaculture: diets effects and environmental impact of aquaculture from a microbiome perspective

There is a lot of interest to optimize aquaculture production due to its overexploitation of marine resources, ocean pollution and habitat destruction. Since feed production is one of the greatest issues in aquaculture, feeding strategy optimization is important. The study of several different feed additives or supplementation is important to secure optimal growth, gut health, and function in farmed fish. Feed additives are typically supplied to ensure good health and to help the animal ward off pathogens during both normal and challenging conditions, which could stress animals and promote insurgence of pathologies or pathogens invasions. In this context has an increasing interest the study of host associated microbiome to understand the influence of novel functional feed on the health and physiology of animals. To achieve a more sustainable aquaculture sector, show a great importance the understanding of the environmental impact of this human activity in terms of habitat destruction, ocean pollution and reduction marine environments biodiversity. Marine microbiomes, either free-living or associated with multicellular hosts, is acquiring an increasing interest because their role in supporting the functioning and biodiversity of marine ecosystems, providing essential ecological services. Becoming extremely important to understand how these activities can affect marine microbiomes by altering their function and diversity. In this thesis work, we were able to present a comprehensive evaluation of different functional feeds assessing their effects in terms of growth and gut health of three fish species, Rainbow Trout (Oncorhynchus mykiss), Gilthead seabream (Sparus aurata) and Zebrafish (Danio rerio). We also explored the impact of Aquaculture on the surrounding marine microbiomes, using Patella caerulea as a model holobionts. Finally, we provided a synoptical study on the microbiomes of the water column and surface sediments in North-Western Adriatic Sea (Italy), providing the finest-scale mapping of marine microbiomes in the Mediterranean Sea.