On the activity of pollinators depends the production of about 75% of crops. Yet due to the conversion of semi-natural habitats to urban or intensively cultivated areas, pesticide use, and climate change, pollinating insects are in decline. In this thesis, we monitored the diversity and abundance of pollinator insects in different types of habitats within ten landscapes in Veneto. To do this, we sampled with transects 10 selected landscapes within the Veneto plain, including cultivated fields and natural or semi-natural areas, for a total of 150 sites. There were 1055 insects captured, including 476 bees and 554 hoverflies. We observed a strong effect of habitat type and landscape on bee diversity and on the abundance of bees and hoverflies. For both variables, the highest values were recorded in predominantly natural landscapes; in contrast, agricultural landscapes had a negative influence. Habitat type also strongly influenced pollinator diversity and abundance. For bees, the highest values were recorded in sites including hedgerows and field margins, while, for hoverflies, the highest abundance was observed in perennial agricultural habitats, in this case represented by vineyards. It is important to know the effects that habitat types and landscapes have on pollinating insects so that efficient strategies can be developed to preserve their biodiversity. This study found that a great threat to pollinating insects are habitat loss and fragmentation; it was shown that the presence and proximity of natural landscapes characterized by high diversity of flowering species and subjected to minimal anthropogenic disturbance is fundamental for pollinator conservation.
Dall’attività degli impollinatori dipende la produzione di circa il 75% delle colture. Eppure a causa della conversione di habitat semi-naturali in aree urbane o coltivate intensivamente, dell’uso dei pesticidi e del cambiamento climatico, gli insetti impollinatori sono in declino. In questa tesi, abbiamo monitorato la diversità e l'abbondanza di insetti impollinatori in diversi tipi di habitat all’interno di dieci paesaggi in Veneto. Per fare ciò abbiamo campionato i due gruppi più importanti di impollinatori, cioè api e sirfidi, mediante transetti in dieci paesaggi scelti all'interno della pianura veneta, includendo campi coltivati e zone naturali o seminaturali, per un totale di 150 siti. Gli insetti catturati sono stati 1055 esemplari, di cui 476 apoidei e 554 sirfidi. Abbiamo osservato un forte effetto del tipo di paesaggio sulla diversità di apoidei e sull’abbondanza di apoidei e sirfidi. Per entrambe le variabili i valori più elevati sono stati registrati in paesaggi prevalentemente naturali, al contrario, i paesaggi agricoli hanno avuto un’influenza negativa. Anche il tipo di habitat ha influenzato fortemente diversità e abbondanza; per quanto riguarda gli apoidei, i valori più elevati sono stati registrati nei siti che comprendono siepi e margini di campo, mentre, per i sirfidi, l’abbondanza maggiore si è osservata in habitat agricoli perenni, in questo caso rappresentati da vigneti. È importante conoscere gli effetti che habitat e paesaggio hanno sugli insetti impollinatori in modo da poter elaborare strategie efficienti per preservarne la biodiversità. Da questo studio è emersa la conferma che una grande minaccia per gli insetti impollinatori è rappresentata dalla scomparsa e dalla frammentazione degli habitat. Inoltre, si è dimostrato che la presenza e la vicinanza tra habitat naturali, caratterizzati da un’elevata diversità di specie a fiore e sottoposti al minimo disturbo antropogenico, costituiscono un fattore fondamentale per la conservazione degli insetti impollinatori.
Effetto del tipo di habitat e del paesaggio su diversità e abbondanza di insetti impollinatori in Veneto
ROBERTO, CHIARA
2022/2023
Abstract
On the activity of pollinators depends the production of about 75% of crops. Yet due to the conversion of semi-natural habitats to urban or intensively cultivated areas, pesticide use, and climate change, pollinating insects are in decline. In this thesis, we monitored the diversity and abundance of pollinator insects in different types of habitats within ten landscapes in Veneto. To do this, we sampled with transects 10 selected landscapes within the Veneto plain, including cultivated fields and natural or semi-natural areas, for a total of 150 sites. There were 1055 insects captured, including 476 bees and 554 hoverflies. We observed a strong effect of habitat type and landscape on bee diversity and on the abundance of bees and hoverflies. For both variables, the highest values were recorded in predominantly natural landscapes; in contrast, agricultural landscapes had a negative influence. Habitat type also strongly influenced pollinator diversity and abundance. For bees, the highest values were recorded in sites including hedgerows and field margins, while, for hoverflies, the highest abundance was observed in perennial agricultural habitats, in this case represented by vineyards. It is important to know the effects that habitat types and landscapes have on pollinating insects so that efficient strategies can be developed to preserve their biodiversity. This study found that a great threat to pollinating insects are habitat loss and fragmentation; it was shown that the presence and proximity of natural landscapes characterized by high diversity of flowering species and subjected to minimal anthropogenic disturbance is fundamental for pollinator conservation.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/54064