Supporting functional diversity of flower-feeding insects

Abstract

Flower-feeding insects supply agricultural production with important ecosystem services, including crop pollination and natural control of crop pests. They are also a key component of biodiverse landscapes. While there has been increasing work dedicated to studying flower-feeding insects in agroecosystems, this work has had regional biases, with most studies conducted in America and Europe. Data from other geographic regions is important for informing local management recommendations and understanding which data trends are general across space and taxa. This thesis aims to better understand flower-feeding insects in Australian agroecosystems. Patterns in flower-feeding insect diversity are examined in two spring-flowering orchard systems in Tasmania (apple/ blueberry) (Chapter 2). Further, flower-insect interactions in small-scale cropping systems (market-gardens) in both Tasmania (Chapter 3) and south-east NSW (Chapter 4). Finally, an experimental study examining changes in the foraging behaviour of potential crop pollinators in the presence of a highly attractive plant (Chapter 5). Overall, results show that: (i) a large proportion of crops in orchards and market-gardens in my study regions are visited mostly or exclusively by introduced bees, Apis mellifera, and (Tasmania only) Bombus terrestris, (ii) some crops are visited more frequently by native insects than others (e.g. Exoneura), (iii) plant species richness and abundance did not affect either diversity or abundance of native insects. Rather, it appeared that key plant species may be more important for attracting insect diversity than overall plant diversity in these agroecosystems; and (iv) the different foraging behaviours of pollinating taxa may account for the variable impacts of non-crop floral resources on crop pollination. The data in this thesis gives insight into specific flower-feeding insects supported in Australian horticultural systems and aids local ecological land management decisions.