Assessing the pollination contribution of bees within the southeastern United States

Abstract

Over 80% of the world’s flowering plants rely on animal pollinators, and approximately 75% of the world’s food crops depend on insect pollinators. Insects are crucial in the pollination of many cultivated and wild flowering plants, yet specific details (including the insects they attract) are not often fully understood. For this reason, my dissertation focused on studying the pollination requirements of both a specialty crop and native wildflowers in the southeastern United States. Kiwifruit (Actinidia chinensis var. chinensis Planch) has been grown commercially within the United States since the 1960s, yet the pollination biology of specific cultivars grown within the United States is largely unknown. For this reason, orchard managers implement multiple pollination methods on a single crop to achieve high fruit yields, but this is an inefficient use of resources. My two-year study on the pollination of kiwifruit revealed that artificial pollination results in higher quantity and quality of fruit compared to flowers pollinated by wind or by insects. Additionally, my study suggests that managed bee species (Apis mellifera L. or B. impatiens Cresson,) which are commonly used in commercial kiwifruit operations, contribute minimally to the pollination of kiwifruit and may be negatively influenced by the presence of non-kiwifruit flowers. I conclude that orchard managers should implement artificial pollination of their crops to ensure high fruit yields. Anthropogenic pressures, including habitat loss, agricultural intensification, diseases, pesticides, and climate change, are thought to be main drivers of insect declines worldwide. About 20% of all plant species are at risk of extinction, and estimates suggest 40% of the world’s insect species could become extinct in a few decades. Recent government incentives within the United States have recognized the importance of providing sufficient forage in the form of wildflowers to support pollinators, yet the pollination biology including the attractiveness and dependence on pollinators of common and widespread wildflower species is lacking. I planted eighteen species of wildflowers native to the southeastern United States to assess their attractiveness towards native bees. Additionally, I conducted an insect exclusion experiment to assess the dependence of thirteen wildflower species on pollinators. My experiments suggest that not all wildflower species are equal when it comes to attracting pollinators, and that many wildflower species depend on insect pollinators to complete their life cycles.