Enhancing plants and potential pollinator diversity: A case study of Mediterranean fruit orchards in agroecological transition

Abstract

Chemical-intensive agriculture greatly impacts on environmental sustainability and global insect biodiversity. Hence, it is essential to find ecological alternatives that preserve both non-crop plants and beneficial insects in agroecosystems. This research evaluates the effects of the abundance and diversity in flora and flower visitors of four ecological infrastructures in eastern Spain (field margins, sown ground cover, spontaneous ground cover, flowerbeds); and one control (herbicide-treated) in fruit orchards under agroecological transition. Flowerbeds exhibited the highest average ground cover (57.4 %) and flowering (59.5 %) whereas sown and spontaneous ground covers showed the highest average number of flowering plants (around 8 species/sampling), followed by field margins (3.6). Only a few plants were detected in the herbicide-treated orchard. Spring had a higher average flowering percentage (24.5 %), while winter (16.4 %) was comparable to autumn (17.6 %) and summer (15.9 %). A total of 59 flowering species were visited by potential pollinators, with Scabiosa atropurpurea being the most popular in the summer and Diplotaxis erucoides attracting the most honeybees. In total, 1775 individual insects belonging to 52 different species (or genera) were counted. Honeybees and Pieris butterflies were the most prevalent species. The ecological infrastructures made up 98 % of the counted insects, of which 63 % were found in the ground covers (sown and spontaneous), 23 % in flowerbeds, and 15 % in field margins. The best strategy, therefore, is combining spontaneous ground covers with specific flowerbeds (perennials) and preserve field margins to conserve the native plants. Thus, installing or preserving ecological infrastructures is key in the agroecological transition for biodiversity conservation.