Effects of Managed and Unmanaged Floral Margins on Pollination Services and Production in Melon Crops

SIMPLE SUMMARY: Improving floral margins around crops can help to maintain and conserve populations of wild pollinators, mainly insects, in agroecosystems, and can improve the ecosystem services they provide, such as pollination of many crops and wild plants. Some crops, such as melon, depend on insects for reproduction, which is why they are at risk, as pollination services are declining. Our study shows that the implementation of margins around melon crops showed a positive effect on the abundance and richness of pollinating insects in general, which was stronger in the second year after establishment. Specifically, managed shrubby margins favored the populations of Syrphidae, Andrenidae, Apidae (excl. Apis mellifera), and other pollinator groups, and bee richness, suggesting that this type of margin increases pollinators’ activity to a greater extent than the other two types of margins (managed and unmanaged herbaceous margins). However, the type of margin did not show any added advantages for melon yield. ABSTRACT: Melon is among the most consumed fruits in the world, being a crop that depends almost entirely on insects for its reproduction, which is why it is especially sensitive to declining pollination services. Restoration and maintenance of hedgerows and agricultural borders around crops are generally carried out by sowing flowering herbaceous plants or establishing shrubby species; however, a cost-effective and lower-maintenance alternative for farmers could be as simple as allowing vegetation to regenerate naturally without any management actions. This work aimed to test the effects of three different types of margins (managed herbaceous, managed shrubby, and unmanaged herbaceous) on the overall abundance and richness of wild pollinators in melon crops. The work was performed in three localities in southern Spain over two years. Pollinators were monitored visually using 1 × 1 m sampling squares and pan traps within melon fields. Moreover, crop yield was estimated by measuring fruit weight and the number of seeds. In general, higher abundances of pollinators were observed in melon fields during the second year. In addition, the abundances of Syrphidae, Andrenidae, Apidae (excl. Apis mellifera), and pollinators other than bees, belonging to the orders Diptera, Coleoptera, Hymenoptera, and Lepidoptera, showed higher values in melon fields with shrubby margins than in fields with herbaceous margins (managed or unmanaged). However, no effect of floral margins on the yield of melon crops was found.