Beneficial insects are associated with botanically rich margins with trees on small farms

Abstract

Beneficial insect communities on farms are influenced by site- and landscape-level factors, with pollinator and natural enemy populations often associated with semi-natural habitat remnants. They provide ecosystem services essential for all agroecosystems. For smallholders, natural pest regulation may be the only affordable and available option to manage pests. We evaluated the beneficial insect community on smallholder bean farms (Phaseolus vulgaris L.) and its relationship with the plant communities in field margins, including margin trees that are not associated with forest fragments. Using traps, botanical surveys and transect walks, we analysed the relationship between the floral diversity/composition of naturally regenerating field margins, and the beneficial insect abundance/diversity on smallholder farms, and the relationship with crop yield. More flower visits by potential pollinators and increased natural enemy abundance measures in fields with higher plant, and particularly tree, species richness, and these fields also saw improved crop yields. Many of the flower visitors to beans and potential natural enemy guilds also made use of non-crop plants, including pesticidal and medicinal plant species. Selective encouragement of plants delivering multiple benefits to farms can contribute to an ecological intensification approach. However, caution must be employed, as many plants in these systems are introduced species.

Dominance of honey bees is negatively associated with wild bee diversity in commercial apple orchards regardless of management practices

“…In light of our results and the abovementioned considerations, we argue that more experimental research should seek to confirm our conclusions and investigate how a reduction of honey bee populations in apple orchards (and thus a lowered reliance on them by growers) could benefit wild bee populations in terms of diversity and functionality, thereby strengthening the ecosystem services they provide. Future studies should include potential confounding effects not measured here, such as latitude or longitude, altitude, local floral resources, landscape context, thinning practices and blossom density, among others (Arnold et al, 2021;Martins et al, 2015;McKerchar et al, 2020). Furthermore, our results advocate for the need to redesign apple orchards and management practices, beyond agricultural input substitution (Joshi et al, 2020;Penvern et al, 2012).…”

Plant Diversity Increased Arthropod Diversity and Crop Yield in Traditional Agroforestry Systems but Has No Effect on Herbivory

“…Arthropods are both pests and beneficial components of agricultural systems [29,[53][54][55]. As such, they can cause crop damage through herbivory but also serve as predators of insect herbivores, thereby providing beneficial services that can increase crop yield.…”

“…Consequently, the role of remnant natural vegetation and plant diversity in agricultural systems in improving crop yield with limited chemical inputs has received increasing attention [25]. Plant diversity in agricultural systems provides functional diversity that can limit the spread of pathogens and pests and promote beneficial insects for efficient biological control and pollination services [26][27][28][29][30]. Sustainable production of food in poor or developing countries therefore requires diversified agro-ecosystems to control crop herbivory [25,26,31].…”

Field Margin Plants Support Natural Enemies in Sub-Saharan Africa Smallholder Common Bean Farming Systems

“…For example, natural enemies (NEs) that predate or parasitize insect pests can be a key component of sustainable pest management [ 13 , 14 , 15 ]. NEs benefit from non-crop plants in agricultural systems through the provision of shelter, nectar, and pollen for effective biological control [ 11 , 16 , 17 ]. It is possible to optimize the pest management contribution of NEs by managing field margin plants.…”

“…Most studies focus on NE and the floral resource requirements in a specific context; either the benefit of the plants on NE in a controlled environment (e.g., cage), or whether the NE interact in the field with the margin plants and enhance NPR [ 11 , 12 , 16 , 17 ]. However, combining this information could help to better understand which plants will be most valuable in specific approaches supporting conservation biological control.…”