Plant-Rich Field Margins Influence Natural Predators of Aphids More Than Intercropping in Common Bean

Abstract

Field margins support important ecosystem services including natural pest regulation. We investigated the influence of field margins on the spatial and temporal distribution of natural enemies (NEs) of bean pests in smallholder farming systems. We sampled NEs from high and low plant diversity bean fields using sweep netting and coloured sticky traps, comparing monocropped and intercropped farms. NEs collected from within crops included predatory bugs, lacewings, predatory flies, parasitic flies, parasitic wasps, lady beetles, and a range of other predatory beetles; with the most dominant group being parasitic wasps. Overall, high plant diversity fields had a higher number of NEs than low-diversity fields, regardless of sampling methods. The field margin had a significantly higher number of lacewings, parasitic wasps, predatory bugs, syrphid flies, and other predatory beetles relative to the crop, but beneficial insects were collected throughout the fields. However, we observed marginally higher populations of NEs in intercropping than in monocropping although the effect was not significant in both low and high plant diversity fields. We recommend smallholder farmers protect the field margins for the added benefit of natural pest regulation in their fields.

Integrating Metarhizium anisopliae entomopathogenic fungi with border cropping reduces black bean aphids (Aphis fabae) damage and enhances yield and quality of French bean

“…Finding similar to this current study have showed that border crop integrated with other management system can effectively suppressed insect pest population and the subsequent damage effect on plants [ 27 , 29 ]. Border cropping approach is thought to effectively reduce aphid population by distracting pests to other crops not primary and attracting their natural enemies, reducing the target pest population and economic loss impact on the crop while enhancing biological control [ 43 ]. Unlike, the extra shelter and floral resources for insect pests and/or predators boosting ecosystem services functionality at the border crop system.…”

Field margins and cropping system influence diversity and abundance of aphid natural enemies in Lablab purpureus

“…The finding is in line with results of the cage experiment where B. pilosa and G. parviflora supported emergence of high number of live parasitoids. Presence of nectar and pollen in these plants have been documented to significantly increase the activity, longevity and fecundity of predators and parasitoids (Bianchi & Wäckers, 2008; Ndakidemi et al, 2022; Parajulee et al, 1994). Conversely, Tagetes minuta showed little evidence of use by natural enemies captured from the crop, in contrast to other studies recording beneficial insect interactions with this plant (Souza et al, 2019).…”