Evaluation of Cowpea (Vigna unguiculata) in an Intercropping System as Pollinator Enhancer for Increased Crop Yield

Abstract

Production of pollinator-dependent crops (PDCs) is increasing. However, pollinators are declining partly due to loss of floral resources. There is urgency to mitigate this decline and the potential risks to the production of PDCs and food security. One way is by promoting farming systems that enhance flower-rich habitats. In a two-year study, Pinkeye Purple Hull and Whippoorwill cowpea varieties attractive to pollinators were intercropped with three PDCs (squash, okra, and watermelon). We evaluated whether cowpea intercrop increases the abundance and diversity of pollinators, other beneficial insects, and crop yield, and decreases the abundance of the brown marmorated stink bug (BMSB). Diverse pollinators were recorded in both years for a total of 80,379, representing seven pollinator families (Andrenidae, Apidae, Crabronidae, Formicidae, Halictidae, Tachinidae, and Vespidae) captured in pan traps, six families (Apidae, Crabronidae, Halictidae, Pyralidae, Tachinidae, and Vespidae) from sticky traps, and five pollinator types (bumble bees, carpenter bees, honeybees, butterflies and moths, and wasps) through direct visual count. Pollinator abundance and diversity was highest on the cowpea-intercropped treatments than controls. PDCs intercropped with cowpea recorded more beneficial insects than BMSB. Okra, squash, and watermelon intercrops produced 7%, 27%, and 54% more fruits than the control, respectively. Our findings indicate that intercropping cowpeas with PDCs attracted more and diverse pollinators and resulted in increased crop yield. However, to optimize pollination, factors such as planting dates to synchronize the flowering of both cowpeas and PDCs should be taken into consideration.