Assessing the Impacts of Different Cropping Systems and Pesticide Use on Pollinator Communities in Mbire District, Zimbabwe

Abstract

Pollination contributes immensely to food security, yet little is known about pollinator conservation practices in rural communities. This work assessed farmers' knowledge of pollinators and examined pesticide use in Mbire district of Zimbabwe. A structured questionnaire was distributed to 102 respondents who were sampled using the stratified purposive approach to collect information on perceptions of pollinators and chemicals used to control pests. Pan traps and sweep nets were used to capture pollinators from chemically treated and untreated plots in different cropping systems. Honeybees were the most cited pollinators (99% of respondents), while other pollinators like wasps, beetles, and true flies were mentioned. Awareness of pollinators was higher in males than in females and among middle-aged to old-aged farmers. A total of 38 different pesticides were used, with four belonging to the highly toxic pesticide category. Field sampling collected 239 individuals from nine pollinator families and three orders, with Lepidoptera (55.2%) being the dominant order. Pollinator abundance was highest in mixed-cropping systems and lowest in natural plots. Generalized Linear Mixed Models (GLMMs) showed that sweep netting captured significantly more pollinators than pan trapping (β = 0.575, SE = 0.173, p = 0.009). In addition, spraying alone showed no significant association with pollinator abundance. However, the interaction between monocropping and spraying resulted in relatively fewer pollinator visitors compared to the interaction between mixed cropping and spraying (p = 0.055). Further, Maerua edulis was the most mentioned plant used in traditional pest management. To increase pollinator awareness, there is a need for farmer training to promote systems such as mixed-cropping systems, as they support more pollinators. The use of highly toxic pesticides is concerning, and efforts are needed to minimize their application and promote eco-friendly alternatives and traditional methods.