Natural land cover drives pollinator abundance and richness, leading to reductions in pollen limitation in cotton agroecosystems

Abstract

Cotton is the most economically and culturally important fiber crop worldwide. Though cotton may potentially benefit from animal mediated pollination, it is unknown if the species is indeed pollen limited across agroecological landscapes. Our study had three objectives: (1) identify the land use attributes that impact wild pollinator abundance and diversity, (2) investigate the relationship between pollinator community composition and cotton pollen limitation and (3) determine the extent of direct and indirect effects of land use on pollinator community composition and pollination service. To address these objectives, we used a combination of pollinator community surveys, GIS analysis, and pollen limitation experiments across 12 cotton landscapes in South Texas. Overall, we found that pollinator community composition was closely related to the abundance of natural areas (250m radius). We also found evidence of substantial cotton pollen limitation, as significantly larger bolls were produced with the addition of outcross pollen. Further, we reveal that pollen limitation was negatively correlated with pollinator abundance and richness. Path analysis confirmed the two direct effects of land use composition on pollinator community and pollinator community composition on pollen limitation. Overall, our results reveal potential for increased crop yields via wild pollinator-mediated fruit set, equivalent to more than $108/acre with a regional gain of over $1.1 million USD. Further, our research provides insight into the specific land management practices that support pollinator communities within cotton agroecosystems. Cotton landscapes that maintain natural areas promote wild pollinator abundance and diversity, and subsequently experience reduced pollination limitation and increased crop yields.