Unexpected functional complementarity from non-bee pollinators enhances cotton yield

Abstract While greater biodiversity is often assumed to predict greater ecological function, a number of recent meta-analyses have challenged this notion, arguing instead that a few dominant species can contribute the majority of ecological function provided in a given ecosystem. In the case of mobile ecosystem service providers, such as pollinating insects, the abundance and diversity of the most common taxa (e.g. bees) is often assumed to be the primary driver of service provision across ecosystems. This assumption persists despite the presence and possible contribution of less-dominant service-providing taxa. In this study, we investigate the taxonomic contribution of different pollinator orders to multiple axes of functional complementarity in US Gulf Coast cotton agroecosystems. We find that, contrary to conventional wisdom, non-bee pollinators, including butterflies and flies, contribute significantly to pollination function and expand the multidimensional functional space of visitation by more than 50%. Specifically, butterflies and flies provide critical functional complementarity by visiting spatially and temporally unique flowers that otherwise may have gone without pollination service. We estimate that butterflies and flies together may contribute as much as 120 million USD (of the 1.8 billion USD) per annum of cotton production in the state of Texas. We conclude that conservation efforts should target not only dominant service providers, but also those that complement their service, such as butterflies and flies, to maintain functional breadth and resulting crop profitability in the face of dynamic future agricultural scenarios.