The ecology of predatory hoverflies as ecosystem-service providers in agricultural systems

The main contemporary challenge for agriculture is to meet the food demands of the increasing world population while becoming more environmentally sustainable. One way to achieve this is through the promotion of functional biodiversity and the ecosystem (nature's) services (ES) that it can provide. The Syrphinae subfamily is a widespread group of hoverflies with a high potential for that service. Hence, the present review aims to synthesize the existing literature on this group. This review is divided in three main sections. First, we focus on those aspects of the ecology of hoverflies that are relevant to their role in biological control. These are divided into nutrition, feeding preferences and prey detection of the different developmental stages, overwintering and the effect of landscape on their dispersal and efficacy. Second, we review the ES that predatory hoverflies can provide, particularly pollination and biological control. Finally, we discuss those farming practices that can affect the effectiveness of these Diptera as providers of ES. Overall, this review highlights the potential, as well as limitations and current gaps in knowledge, for enhancing the efficacy of hoverflies as ecosystem-service providers in agricultural systems.