Pollen grains as markers to track the movements of generalist predatory insects in agroecosystems

Abstract

This special issue provides ample evidence why it is becoming increasingly important to be able to track the movement of predatory insects in agroecosystems through space and time. Tracking predatory insects presents a considerable challenge as they are often small, cryptic and highly mobile organisms. Using insect-borne pollen present either on the exoskeleton or within the gut, presents a useful technique by which the movements (spatial displacements) of insects can be determined, based on the distribution of flowering plants in the area, an appropriate pollen key or atlas, and an understanding of pollination ecology. Pollen has successfully been used to track the movement of bees and moths, but has rarely been used to track predatory insects. Since many predators are likely to encounter pollen as they forage on flowers, they are good candidates for this technique. In this review we examine two types of study that use pollen to track the movements of predatory insects: (a) those in which pollen from the surrounding landscape is used to assess habitat usage and short-term movement of generalist predators from a range of insect orders, and (b) those in which pollen from a known point-source is used to assess the movement and dispersal distance of the insects. We discuss the benefits and limitations of using pollen to determine the movement of predatory insects, and explain how the information derived can contribute to optimising the use of predatory insects within the agricultural landscape in integrated pest management programmes.