The Potential of Fluorescence Imaging to Distinguish Insect Pest and Non-pest Species

Abstract

Studying the presence and movement of insects is important in biological research for practical purposes regarding control of pests and environmental monitoring. Detection of insects by conventional trapping (e.g. the Rothamsted Insect Survey) and tracking technologies (e.g. the Rothamsted Radar Entomology Unit) have been effective for monitoring and forecasting pest migration but often require significant investment in capital costs and/or staff time. Insect detection using imaging of natural fluorescence (without additional fluorescent dyes) has been considered less, and much of the work on natural fluorescence in the animal world has been on marine organisms. Work on terrestrial arthropods has been more limited and restricted primarily to non-insect arthropods. Very early work on the distribution of fluorescent pigments in butterflies was demonstrated using long wave mercury vapour lamps followed by more work in the 1950s on butterflies, arthropods; including beetles, spiders and millipedes, cockroaches and eggs of Orthoptera. These studies often involved qualitative approaches; dissecting the animals and investigating internal organs and fluids for fluorescence as well as whole body studies. More recent studies have included quantitative work on butterflies and pest insects plus fluorescence studies in damselflies, moths, millipedes, bees and spiders. Fluorescence in juvenile stages is a property used for detection of flies and beetles in food stuffs. The vast majority of insects, however, have not been investigated for fluorescence and even in those taxa that have been studied, e.g. butterflies, the dataset is incomplete. The easiest way to observe fluorescence is to illuminate a subject with a known waveband of light in otherwise darkness and view or record an image via a filter that blocks the wavelength of the illuminating light. Any light viewed or captured at a different wavelength to the illumination, must have been produced by fluorescence. In contrast, some living organisms themselves can produce light or luminescence by internal chemical means. This work aimed to look at the potential of using natural fluorescence to detect and identify insects, particularly pests.