Evaluation and prediction of butterfly flight patterns over field scales

With the advent of harmonic radar it has become possible to monitor and record the flight patterns of individual insects over landscape scales (up to several hundred metres). These experiments have revolutionised our understanding of the flight patterns honeybees, bumblebees and moths. Honeybees caught at feeders and then displaced have been shown to adopt an optimal searching strategy when seeking the hive location. This optimal searching strategy is also adopted by bumblebees when they first leave the nest in search of forage. Male moths adopt an entirely different searching strategy when locating sexual partners. When they detect the scent from sex pheromone released by a female moth they fly in an upwind direct in search of its source. The results of a preliminary analysis suggest that butterflies fly upwind in response to floral scent from clusters of flowers and then locate individual flowers within a cluster by employing of an optimal searching strategy. The behaviour characteristics of butterflies may therefore provide an intriguing bridge between the behaviour characteristics of bees and moths. The analysis is based on the flight patterns of just ten butterflies and an idealised theory of searching. The proposed research will substantiate the preliminary study by monitoring the flight patterns of many butterflies and by developing new theories of searching that account explicitly for the influence of 'flight guides', such as dense tree-lines that are known to be used by butterflies. This new research will lead to a better understanding of insect flight patterns over field scales and will result in a validated, predictive theory of these flight patterns. This has important ramifications for the understanding and prediction of plant pollination and insect populations.

Analysis of data from the first harmonic radar study of butterfly flight patterns over landscape scales (up to several hundred metres) [Cant et al., 2005] suggests that butterflies locate distant clusters of flowers by undertaking scent-mediated, anemotactic flights. This is akin to the pheromone-mediated, anemotactic flights undertaken by male moths when seeking sexual mates [Mafra and Cardé, 1994, 1997; Baker and Vickers, 1997, and references therein]. It complements the widely held view that while butterflies often use visual floral traits when selecting which flowers to visit or lay eggs on, it is floral scents which elicit behavioural responses that initiate and maintain foraging of flowers and oviposition of eggs. The analysis also suggests that butterflies adopt an optimal scale-free (Levy-flight) searching strategy [Viswanathan et al., 1999 and subsequent developments] when seeking individual flowers within a cluster. The analysis is based upon the flight patterns of just ten butterflies. If substantiated by a more extensive study, the findings would advance considerably the understanding of butterfly flight patterns of landscape scales. The flight patterns of butterflies have not yet been quantified and the olfactory-driven flights have not been reported on. Together with advances made recently by the PI [e.g. Reynolds, Physical Review E 2005; Reynolds, Physics Letters A, 2006] in the interpretation of honeybee, bumblebee and moth flight patterns, it would also facilitate the development and validation of a predictive, unified theory of insect flight patterns over landscape scales. The proposed reseach will address this challenge by using harmonic radar to monitor and record the flight patterns of many butterflies over landscape scales. Flight patterns will then be analysed within the context of new theories of optimal scale-free searching that will be developed during the course of the project.