Modeling the distances traveled by flying insects based on the combination of flight mill and mark-release-recapture experiments

The number of invasive species is increasing throughout the world. One of the corner stones to successfully control them is to better estimate their dispersal capabilities. For flying insects, dispersal performance is commonly estimated through flight mill and mark-release-recapture experiments. However, each approach has its own bias, over- and under-estimating flying distances respectively. The objective of this study was to develop an individual-based dispersal model to circumvent these drawbacks. The shape of the dispersal kernel was calibrated on distances recorded in flight mill experiments (previously done) and then model parameters were fine-tuned based on mark-release-recapture experiments (presented in this study). The pine sawyer beetle, Monochamus galloprovincialis, was used as case study because it is the European vector of the invasive pine wood nematode, Bursaphelenchus xylophilus, recognized as one of the biggest threats to pine forests worldwide. The best fitted model to mark-release-recapture data was parameterized with a mean flying distance of 2000 m per day, which is consistent with flight mill data. It was used to further simulate the dispersal of 100 beetles in non-fragmented pine forests. The cumulative flight distance was 63 km on average at the end of their adult life stage, and the mean dispersal distance as the crow flies was of ca. 13 km. At the end of the maturation period, when most nematodes have been already transmitted to host pines via shoot feeding, about 80% of the insects were located at more than 500 m from the emergence point. These outcomes clearly question the relevance of clear-cut zones of 500 m radius required by the European regulation for the eradication of the invasive nematode. Such dispersal model could be used to support decision-making for eradication programs.