Pushing the frontiers of applied ecological science with the use of harmonic radar and micro-tagged insects to address questions related to the management of invasive species

Background/Question/Methods

A key question in the invasion process is how exotic, invasive species disperse and move between habitats in the landscape. This is especially important for polyphagous species, such as the brown marmorated stink bug (Halyomorpha halys), which have been demonstrated to move from crop to crop in agricultural settings, following the phenology of plants as fruits become mature. Just as invasive species are becoming more frequent, technology is improving for tracking individual insects in situ. One such technology is harmonic radar, which can track small tagged insects reliably up to 15 m away, and has been shown to be durable, have no effect on the dispersal behavior or survivorship of H. halys. In this study, we evaluated the retention capacity of various host plant species either augmented with pheromonal and kairomonal stimuli or alone for H. halys using harmonic radar. These host plants have the potential to be used for controlling H. halysvia trap cropping in organic agriculture, or attract-and-kill sites in conventional apple orchards. 

Results/Conclusions

We found that retention time for the potential trap crops, sorghum and sunflower, were 1.5 times greater than for the cash crop of organic peppers, while the distance moved by H. halys from the release point in the trap crops was half that in the cash crop. These significant differences were modulated by the phenology of both the cash and trap crops during the season, with the greatest retention capacity of the trap crops demonstrated when the peppers were flowering. In the case of apple trees, augmenting apple trees with attractive pheromonal and kairomonal stimuli increased the retention time from ~3h to greater than 20 h. In addition, the distance moved by H. halys decreased 5-fold in augmented apple trees. Overall, we show that we can use novel technologies such as harmonic radar to push the frontiers of applied science by asking novel ecological questions aimed at improving management of this invasive species.