Following <i>Diachasmimorpha longicaudata</i> (Hymenoptera: Braconidae) movements with harmonic radar: flight testing, cage studies, and field tracking

Increasing our understanding of parasitoid behavioral movement dynamics is critical to improving biological control strategies. The development of miniature harmonic radar (HR) tags, made with superelastic nitinol wire antennas, means tracking parasitoid wasps may now be possible. This study assessed the suitability of using HR tags (weighing ∼135 μg) for tracking individual Diachasmimorpha longicaudata (Ashmead, 1905) wasps. These braconid wasps are endoparasitoids of the larvae of many agriculturally important tephritid fruit fly species. HR tagged female D. longicaudata were found to be flight capable, but a laboratory flight bioassay showed some potential adverse effects of tagging, including slightly decreased cage landing heights and a numerical decrease in flight times. Flight tests in a large outdoor screen cage showed that D. longicaudata had biased landing distributions favoring a darker colored wall. Additionally, an attempt to observe wasp attraction to fruit was not successful. A multi-day experiment conducted in a coffee field demonstrated the feasibility of successfully following tagged wasp movements over time. Tagged D. longicaudata were found to be largely sedentary, with the longest recorded movement paths (sum of all observed moves) remaining under 10 m over a 3-d period. Mean observed movement distance was 2.7 ± 0.4 m with a mean movement rate of 0.11 ± 0.03 m/h (both values exclude wasps that remained in the release tree). This tracking approach is promising for future studies on parasitoid dispersal, chemical ecology, and parasitoid/predator/prey interactions in natural habitats, thus potentially enhancing the efficiency of biological control using D. longicaudata.