Harmonic radar: assessing the impact of tag weight on walking activity of Colorado potato beetle, plum curculio, and western corn rootworm

The impact of electronic dipole tags on the walking activity of three insects was determined using video tracking software. Results varied within and between the three species studied. The heaviest tag mounted on the pronotum of the Colorado potato beetle, Leptinotarsa decemlineata (Say), reduced its mean horizontal speed slightly but significantly. The mean horizontal speed of plum curculio, Conotrachelus nenuphar (Herbst), was significantly reduced by a light tag but not by heavier tags. The mean horizontal speed of the western corn rootworm, Diabrotica virgifera virgifera (LeConte), increased slightly when a tag was attached. A tag mounted to the dorsum of the Colorado potato beetle and the plum curculio slightly changed their climbing speed. Changes in the walking speed were variable but remained well within the range of values recorded in the literature. The impact of the additional tag weight was within the range of constraints to movement (e.g., slopes, barriers, etc.) normally experienced by insects in their environment. The results confirm that tags presently available will have minimal impact on the walking behavior of Colorado potato beetle, provide an estimate of the optimal tag weight for the plum curculio and show that a lighter tag and a better attachment method are required for the western corn rootworm. Because of the ability of insects to adapt to a wide range of landscapes and to their own body weight changes, the additional tag weight had a limited impact compared with the value of the ecological information gathered using this technology.