A TRANSPONDER FOR HARMONIC RADAR TRACKING OF THE BLACK VINE WEEVIL IN BEHAVIORAL RESEARCH

The black vine weevil (BVW), Otiorhynchus sulcatus (Fabricius), is a major economic insect pest for growers of ornamental nursery crops and small fruits. Development of management strategies by entomologists and growers has been hampered by a lack of behavioral information on movement of BVW within agroecosystems. Although insects can be tracked using tag-and-release methods, the BVW is active primarily at night, cannot fly, and can be difficult to relocate. Harmonic radar technology has been used in entomological research and was investigated for applicability to the BVW problem. An insect-mounted, miniature transponder was developed to facilitate location in conjunction with a commercially available harmonic radar transceiver detector. The transponder, powered by a 0.917 GHz signal from the detector, returns a 1.834 GHz signal when detected. The transponder consists of a Schottky barrier diode with an inductively loaded monopole antenna and is lightweight at about 27% of a BVW body mass. In field trials, insects were successfully released, relocated, and recovered after several days.