P. D. Lingren

Migration pathways of corn earworm (Lepidoptera: Noctuidae) indicated by tetroon trajectories

The corn earworm moth, Helicoverpa zea (Lepidoptera: Noctuidae), is a nocturnal pest insect that is capable of long-distance flights. Buoyant superpressure balloons (tetroons) with attached transponders were tracked as surrogate markers of moths migrating from three corngrowing regions in Texas. Launches were synchronized with peak emergence of corn earworm moths in June and July 1992. The tetroons were launched at the time (approximately 0.5 h after sunset) of peak take off (ascent of moths into the boundary layer) from the corn-growing areas, and ballasted to drift near the altitude (500-1000 m a.g.1.) of the maximum insect flight concentration. Each tetroon was followed by a tracking vehicle or the Argos satellite for maximum distances of 466 km per 9 h night flight, and for one to four successive nights. The endpoints of four of the six tetroons that were tracked for 9 h from Weslaco, Texas were clustered within a 40 km radius circle centered 35 km east of Uvalde, Texas. The prorated (9 h) vector-average of National Weather Service forecast trajectories at the surface and 85.0 kPa geopotential-height estimated mean atmospheric displacements 57% as long as, and 3” clockwise from seven observed 9 h tracks of tetroons. Implications of these findings are discussed relative to the prediction of insect migrations and development of area-wide pest management.