MIGRATION PATHWAYS OF CORN-EARWORM (LEPIDOPTERA, NOCTUIDAE) INDICATEDBY TETROON TRAJECTORIES

The corn earworm moth, Helicoverpa tea (Lepidoptera: Noctuidae), is a nocturnal pest insect that is capable of long-distance flights. Buoyan t superpressure balloons (tetroons) with attached transponders were tr acked as surrogate markers of moths migrating from three corn-growing regions in Texas. Launches were synchronized with peak emergence of co rn 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 o f moths into the boundary layer) from the corn-growing areas, and ball asted to drift near the altitude (500-1000 m a.g.l.) of the maximum in sect flight concentration, Each tetroon was followed by a tracking veh icle or the Argos satellite for maximum distances of 466 km per 9 h ni ght flight, and for one to four successive nights. The endpoints of fo ur of the six tetroons that were tracked for 9 h from Weslaco, Texas w ere clustered within a 40 km radius circle centered 35 km east of Uval de, Texas. The prorated (9 h) vector-average of National Weather Servi ce forecast trajectories at the surface and 85.0 kPa geopotential-heig ht estimated mean atmospheric displacements 57% as long as, and 3 degr ees 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.