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

Abstract

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 corn-growing 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.l) 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.