3.5
MIGRATORY FLIGHTS OF BOLLWORMS, HELICOVERPA ZEA (BODDIE), INDICATED BY DOPPLER WEATHER RADAR

John K. Westbrook, USDA, College Station, TX; and W. W. Wolf

Reflectivity from flying organisms including the adult bollworm, Helicoverpa zea (Boddie), is often detected in clear-air mode by WSR-88D Doppler weather radars of the NEXRAD system. During migratory seasons in south-central Texas, reflectivity from these targets reached 5 to 30 dBZ, which exceeds the lower threshold for precipitation mode. Sequential reflectivity scans showed a rapid increase in reflectivity (i.e., aerial insect abundance) over the cropped land of the Lower Rio Grande Valley by 0.5 hours after sunset. The nightly pattern of maximum reflectivity displaced approximately downwind. Results show strong positive relationships between insect concentration measured by (X- band) entomological radar and WSR-88D reflectivity, and between wind velocity and doppler velocity. Considerations due to the WSR-88D beam geometry and characteristics of insect distribution will be discussed.

The 13th Conference on Biometeorology and Aerobiology