Doppler weather radar detects emigratory flights of noctuids during a major pest outbreak

An outbreak of beet armyworm (Spodoptera exigua (Hübner)), cabbage looper, (Trichoplusia ni (Hübner)), and other noctuid pests devastated cotton production in the Lower Rio Grande Valley, TX, in 1995. Major infestations occurred later in the year several hundred kilometers away in other cotton production areas in Texas and Oklahoma, but information is lacking to connect regional infestations by these migratory pests. The objective of this study was to evaluate the capability of WSR-88D Doppler weather radar in locating and monitoring pest emigration from severely infested areas. Maximum radar reflectivity identified possible source areas in the vicinity of major infestations in cotton by beet armyworms and cabbage loopers that had been reported in Willacy County, TX. Areas of maximum clear-air radar reflectivity 13.5-16.5 dBZ) appeared approximately 0.5 h after sunset and displaced downwind toward susceptible cotton production regions in the Winter Garden and Southern Rolling Plains of west-central TX. Our results suggest that WSR-88D weather radar data may be useful in the development of crop pest advisories that estimate the timing, intensity, and displacement of insect migration flights, especially with recent enhancements in timely public access to WSR-88D radar data and radar data processing and analysis software.