Flights of Gray Looper (Rachiplusia ou) (Noctuidae) and Soybean Looper (Chrysodeixis includens) (Noctuidae) in Southeast Missouri Soybean

Abstract

Noctuid moths include economic species of importance such as the soybean podworm, black cutworm, soybean looper, and fall armyworm. The gray looper feeds on a wide variety of low-growing plants including tobacco, soybean, cotton, clover, and common wheat. Soybean looper can likewise be found in soybean and cotton. To monitor the flights and numbers of gray and soybean loopers in Southeast Missouri, funnel traps were baited with Autographa gamma or Pseudoplusia includens lures and dispensed on 1 May 2015 in 8 randomly selected soybean fields. Traps were monitored weekly (1 May - 1 Oct 2015). Degree days began at biofix, and a single sin method with a lower threshold of 15˚ was used to calculate accumulative degrees days. Temperature data was obtained from NOAA. Each peak flight was assigned accumulative number of degree days. Degree days for the current soybean looper model (egg to adult, 435dd) were compared with estimated models for gray and soybean loopers. These models were developed by averaging accumulated degree days between counties for peaks 1 -4 (204, 496, 937, and 1527 degree-days, gray looper) and for peaks 1 – 5 (349, 641, 962, 1258, and 1540 degree days, soybean looper). Soybean looper model was accurate for flights 1 – 3 for gray looper. For soybean looper management, the new soybean looper model worked best for estimating future peak flights. This confirmation of model data should help growers with their insecticide application decisions.