Soybean Looper and Cabbage Looper (Lepidoptera: Noctuidae) Populations in Cotton and Soybean Cropping Systems in Mississippi

Colonization and abundance of soybean looper, Pseudoplusia includens (Walker), and cabbage looper, Trichoplusia ni (Hübner), adults and larvae were monitored in cotton and soybean cropping systems in the Delta region of Mississippi for three growing seasons (1994–1996). Soybean looper and cabbage looper adults were initially observed in pheromone traps during the last week of May or first week of June, although adults may have been present in the collection area prior to trap establishment. Adult populations of both species remained low until early August, after which moth density increased coincident with the bloom stages of cotton and soybean. Larvae were first collected from the crops when plants were in bloom, with the greatest increase in population density occurring in early to mid-August. Although samples were not taken after mid-August, looper populations generally decline to low levels during September in Mississippi. More soybean looper larvae usually were collected from soybean than in cotton, whereas fewer cabbage looper larvae were collected from soybean than cotton. Cabbage looper larvae were collected in soybean on the same sample date in 1995, but approximately 5 wk after soybean looper larvae in 1996. The occurrence of soybean and cabbage loopers in cotton and soybean agroecosystems in Mississippi appears to be similar to patterns of activity recorded for these insects 20 to 40 years ago in other areas of the southeastern United States.