Temporal occurrence of plusiinae on soybean in the Mississippi River Delta

Authors: Allen, Clint; Little, Nathan; Perera, Omaththage

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2020
Publication Date: 1/13/2021
Citation: Allen, K.C., Little, N., Perera, O.P. 2021. Temporal occurrence of plusiinae on soybean in the Mississippi River Delta. Journal of Economic Entomology. 114(2):723-727. https://doi.org/10.1093/jee/toaa308.
DOI: https://doi.org/10.1093/jee/toaa308

Interpretive Summary: “Loopers” are defoliating caterpillars that belong to a subfamily of insects made up of approximately 400 species worldwide. Two species of the subfamily, the soybean looper, and the cabbage looper are important defoliating insect pests of various field crops and have been the subject of previous surveys in the Southern U.S. Soybean fields were sampled in the Mississippi Delta from 2010-2012 to determine the temporal occurrence of various looper species on soybean. As in previous surveys, soybean loopers were the most common looper species in soybean during the three-year survey, especially in late season collections (July – September). The gray looper moth was the predominant species observed in early season collections (May-early July). Only three collected larvae successfully developed into cabbage looper adults, one each collected during May, June, and July. Although the gray looper moth was not normally reported in previous studies on soybean, it occurred in low numbers during June and July during the three-year study. The temporal occurrence and species composition followed a predictable pattern in all three years of the study, which is especially important when differences in the use of insecticides occur for their control.

Technical Abstract: The subfamily Plusiinae of the moth family Noctuidae is made up 400 species worldwide. Two species of the subfamily, the soybean looper, Chrysodeixis includens (Walker), and the cabbage looper, Trichoplusia ni (Hübner), are important defoliating insect pests of various field crops and have been the subject of previous Plusiinae surveys in the Southern U.S. Soybean fields were sampled in the Mississippi Delta from 2010-2012 to determine the temporal occurrence of various Plusiinae species on soybean. As in previous surveys, C. includens was the most common Plusiinae species in soybean during the three-year survey, especially in late season collections (July – September). Rachiplusia ou, (Guenée), was the predominant species observed in early season collections (May-early July). Populations of R. ou during the first sample dates during 2010 were much higher than those observed during the other years of the survey. Only three collected larvae successfully developed into T. ni adults, one each collected during May, June, and July. Although R. ou was not normally reported in previous studies on soybean, it occurred in low numbers during June and July during the three-year study. The temporal occurrence and species composition followed a predictable pattern in all three years of the study, which is especially important when differences in the use of insecticides occur for their control.