Population development, fecundity, and flight of Spodoptera frugiperda (Lepidoptera: Noctuidae) reared on three green manure crops: implications for an ecologically based pest management approach in China

Authors: WU, FEIFEI - Chinese Academy Of Agricultural Sciences; ZHANG, LEI - Chinese Academy Of Agricultural Sciences; LIU, YUEQIU - Chinese Academy Of Agricultural Sciences; CHENG, YUNXIA - Chinese Academy Of Agricultural Sciences; SU, JIANYA - Nanjing Agricultural University; Sappington, Thomas; JIANG, XINGFU - Chinese Academy Of Agricultural Sciences

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2021
Publication Date: 2/1/2022
Citation: Wu, F., Zhang, L., Liu, Y., Cheng, Y., Su, J., Sappington, T.W., Jiang, X. 2022. Population development, fecundity, and flight of Spodoptera frugiperda (Lepidoptera: Noctuidae) reared on three green manure crops: implications for an ecologically based pest management approach in China. Journal of Economic Entomology. 115(1):124-132. https://doi.org/10.1093/jee/toab235.
DOI: https://doi.org/10.1093/jee/toab235

Interpretive Summary: The fall armyworm is a severe insect pest of many crops, especially corn, wheat, and rice. It is native to the Americas, but invaded China in 2019 from southern Asia. It is a migratory moth that overwinters in subtropical regions in the south, then flies north in the spring and summer to infest northern crops. The number and severity of fall armyworm outbreaks in northern China in the summer depends on the number of migrants leaving populations in the south in the spring. In China, farmers are being encouraged to revitalize their soils in the south by planting so-called "green manure" crops, which include various vetch species that introduce nitrogen to the soil. The purpose of this study was to determine how well the three most commonly planted vetch species can support the growth and development of fall armyworm. The results showed that these vetch species are poor host plants for fall armyworm. Furthermore, population growth models based on the developmental data suggest that if these green manure crops can be used to replace host crops like corn and wheat over large areas, overwintering populations will be suppressed and there will be fewer outbreaks of this pest in the north each year. This information will be used by scientists worldwide, including the U.S., South America, Africa, and Asia to develop environmentally friendly methods to suppress fall armyworm populations in ways that will reduce the need for insecticides to control outbreaks.

Technical Abstract: The fall armyworm, Spodoptera frugiperda, is a newly invasive pest of corn, wheat and cereal crops, which are colonized year round in southern China. Cultivation of crops unsuitable as host plants has been an effective pest management scheme for some destructive migratory insect pests, but the effects of green manure crops on S. frugiperda have not been investigated. Here, age-stage two-sex population life table parameters of S. frugiperda feeding indoors on different green manure species were obtained, and a population dynamics model established. Growth and development of S. frugiperda on three green manure crop species were analyzed to explore the potential impacts of extensive planting of green manure crops on the risk of outbreaks for this insect. Developmental durations of stages, survival rates, and fecundities of S. frugiperda differed significantly when fed on different green manure species. Larvae fed on Astragalus sinicus did not complete development, and the mortality rate was 100%. Although larvae fed Vicia villosa and Vicia sativa completed development, generation time was significantly prolonged, egg production decreased to less than 50%, and net reproductive rate decreased to 31% and 3% compared to those reared on corn, respectively. Survival rates of early-instar larvae of S. frugiperda that fed on V. villosa and V. sativa were significantly lower than those of larvae that fed on corn. Generation time of S. frugiperda reared on V. sativa was 3.8 d and 14.3 d longer than those that fed on V. villosa and corn, respectively. S. frugiperda fed on corn had the highest probability of surviving from egg to adult (70%), whereas those reared on V. sativa had the lowest probability at only 3%. The population dynamics projections over 90 days showed that the number of generations of S. frugiperda that fed on V. villosa and V. sativa was much lower than those reared on corn. The three green manure crops tested in this study are not suitable host plants for S. frugiperda. Therefore, reducing the area planted to corn in southern China, combined with rotating between fallow and green manure crops, may be a feasible method of ecological regulation of this major corn pest.