Population projection and development of the loreyi leafworm, Mythimna loreyi, as affected by temperature: application of an age-stage, two-sex life table

Authors: QIN, JIANYANG - Chinese Academy Of Agricultural Sciences; JIANG, XINGFU - Chinese Academy Of Agricultural Sciences; ZHANG, LEI - Chinese Academy Of Agricultural Sciences; Sappington, Thomas; CHENG, YUNXIA - Chinese Academy Of Agricultural Sciences; LUO, LIZHI - Chinese Academy Of Agricultural Sciences

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2017
Publication Date: 5/25/2017
Citation: Qin, J., Jiang, X., Zhang, L., Sappington, T.W., Cheng, Y., Luo, L. 2017. Population projection and development of the loreyi leafworm, Mythimna loreyi, as affected by temperature: application of an age-stage, two-sex life table. Journal of Economic Entomology. 110(4):1583-1591. doi:10.1093/jee/tox138.

Interpretive Summary: The loreyi leafworm has suddenly emerged as a serious agricultural pest of several crops including corn in China. It is a close relative of the true armyworm in North America and the oriental armyworm in Eurasia, which have long been major pests of corn and other crops. To develop efficient and effective management strategies for any new insect pest requires an understanding of its population dynamics. A critical first step to achieve that understanding is to collect data that can be used to project population increases and decreases given environmental conditions, especially temperature which controls rate of development in all insects. Experiments were conducted that clarified the effects of different temperatures on different developmental stages (egg, larva, pupa, etc.) of the loreyi leafworm. The development rates determined from the experiments were used to project rates of population growth at different temperatures. This information will be used by university, government, and industry scientists to understand the population dynamics of this new and serious pest, with ramifications for better understanding and management of closely related species in the U.S. and worldwide.

Technical Abstract: The loreyi leafworm, Mythimna (=Leucania) loreyi (Duponchel), has recently emerged as a major pest of grain crops in China. Little is known about its basic biology and ecology, making it difficult to predict its population dynamics. An age-stage, two-sex life table was constructed for this insect when reared on maize in the laboratory at five constant temperatures (18, 21, 24, 27 and 30°C). Both the intrinsic rate of increase (r) and finite rate increase (') increased as temperature significantly increased and mean generation time (T) decreased significantly with increasing temperature. The highest values for net reproductive rate (R0), and fecundity were observed at 24°C. However, M. loreyi was able to develop, survive and lay eggs at all temperatures tested (18-30°C). Development rates at different temperatures for the egg, larval, pupal, as well as for a total pre-oviposition period, fit a linear equation. The lower threshold temperatures of egg, larval, pupal, pre-oviposition and total pre-oviposition period were 8.83, 10.95, 11.67, 9.30, and 9.65',respectively. Their effective accumulated temperatures were 87.64, 298.51, 208.33, 66.47, and 729.93 degree-days, respectively. This study provides insight into the temperature-based phenology and population ecology in M. loreyi. The results will benefit population dynamics monitoring, prediction and management of this insect pest in the field.