Experimental heatwaves impair male fertility in oriental armyworm, Mythimna separata

Authors: LV, WEIXIANG - China West Normal University; WANG, FANG - Chinese Academy Of Agricultural Sciences; JIANG, CHEN - China West Normal University; LIU, HUAFENG - China West Normal University; Stanley, David; ZHANG, LEI - Chinese Academy Of Agricultural Sciences

Submitted to: Entomologia Generalis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2024
Publication Date: 7/29/2024
Citation: Lv, W., Wang, F., Jiang, C., Liu, H., Stanley, D.W., Zhang, L. 2024. Experimental heatwaves impair male fertility in oriental armyworm, Mythimna separata. Entomologia Generalis. https://doi.org/10.1127/entomologia/2024/2476.
DOI: https://doi.org/10.1127/entomologia/2024/2476

Interpretive Summary: Rising global temperatures are leading to increasing risks of temperature-driven weather events, such as forest fires, hurricanes and tornadoes. Some insect species arrive in their summer breeding areas earlier in the year and spread to higher latitudes. Such changes can seriously impede the effective monitoring and management of migratory pest insects. The negative influence of rising temperatures on sperm of mammals, birds and some insect species is well-documented, yet there is only limited data on the influence of temperature increases on male migratory insect pests. In this paper we show that rising temperatures lead to reduced reproductive performances, such as mating frequency, numbers of offspring, and sperm counts in the oriental armyworm, a long-distance migratory insect in Asia. Such new information is necessary to improve pest management programs for migrant pest insects. These data will be used by scientists working on global pest management systems to sustain long term production of healthy and attractive foods for a growing human population.

Technical Abstract: Rising frequencies and intensity of heatwaves has pronounced impacts on animal survival and reproduction. Yet, such events how impact male fertility in migratory insects has remained unexplored to date. Using the oriental armyworm (Mythimna separata), a destructive agricultural pest throughout Asia and Australia, we investigated the effects of simulated heatwaves (7 °C above the optimum for 5 days) on reproduction and sperm traits, and then explored how heatwave exposure at different life stages on male fertility. We further assessed the transgenerational impacts of heatwaves on the reproductive potential of offspring, and the potential adaptability of male offspring exposed to parental heat exposure. Here, we found that heatwaves damaged male fertility, sperm production, and viability, but not female reproduction. Heatwaves affected male fertility depending on the specific life stages. Transgenerational negative impacts on survival and reproductive potential of offspring by paternal heatwaves and fitness of male offspring by paternal and maternal heatwave exposure were found. Our experiments revealed that heatwaves could cause a loss of male fertility and even mediate cross-generational effects in migratory insects. Our study highlights the importance of understanding thermal adaptation and the consequences of global change for predicting the population dynamics of migratory pests.