Effects of temperature on life-history traits of the newly invasive fall armyworm, Spodoptera frugiperda in Southeast China

In mid-May, 2019, the fall armyworm (FAW) Spodoptera frugiperda invaded Jiangxi Province, China, and caused extensive damage to corn crops. However, little attention has been given to the life-history traits of the FAW. In the present study, we systematically investigated the life-history traits of the newly invasive FAW on corn leaves at 19, 22, 25, 28, and 31 degrees C under a photoperiod of LD 15:9 hr. The FAW thrived on the corn leaves with short developmental periods, high survival rates of larvae and pupae, very high mating success rates, and high fecundity. The pupal developmental stage was significantly longer in males than females at all temperatures, thus resulting in a protogyny phenomenon. The pupal weight was heaviest after a relatively shorter larval development stage at a higher temperature (25 degrees C); thus, the FAW did not follow the temperature-size rule. Females were smaller than males, indicating sexual size dimorphism. A small proportion of females delayed their pre-oviposition period and began to lay eggs on the 7th to 9th day after adult emergence. There were positive relationships between pupal weight and larval developmental time and between adult weight and fecundity. There was a negative relationship between fecundity and longevity. These findings can help us to predict the population dynamics of the FAW on corn and to develop a suitable and practical management strategy.

Automated summary

The fall armyworm invaded Jiangxi Province, China in mid-May 2019, causing extensive damage to corn crops. Research showed that the fall armyworm thrived on corn leaves with short developmental periods, high survival rates, high mating success rates, and high fecundity. There were positive relationships between pupal weight and larval developmental time, as well as between adult weight and fecundity, while a negative relationship was found between fecundity and longevity.