A comparison of the reproductive systems: a virgin and mated female Spodoptera frugiperda (Lepidoptera: Noctuidae)

The fall armyworm ( Spodoptera frugiperda ) has lately been a threat to maize and other crops in the graminaceous family in most parts of the world. For a long time, this devastating pest has been a resident of the Western Hemisphere. However, in 2018, it was reported in Africa, and subsequently in Asia in 2019. This study aimed to understand the reproductive system of virgin and mated female fall armyworm to be able to envisage its population trend and hence suggest how to contain its infection. The virgin and copulated females were dissected to observe their reproductive structures. There was no significant difference in the number of ovarioles in each ovary due to the mating of Spodoptera frugiperda , although ovarian development was affected. Notably, the ovaries enlarged in the early stages after adult emergence, and there was more yolk deposit present in mated females than virgin females. It was found that ovarian advancement begins in the pupal stage. It was also noted that the beginning of ovarian development happens 4–5 days after the pupation of the female. At this stage, the ovarioles begin to develop. However, no eggs or yolk deposition were observed. Stage six, which is the final stage of oviposition, occurs 20 and 24 days after female adult emergence. After mating, oviposition occurs between 11 and 13 days and ends with their mortality. This study goes a long way in understanding the population trend of fall armyworm and hence determining the best stage for control. The results will also be useful to the researchers who are currently working on this insect in laboratories around the world to sustain the fall armyworm populations for further experiments.