Morphology and development of immature stages of Microplitis manilae (Hymenoptera: Braconidae), an important endoparasitoid of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Microplitis manilae (Ashmead) (Hymenoptera: Braconidae) is a solitary endoparasitic wasp of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), a significant agricultural pest. We compared the parasitism of M. manilae on the first-, second-, and third-instar larvae of S. frugiperda and found that M. manilae prefered the second instar. We investigated the effect of 5 temperatures (18, 22, 26, 30, and 34 °C) on the development period in the immature stage of M. manilae and found that moderately high temperatures shortened the development time. Considering the development period, cocooning rate, and emergence rate, 26 °C was the optimal temperature for the highest value of females’ fecundity. We also examined the development of the immature stage of M. manilae by dissecting parasitized hosts and cocoons in the laboratory. Our results revealed that the eggs matured within 2 d, and the larvae progressed through 3 instars, culminating in a total developmental period of about 9 d. The prepupal stage retained the larval form, and the pupa pigment gradually precipitated after molting. All stages were documented in detailed micrographs. Our study lays a robust foundation for further studies on the physiological interactions between M. manilae and S. frugiperda.