Influence of four noctuid pests on preference and offspring fitness of Cotesia ruficrus

Abstract

Corn, as a crucial staple food crop, has historically faced significant challenges from a variety of pests, particularly those belonging to Lepidoptera order. The parasitoid Cotesia ruficrus has demonstrated efficacy in controlling certain Lepidoptera pests. This study aimed to elucidate the parasitism preference and fitness outcomes of C. ruficrus across four prominent noctuid pests: Spodoptera frugiperda, Mythinma separata, Helicoverpa armigera, and Spodoptera litura. The results showed that C. ruficrus exhibited a preference for the four herbivore species as follows: M. separata > S. frugiperda/H. armigera > S. litura. While C. ruficrus could successfully complete its life cycle within the bodies of M. separata and S. frugiperda, the same was not feasible with H. armigera and S. litura as hosts. Moreover, the number of offspring produced by C. ruficrus per host was significantly higher when parasitizing M. separata compared to S. frugiperda. However, the mature egg count in the ovaries and adult body size of C. ruficrus were notably smaller when utilizing M. separata as a host. In summary, the study revealed that C. ruficrus displays a preference for parasitizing M. separata among the four herbivores, yielding improved offspring numbers and performance. These findings provide valuable insights for the biological control of the studied pests and contribute to enhancing the propagation techniques of C. ruficrus.