Transcriptome analysis reveals divergent parasitic strategies between two larval endoparasitoids of Spodoptera frugiperda

In nature, certain hosts are attacked by multiple species of parasitoid wasps. Despite sharing a common host, parasitoid wasps adopt different parasitic strategies and regulatory systems to manage the host. With the invasion of the fall armyworm (FAW) Spodoptera frugiperda in China, many native parasitoid wasps have been investigated. Two larval endoparasitoid wasps, Microplitis manilae and Meteorus pulchricornis, are important natural enemies of the invasive pest FAW. However, the interactions of these two parasitoid wasps with FAWs are still largely unknown. In this study, we analysed the transcriptome data of FAW after parasitization by Mi. manilae or Me. pulchricornis. Our analyses showed that the critical regulatory periods for the two parasitoid wasps were at 1, 3 and 7 days post parasitization (dpp) for Mi. manilae and 5 and 7 dpp for Me. pulchricornis. Besides the suppression of the host’s innate immune system, the two parasitic wasps have different effects on host metabolism and development. Mi. manilae influences the host’s growth and physiological conditions by inhibiting cuticle development and lipid metabolism, and facilitating carbohydrate metabolism. Alternatively, Me. pulchricornis has minimal impact on the host until the final stage. In conclusion, Mi. manilae has a sophisticated ‘regulatory’ strategy with considerable alterations in the host at each time point, while Me. pulchricornis likely adopts a ‘conformer’ approach, especially at the early parasitism stage. Our study lays a groundwork for future research and applications of these parasitoids in the biological control of FAW.