Partiti-like viruses from African armyworm increase larval and pupal mortality of a novel host : the Egyptian cotton leafworm

Xu, Pengjun and Rice, Annabel and Li, Tong and Wang, Jie and Yang, Xianming and Yuan, He and Graham, Robert I and Wilson, Kenneth (2022) Partiti-like viruses from African armyworm increase larval and pupal mortality of a novel host : the Egyptian cotton leafworm. Pest Management Science, 78 (4). pp. 1529-1537. ISSN 1526-498X

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Abstract

The general principle of using microbes from one species to manage a different pest species has a clear precedent in the large-scale release of mosquitoes carrying a Wolbachia bacterium derived from Drosophila flies. New technologies will facilitate the discovery of microbes that can be used in a similar way. Previously, we found three novel partiti-like viruses in the African armyworm (Spodoptera exempta). To investigate further the utility and consistency of host shift of insect viruses as a potential pest management tool, we tested the interaction between the partiti-like viruses and another novel host, the Egyptian cotton leafworm (Spodoptera littoralis). We found that all three partiti-like viruses appeared to be harmful to the novel host S. littoralis, by causing increased larval and pupal mortality. No effect was observed on host fecundity, and partiti-like virus infection did not impact host susceptibility when challenged with another pathogen, the baculovirus SpliNPV. Transcriptome analysis of partiti-like virus-infected and noninfected S. littoralis indicated that the viruses could impact host gene-expression profiles of S. littoralis, but they impact different pathways to the two other Spodoptera species through effects on pathways related to immunity (Jak-STAT/Toll and Imd) and reproduction (insulin signaling/insect hormones). Taken together with the previous findings in the novel host S. frugiperda, these results indicate a parasitic relationship between the partiti-like viruses and novel insect hosts, suggesting a possible use and novel pest management strategy through the artificial host shift of novel viruses. [Abstract copyright: © 2021 Society of Chemical Industry.]