Infection pattern of male-killing viruses alters phenotypes in the tea tortrix moth, Homona magnanima

Abstract Male-killing is a microbe-induced reproductive manipulation in invertebrates whereby male hosts are eliminated during development. In the tea tortrix moth Homona magnanima, Osugoroshi viruses 1‒3 (OGVs/ Partitiviridae) induce male-killing. OGVs co-infect with a host individual, however, it is still unclear how infection patterns influence host phenotypes remains largely unknown. Using field-collected larvae, we established the OGV1 and OGV3 double infection line, in addition to a triple infection line, and examined the dsRNA segments, purified viral proteins, OGVs density, and host phenotypes. PCR analysis showed that the triple infection line lost one dsRNA segment, while the double infection line lost eight segments including one RNA-dependent RNA polymerase (RdRp) gene. LC-MS analysis detected three potential structural proteins in the OGVs. Males died in the larval stage when infected with three different OGVs and at the embryo-larval stages when infected with OGVs 1 and OGV3, even though no apparent correlation between virus density and lethal stages was found. Compared to the triple infection line, the larval period of the double infection line was significantly longer. These results suggest that, rather than viral density, the pattern of viral infection controls the stage of development at which male-killing occurs. The shorter larval period of in the triple-infection line would probably be advantageous over the double-infection line in maximizing transmission efficiency.