The impact of wheat streak mosaic virus (WSMV) on the population growth rate of wheat curl mite (WCM), Aceria tosichella Keifer

Abstract: Wheat streak mosaic virus (WSMV) (Potyviridae, Tritimovirus) is a worldwide
distributed virus that affects cereals, mainly wheat. The only vector for WSMV is Aceria
tosichella (wheat curl mite, WCM), which belongs to the Eriophyidae family, highly specialized obligate phytophagous mites. According to vector manipulation hypothesis, plant viruses can affect its’ arthropod vectors to facilitate their spread. It was suggested WSMV manipulates WCM to increase the number of dispersible viruliferous mites. The aim of the study was to determine the population growth rate of the WCM population in 7, 14, 21, and 28 days after colonisation of the mites on WSMV-positive and -negative Triticum aestivum L. In addition, the number of leaves was counted, and their leaf area and the percentage of withered tissue were assessed to determine mite densities. The results showed that the WSMV infection had a positive effect on mite population density. The mite populations feeding on plants without WSMV on average reached a faster overall growth rate per plant than the mite population feeding on the WSMV-infected plants. However, as WSMV-infected plants were smaller and had a higher percentage of withered tissue than that of the uninfected, mite populations reached higher densities on them. The increasing population density, along with deteriorating host plant condition are probable cues for mite windborne dispersal. This is the first insight into the virusvector manipulation phenomenon in mites transmitting plant viruses, because the viral manipulation strategy had previously been demonstrated for their insect vectors.