First discovery of Arsenophonus infection in spiders, predators of insect pests

Infection of insect pests and their parasitoids with the facultative endosymbiont Arsenophonus has been well studied, whereas infection of insect pest predators with this symbiont has not been reported. Here, we studied this symbiont in the spider Pardosa pseudoannulata, an important predator of rice planthoppers, collected from rice paddies in 8 geographical regions in China. Diagnostic PCR showed that Arsenophonus was present in 4 of the 8 sampled populations of the spider. In these 4 populations infected with Arsenophonus, the infection incidence was between 2.1% and 16.7% and significantly differed between the Li Shui (LS) population and the other three populations. It also showed that Arsenophonus could coexist with Wolbachia in 2 populations of P. pseudoannulata, and Arsenophonus populations from different geographical regions exhibited low genetic differentiation.