Female-Biased Symbionts and Tomato Yellow Leaf Curl Virus Infections in Bemisia tabaci

The female-biased infection of facultative symbionts has been found in Bemisia tabaci; however, whether there are any differences in tomato yellow leaf curl virus (TYLCV) and obligate symbiont infection rates between females and males is unknown. Determining whether such differences exist would be very important for understanding the spread of the plant virus and of the symbionts. We compared both symbiont infection types, including obligate and facultative symbionts, and the rates of TYLCV infection in both sexes in five field populations from Jiangsu Province, China. The obligate symbiont Portiera aleyrodidarum was not found in every whitefly tested. In all tested populations, more females than males were found to harbor P. aleyrodidarum; and more females than males also harbored Hamiltonella defense, the most common facultative symbiont as well as Cardinium. In addition to female-biased symbiont infections, there were also female-biased TYLCV infections, and the infection frequencies of this plant virus in females were higher than those in males. Taken together, these results suggested that both the female-biased symbiont infections and female-biased TYLCV infections promoted the rapid spread of TYLCV in China.