The damage risk evaluation of Aphis gossypii on wheat by host shift and fitness comparison in wheat and cotton

Aphids are considered as one of the key pests for wheat production worldwide. Major aphid species that infest wheat in China include Sitobion avenae, Rhopalosiphum padi, Schizaphis graminum and Metopolophium dirhodum. However, during our wheat field survey in Wenshang County of Shangdong Province, China, we observed that Aphis gossypii can feed on wheat. The damage risk of A. gossypii on wheat was assessed using host shift method. A population of A. gossypii collected from a wheat field in 2015 and another population reared on cotton under laboratory conditions for a decade without exposure to insecticides were used in the study. The results of host shift demonstrated that the A. gossypii colony from wheat has not yet developed wheat specialization. Moreover, the assessment of A. gossypii fitness on wheat and cotton showed that fecundity and net reproductive rate of A. gossypii population fed on wheat was significantly higher comparing to the population fed on cotton, whether the initial host of A. gossypii population was wheat or cotton. This study raises a warning that the cotton aphid has potential to establish well on wheat and it may cause significant effects under specific circumstances. Therefore, future studies are required to evaluate the effects of A. gossypii on wheat production.