Dynamic monitoring (B versus Q) and further resistance status of Q-type Bemisia tabaci in China

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) causes serious economic losses in many countries and has developed substantial resistance to commonly used insecticides. To determine whether the ratio of B. tabaci B to B. tabaci Q has continued to change in China, we collected specimens in 2013 and 2014 from most provinces in the country. Resistance to insecticides was also assessed in Q-type B. tabaci. B. tabaci Q remained much more abundant than B. tabaci B throughout China in 2013 and 2014, representing 82% of the specimens in 2013 and 88% in 2014. B. tabaci B was mainly found in the southeast coast and Yangtze river basin. Abamectin remained highly toxic to B. tabaci adults, with LC50 values <0.2 mg/l in 2013 and 2014. Thiamethoxam showed lower toxicity to HN and HB strains, with LC50 values >500 mg/l in 2014. Although cyantraniliprole also remained highly toxic to pre-adults of B. tabaci, the resistance ratio (relative to the sensitive Lab-Q strain) increased to 27.80 for eggs and to 35.79 for larvae. B. tabaci Q continues to dominate in China. As of 2014, abamectin, cyantraniliprole, and pyriproxyfen were still effective against B. tabaci based on our laboratory bioassays but moderate resistance to cyantraniliprole and pyriproxyfen was detected in some areas.