JIA-2019-11

2572 WANG Ran et al. Journal of Integrative Agriculture 2019, 18(11): 2571–2578 led to clear weakening in the control efficiency of these chemical agents in more and more cases of B. tabaci damage (Castle and Prabhaker 2013; Shadmany et al. 2015; Ahmad and Khan 2017; Naveen et al. 2017; Dângelo et al. 2018). Furthermore, some of the above agents show varying degrees of toxicity on many non-target organisms (Zeng et al. 2013; Cimino et al. 2017). Within the cryptic species complex of B. tabaci in China, Middle East-Minor Asia 1 (MEAM1, also called biotype B) used to be the dominant cryptic species and had resulted in significant losses in agricultural production (Chu et al. 2006; Pan et al. 2011, 2015). Recently, MEAM1 has been displaced by Mediterranean (MED, also called biotype Q) and research has shown that MED predominates in most areas of China (Wang et al. 2010; Zheng et al. 2017). Due to extensive or excessive applications of chemical insecticides, many cases of resistance have been reported in the field from many regions of China (Yao et al. 2017; Zheng et al. 2017; Wang et al. 2018a). Cyantraniliprole is a second-generation systemic insecticide of anthranilic diamides that has exhibited effective control of many insect pests from a variety of orders (Knight and Flexner 2007; Yeoh and Lee 2007; Koppenhöfer and Fuzy 2008; Peck et al. 2008; Jacobson and Kennedy 2011). As the first-generation product of anthranilic diamides, chlorantraniliprole has been widely used due to its efficacy, but in the middle of all the anthranilic diamides, cyantraniliprole is the primary choice to control sucking pests (Sattelle et al. 2008; Barry et al. 2015), and it is very effective in managing aphids, psyllids and whiteflies (Foster et al. 2012; Qureshi et al. 2014; Grávalos et al. 2015; Echegaray et al. 2016). In particular, cyantraniliprole was shown to be effective in controlling different stages of B. tabaci and contributed to weakening the ability to transmit plant viruses (Civolani et al. 2014; Xie et al. 2014; Caballero et al. 2015). Furthermore, due to its unique mode of action, cyantraniliprole shows almost no cross-resistance to several conventional insecticides, suggesting that it could be used to delay the evolution of resistance to other insecticides in B. tabaci (Grávalos et al. 2015). However, after two-year monitoring of resistance in B. tabaci from different provinces of China, we found that resistance to cyantraniliprole has rapidly evolved in several areas of China (Wang et al. 2018b). Understanding the stability, resistance patterns, inheritance and synergism of a field-evolved resistance to cyantraniliprole in B. tabaci is important for developing strategies to delay the evolution of resistance in the field. Many studies have been conducted on resistance mechanisms of various commercialized insecticides in whiteflies but there is minimal published information concerning resistance to cyantraniliprole. In this study, stability, patterns of cross-resistance, inheritance and synergism of cyantraniliprole were studied with one field- evolved resistant population of B. tabaci from China (Wang et al. 2018b). 2. Materials and methods 2.1. Insects The susceptible strain of B. tabaci MED (MED-S), which was reared in the lab without exposure to insecticides, was collected from Beijing, China in 2009 (Pan et al. 2012). The population of B. tabaci collected from Shanxi Province, China, in 2016 was named as SX population (Wang et al. 2018b). At the F 3 generation, two strains were originated from the SX population. One strain was selected with cyantraniliprole for 13 continuous generations and established as the SX-R strain. Adults of each generation were screened at the LC 50 , and average mortality during selection was about 45%. The other strain has been reared without cyantraniliprole selection since F 3 generation and named as SX strain, which is used to determine the rate of resistance reversion. Tested strains of B. tabaci were maintained on cotton ( Gossypium hirsutum L. var. Shiyuan 321) and kept in a growth chamber at (26±1)°C and (60±10)% relative humidity (RH) under a 16 h light:8 h dark photoperiod. All strains were identified as MED by sequencing of mitochondrial cytochrome oxidase I (Luo et al. 2002). 2.2. Insecticides and chemicals In all bioassays, formulated insecticides used included: 10% cyantraniliprole emulsifiable concentrate (Dupont Agricultural Chemicals Ltd., Shanghai, China); 5% abamectin emulsifiable concentrate (Shandong Weifang Runfeng Chemical Industry Co., Ltd., China); 10% imidacloprid wettable powder (Nanjing Red Sun Co., Ltd., China); 25% thiamethoxam water dispersible granule (Nanjing Red Sun Co., Ltd., China); 50% sulfoxaflor water dispersible granule (Dow Agro Sciences Co., Ltd., USA); and 2.5% bifenthrin emulsifiable concentrate (Hebei Enge Biotech Co., Ltd., China). Triphenyl phosphate (TPP) and diethyl maleate (DEM) were purchased from Shanghai Chemical Reagent Co., Ltd. Piperonyl butoxide (PBO) was bought from Sigma (St. Louis, MO, USA). 2.3. Bioassays Bioassays using the leaf-dip method were conducted for all insecticides (Wang et al. 2018a). Insecticides were diluted with distilled water to generate five serial dilutions. Leaf