First report of field resistance to cyantraniliprole, a new anthranilic diamide insecticide, on Bemisia tabaciMED in China

The Bemisia tabaci （Gennadius） cryptic species complex comprises important insect pests that cause devastating damage to agricultural crops worldwide. In China, the B. tabaci Mediterranean （MED） （or biotype Q） species is threatening agricul- tural production all over the country as resistance to commonly used insecticides has increased. This situation highlights the need for alternative pest control measures. Cyantraniliprole, a novel anthraniiic diamide insecticide, has been widely employed to control Hemipteran pests. To monitor the levels of resistance to cyantraniliprole in B. tabaci field populations in China, bioassays were conducted for 18 field samples from nine provinces over two years. Compared with median lethal concentration （LC^0） for the MED susceptible strain, all field samples had significantly higher resistance to cyantraniliprole. Furthermore, resistance factors （RFs） increased significantly in samples from Shanxi （from 5.62 in 2015 to 25.81 in 2016）, Hunan （3.30 in 2015 to 20.97 in 2016） and Hubei （from 9.81 in 2015 to 23.91 in 2016） provinces. This study indicates a considerable decrease in the efficacy of cyantraniliprole against B. tabaci and establishes a baseline of susceptibility that could serve as a reference for future monitoring and management of B. tabaci resistance to cyantraniliprole.

Characterization of field-evolved resistance to cyantraniliprole in Bemisia tabaci MED from China

Cyantraniliprole is a novel anthranilic diamide insecticide with significant efficacy against Bemisia tabaci,an important pest insect worldwide.In this study,we conducted reversion and selection work and genetic analysis,and determined cross-resistance spectrum and synergism of cyantraniliprole resistance based on the reported population,SX population,of B.tabaci collected from Shanxi Province,China.Compared with a susceptible strain(MED-S),SX population,the field-evolved cyantraniliprole-resistant population exhibited 26.4-fold higher resistance to cyantraniliprole.In SX,a sharp decline of cyantraniliprole resistance was shown in the absence of selection.Another tested strain,SX-R,was established from SX population after successive selection with cyantraniliprole and recently developed 138.4-fold high resistance to cyantraniliprole.SX-R had no cross-resistance to abamectin,imidacloprid,thiamethoxam,sulfoxaflor,or bifenthrin.Genetic analysis illustrated that cyantraniliprole resistance in SX-R was autosomally inherited and incompletely dominant.Additionally,piperonyl butoxide(PBO)significantly inhibited cyantraniliprole resistance in the SX-R strain.In conclusion,the selection of SX with cyantraniliprole led to high resistance to cyantraniliprole which is incompletely dominant and no cross-resistance to several common types of insecticides.Enhanced oxidative metabolism is possibly involved in the resistance of SX-R,yet target-site resistance could not be excluded.

Effect of Cyantraniliprole on Feeding Cessation of Q Biotype Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)

The whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae) is one of the most devastating agricultural pests in many cropping systems worldwide. Growers rely on the use of insecticides to control this pest. However, some insecticides do not reduce the feeding of B. tabaci fast enough to prevent the direct and indirect damage produced by this insect. The effect of a new insecticide, cyantraniliprole 10OD (CyazypyrTM), on the feeding of B. tabaci adults, was studied under laboratory conditions. Cyantraniliprole 10OD is an insecticide that belongs to the IRAC Group 28 with a new mode of action for sucking insects, which provides rapid feeding cessation by impairing muscle function, resulting in reduced transmission of important insect vectored crop diseases. Laboratory experiments were conducted to determine the effect of cyantraniliprole along with some other commercially available insecticides on the feeding of B. tabaci adults by measuring the excretion of honeydew as an indirect assessment of insect feeding. In these experiments, cyantraniliprole resulted in significantly higher reduction of honeydew excretion (64.0%) by Q biotype B. tabaci adults during the first 30 minutes of exposure than diafenthiuron, triazophos, acetamiprid and spiromesifen, with all treatments having no adult mortality. Observations between 1 and 48 hours after exposure indicated that cyantraniliprole had numerically higher or similar reduction in honeydew production as the other insecticides, but by 48 hours (mid and high rate) and 96 hours (high rate) of exposure, cyantraniliprole had significantly higher reduction of honeydew excretion than all other insecticides tested. Low adult mortality was observed during first 24 hours of exposure in all treatments. Cyantraniliprole resulted in numerical or significantly higher adult mortality than all other treatments at the later observation intervals (72 - 96 hours). The higher reduction in honeydew excretion by cyantraniliprole appeared to be related to faster feeding cessation during the initial hours of exposure by a combination of feeding cessation and direct mortality as the exposure time increased. These findings document significant effects of cyantraniliprole on feeding cessation in Bemisia tabaci.

Study on Residues and Digestion of Cyantraniliprole in Chewing Cane

[Objective]The paper was to establish a method for the determination of cyantraniliprole residue in chewing cane,and analyze the residue and digestion dynamics of cyantraniliprole in chewing cane.[Method]The chewing cane samples were extracted by acetonitrile,purified by improved QuEChERS method,and detected by UPLC/MS/MS.[Result]Cyananseramide showed a good linear relationship in the concentration range of 0.005-0.250 mg/L(R2=0.9991).When the added mass concentration ranged from 0.02 to 0.40 mg/kg,the recovery rates of cyantraniliprole were respectively 83.1%-110.1%for chewing cane leaves and 88.2%-109.2%for chewing cane stems;the relative standard deviations were respectively2.38%-7.98%for chewing cane leaves and 2.26%-3.10%for chewing cane stems.The limit of detection(LOD)in chewing cane was 0.05μg/kg and the limit of quantification(LOQ)was 0.02 mg/kg.The trial results of two chewing cane fields in Guangxi showed that the half-lives of cyantraniliprole in chewing cane leaves were 7.76 and 6.12 d,respectively,and the correlation coefficients were 0.9570 and 0.9241,respectively.[Conclusion]The method is sensitive,accurate,simple and rapid,and it can be used to determine the residue and half-life of cyantraniliprole in chewing cane.The results will provide technical support for the safe use of cyantraniliprole in chewing cane.

Up-regulation of calmodulin involved in the stress response to cyantraniliprole in the whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)

Cyantraniliprole is the first diamide insecticide to have cross-spectrum activity against a broad range of insect orders.The insecticide,like other diamides,selectively acts on ryanodine receptor,destroys Ca^(2+) homeostasis,and ultimately causes insect death.Although expression regulations of genes associated with calcium signaling pathways are known to be involved in the response to diamides,little is known regarding the function of calmodulin(CaM),a typical Ca^(2+)sensor central in regulating Ca^(2+) homeostasis,in the stress response of insects to the insecticide.In this study,we cloned and identified the full-length complementary DNA of CaM in the whitefly,Bemisia tabaci(Gennadius),named BtCaM.Quantitative real-time reverse transcription polymerase chain reaction-based analyses showed that the messenger RNA level of BtCaM was rapidly induced from l.5l-to 2.43-fold by cyantraniliprole during 24 h.Knockdown of BtCaM by RNA interference increased the toxicity of cyantraniliprole in whiteflies by 42.85%.In contrast,BtCaM expression in Sf9 cells significantly increased the cells,tolerance to cyantraniliprole as much as 2.91-fold.In addition,the expression of BtCaM in Sf9 cells suppressed the rapid increase of intracellular Ca^(2+) after exposure to cyantraniliprole,and the maximum amplitude in the Sf9-BtCaM cells was only 34.9%of that in control cells(Sf9-PIZ/V5).These results demonstrate that overexpression of BtCaM is involved in the stress response of B.tabaci to cyantraniliprole through regulation of Ca^(2+)concentration.As CaM is one of the most evolutionarily conserved Ca^(2+) sensors in insects,outcomes of this study may provide the first details of a universal insect response to diamide insecticides.

Cyazypyr^(TM) Selectivity for Three Species of Phytoseiid for Coffee and Other Relevant Agricultural Crops in Brazil

Mites belonging to the family Phytoseiidae are the most important and most widely studied among predatory mites of phytophagous mites. The phytophagous mites Brevipalpus phoenicis (Geijskes, 1939) (Tenuipalpidae) and Oligonychus ilicis (McGregor, 1917) (Tetranychidae) on coffee (Coffea spp.), are frequently found in combination with the predaceous mites Iphiseiodes zuluagai Denmark & Muma, 1972;Euseius alatus DeLeon, 1966 and Amblyseius herbicolus (Chant, 1959) (Acari: Phytoseiidae), among others. The purpose of this research was to study the effects of the product CyazypyrTM (cyantraniliprole 100 OD) on these three species of Phytoseiidae, relevant to coffee, citrus and other agricultural crops in Brazil, following standard laboratory procedures. Mated female mites were exposed to fresh-dried residues on a glass surface, with 8 treatments, 5 mites per glass plate and 6 replicates, in a completely randomized experimental design. Each test lasted eight days, with a daily count of the surviving females and of eggs laid. CyazypyrTM, in all tested doses (75, 100, 125, 150, 175 and 200 g a.i./ha), was selective for the studied species, A. herbicolus, I. zuluagai, and E. alatus. Overall the treatments resulted in low mortality rates and negligible impact on the reproduction. Therefore, based on IOBC standards, CyazypyrTMcan be classified as not harmful (class 1) or slightly harmful (class 2), comparable to the agrochemical TalentoTM (hexythiazox 500 WP-12 g a.i./ha) equivalent to a harmless standard of selectivity in the laboratory. CyazypyrTM is therefore a complement to programs of integrated pest management, to preserve the populations of predatory mites in crops of coffee and citrus, among others, in Brazil.