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Shi X.-q.,Nanjing Agricultural University | Xiong M.-H.,Nanjing Agricultural University | Jiang W.-H.,Nanjing Agricultural University | Wang Z.-T.,Nanjing Agricultural University | And 4 more authors.
Journal of Pest Science | Year: 2012

The Colorado potato beetle (Leptinotarsa decemlineata [Say]) in the north Xinjiang Uygur autonomous region in China has evolved resistance to pyrethroids and carbamates. Mutations resulting in target site insensitivity, namely L1014F in LdVssc1 voltage-sensitive sodium channel and S291G in acetylcholine esterase, confer, at least partially, the resistance. Insecticides with different modes of action may serve as likely replacements. Endosulfan and fipronil are GABA-gated chloride channel-blocking insecticides. In this article, we found that the contact toxicities of the two compounds were among the highest ever estimated to the 4th-instar larvae and the adults and affirmed that they were useful for L. decemlineata control in north Xinjiang. Regarding stomach toxicities of the two compounds, adult beetles were less sensitive than 2nd-, 3rd-, and 4th-instar larvae, suggesting that the appropriate timing for spraying is the early larval stage. Mixtures of endosulfan and α-cypermethrin at 1:160, 1:80, and 1:40 ratios, of endosulfan and phoxim at 1:24 ratio, and of endosulfan and isocarbophos at 1:72 and 1:288 ratios, significantly increased toxicity in a field population. The combination indices were significantly below 1 at both LD50 and LD90 levels, revealing synergistic effects. Our results demonstrated that endosulfan and fipronil could be applied alone and endosulfan may also be used in binary mixtures to restore pyrethroid susceptibility. These findings may have considerable practical implications for L. decemlineata resistance management. © 2012 Springer-Verlag.

Jiang W.-H.,Nanjing Agricultural University | Lu W.-P.,Nanjing Agricultural University | Guo W.-C.,Xinjiang Academy of Agricultural Science | Xia Z.-H.,Station of Agricultural Techniques Extension in Yili | And 2 more authors.
Journal of Economic Entomology | Year: 2012

The Colorado potato beetle (Leptinotarsa decemlineata (Say)) in the north Xinjiang Uygur autonomous region has evolved resistance to various types of insecticides. Chlorantraniliprole is a novel anthranilic diamide insecticide that binds and activates ryanodine receptors. It exhibited excellent efficacy against L. decemlineata in several field trails in Europe. In the present paper, the susceptibility of L. decemlineata fourth-instar larvae derived from six field populations and L. decemlineata adults derived from three field populations to chlorantraniliprole was determined by a topical application. The fourth-instar larvae were substantially more susceptible to chlorantraniliprole than adults, although the range of susceptibility was far greater among the fourth-instar larvae. Regarding stomach toxicities, adult beetles were less susceptible to chlorantraniliprole than larvae. Chlorantraniliprole was most toxic to second-instar larvae, followed by third-and fourth-instar larvae. These data suggested that the appropriate timing for chlorantraniliprole spraying is the early larval stage. More-over, the synergistic activities of chlorantraniliprole in combination with triphenyl phosphate, diethyl maleate, or piperonyl butoxide against fourth-instar larvae from two field populations and adults from one field population were tested. Piperonyl butoxide had synergistic effects with chlorantraniliprole against fourth-instar larvae but not against adult beetles. Conversely, triphenyl phosphate and diethyl maleate exerted little synergistic effects. It appears that there is a potential risk of resistance against chlorantraniliprole resulting from cytochrome P450 monooxygenase activity. © 2012 Entomological Society of America.

Lu W.-P.,Nanjing Agricultural University | Shi X.-Q.,Nanjing Agricultural University | Guo W.-C.,Xinjiang Academy of Agricultural Science | Jiang W.-H.,Nanjing Agricultural University | And 3 more authors.
Journal of Agricultural and Urban Entomology | Year: 2010

The Colorado potato beetle Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) in the northern part of the Xinjiang Uygur Autonomous Region has evolved resistance to several pyrethroid and carbamate insecticides. Biological control methods should be a major component of integrated pest management for L. Decemlineata. Spinosad and abamectin are two biopesticides that have unique mechanisms of action. In this study, the contact toxicities of spinosad and abamectin to L. Decemlineata fourth instars and adults were determined by topical applications to several field populations. The average LD50 values of spinosad and abamectin for adults were 0.1275 and 0.0101 g (a.i.) per individual, and for fourth instars they were 0.0181 and 0.0016 g (a.i.) per individual, respectively. These data were among the lowest LD50s ever estimated, which affirmed that the two biopesticides are useful for L. Decemlineata control in north Xinjiang. Susceptibilities to the two biopesticides varied slightly but significantly among tested field populations and the variations did not result from cross-resistance to conventional insecticides. Regarding stomach toxicities, the LC50 values of spinosad applied to excised potato leaves for second instars, third instars, fourth instars, and adults were 0.2840, 0.4093, 1.2413, and 2.3783 mg/L (a.i.), respectively. The LC50 values of abamectin for second instars, third instars, fourth instars, and adults were 0.0036, 0.0088, 0.0177, and 0.2591 mg/L (a.i.), respectively. The two biopesticides were most toxic to second instars, followed by third, then fourth instars, and they were least toxic to adults. These data suggested that the appropriate timing for spinosad or abamectin spraying is to early larval stages. © 2011 The South Carolina Entomological Society, Inc.

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