| Plutella xylostella (L.) is a worldwide pest which does serious harm to cruciferous vegetables. Indoxacarb is one kind of oxazine insecticide with unique mechanism, broad-spectrum disinsection and low toxicity to non-target organisms. However, the Plutella Xylostella has increasing resistance to indoxacarb due to long-term and continuous use, which impaired indoxacarb's application value of treatment to Plutella. This article first describes the resistance monitoring to Plutella xylostella on field population in Hunan province in anticipation of offering some constructive proposals on comprehensive control to Plutella Xylostella in Hunan province. ABC transporter superfamily gene, which plays an important role in absorption, transfer and metabolism of exogenous toxic substances, is likely to be a mechanism resulting in pesticide resistance in target organisms. ABCG2 gene is one type of ABC gene. This article also discusses the selection of Indoxacarb-resistant strain in laboratory and the variation of mRNA expression level of ABCG2 gene detected at different instars on different parts of the tissue. Besides, the expression level variation of ABCG2 gene transcriptional level between indoxacarb anti-allergy strains is analyzed so as to understand the role of ABCG2 gene played in the generating process of indoxacarb resistance in diamondback moth.1. Monitoring of insecticide resistance in the diamondback mothThe resistance of field population of Plutella xylostella to nine insecticides in Hunan was determined through leaf-dip method under experimental condition. The result showed that P.xylostella have an extremely high level of resistance to beta-cypermethrin; have high level of resistance to abamectin, chlorfluazuron and indoxacarb; have moderate level of resistance to chlorfenapyr?emamectin and pleocidin benzoate; remain a relatively of sensitivity to chlorantaniliprole and bacillus thuringiensis. Therefore, the prevention of Plutella xylostella should focus on the alternative use of chlorfenapyr, emaectin, chlorantraniliprole and bacillus thuringiensis, and stop using chlorfluazuron, abamectin, indoxacarb and beta-cypermethrin, in order to delay and control the development of resistance to insecticides.2. laboratory breeding of indoxacarb resistance in Plutella xylostellaThe resistance R strain was processed continuously with indoxacarb treatment. The resistance level at 208.52 times and the LCso is 39.62mg/L.3. Analysis of ABCG2 Gene Expression Characteristics of Diamondback MothDuring experiment, the ABCG2 gene expression was found throughout the life span of Diamondback Moth. The expression level presented an increasing trend during larval stage and the expression of ABCG2 in male adult worm was significantly higher than that at other growth stages, about 5.63 times the expression of third-instar larvae,3.67 times of fourth-instar larvae?7.36 times of pupal stage and 3.51 times of female adult worm. The relative expression level of ABCG2 gene came to be the highest in midgut, about 3.12 times the expression of malpighian tubules?8.96 times of testes and 7.33 times of carcass, while the expression level in head and ntegumentum is low. The study also found that Plutella xylostella presented high expression of ABCG2 gene under temporary indoxacarb stimulus. In addition, the indoxacarb resistance strain (R) also showed relative higher expression than susceptible strain (S), about 11.23 times that in susceptible strain. Therefore, it can be initially inferred that the ABCG2 gene play a certain role in the transportation and metabolism of exogenous substances, and it is likely to involve in the transportation and metabolism of Indoxacarb in diamondback moth. That is to say, it has certain relation to the forming of Indoxacarb resistance in Plutella xylostella. |
PDF Full Text Request