Cross-resistance, resistance mechanisms, and mode of inheritance of spinosad resistance were studied in the western flower thrip, Frankliniella occidentalis (Pergande). Spinosad (naturalyte insecticide) showed low...Cross-resistance, resistance mechanisms, and mode of inheritance of spinosad resistance were studied in the western flower thrip, Frankliniella occidentalis (Pergande). Spinosad (naturalyte insecticide) showed low cross-resistance to prothiophos (organophosphorus insecticide) and chlorphenapyr (respiratory inhibitor) showed some cross-resistance to thiocyclam (nereistoxin). The synergists PBO (piperonyl butoxide), DEM (diethyl maleate), and DEF (s,s,s-tributyl phosphorotrithioate) did not show any synergism on the toxicity of spinosad in the resistant strain (ICS), indicating that metabolic- mediated detoxification was not responsible for the spinosad resistance, suggesting that spinosad may reduce sensitivity of the target site: the nicotinic acetylcholine receptor and GABA receptor. Following reciprocal crosses, dose-response lines and dominance ratios indicated that spinosad resistance was incompletely dominant and there were no maternal effects. The results of backcross showed that spinosad resistance did not fit a single-gene hypothesis, suggesting that resistance was influenced by several genes.展开更多
The novel full length of cytochrome P450 gene has been isolated in insecticideresistant (named CYP6CXlvl) and -susceptible (named CYP6CXlv2) Bemisia tabaci, which was identified as B biotype, in Shangjie, Fujian, ...The novel full length of cytochrome P450 gene has been isolated in insecticideresistant (named CYP6CXlvl) and -susceptible (named CYP6CXlv2) Bemisia tabaci, which was identified as B biotype, in Shangjie, Fujian, China (Sj). CYP6CX1 (1 940 bp contained a 1 557 bp open reading frame) included conserved domains common to CYP6 members, such as heme-binding motif PFGEGPRFCIA, putative "meander"-binding sequence ETLR and PERF in helix-K, oxygen-binding motif AGLDPV and conserved sequence PEKFNP near the carboxyl end. There were four different replacements of amino acid residues between R and S B. tabaci (Thr300 Ala, Thr354Pro, Arg486His and Ile503Thr), among which the substitution Ile503Thr was located in the substrate recognition sites region. The mRNA transcription level of CYP6CXlvl was 2.38-fold as high as that of CYP6CXlv2. The results indicated that the CFP6CX1 from the B biotype B. tabaci in Sj was one of the CYP6 members, and enhanced CYP6CX1 expression and substitute of amino acid residues might be involved in the resistance mechanisms in field B. tabaci.展开更多
Temporal and spatial correlated variations on the methamidophos resistance and biomolecular rate constant of acetylcholinesterase to insecticides were found between the turnip aphid, Lipaphis erysimi and its endoparas...Temporal and spatial correlated variations on the methamidophos resistance and biomolecular rate constant of acetylcholinesterase to insecticides were found between the turnip aphid, Lipaphis erysimi and its endoparasitoid, Diaeretilla rapae, collected from field colonies and an insecticide-free field insectarium in Fujian, China. Compared to the related susceptible insectarium population, L. erysimi and D. rapae displayed 7.4-29.2- and 2.6- 9.2-fold resistance ratios, respectively. In addition, two populations ofL. erysimi with different methamidophos resistance levels, that is, a field (with 5.8-fold resistance ratio) and an insectarium population, were used to study the effects of methamidophos ingested by the host insect on D. rapae development. The percentage of D. rapae cocoon formation decreased significantly when the parasitized L. erysimi were fed on cauliflower leaves treated with methamidophos at lethal concentration dosages 10 (LC50) or LC520. At LC50 dosages the percentage of D. rapae cocoon formation and adult emergence decreased significantly. When the parasitized L. erysimi were fed on methamidophos at LC50 dosage, no D. rapae cocoons were found. When the field or insectarium L. erysimi were treated with methamidophos at LC50, the susceptibility to methamidophos in the adult D. rapae emerged from the treated host insect was similar to the control. However, the susceptibility to methamidophos in the adult D. rapae became lower than the control when the host insects were treated at LC50 dosages. The data thus suggested that the methamidophos ingested by the host insect L. erysimi could be an important factor in the endoparasitoids' insecticide resistance development. The natural selectivity would favor the parasitoids that had developed an insensitivity to the insecticide(s).展开更多
文摘Cross-resistance, resistance mechanisms, and mode of inheritance of spinosad resistance were studied in the western flower thrip, Frankliniella occidentalis (Pergande). Spinosad (naturalyte insecticide) showed low cross-resistance to prothiophos (organophosphorus insecticide) and chlorphenapyr (respiratory inhibitor) showed some cross-resistance to thiocyclam (nereistoxin). The synergists PBO (piperonyl butoxide), DEM (diethyl maleate), and DEF (s,s,s-tributyl phosphorotrithioate) did not show any synergism on the toxicity of spinosad in the resistant strain (ICS), indicating that metabolic- mediated detoxification was not responsible for the spinosad resistance, suggesting that spinosad may reduce sensitivity of the target site: the nicotinic acetylcholine receptor and GABA receptor. Following reciprocal crosses, dose-response lines and dominance ratios indicated that spinosad resistance was incompletely dominant and there were no maternal effects. The results of backcross showed that spinosad resistance did not fit a single-gene hypothesis, suggesting that resistance was influenced by several genes.
文摘The novel full length of cytochrome P450 gene has been isolated in insecticideresistant (named CYP6CXlvl) and -susceptible (named CYP6CXlv2) Bemisia tabaci, which was identified as B biotype, in Shangjie, Fujian, China (Sj). CYP6CX1 (1 940 bp contained a 1 557 bp open reading frame) included conserved domains common to CYP6 members, such as heme-binding motif PFGEGPRFCIA, putative "meander"-binding sequence ETLR and PERF in helix-K, oxygen-binding motif AGLDPV and conserved sequence PEKFNP near the carboxyl end. There were four different replacements of amino acid residues between R and S B. tabaci (Thr300 Ala, Thr354Pro, Arg486His and Ile503Thr), among which the substitution Ile503Thr was located in the substrate recognition sites region. The mRNA transcription level of CYP6CXlvl was 2.38-fold as high as that of CYP6CXlv2. The results indicated that the CFP6CX1 from the B biotype B. tabaci in Sj was one of the CYP6 members, and enhanced CYP6CX1 expression and substitute of amino acid residues might be involved in the resistance mechanisms in field B. tabaci.
文摘Temporal and spatial correlated variations on the methamidophos resistance and biomolecular rate constant of acetylcholinesterase to insecticides were found between the turnip aphid, Lipaphis erysimi and its endoparasitoid, Diaeretilla rapae, collected from field colonies and an insecticide-free field insectarium in Fujian, China. Compared to the related susceptible insectarium population, L. erysimi and D. rapae displayed 7.4-29.2- and 2.6- 9.2-fold resistance ratios, respectively. In addition, two populations ofL. erysimi with different methamidophos resistance levels, that is, a field (with 5.8-fold resistance ratio) and an insectarium population, were used to study the effects of methamidophos ingested by the host insect on D. rapae development. The percentage of D. rapae cocoon formation decreased significantly when the parasitized L. erysimi were fed on cauliflower leaves treated with methamidophos at lethal concentration dosages 10 (LC50) or LC520. At LC50 dosages the percentage of D. rapae cocoon formation and adult emergence decreased significantly. When the parasitized L. erysimi were fed on methamidophos at LC50 dosage, no D. rapae cocoons were found. When the field or insectarium L. erysimi were treated with methamidophos at LC50, the susceptibility to methamidophos in the adult D. rapae emerged from the treated host insect was similar to the control. However, the susceptibility to methamidophos in the adult D. rapae became lower than the control when the host insects were treated at LC50 dosages. The data thus suggested that the methamidophos ingested by the host insect L. erysimi could be an important factor in the endoparasitoids' insecticide resistance development. The natural selectivity would favor the parasitoids that had developed an insensitivity to the insecticide(s).
基金Acknowledgments This work was supported by the Natural Science Foundation of Fujian, China (No. B0410016) and China-Japan Cooperation Program by Science and Technique Bureau of Fujian Province, China (20051002). This work was also supported in part by Grants-in-Aid from the Japan Society for the Promotion of Science (Nos. (A) 11356002 and (C) 14606001) and China-Japan Cooperated Program by JSPS.