The resistance of field populations of Plutella xylostella, from the three vegetable producing areas (Nianyuxu Town of Yueyang City, Canggang Town of Changde City and Shatou Town of Yiyang City) in northern Hunan, t...The resistance of field populations of Plutella xylostella, from the three vegetable producing areas (Nianyuxu Town of Yueyang City, Canggang Town of Changde City and Shatou Town of Yiyang City) in northern Hunan, to seven insecticides was determined using leaf dipping method in door. The results showed that Plutella xylostella showed an extremely high-level resistance to beta-cypermethrin (resistance ratio, RR=257.13), a high-level resistance to abamectin (RR=135.15) and indoxacarb (RR=103.08) and a moderate-level resistance to chlorfenapyr and emamectin benzoate. But Plutella xylostella is relatively sensitive to chlorantraniliprole and Bacillus thuringiensis (Bt). Therefore, the prevention of Plutella xylostella in northern Hunan should focus on the alternative use of chlorfenapyr, emamectin benzoate, chlorantraniliprole and Bacillus thuringiensis and avoid the use of beta-cypermethrin so as to delay the generation and development of resistance to insecticides in Plutella xylostella.展开更多
Carboxylesterase(CarE)was considered as important phase-I detoxifying enzymes which participated in detoxification of different types of insecticides.Up-regulation of CarE genes has been proved playing a major role in...Carboxylesterase(CarE)was considered as important phase-I detoxifying enzymes which participated in detoxification of different types of insecticides.Up-regulation of CarE genes has been proved playing a major role in insecticide resistance in many pest insects,but its involvement in resistance to insecticides in Plutella xylostella has been rarely reported.In this study,a CarE cDNA named PxαE8 was identified in P.xylostella,which has an open reading frame of 1599 nucleotides and putatively encodes 532 amino acids.The investigation of spatial expression profiles of PxαE8 revealed that it was expressed in all developmental stages,especially in larvae and adults.The body part/tissue-specific expression profiles showed that the PxαE8 mainly expressed in fat body,malpighian tubule and hemolymph of larvae.Further,the relative expression of PxαE8 in two multi-resistant field populations,Hainan(HN)and Guangdong(GD)populations,was found 24.4-and 15.5-fold higher than that in susceptible population,respectively.Knockdown of PxαE8 by RNA interference dramatically increased the mortalities of larvae of HN population treated with LC_(50) of beta-cypermethrin and phoxim by 25.3 and 18.3%,respectively.These results suggested that up-regulation of PxαE8 was involved in resistance to both beta-cypermethrin and phoxim in P.xylostella,which shed light on further understanding of molecular mechanisms of multi-insecticide-resistance in P.xylostella and other pest insects.展开更多
The identification of functional midgut receptors for pesticidal proteins produced by Bacillus thuringiensis(Bt)is critical for deciphering the molecular mechanism of Bt resistance in insects.Reduced expression of the...The identification of functional midgut receptors for pesticidal proteins produced by Bacillus thuringiensis(Bt)is critical for deciphering the molecular mechanism of Bt resistance in insects.Reduced expression of the PxABCB1 gene was previously found to be associated with Cry1Ac resistance in the diamondback moth,Plutella xylostella(L.).To directly validate the potential receptor role of PxABCB1 and its contribution to Bt Cry1Ac toxicity in P.xylostella,we used CRISPR/Cas9 to generate a homozygous knockout ABCB1KO strain with a 5-bp deletion in exon 3 of its gene.The ABCB1KO strain exhibited a 63-fold resistance to Cry1Ac toxin compared to the parental DBM1Ac-S strain.Intriguingly,the ABCB1KO strain also exhibited significant increases in susceptibility to abamectin and emamectin benzoate.No changes in susceptibility to various other Bt Cry proteins or synthetic insecticides were observed.The knockout strain exhibited no significant fitness costs.Overall,our study indicates that PxABCB1 can protect the insect against avermectin insecticides on one hand,while on the other hand it facilitates the toxic effect of the Bt Cry1Ac toxin.The results of this study will help to inform integrated pest management approaches against this destructive pest.展开更多
Five reduced-risk insecticides were compared for their toxicities to male and female third instar larvae of diamondback moth (DBM), Plutella xylostella L. (Lepidoptera:Plutellidae) obtained from a laboratory colo...Five reduced-risk insecticides were compared for their toxicities to male and female third instar larvae of diamondback moth (DBM), Plutella xylostella L. (Lepidoptera:Plutellidae) obtained from a laboratory colony. Leaf-dip bioassays were used to assess larval mortality at different insecticides rates (ranging from 0.01 mg AI/L to 100 mg A1/L) and exposure times (24, 48 and 72 h after treatment). Toxicity of the insecticides generally increased with rate and exposure time. At 72 h after treatment, median lethal concentrations (LCs0s) of methoxyfenozide, spinosad, novaluron, indoxacarb and Bacillus thuringiensis (Bt) against the male third instar larvae of P, xylostella were 0.0524, 0.1117, 0.9149, 1.1939 and 4.4983 mg AI/L, respectively, and were 0.1008, 0.2583, 1.0649, 0.2850 and 5.3053 mg AI/L against female third instar larvae, respectively. At 0.1% of the approximate recommended field rates, methoxyfenozide (60%-75%) and spinosad (53%-57%) were the most toxic, while Bt (30%-45% mortality) was the least toxic to male and female P. xylostella larvae. Spinosad was the fastest acting and the only insecticide that caused significant larval mortality (17%) at 24 h after exposure. Significant sexual differences were recorded in the susceptibility of P. xylostella larvae to two of the insecticides: spinosad and indoxacarb. Male larvae were two-fold more susceptible to spinosad but 10-fold more tolerant to indoxacarb than female larvae.展开更多
The insecticide chlorantraniliprole exhibits good efifcacy and plays an important role in controlling the diamondback moth, Plutella xylostella Linnaeus. However, resistance to chlorantraniliprole has been observed re...The insecticide chlorantraniliprole exhibits good efifcacy and plays an important role in controlling the diamondback moth, Plutella xylostella Linnaeus. However, resistance to chlorantraniliprole has been observed recently in some ifeld populations. At present study, diamondback moths with resistance to chlorantraniliprole (resistant ratio (RR) was 82.18) for biochemical assays were selected. The assays were performed to determine potential resistance mechanisms. The results showed that the selected resistant moths (GDLZ-R) and susceptible moth could be synergized by known metabolic inhibitors such as piperonyl butoxide (PBO), triphenyl phosphate (TPP) and diethyl-maleate (DEM) at different levels (1.68-5.50-fold and 2.20-2.89-fold, respectively), and DEM showed the maximum synergism in both strains. In enzymes assays, a high level of glutathione-S-transferase (GST) was observed in the resistant moth, in contrast, moths that are susceptible to the insecticide had only 1/3 the GST activity of the resistant moths. The analysis of short-term exposure of chlorantraniliprole on biochemical response in the resistant strain also showed that GST activity was signiifcantly elevated after exposure to a sub-lethal concentration of chlorantraniliprole (about 1/3 LC50, 12 mg L-1) 12 and 24 h, respectively. The results show that there is a strong correlation between the enzyme activity and resistance, and GST is likely the main detoxiifcation mechanism responsible for resistance to chlorantraniliprole in P. xylostella L., cytochrome P450 monooxygenase (P450) and carboxy-lesterase (CarE) are involved in to some extent.展开更多
The diamondback moth,Plutella xylostella(L.),is one of the most destructive migratory pest species of cruciferous vegetables worldwide and has developed resistance to most of the insecticides used for its control.The ...The diamondback moth,Plutella xylostella(L.),is one of the most destructive migratory pest species of cruciferous vegetables worldwide and has developed resistance to most of the insecticides used for its control.The migration regularity,migratory behavior,and relationship between flight and reproduction of P.xylostella have been widely reported.However,the effect of migration on insecticide resistance in this pest is still unclear.In this study,the effect of migration on P.xylostella resistance to seven insecticides was investigated using populations across the Bohai Sea that were collected in the early and late seasons during 2017–2019.The bioassay results showed that the early season populations of P.xylostella from south China possessed much higher resistance to insecticides because of intensive insecticide application;alternatively,the late season populations migrated from northeast China,where the insecticides were only used occasionally,showed much lower insecticide resistance.The genome re-sequencing results revealed that,among the eight mutations involved in insecticide resistance,the frequencies of two acetylcholinesterase mutations(A298S and G324A)responsible for organophosphorus insecticide resistance were significantly decreased in the late season populations.The results indicated that P.xylostella migration between tropical and temperate regions significantly delayed the development of insecticide resistance.These findings illustrated the effect of regional migration on the evolution of insecticide resistance in P.xylostella,and provided foundational information for further research on the relationship between migration and insecticide resistance development in other insects.展开更多
Carboxylesterase is a multifunctional superfamily and can be found in almost all living organisms. As the metabolic enzymes, carboxylesterases are involved in insecticides resistance in insects for long time. In our p...Carboxylesterase is a multifunctional superfamily and can be found in almost all living organisms. As the metabolic enzymes, carboxylesterases are involved in insecticides resistance in insects for long time. In our previous studies, the enhanced c arboxylesterase activities were found in the chlorantraniliprole resistance strain of diamondback moth(DBM). However, t he related enzyme gene of chlorantraniliprole resistance has not been clear in this strain. Here, a full-length c DNA of carboxylesterase pxCCE016 b was cloned and exogenously expressed in Escherichia coli at the first time, which contained a 1 693 bp open reading frame(ORF) and encoded a protein of 542 amino acids. Sequence analysis showed that this c DNA has a predicted mass of 61.56 k Da and a theoretical isoelectric point value of 5.78. The sequence of deduced amino acid possessed the classical structural features: a type-B carboxylesterase signature 2(EDCLYLNVYTK), a type-B carboxylesterase serine active site(FGGDPENITIFGESAG) and the catalytic triad(S er186, Glu316, and His444). The real-time quantitative PCR(q PCR) analysis showed that t he expression level of the p x CCE016 b was significantly higher in the chlorantraniliprole resistant strain than in the susceptible strain. Furthermore, pxCCE016 b was highly expressed in the midgut and epidermis of the DBM larvae. When the 3rd-instar larvae of resistant DBM were exposed to abamectin, alpha-cypermethrin, chlorantraniliprole, spinosad, c hlorfenapyr and indoxacarb insecticides, the up-regulated expression of pxCCE016 b was observed only in the group treated by chlorantraniliprole. In addition, recombinant vector p ET-pxCCE016 b was constructed with the most coding region(1 293 bp) and large number of soluble recombinant proteins(less than 48 k Da) were expressed successfully with prokaryotic cell. Western blot analysis showed that it was coded by pxCCE016 b. All the above findings provide important information for further f unctional study, although we are uncertainty whether the pxCCE016 b gene is actually i nvolved in chlorantraniliprole resistance.展开更多
The diamondback moth (DBM), Plutella xylostella (L.), is a major pest of cruciferous crops. Tebufenozide, a novel nonsteroidal ecdysone agonist, exhibits good efficacy and has played an increasingly important role...The diamondback moth (DBM), Plutella xylostella (L.), is a major pest of cruciferous crops. Tebufenozide, a novel nonsteroidal ecdysone agonist, exhibits good efficacy and has played an increasingly important role in the control of Lepidopteran pests in China. For its resistance management, the genetic basis of tebufenozide resistance was studied using a laboratory selected resistant strain of DBM (resistant ratio, RR = 268). A series of crosses with laboratory susceptible and resistant strains revealed that tebufenozide resistance in this pest was partially biased toward female heredity, with a large difference in RR for F1 (RR = 29) and rF1 progeny (RR = 147). The dominance calculated for these 2 cross progeny was -0.788 and 0.09, respectively. Further analysis showed that the susceptible male and female larvae were similar in theft sensitivity to tebufenozide, but the resistant female larvae showed significantly higher resistance than the resistant male larvae. The heredity of tebufenozide resistance in DBM might be linked with the W sex chromosome, which suggested that DBM has the ability to develop high levels of resistance to tebufenozide. This is the first report of sex-linked inheritance oftebufenozide resistance in P xylostella (L.).展开更多
The seasonal changes of insecticide resistance and stability in hymenopteran Cotesia plutellae, collected from Jianxin, Fuzhou-City, and Shangjie, Minhou-County, Fujian, China, were assessed by using a dry residual fi...The seasonal changes of insecticide resistance and stability in hymenopteran Cotesia plutellae, collected from Jianxin, Fuzhou-City, and Shangjie, Minhou-County, Fujian, China, were assessed by using a dry residual film method. The resistance to two insecticides in the field populations of C. plutellae was not stable under insecticide-free conditions in the insectarium. Compared with susceptible F11 progeny of C. plutellae in the insectarium, the resistance ratios (RR) in F0 parents were 18.4 for fenvalerate and 11.4 for cypermethrin based on LC50 at 9 hours, and 32.8 for fenvalerate and 28.5 for cypermethrin based on LC50 at 24 hours when the parasitoids were left in contact with the insecticides for 1 hour and mortalities were recorded at 9 and 24 hours, respectively. However, the RR in a field population of C. plutellae were 9.2 for fenvalerate and 12.7 for cypermethrin, if the parasitoids were left in contact with the insecticides for 24 hours. The resistances to the two pyrethroids in other field populations collected from Jianxin and Shangjie from November 2000 and July 2004 were also determined. Significant seasonal variations of resistance to the two insecticides in the field populations of C. plutellae were found. The RR were 3.0-18.4 for fenvalerate and 4.8-20.6 for cypermethrin in Jianxin populations from November 2000 to April 2002 based on LC50 at 9 h, and 2.3-13.6 for fenvalerate and 3.6-16.0 for cypermethrin in Shangjie populations from May 2002 to July 2004 based on LC50 at 24 hours. The resistance levels were high in spring and autumn and decreased sharply in summer. In addition, significant recovery from the knocked-down caused by the insecticides was found in the F0 and field populations of C. plutellae which were resistant to fenvalerate and cypermethrin if the parasitoids were left in contact with the pyrethroids for 1 hour. However, no recovery was found in susceptible F11 progeny.展开更多
Diamondback moth, Plutella xylostella (L.) is one of the most serious insect pests for its remarkable ability to develop resistance to virtually every insecticide that has been used against it. In the present study,...Diamondback moth, Plutella xylostella (L.) is one of the most serious insect pests for its remarkable ability to develop resistance to virtually every insecticide that has been used against it. In the present study, amplified fragment length poly- morphism (AFLP) is used to study the genetic differentiation as well as the effects of abamectin-selection on population genetic differentiation for P. xylostella. A dendrogram was constructed from the matrix of genetic distances using the STATISTICA software (Version 4.5) and unweighted pair-group method with arithmetic averages (UPGMA). The data demonstrated that compared to the susceptible strain (ABM-s), the heterozy- gosity in the abamectin-resistant strain (ABM-r) decreased with the increased selection pressure and resistant level. When the resistance ratio was below 4.3, there was no sig- nificant differentiation at the genome DNA level. When the resistance ratio reached 5.8, a fairly significant differentiation began to appear, and when the resistance ratio reached and exceeded 8.1, there appeared a significant genetic differentiation. The results suggest that abamectin selection is associated with increased genetic polymorphism in P. xylostella.展开更多
Xenorhabdus nematophila, a Gram-negative proteobacterium belonging to the family Enterobacteriaceae and associated symbiotically with soil entomopathogenic nematodes, Steinernema carpocapsae, is pathogenic to a wide r...Xenorhabdus nematophila, a Gram-negative proteobacterium belonging to the family Enterobacteriaceae and associated symbiotically with soil entomopathogenic nematodes, Steinernema carpocapsae, is pathogenic to a wide range of insects. A protein complex with insecticidal activity was isolated from the cells ofX. nematophila HB310 strain using methods of salting out and native polyacrylamide gel electrophoresis (PAGE). Seven polypeptides ranging 50~250 kDa were well separated from the protein complex (named Xnpt) by sodium dodecyl sulfate (SDS)-PAGE, five of which are identified as XptA2, xptC 1, XptB 1, GroEL and hypothetical protein by matrix-assisted laser desorption- time-of-flight mass spectrometry (MALDI-TOFMS). Xnpt showed high oral virulence to larvae of diamondback moth (DBM), Plutella xylostella L. (Lepidoptera, Plutellidae) as its median lethal concentration (LC50) against second and third instar larvae were 331.45 ng/mL and 553.59 ng/mL at 72 h, respectively. The histological analysis of Xnptfed DBM larvae showed extensive histopathological effects on the midgut. Biochemical analysis indicated that Xnpt markedly inhibited the activities of three important enzymes in the midgut. Overall, our data showed that the protein complex isolated from X. nematophila HB310 induced the antifeedant and death of insects by destroying midgut tissues and inhibiting midgut proteases activities.展开更多
Field trials were conducted in China in 2008 and 2009 to evaluate the efficacy of mating disruption (MD) on diamondback moth, Plutella xylostella, in cabbage, Brassica oleracea var. capitata. Effectiveness was posit...Field trials were conducted in China in 2008 and 2009 to evaluate the efficacy of mating disruption (MD) on diamondback moth, Plutella xylostella, in cabbage, Brassica oleracea var. capitata. Effectiveness was positively correlated with the MD dispenser density in the field. A density of 167 MD dispensers per ha produced an average population decrease of about 50% compared to the conventional-practice field. Significant fewer males were captured in pheromone-treated and conventional-practice fields than in the blank control field, but the difference was not significant between the pheromone-treated and conventional-practice fields. In addition, fewer eggs and larvae were observed in pheromone-treated fields. Our results suggest mating disruption coupled with minimal insecticidal supplements is a promising solution for resistance management and control of diamondback moth infestation.展开更多
The present study explored the Spilanthes acmella Murr. for insecticidal principle, a plant of high value. The seed extract showed insecticidal activity against Plutella xylostella. Further, bioassay guided isolation ...The present study explored the Spilanthes acmella Murr. for insecticidal principle, a plant of high value. The seed extract showed insecticidal activity against Plutella xylostella. Further, bioassay guided isolation of bioactive compounds resulted in insecticidal active molecule, which was identified with the help of ESI-MS and NMR. Highest activity of 95 - 100 percent was observed at low dose of 2 g/l with spilanthol, while 60 - 70 and 80 - 90 percent mortality at 5 g/l in crude seed extracts prepared in methanol and hexane after 48 hours exposure, respectively. LC50 of 1.49, 5.14, 5.04, 11.75 g/l was observed with spilanthol, crude seed extract of methanol, hexane, deltamethrin, respectively. The findings indicate the potential of S. acmella with potent insecticidal toxicity for the management of P. xylostella and other insects of agricultural importance.展开更多
文摘The resistance of field populations of Plutella xylostella, from the three vegetable producing areas (Nianyuxu Town of Yueyang City, Canggang Town of Changde City and Shatou Town of Yiyang City) in northern Hunan, to seven insecticides was determined using leaf dipping method in door. The results showed that Plutella xylostella showed an extremely high-level resistance to beta-cypermethrin (resistance ratio, RR=257.13), a high-level resistance to abamectin (RR=135.15) and indoxacarb (RR=103.08) and a moderate-level resistance to chlorfenapyr and emamectin benzoate. But Plutella xylostella is relatively sensitive to chlorantraniliprole and Bacillus thuringiensis (Bt). Therefore, the prevention of Plutella xylostella in northern Hunan should focus on the alternative use of chlorfenapyr, emamectin benzoate, chlorantraniliprole and Bacillus thuringiensis and avoid the use of beta-cypermethrin so as to delay the generation and development of resistance to insecticides in Plutella xylostella.
基金supported by the National Natural Science Foundation of China (31371956, 31572023 and 31772186)
文摘Carboxylesterase(CarE)was considered as important phase-I detoxifying enzymes which participated in detoxification of different types of insecticides.Up-regulation of CarE genes has been proved playing a major role in insecticide resistance in many pest insects,but its involvement in resistance to insecticides in Plutella xylostella has been rarely reported.In this study,a CarE cDNA named PxαE8 was identified in P.xylostella,which has an open reading frame of 1599 nucleotides and putatively encodes 532 amino acids.The investigation of spatial expression profiles of PxαE8 revealed that it was expressed in all developmental stages,especially in larvae and adults.The body part/tissue-specific expression profiles showed that the PxαE8 mainly expressed in fat body,malpighian tubule and hemolymph of larvae.Further,the relative expression of PxαE8 in two multi-resistant field populations,Hainan(HN)and Guangdong(GD)populations,was found 24.4-and 15.5-fold higher than that in susceptible population,respectively.Knockdown of PxαE8 by RNA interference dramatically increased the mortalities of larvae of HN population treated with LC_(50) of beta-cypermethrin and phoxim by 25.3 and 18.3%,respectively.These results suggested that up-regulation of PxαE8 was involved in resistance to both beta-cypermethrin and phoxim in P.xylostella,which shed light on further understanding of molecular mechanisms of multi-insecticide-resistance in P.xylostella and other pest insects.
基金the Laboratory of Lingnan Modern Agriculture Project,China(NT2021003)National Natural Science Foundation of China(32022074,32221004 and 32172458)Beijing Key Laboratory for Pest Control and Sustainable Cultivation of Vegetables,Chinese Academy of Agricultural Sciences,and the Innovation Program of the Chinese Academy of Agricultural Sciences(CAAS-CSCB-202303)。
文摘The identification of functional midgut receptors for pesticidal proteins produced by Bacillus thuringiensis(Bt)is critical for deciphering the molecular mechanism of Bt resistance in insects.Reduced expression of the PxABCB1 gene was previously found to be associated with Cry1Ac resistance in the diamondback moth,Plutella xylostella(L.).To directly validate the potential receptor role of PxABCB1 and its contribution to Bt Cry1Ac toxicity in P.xylostella,we used CRISPR/Cas9 to generate a homozygous knockout ABCB1KO strain with a 5-bp deletion in exon 3 of its gene.The ABCB1KO strain exhibited a 63-fold resistance to Cry1Ac toxin compared to the parental DBM1Ac-S strain.Intriguingly,the ABCB1KO strain also exhibited significant increases in susceptibility to abamectin and emamectin benzoate.No changes in susceptibility to various other Bt Cry proteins or synthetic insecticides were observed.The knockout strain exhibited no significant fitness costs.Overall,our study indicates that PxABCB1 can protect the insect against avermectin insecticides on one hand,while on the other hand it facilitates the toxic effect of the Bt Cry1Ac toxin.The results of this study will help to inform integrated pest management approaches against this destructive pest.
文摘Five reduced-risk insecticides were compared for their toxicities to male and female third instar larvae of diamondback moth (DBM), Plutella xylostella L. (Lepidoptera:Plutellidae) obtained from a laboratory colony. Leaf-dip bioassays were used to assess larval mortality at different insecticides rates (ranging from 0.01 mg AI/L to 100 mg A1/L) and exposure times (24, 48 and 72 h after treatment). Toxicity of the insecticides generally increased with rate and exposure time. At 72 h after treatment, median lethal concentrations (LCs0s) of methoxyfenozide, spinosad, novaluron, indoxacarb and Bacillus thuringiensis (Bt) against the male third instar larvae of P, xylostella were 0.0524, 0.1117, 0.9149, 1.1939 and 4.4983 mg AI/L, respectively, and were 0.1008, 0.2583, 1.0649, 0.2850 and 5.3053 mg AI/L against female third instar larvae, respectively. At 0.1% of the approximate recommended field rates, methoxyfenozide (60%-75%) and spinosad (53%-57%) were the most toxic, while Bt (30%-45% mortality) was the least toxic to male and female P. xylostella larvae. Spinosad was the fastest acting and the only insecticide that caused significant larval mortality (17%) at 24 h after exposure. Significant sexual differences were recorded in the susceptibility of P. xylostella larvae to two of the insecticides: spinosad and indoxacarb. Male larvae were two-fold more susceptible to spinosad but 10-fold more tolerant to indoxacarb than female larvae.
基金sponsored by the Special Fund for AgroScientific Research in the Public Interest of China (201103021)the President Foundation of Guangdong Academy of Agricultural Sciences, China (201206)the Guangdong Natural Science Foundation, China (S2013010012529)
文摘The insecticide chlorantraniliprole exhibits good efifcacy and plays an important role in controlling the diamondback moth, Plutella xylostella Linnaeus. However, resistance to chlorantraniliprole has been observed recently in some ifeld populations. At present study, diamondback moths with resistance to chlorantraniliprole (resistant ratio (RR) was 82.18) for biochemical assays were selected. The assays were performed to determine potential resistance mechanisms. The results showed that the selected resistant moths (GDLZ-R) and susceptible moth could be synergized by known metabolic inhibitors such as piperonyl butoxide (PBO), triphenyl phosphate (TPP) and diethyl-maleate (DEM) at different levels (1.68-5.50-fold and 2.20-2.89-fold, respectively), and DEM showed the maximum synergism in both strains. In enzymes assays, a high level of glutathione-S-transferase (GST) was observed in the resistant moth, in contrast, moths that are susceptible to the insecticide had only 1/3 the GST activity of the resistant moths. The analysis of short-term exposure of chlorantraniliprole on biochemical response in the resistant strain also showed that GST activity was signiifcantly elevated after exposure to a sub-lethal concentration of chlorantraniliprole (about 1/3 LC50, 12 mg L-1) 12 and 24 h, respectively. The results show that there is a strong correlation between the enzyme activity and resistance, and GST is likely the main detoxiifcation mechanism responsible for resistance to chlorantraniliprole in P. xylostella L., cytochrome P450 monooxygenase (P450) and carboxy-lesterase (CarE) are involved in to some extent.
基金supported by Laboratory of Lingnan Modern Agriculture Project(NT2021003).
文摘The diamondback moth,Plutella xylostella(L.),is one of the most destructive migratory pest species of cruciferous vegetables worldwide and has developed resistance to most of the insecticides used for its control.The migration regularity,migratory behavior,and relationship between flight and reproduction of P.xylostella have been widely reported.However,the effect of migration on insecticide resistance in this pest is still unclear.In this study,the effect of migration on P.xylostella resistance to seven insecticides was investigated using populations across the Bohai Sea that were collected in the early and late seasons during 2017–2019.The bioassay results showed that the early season populations of P.xylostella from south China possessed much higher resistance to insecticides because of intensive insecticide application;alternatively,the late season populations migrated from northeast China,where the insecticides were only used occasionally,showed much lower insecticide resistance.The genome re-sequencing results revealed that,among the eight mutations involved in insecticide resistance,the frequencies of two acetylcholinesterase mutations(A298S and G324A)responsible for organophosphorus insecticide resistance were significantly decreased in the late season populations.The results indicated that P.xylostella migration between tropical and temperate regions significantly delayed the development of insecticide resistance.These findings illustrated the effect of regional migration on the evolution of insecticide resistance in P.xylostella,and provided foundational information for further research on the relationship between migration and insecticide resistance development in other insects.
基金funded by following research programs:theNational Natural Science Foundation of China(31501664)the President Foundation of Guangdong Academy of Agricultural Sciences,China(201514)+1 种基金the Science and Technology Planning Project of Guangdong Province, China(2013B050800019 and 2014B070706017)the Agro-Scientific Research Special Fund in the Public Interest, China(201103021)
文摘Carboxylesterase is a multifunctional superfamily and can be found in almost all living organisms. As the metabolic enzymes, carboxylesterases are involved in insecticides resistance in insects for long time. In our previous studies, the enhanced c arboxylesterase activities were found in the chlorantraniliprole resistance strain of diamondback moth(DBM). However, t he related enzyme gene of chlorantraniliprole resistance has not been clear in this strain. Here, a full-length c DNA of carboxylesterase pxCCE016 b was cloned and exogenously expressed in Escherichia coli at the first time, which contained a 1 693 bp open reading frame(ORF) and encoded a protein of 542 amino acids. Sequence analysis showed that this c DNA has a predicted mass of 61.56 k Da and a theoretical isoelectric point value of 5.78. The sequence of deduced amino acid possessed the classical structural features: a type-B carboxylesterase signature 2(EDCLYLNVYTK), a type-B carboxylesterase serine active site(FGGDPENITIFGESAG) and the catalytic triad(S er186, Glu316, and His444). The real-time quantitative PCR(q PCR) analysis showed that t he expression level of the p x CCE016 b was significantly higher in the chlorantraniliprole resistant strain than in the susceptible strain. Furthermore, pxCCE016 b was highly expressed in the midgut and epidermis of the DBM larvae. When the 3rd-instar larvae of resistant DBM were exposed to abamectin, alpha-cypermethrin, chlorantraniliprole, spinosad, c hlorfenapyr and indoxacarb insecticides, the up-regulated expression of pxCCE016 b was observed only in the group treated by chlorantraniliprole. In addition, recombinant vector p ET-pxCCE016 b was constructed with the most coding region(1 293 bp) and large number of soluble recombinant proteins(less than 48 k Da) were expressed successfully with prokaryotic cell. Western blot analysis showed that it was coded by pxCCE016 b. All the above findings provide important information for further f unctional study, although we are uncertainty whether the pxCCE016 b gene is actually i nvolved in chlorantraniliprole resistance.
文摘The diamondback moth (DBM), Plutella xylostella (L.), is a major pest of cruciferous crops. Tebufenozide, a novel nonsteroidal ecdysone agonist, exhibits good efficacy and has played an increasingly important role in the control of Lepidopteran pests in China. For its resistance management, the genetic basis of tebufenozide resistance was studied using a laboratory selected resistant strain of DBM (resistant ratio, RR = 268). A series of crosses with laboratory susceptible and resistant strains revealed that tebufenozide resistance in this pest was partially biased toward female heredity, with a large difference in RR for F1 (RR = 29) and rF1 progeny (RR = 147). The dominance calculated for these 2 cross progeny was -0.788 and 0.09, respectively. Further analysis showed that the susceptible male and female larvae were similar in theft sensitivity to tebufenozide, but the resistant female larvae showed significantly higher resistance than the resistant male larvae. The heredity of tebufenozide resistance in DBM might be linked with the W sex chromosome, which suggested that DBM has the ability to develop high levels of resistance to tebufenozide. This is the first report of sex-linked inheritance oftebufenozide resistance in P xylostella (L.).
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.
文摘The seasonal changes of insecticide resistance and stability in hymenopteran Cotesia plutellae, collected from Jianxin, Fuzhou-City, and Shangjie, Minhou-County, Fujian, China, were assessed by using a dry residual film method. The resistance to two insecticides in the field populations of C. plutellae was not stable under insecticide-free conditions in the insectarium. Compared with susceptible F11 progeny of C. plutellae in the insectarium, the resistance ratios (RR) in F0 parents were 18.4 for fenvalerate and 11.4 for cypermethrin based on LC50 at 9 hours, and 32.8 for fenvalerate and 28.5 for cypermethrin based on LC50 at 24 hours when the parasitoids were left in contact with the insecticides for 1 hour and mortalities were recorded at 9 and 24 hours, respectively. However, the RR in a field population of C. plutellae were 9.2 for fenvalerate and 12.7 for cypermethrin, if the parasitoids were left in contact with the insecticides for 24 hours. The resistances to the two pyrethroids in other field populations collected from Jianxin and Shangjie from November 2000 and July 2004 were also determined. Significant seasonal variations of resistance to the two insecticides in the field populations of C. plutellae were found. The RR were 3.0-18.4 for fenvalerate and 4.8-20.6 for cypermethrin in Jianxin populations from November 2000 to April 2002 based on LC50 at 9 h, and 2.3-13.6 for fenvalerate and 3.6-16.0 for cypermethrin in Shangjie populations from May 2002 to July 2004 based on LC50 at 24 hours. The resistance levels were high in spring and autumn and decreased sharply in summer. In addition, significant recovery from the knocked-down caused by the insecticides was found in the F0 and field populations of C. plutellae which were resistant to fenvalerate and cypermethrin if the parasitoids were left in contact with the pyrethroids for 1 hour. However, no recovery was found in susceptible F11 progeny.
文摘Diamondback moth, Plutella xylostella (L.) is one of the most serious insect pests for its remarkable ability to develop resistance to virtually every insecticide that has been used against it. In the present study, amplified fragment length poly- morphism (AFLP) is used to study the genetic differentiation as well as the effects of abamectin-selection on population genetic differentiation for P. xylostella. A dendrogram was constructed from the matrix of genetic distances using the STATISTICA software (Version 4.5) and unweighted pair-group method with arithmetic averages (UPGMA). The data demonstrated that compared to the susceptible strain (ABM-s), the heterozy- gosity in the abamectin-resistant strain (ABM-r) decreased with the increased selection pressure and resistant level. When the resistance ratio was below 4.3, there was no sig- nificant differentiation at the genome DNA level. When the resistance ratio reached 5.8, a fairly significant differentiation began to appear, and when the resistance ratio reached and exceeded 8.1, there appeared a significant genetic differentiation. The results suggest that abamectin selection is associated with increased genetic polymorphism in P. xylostella.
基金Acknowledgments This work was supported by the National Nature Science Foundation of China (NSFC, No. 30400296), Natural Science Foundation of Hebei Province, China (C2006000443, C2008000277, C2010000706)
文摘Xenorhabdus nematophila, a Gram-negative proteobacterium belonging to the family Enterobacteriaceae and associated symbiotically with soil entomopathogenic nematodes, Steinernema carpocapsae, is pathogenic to a wide range of insects. A protein complex with insecticidal activity was isolated from the cells ofX. nematophila HB310 strain using methods of salting out and native polyacrylamide gel electrophoresis (PAGE). Seven polypeptides ranging 50~250 kDa were well separated from the protein complex (named Xnpt) by sodium dodecyl sulfate (SDS)-PAGE, five of which are identified as XptA2, xptC 1, XptB 1, GroEL and hypothetical protein by matrix-assisted laser desorption- time-of-flight mass spectrometry (MALDI-TOFMS). Xnpt showed high oral virulence to larvae of diamondback moth (DBM), Plutella xylostella L. (Lepidoptera, Plutellidae) as its median lethal concentration (LC50) against second and third instar larvae were 331.45 ng/mL and 553.59 ng/mL at 72 h, respectively. The histological analysis of Xnptfed DBM larvae showed extensive histopathological effects on the midgut. Biochemical analysis indicated that Xnpt markedly inhibited the activities of three important enzymes in the midgut. Overall, our data showed that the protein complex isolated from X. nematophila HB310 induced the antifeedant and death of insects by destroying midgut tissues and inhibiting midgut proteases activities.
基金The authors would like to thank Prof. Anthony M. Shelton and Ms. Hilda L. Collins in Cornell University for review- ing the manuscript. This work was funded by grants from the National Basic Research and Development Program, China (2009CB 119004), Special Fund for Agro-scientific Research in the Public Interest (201103021) and the Nat- ural Science Foundation of China (31071709).
文摘Field trials were conducted in China in 2008 and 2009 to evaluate the efficacy of mating disruption (MD) on diamondback moth, Plutella xylostella, in cabbage, Brassica oleracea var. capitata. Effectiveness was positively correlated with the MD dispenser density in the field. A density of 167 MD dispensers per ha produced an average population decrease of about 50% compared to the conventional-practice field. Significant fewer males were captured in pheromone-treated and conventional-practice fields than in the blank control field, but the difference was not significant between the pheromone-treated and conventional-practice fields. In addition, fewer eggs and larvae were observed in pheromone-treated fields. Our results suggest mating disruption coupled with minimal insecticidal supplements is a promising solution for resistance management and control of diamondback moth infestation.
文摘The present study explored the Spilanthes acmella Murr. for insecticidal principle, a plant of high value. The seed extract showed insecticidal activity against Plutella xylostella. Further, bioassay guided isolation of bioactive compounds resulted in insecticidal active molecule, which was identified with the help of ESI-MS and NMR. Highest activity of 95 - 100 percent was observed at low dose of 2 g/l with spilanthol, while 60 - 70 and 80 - 90 percent mortality at 5 g/l in crude seed extracts prepared in methanol and hexane after 48 hours exposure, respectively. LC50 of 1.49, 5.14, 5.04, 11.75 g/l was observed with spilanthol, crude seed extract of methanol, hexane, deltamethrin, respectively. The findings indicate the potential of S. acmella with potent insecticidal toxicity for the management of P. xylostella and other insects of agricultural importance.