The brown planthopper （BPH）, Nilaparvata lugens （Stal）, is one of the major pests of rice throughout Asia. Extensive use of insecticides for suppressing N. lugens has resulted in the development of insecticide res...The brown planthopper （BPH）, Nilaparvata lugens （Stal）, is one of the major pests of rice throughout Asia. Extensive use of insecticides for suppressing N. lugens has resulted in the development of insecticide resistance leading to frequent control failures in the field. The aim of the present study was to evaluate resistance in the field populations of N. lugens from major rice growing states of South India to various insecticides. We also determined the activity of detoxifying enzymes （esterases [ESTs], glutathione S- transferases [GSTs], and mixed-fimction oxidases [MFOs]）. Moderate levels of resistance were detected in the field populations to acephate, thiamethoxam and buprofezin （resistance factors 1.05-20.92 fold, 4.52-14.99 fold, and 1.00-18.09 fold, respectively） as compared with susceptible strain while there were low levels of resistance to imidacloprid （resistance factor 1.23-6.70 fold） and complete sensitivity to etofenoprox （resistance factor 1.05- 1.66 fold）. EST activities in the field populations were 1.06 to 3.09 times higher than the susceptible strain while for GST and MFO the ratios varied from 1.29 to 3.41 and 1.03 to 1.76, respectively. The EST activity was found to be correlated to acephate resistance （r = 0.999, P ≥ 0.001）. The high selection pressure of organophosphate, neonicotinoid, and insect growth regulator （IGR） in the field is likely to be contributing for resistance in BPH to multiple insecticides, leading to control failures. The results obtained will be beneficial to IPM recommendations for the use of effective insecticides against BPH.展开更多
Background The pink bollworm,Pectinophora gossypiella(Saunders),is a devastating global pest of cotton that has caused substantial economic damage to Bt Bollgard-Ⅱ~?cotton plants in recent years due to the evolution ...Background The pink bollworm,Pectinophora gossypiella(Saunders),is a devastating global pest of cotton that has caused substantial economic damage to Bt Bollgard-Ⅱ~?cotton plants in recent years due to the evolution of Bt resistance.The associated fitness cost is assumed to be one of the factors delaying the development of resistance against Bt transgenic crops.Hence,the present study was undertaken to assess the biological performance of pink bollworms by comparing the life history and demographic parameters of a resistant(Field-R)and susceptible(Lab-S)population.Results Prolonged larval duration(23.40 days in Field-R vs 18.80 days in Lab-S population),total life cycle(male=50.00 vs 42.80 days;female=53.60 vs 46.20 days),reduced fecundity(100.60 vs 154.20 eggs/female)and fertility(88.00 vs 138.00 fertile eggs/female)was observed.The demographic parameters indicated a significant reduction in the net reproductive rate(184.27 vs 276.72),innate capacity for increase in number(0.11 vs 0.15),finite rate of increase in number(1.12 vs 1.16 female progenies produced/female/day),weekly multiplication rate(2.16 vs 2.86),potential fecundity(545.06 vs 634.11 eggs),number of hypothetical F_2 females(33955.65 vs 76572.41),but longer mean length of generation(47.54 vs 37.74 days)and population doubling time(6.30 vs 4.62 days)in Field-R compared with Lab-S population.A stage-specific life to ble demonstrated the differences in survival rates between susceptible and resistant populations at various life stages,with the resistant population having higher generation mortality(0.22vs 0.19).Conclusions The study confirms the involvement of fitness costs associated with Bt resistance in P.gossypiella.Despite reduced reproductive fitness,the resistant population tried prolonging the larval stage as a compensatory mechanism to repair the damaged host tissues due to Bt intoxication and for accumulation of enough nutrient reserves for normal pupation and adult emergence.Presence of a high proportion of double Bt-resistant larvae in the field coupled with continued noncompliance with refug planting certainly favours the flaring up of this monophagous pest despite the observed fitness costs.The resistance cannot be effectively reversed unless suitable alternative management strategies are deployed.展开更多
文摘The brown planthopper （BPH）, Nilaparvata lugens （Stal）, is one of the major pests of rice throughout Asia. Extensive use of insecticides for suppressing N. lugens has resulted in the development of insecticide resistance leading to frequent control failures in the field. The aim of the present study was to evaluate resistance in the field populations of N. lugens from major rice growing states of South India to various insecticides. We also determined the activity of detoxifying enzymes （esterases [ESTs], glutathione S- transferases [GSTs], and mixed-fimction oxidases [MFOs]）. Moderate levels of resistance were detected in the field populations to acephate, thiamethoxam and buprofezin （resistance factors 1.05-20.92 fold, 4.52-14.99 fold, and 1.00-18.09 fold, respectively） as compared with susceptible strain while there were low levels of resistance to imidacloprid （resistance factor 1.23-6.70 fold） and complete sensitivity to etofenoprox （resistance factor 1.05- 1.66 fold）. EST activities in the field populations were 1.06 to 3.09 times higher than the susceptible strain while for GST and MFO the ratios varied from 1.29 to 3.41 and 1.03 to 1.76, respectively. The EST activity was found to be correlated to acephate resistance （r = 0.999, P ≥ 0.001）. The high selection pressure of organophosphate, neonicotinoid, and insect growth regulator （IGR） in the field is likely to be contributing for resistance in BPH to multiple insecticides, leading to control failures. The results obtained will be beneficial to IPM recommendations for the use of effective insecticides against BPH.
基金the award of the DST-INSPIRE fellowship(IF190948)by the Department of Science and Technology,Government of India。
文摘Background The pink bollworm,Pectinophora gossypiella(Saunders),is a devastating global pest of cotton that has caused substantial economic damage to Bt Bollgard-Ⅱ~?cotton plants in recent years due to the evolution of Bt resistance.The associated fitness cost is assumed to be one of the factors delaying the development of resistance against Bt transgenic crops.Hence,the present study was undertaken to assess the biological performance of pink bollworms by comparing the life history and demographic parameters of a resistant(Field-R)and susceptible(Lab-S)population.Results Prolonged larval duration(23.40 days in Field-R vs 18.80 days in Lab-S population),total life cycle(male=50.00 vs 42.80 days;female=53.60 vs 46.20 days),reduced fecundity(100.60 vs 154.20 eggs/female)and fertility(88.00 vs 138.00 fertile eggs/female)was observed.The demographic parameters indicated a significant reduction in the net reproductive rate(184.27 vs 276.72),innate capacity for increase in number(0.11 vs 0.15),finite rate of increase in number(1.12 vs 1.16 female progenies produced/female/day),weekly multiplication rate(2.16 vs 2.86),potential fecundity(545.06 vs 634.11 eggs),number of hypothetical F_2 females(33955.65 vs 76572.41),but longer mean length of generation(47.54 vs 37.74 days)and population doubling time(6.30 vs 4.62 days)in Field-R compared with Lab-S population.A stage-specific life to ble demonstrated the differences in survival rates between susceptible and resistant populations at various life stages,with the resistant population having higher generation mortality(0.22vs 0.19).Conclusions The study confirms the involvement of fitness costs associated with Bt resistance in P.gossypiella.Despite reduced reproductive fitness,the resistant population tried prolonging the larval stage as a compensatory mechanism to repair the damaged host tissues due to Bt intoxication and for accumulation of enough nutrient reserves for normal pupation and adult emergence.Presence of a high proportion of double Bt-resistant larvae in the field coupled with continued noncompliance with refug planting certainly favours the flaring up of this monophagous pest despite the observed fitness costs.The resistance cannot be effectively reversed unless suitable alternative management strategies are deployed.
