Efficiency of imidacloprid and pymetrozine on population growth parameters of cabbage aphid, Brevicoryne brassicae L. （Homoptera： Aphididae） was determined using demographic toxicology by leaf dip method. At first,...Efficiency of imidacloprid and pymetrozine on population growth parameters of cabbage aphid, Brevicoryne brassicae L. （Homoptera： Aphididae） was determined using demographic toxicology by leaf dip method. At first, bioassay tests were performed. The LC50 value and confidence limit for imidacloprid and pymetrozine were 1.61 × 10^-5 mol/L （0.74 × 10^-5-2.66 × 10^-5） and 2.14 × 10^-4 mol/L （1.24 × 10^-4-3.40 × 10^-4）, respectively. To evaluate the sublethal effect of two insecticides on population growth parameters of cabbage aphid, LC30 concentrations of imidacloprid and pymetrozine were used at 5 mol/L and 30 mol/L. The experiments were carried out in a incubator at 20±1℃, 60% ± 5% RH and 16：8 （L：D） photoperiod on canola seedlings, Brassica napus L. var. ＇PF＇. Net fecundity rate decreased in both insecticide-treated populations. Intrinsic rates of increase （rm） were lower in imidacloprid and pymetrozine treatments than in controls. Intrinsic birth rates also decreased in treated populations. There was a relative increase in intrinsic death rates of treated populations. The mean generation times and doubling time were also lower in populations treated with insecticides than in controls. There was a considerable reduction in the average numbers of nymphs reproduced per female as compared with the control. The average longevity of female adults in the control was significantly different from those treated with imidacloprid and pymetrozine. However, there was no significant differences in aphid life-table parameters between the two insecticide-treated populations （P 〉 0.01）.展开更多
Plants show phenotypic changes when challenged with herbivorous insects. The mechanisms underlying these changes include the activation of transcriptional responses, which are dependent on the attacking insect. Most t...Plants show phenotypic changes when challenged with herbivorous insects. The mechanisms underlying these changes include the activation of transcriptional responses, which are dependent on the attacking insect. Most transcriptomic studies on crucifer-insect interactions have focused on the model plant Arabidopsis thaliana, a species that faces low herbivore pressure in nature. Here, we study the transcriptional responses of plants from a wild black mustard （Brassica nigra） population to herbivores of different feeding guilds using an A. thaliana-based whole-genome microarray that has previously been shown to be suitable for transcriptomic analyses in Brassica. Transcriptional responses of B. nigra after infestation with either Pieris rapae caterpillars or Brevicoryne brassicae aphids are analyzed and compared. Additionally, the insect-induced expression changes of some individual genes are analyzed through quantitative real-time polymerase chain reaction. The results show that feeding by both insect species results in the accumulation of transcripts encoding proteins involved in the detoxification of reactive oxygen species, defensive proteins and glucosinolates and this is correlated with experimental evidence in the literature on such biochemical effects. Although genes encoding proteins involved in similar processes are regulated by both insects, there was little overlap in the induction or repression of individual genes. Furthermore, P. rapae and B. brassicae seem to affect different phytohormone signaling pathways. In conclusion, our results indicate that B. nigra activates several defense-related genes in response to P rapae or B. brassicae feeding, but that the response is dependent on the attacking insect species.展开更多
文摘Efficiency of imidacloprid and pymetrozine on population growth parameters of cabbage aphid, Brevicoryne brassicae L. （Homoptera： Aphididae） was determined using demographic toxicology by leaf dip method. At first, bioassay tests were performed. The LC50 value and confidence limit for imidacloprid and pymetrozine were 1.61 × 10^-5 mol/L （0.74 × 10^-5-2.66 × 10^-5） and 2.14 × 10^-4 mol/L （1.24 × 10^-4-3.40 × 10^-4）, respectively. To evaluate the sublethal effect of two insecticides on population growth parameters of cabbage aphid, LC30 concentrations of imidacloprid and pymetrozine were used at 5 mol/L and 30 mol/L. The experiments were carried out in a incubator at 20±1℃, 60% ± 5% RH and 16：8 （L：D） photoperiod on canola seedlings, Brassica napus L. var. ＇PF＇. Net fecundity rate decreased in both insecticide-treated populations. Intrinsic rates of increase （rm） were lower in imidacloprid and pymetrozine treatments than in controls. Intrinsic birth rates also decreased in treated populations. There was a relative increase in intrinsic death rates of treated populations. The mean generation times and doubling time were also lower in populations treated with insecticides than in controls. There was a considerable reduction in the average numbers of nymphs reproduced per female as compared with the control. The average longevity of female adults in the control was significantly different from those treated with imidacloprid and pymetrozine. However, there was no significant differences in aphid life-table parameters between the two insecticide-treated populations （P 〉 0.01）.
文摘Plants show phenotypic changes when challenged with herbivorous insects. The mechanisms underlying these changes include the activation of transcriptional responses, which are dependent on the attacking insect. Most transcriptomic studies on crucifer-insect interactions have focused on the model plant Arabidopsis thaliana, a species that faces low herbivore pressure in nature. Here, we study the transcriptional responses of plants from a wild black mustard （Brassica nigra） population to herbivores of different feeding guilds using an A. thaliana-based whole-genome microarray that has previously been shown to be suitable for transcriptomic analyses in Brassica. Transcriptional responses of B. nigra after infestation with either Pieris rapae caterpillars or Brevicoryne brassicae aphids are analyzed and compared. Additionally, the insect-induced expression changes of some individual genes are analyzed through quantitative real-time polymerase chain reaction. The results show that feeding by both insect species results in the accumulation of transcripts encoding proteins involved in the detoxification of reactive oxygen species, defensive proteins and glucosinolates and this is correlated with experimental evidence in the literature on such biochemical effects. Although genes encoding proteins involved in similar processes are regulated by both insects, there was little overlap in the induction or repression of individual genes. Furthermore, P. rapae and B. brassicae seem to affect different phytohormone signaling pathways. In conclusion, our results indicate that B. nigra activates several defense-related genes in response to P rapae or B. brassicae feeding, but that the response is dependent on the attacking insect species.
