| The Dianmondback month(DBM) is a worldwide pest, and makes a serious damage on cruciferous crops.In this paper, the experiment population life table of DBM was seted up on four host plants including pak-choi,leaf mustard,flowering Chinese cabbage and cabbage.A quantitative analysis of isothiocyanate of four host plants was conducted.The trend of the DBM to isothiocyanate was tested. In this study, resistance recession of the DBM fed on different host plants, and the activity of larvae detoxification enzymes were disscussed. Finally, Mating behavior and ability of the DBM were studied under the laboratory conditions. In order to the comprehensive management of DBM and revealed its rampant mechanisms, provide a theoretical basis. The major results are as follows:1. The experiment population life table of DBM on different host plants was seted up in this paper.The results showed that:the indices of laboratory population trend of the DBM on pak- choi, leaf mustard, chinese cabbage and cabbage were 52.2,40.9,53.7 and 59.8,respectively. The individuals that fed on cabbage presented a larval developmental duration of 6.9 d, which was shorter than those on leaf mustard (7.2d), pak- choi (8.2d), and flowering Chinese cabbage (8.4 d).There were no significant differences in egg developmental duration and pupa developmental duration among the 4 treatments. A female fed on cabbage, pak- cho, flowering Chinese cabbage and leaf mustard totally laid 285,274,271,244 eggs, respectively. The number of oviposition per day were 32.6,26.8,24.3 and 20.7 which fed on cabbage,leaf mustard,flowering Chinese cabbage and pak- choi, respectively. Moreover, the peak of oviposition appeared on the second day when femial fed on cabbage,while reared with other hosts the peak occured on the third day.2. The quantitative analysises of isothiocyanate in the four host plants were conducted by high temperature distillation associated with normal temperature ether extraction.The trend of DBM to isothiocyanate have been studied.The results showed that the content of isothiocyanate of pak-choi,leaf mustard,flowering Chinese cabbage and cabbage were2.701%,1.106%,0.576%,0.309%. Both unmated male and female had stronge responses to isothiocyanate from all host species, and the attractions varied with different concentrations. The male and female of DBM had a selection of 83% and 94% to the isothiocyanate of 2.701%(leaf mustard), and the corresponding values were 67% and 62% when isothiocyanate concentration was 1.106%( pak-choi), 65%and 59% when isothiocyanate concentration was 0.576%(Chinese cabbage),51% and 48% when concentration was 0.309%( cabbage).3. The effect of different host plants to four insecticides on resistance recessior of DBM. The results indicated that the resistance recessior of DBM toDichlorvos,Alphacypermethrin were faster after being fed on pak- choi reared 4 generation, and the ratio of resistance recessior was 1.22,1.44,respectively;the resistance recessior of Bacillus thuringiensis and Avermectins and had not changed significantly , the ratio was 1.17,1.01. The resistance of DBM to alphacypermethrin changed significantly reared with different plants. The susceptibility of DBM fed on cabbage was highest,next was pak- choi,Chinese cabbage,leaf mustard ,the ratio of LC50 of F1ratio to LC50 of F5 were 2.66,2.03,1.96,1.29 respectively. Moreover, the mechanisms of resistance recession were primarily studied on four different plants,the results indicated the activity CarE and GSTS had decreased.4. The behavior of mating behavior and ability for the DBM were investigated under laboratory conditions (25oC±1oC, L12: D12). The adults could mate at the day after them emergenced, and male copulated more than one time in their lifetime. There were 3 mating peaks in one day occurred during 10:30- 12:30,00:30- 02:30 and 6:30- 8:30. The mating ratio at the first day of emergence was low, then increased at 2-4 days after emergence (71.4%- 76%), and finally decreased at 5-7 days after emergence.The mating duration ranged from 50 mins to 125 mins, which was positively correlated with the instar of the DBM. The mating ability of male ranged from 1 time to 13 times, which was mainly influenced by sex ratio. The mating times was 2.87 when sex ratio was 1:1, while the times increased to 5.2- 8.6 when sex ratio was 2♀:1♂- 5♀:1♂. The mating ability and times of female were also affected by sex ratio. The ratio of unmated female ranged from 6.6% to 26.7% when sex ratio was 1♀:1♂- 5♀:1♂.
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