Studies On Filtering Several Plants With Repellency Against Bemisia Tabaci And Control Effect Of Celery On This Insect

Bemisia tabaci(Gennadius)is one of the frequent pests on vegetables.It seriously affects the yield and quality of vegetables and causes serious economic losses.For a long time,the production of chemical control B.tabaci mainly,but with the long-term use of chemical pesticides,increased the resistance rate of B.tabaci increased,increasing the risk of pesticide residues in vegetable products.Therefore,the establishment of the green control system of B.tabaci has become a urgent requirement of pollution-free vegetable production.In this study,several low-preference plants of B.tabaci were used as experimental materials,and the best plant repellent was selected by indoor and field experiments.The volatiles were analyzed by GC/MS,and the volatile compounds were found to be biologically active against B.tabaci.The results provide a theoretical basis for the control of B.tabaci by crop intercropping,and provide a scientific basis for the development of B.tabaci repellent.The main results are as follows:1.The olfactory and visual responses of six vegetables that B.tabaci occurring less were studied.The results showed that the selectivity of six plant species to B.tabaci was small,among which B.tabaci had the lowest selectivity to celery,only 13%,followed by leek(25.5%),and the selectivity of other vegetables:chrysanthemum(44.8%)>parsley(40.2%)>onions(39.6%)>garlic(37.0%).The relative olfactory responses of six vegetable species to B.tabaci were determined by two-choice method.The results showed that B.tabaci had the lowest selectivity to celery,which was significantly lower than the other five plants.The selective selectivity of B.abaci to 6 vegetables in the room showed that the selectivity of B.tabaci to 6 kinds of vegetables was obvious difference.The selectivity of B.tabaci to celery and leek was the smallestThe selectivity of B.tabaci to six vegetables was also different,and the selectivity of B.tabaci to celery and leek was the smallest.On the basis of indoor selection,three kinds of plants,such as celery,leek and onion,were selected for 1:1 intercropping(1 row pepper intercropping 1 row repellent plant),The repellent effect of celery on B.tabaci on field pepper was the best,the repellent rate was 90.6%,followed by leek(86.5%).Therefore,celery was selected as the candidate material for the control of B.tabaci in field.2.The results showed that with the increase of celery intercropping density,population density of B.tabaci decreased continuously,such as cucumber,tomato,pepper and so on.The reduction rate of B.tabaci on pepper was 62.45%,73.33%and 86.67%respectively in the intercropping of 8:1,5:1,3:1.The repellent effect of different celery on different host plants was different,for example,the ratio of 5:1 intercropping celery in pepper and tomato was 73.33%and 75.49%,while the same intercropping density,the repellent effect on B.tabaci on cucumber is not obvious.The repellent effect of celery was different with the 5:1 intercropping,and the rate of insect population decrease was 71.69%,but there was no obvious effect on the tomato.3.GC/MS analysis of volatile components in stems and leaves of celery at different growth stages showed that the volatiles of celery stems and leaves were different at different growth stages.Twenty substances were separated from the volatiles of stems and leaves of bolting celery,seedling celery stems and leaves only 15 kinds of substances,less than the bolting period,and the latter are all included in the former.However,the relative content of Limonene and a-pinene in stems and leaves of seedling stage were higher than that in bolting stage.The seedling celery can be selected to control celery as the research object.The relative contents of Limonene,a-pinene and ?-caryophyllene were determined and the bioactivities of these volatile compounds were analyzed.Olfactory experiments showed that the higher concentrations of Limonene and a-pinene had better repellent effects on B.tabaci,while ?-caryophyllene had no repellent effect on B.tabaci.In field experiments,Limonene had the best repellent effect on B.tabaci,with the highest reduction rate of 77.25%and that of a-pinene was 62.45%,and ?-caryophyllene had no repellent effect on B.tabaci.Limonene was also superior to a-pinene in the distance of action,the 7th strain farthest from the hanging point,30.51%of Limonene treatment on pepper for 12h.In addition,the repellency of B.tabacito was increased with the addition of the reagent to the trapping plants.The reduction rate of B.tabaci was 40.00%higher than that of the untreated plants 9.5%.4.In the stage of B.tabaci transmission and diffusion,the comprehensive control experiment of B.tabaci on cucumber was carried out by using yellow board,sexual attraction and planting celery in the vegetable experimental base.The results showed that during thestage of migration,the effects of different treatments on controlling the migration and migration of B.tabaci were different.Among the treatments,the treatments were treated with different treatments,such as yellow plate + sex attractant and yellow board + celery were the best,and the rate of insect infestation decreased by 65.13%and 79.16%respectively after 20 days of treatment;Compared with the yellow plate alone,yellow plate + celery treatment had a better effect on controlling the spread of B.tabaci to cucumis sativus in the shedding stage of B.Tabaci,such as Sept.17 only yellow plate treatment within the shed reduction rate of insect-74.48%,while the yellow plate + celery greenhouses for 40.43%.