The Research Of Occurrence And Population Ecology Of Bemisia Tabaci (Gennadius) In Cotton In Turpan

Through the investigation of host species, overwinterring, the occurrence and migration laws of Bemisia tabaci in Shanshan Lukeqin and Turpan Yar from 2007 to 2008,showed that:1.The host and damageThe investigation of host plant showed that all of the host plants can be classified into four grades,according to the damage degree caused by B.tabaci.There were 69 species of host plants of B.tabaci belonging to 27 families,among which Cucurbitaceae,Solanaceae, Cruciferae, Malvaceae,Compositae and Leguminosae are the major families.B.tabaci is more serious.2. The overwinterring,occurrence and migration lawsThe investigation of overwintering indoors and outdoors showed that Bemisia tabaci can only overwinter in greenhouse, should not overwinter in soil or outdoors in Turpan area,cause the temperature is too low in winter.The investigation of occurrence and migration laws showed that in mid and late April of the next year,the average temperature stable at 12℃and without frost over night,a small amount of Bemisia tabaci move to nearby weeds,melons and vegetables through the vents of greenhouse.In late May to early June,with the temperature gradually increases,occurrence in daejeon melon and cotton nearby the greenhouse and reproduction of Bemisia tabaci gradually go up after greenhouse opening.Cause the local plant way applies to melon and cotton intercropping,so after the melon riped in mid and late July,the amount of Bemisia tabaci rapid increase in cotton field,include some field far the from greenhouse,the amount of Bemisia tabaci will get peek until mid and late August,and then last for a month.After mid and late September Bemisia tabaci start to move back to greenhouse.The harm of Bemisia tabaci in open field lasts until late autumn in early November,then continue harm on host plant in greenhouse.In the next spring they will move out and harm open field again.3. The distribution in cotton fieldThe research of distribution of Bemisia tabaci in cotton field showed that judging from the vertical distribution,the amount of eggs,nymphs or adults were significantly larger than the number of central and lower part,the amount of eggs on upper leaves are more than the lower leaves,and nearly 8 times to lower leaves;the amount adults on upper leaves are nearly 5 times to lower leaves.The number of nymphs on upper,middle and lower leaves are small and have an insignificant difference.The spatial distribution of each states are aggregating distribution pattern.4. The toxicity research and field trial on Bemisia tabaciThe toxicity research of six kinds of pesticide showed that the toxicity LC50 (mg/L) of 6 pesticides to adults of B.tabaci was:admir 0.000184,fipronil 0.000220,actara 0.000258,acetamiprid 000284,imidacloprid 0.000408,pyrethrins 0.000719.These six insecticide all had high effects on killing the adults of B.tabaci, admire shows the highest toxicity.The toxicity LC50(mg/L) of 6 pesticides to 3～4 instar nymphs of B.tabaci were actara 000190,admire 0.000217,acetamiprid 0.000330,fipronil 0.000350,imidacloprid 0.000418, pyrethrin 0.000746.Actara shows the best toxicity.In totally,admire shows the highest toxicity no matter in adults or instar nymphs.The result of field trial showed the controlling effects of admire,imidacloprid,fipronil is the best and over 80% in 1d,the endurance of pyrethrin is the longest.5. The aversion from different plants to Bemisia tabaci Bemisia tabaci have selective differences on different plants.For the purpose of choosing the plants which have significant aversion to Bemisia tabaci,utilize peanuts and a series of plants intercropping with cotton.The result showed that:at the aversion from plants to adults,all the plants show extremely significant except bean the aversion order of plants to adults is celery > scallions > fennel > coriander > peanut > bean;and the aversion order of plants to nymphs and pupae is celery > scallions > leek > coriander > bean > fennel.