The Dynamic Of Bemisia Tabaci And Prevention By Yellow Board In Liaoyang

This paper focused and studied on the population development dynamic of Bemisia tabaci(Gennadius) on major crops in field and greenhouse at Liaoyang region of Lianning province,meanwhile, we also discussed the best control method by using yellow board for B.tabaci trapping andkilling on major crops.The survey result of the population dynamics of B.tabaci in field showed that: the populationnumber of adult and nymphs were significantly higher in ragweed than in other crops, the maximumnymphs number shows at Aug.19th, about269.9insects per leaf; the maximum adult number shows atAug.2th, about63.8insects per leaf. the dynamic curve in ragweed is above other crops all the yeararound, means the attraction of ragweed to B.tabaci is stronger than other crops. The populationdynamics of adult and nymphs in other crops were relative stable; the population of adult in sunflowerwas quite lower than immature stage; the population dynamics of B.tabaci in piemarker was stable;there was no nymph and adult of B.tabaci found in corn.The survey result of the population dynamic of B.tabaci in greenhouse showed that: the populationnumber of B.tabaci adult and nymphs were significantly higher in eggplant than in other plants, themaximum nymphs number is at about June.20th, about4.1insects per leaf; the maximum adult numberis at about June.3th, about15.2insects per leaf. Meanwhile, the population fluctuation of B.tabaci inchrysanthemum was the largest during all the crops except eggplant. In the other hand, the populationfluctuation of adult in other crops was relative stable; the population number of adult in cucumber waslower than immature stage and the fluctuation was quite stable; there was no nymph and adult found inrose.The experiment of trapping and killing B.tabaci by yellow board in cotton field and hrysanthemumin greenhouses showed that: the different size of yellow board has different control effects; the trappingamount was significant increased while the size enlarging, the board at30cm×30cm has the highesttrapping amount, and the number is2143.6insects per board at Sep.8th. The board at30cm×18cm hasthe highest trapping density; the number is4.28insects per square centimeter at Sep.8th. Furthermore,during the experiments with different hanging heights and densities, there were significantly differenceson B.tabaci amongst. However, there was no significantly difference between treatments in differentsuspending directions of yellow board, so farmers can choose suitable style according to practice.