Studies On The Biology,ecology And Artificial Rearing Of Sweetpotato Whitefly(Bemisia Tabaci Gennadius)

In base of studing on the biology and ecology of sweetpotato whitefly in greenhouse, a series of artificial rearing techique of sweetpotato whitefly were discussed4n order to provide a theoretical basis for the artificial rearing and application of Delphtzvtus catalinae,a predator of sweetpotato whitefly. (l)Morphology Sweetpotato whitefly is a kind of minute corpus and beteronietabola insect.It has four stages with egg,larva,pupe and adultThe larva develops four instartThe 4th-instar larva pupates in coelom, forming the special feature of pupariuzg. (2) Biology Sweetpotato whitefly has a wide host range. It banns the host plant by sucking, ovipositing, excreting honeydew and spreading virus. Through the laboratory rearing and surveying, it is found that sweetpotato whitefly has ten generations per year in greenhouse, with generations overlapping. The peak of population density is from July to December. Adult likes light and humidity,with an intense activity in the fine and hot day, and with the weak flying ability . The r. coition mainly occurs in daytime, It likes to live and oviposite on the tender leaf. The peak of egg laying is at noon. The larva exuviates three times. Except the lst-instar larva, the others have the fixed characteristic. The peak of egg hatching and pupa emergence is at noon. The ratio of female to male is 1. 628 :1. The average longevity of the adults is 14.25 days, and the female longevity is 6.9 days longer than the male. The adults mainly goes on amphigony,also parthenogenesis.Sweetpotato whitefly has the perpendicular distribution characteristic on the host plant. The population density of the back leaf is higher than the front leaf. (3)Eoology The influence of humidity showed that the adult prefers to live in humidity(8O% RH).Under the 60% RH, the survial rate, adult oviposition and longevity, the index of population growth of sweepotate whitefly is maximum. The influence of photoperiocl showed that the photoperiod is longer(9條8 hours), the development, survial rate, adult oviposition and longevity, the index of population growth of sweetpotato whitefly is higher. The influence of temperature showed that the adult oviposition and longevity is maximum at 280(2. High temperature harms the adult longevity greatly, but the influence to the adult oviposition is low. Low temperature has the opposite effect. The durable low temperature harms the adult oviposition and longevity, and the hatching rate of egg kreatly. After the choice of the six sweetpotato varieties, it is found that the three varieties (YOU 1, 1255, 98588) are good for rearing sweetpotato whitefly. In the same time, it is also found that the development survial rate, adult oviposition and longervity, the index of population growth of sweetpotato whitefly is higher by rearing with the tender leaf than the old leaf. (4)Througb planting sweetpotato outdoor, mass rearing sweetpotato whitefly in greenhouse is to provide enough hunting food for the predator Delpbastus aatalinae.