The Research Of Biological Characteristics Of Tetra Lobulifera

By experimental observation of outdoor and indoor, with a serials of raise, the biological characteristics of the Tetra lobulifera (Keifer) of a preliminary was studied.The main results are as follows:1 The influence of photosynthesis of Populus infected with Tetra lobulifera (Keifer) are: with the increasing levels of harm, the photosynthetic rate reduct , stomatal conductance become lower, transpiration rate decreas, intercellular carbon dioxide concentration increase.2 With the increasing level of Tetra lobulifera (Keifer), the growth potential of the host is weakened, under the major site in the same conditions, comparisons has been made under different levels of populi,tree height decreased gradually, field diameter reduced . The more suffered populi, the more developed its collateral, and slow-growing trunk.3 Tetra lobulifera (Keifer) over-winter as female, the over-winter site is the bark of the tree trunk and cracks It begins to hibernate at March the following year. A period of hibernation begin at April.4 Effective temperature of eggs is 109.4±6.9℃/day-degrees , the initial temperature is 7.86±0.69℃; Effective temperature of nymph is109.2±11℃/ day-degrees, whole generation of mites is 218.1±17.39℃/ day-degrees, the initial temperature is 9.06±0.87℃.5 Tetra lobulifera (Keifer) has 11-14 generations every year in Nanjing.6 Both the density of adult and nymph affect fecundity per female. Fecundity per female decrease when the density of nymph increase, and with the density of adult increase, the fecundity decrease.7 With the density of mites increase, diapause rate of Tetra lobulifera (Keifer) increase accordingly. Short-day promote its diapause, long-day restrict its diapause. When light of the day over 13h/d, female adult mites without diapause turn up. Under the same day light, low temperature promote diapause Tetra lobulifera (Keifer), high temperature restrict its diapause.8 Mortality of Tetra lobulifera (Keifer) can be greatly improved by rainfall, but little effect on egg hatching. The lasting rainfall can promote the majority death of mites. Water has the impact of various mites.