| Diorhbda tarsalis Weise is one of the most pests to leave of Glycyrrhiza uralensis Fisch.It had caused huge loss.In 2003 and 2004,the paper had studied systematicly the morphic character,habitus,life history,threshold temperature,effective accumulative temperature and special distribution pattern by room and field experiments.In range of 15-36℃ ,it had been investigated the growth,survival,propaga-tion and so forth.Meantime, the life table of experimental population was established in laboratory at different temperatures and the effective synthetic control measure was drawn up preliminarily.The results are as follows:(1) Biological characters:This insect occur 2 or 3 generations in one year.The adult of the last generation start to live through winter below centimetre 2-3 in earth. Next year,in the second or last ten days of April, the adult appear again and begin to eat,mate and lay eggs. Most eggs were laid in the back of leave or in the soil.The larve has three developmental stagesAdult and larva all eat leave.They noly eat leave of Glycyrrhiza uralensis Fisch.Adult has the character of feign death. It can fly in short distance.Furthermore,adult can mate and lay many times all the life.(2) Effective accumulative temperature:In the range of 15~36℃, the growth speed of Diorhbda tarsalis Weise goes up with the rising of temperature .The relationship of growth speed and temperature accords to Logistic model. And we got the threshold temperature and the effective accumulative temperature of each developmental states respectively.(3 ) Spatial distribution.By estimated with the suitable degree of spatial distribution and x~2 test,spati-al distribution pattern of adult conformed to either the pattern of aggregation or the negative binomial distribution,spatial distribution pattern of larve only conformed to the negative binomial distribution It was also tested that the distribution pattern of larve and adult were all aggregative by aggregation indexes including I-value, M*/M -value,Ca-value,Diffusive coefficient,K-vaiue.It was further conformed by m -m regression analysis law and Toylar power rule.Meantime,the models of theoretical sampling of adult and larve had been set up,too.(4) Effect of temperature to survive:The survival rate of each developmental stage form 23℃ to 30℃ is higher and the highest is at 25℃. When temperature is lower than 23℃ or is higher than 30℃, survival rate drop gradually. In preoviposition,the order of accumulative survival rate from high to low is 25 ℃,27℃,23℃,30℃;21℃,33℃,18℃,36℃,15℃.(5) Effect of temperature to egg productions:In the range of temperature from 18℃ to 36℃, egg productions is the highest at 25℃ and 27℃ When the temperature is higher than 27℃ or is lower than 25℃, egg productions decrease gradually.Moreover,with the rising of temperature, the date of laying eggs is more early,the period of laying eggs is more short,but the range of changes is little gradually. At 15℃ this insect do not lay eggs any longer.(6) Effect of temperature to adult life-span.In the range of temperature from 18℃ to 36℃, with the rising of temperature,the adult life-span becomes more and more short.At the same time,the Logistic model was set up about the relationship between adult life-span and temperature: N = 0.1093/[ 1 + exp( 2.2799-0.069 x ) ] ( R2 = 0.949 ).( 7) The life table of experimental population was established at different constant temperatures.The population trend index is the highest at 25 °C Innate capacity at 33°C is the highest.The period of 1 st instar larva is the crucial period to affect this insect experiment population change by K law and regressive coefficient(b) analysis.(8) The experement of insectiside effectThe test of sensitivity determination of five kinds of insecticides on the adult of Diorhbda tarsalis weise was done by immersion method in room.Phoxim offered the least LC50 and the largest index of relative toxicity.The adult was most sensitive to this pesticide,next come,BtA,chlorpyrifos and omethoate.Imidacloprid offered the largest LC50 and the least index of relative toxicity.The adult was the least sensitive to this pesticide.In field, BtA and DDV was adopted to control this insect,under the same concentration,after the seventh day of insecticides, thepreventi-on effect is same. But BtA is the biological insecticide of a kind of efficient broad table, thus BtA is the medicament of first selection to control Diorhbda tarsalis Weise.( 9) It was suggested to calculate and forecast this pest by climate.occur period and so forth.Meantime, the effective measures of physical and biological control were suggested. |
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