| Galerucella grisescens and Gastrophysa atrocyanea were important natural enemies which could control Polygonaceae weeds especially genus Rumes and Polygonum in a good condition in the fields.The paper dealt with the biology and ecology of G grisescens and G atrocyanea.The results were summarized as follows.1. Biology of G grisescensG. grisescens mainly controlled the weeds by eating leaf and growing point.The 3rd-instar larva was main larval stage of controlling the weeds.The adult could mate several times.The position of oviposition preferred to dorsal side of leaf. The 2nd-instar and 3rd-instar larvae also preferred to dorsal side of leaf. Male adult, 2nd-instar and 3rd-instar larvae all had strong negative phototaxis. Compelled feeding to 56 farm crops and economic crops in 14 families showed that G grisescens was an oligophagous insect,only feeding mainly on Rumex and Polygonum weeds. It occurred four generations in the fields in Sanming City,Fujian Province and had two peak in a year.The peak appeared on first ten days of May and last ten-day of July respectively.It had generations overlapping in the fields.2.Effect of temperature on G grisescensIn the range from 17? to 33?,the durations of various stages were shortened with the increase of temperature.Based on the results in the experiment at constant temperatures, the threshold temperature of its egg, 1st-instar, 2nd-instar, 3rd-instar larva, pupa, pre -oviposition and generation were estimated to be 10.70?, 12.39癈, 11.93?, 11.76?, 11.76 ?,11.92? and 11.35?, respectively. The developmental effective accumulatedtemperature for egg, Ist-instar, 2nd-instar, 3rd-instar larva, pupa, pre-oviposition and generation were 72.91, 35.08, 59.95, 70.23, 53.94, 57.45 and 370.8 day-degrees, respectively.The relationship between survival rate of each stage(y1) , mean total number of eggs laid by per female(y) and temperature(x) were described as parabolas: y(gencration) = -2.7725 +0.2730x -0.0057x, y = -5410.7104 +509.5553x-10.2991x. The relationshipbetween the pre-oviposition period (y3), oviposition period (y4) and temperature (x) were described as following formula: y= 15.7477 - 0.4158x, y= 143.7193 -3.7973x.The experimental population developed fastest on 25 ? . The highest index of population growth occurred at 25 ? and achieved at 261 .22. When temperature reached 35 ?, the population could not survive. The most optimal temperature of fecundity was estimated to be about 25 ?The influence of low temperature (60-810) on vitality of each stage were tested. The order of each stage of enduring low temperature was: adult>pupa>egg. Adult is most suitable stage to freeze preservation.The survival rate of adult still remained about 90% after 15 days under low temperature.3. Influence of relative humidity on G grisescensUnder the relative humidity raged from 45% to 95%. the developmental durations of various stages were different significantly. The developmental duration of each stage exhibited parabo 1 ically increase with the humidities. The oviposition period , lifespan of female and male adult were highest under 75%RH, attaining 59.25d, 65.00d and 57.19d, significantly greater than other humidity.The regression equation for survival rate of each stage(y1), egg number per female (y), index of population growth(y) against temperature(x) were: y(gencration)= -2.5649 + 8.5443x-5.8911; y 2325.4960 +9314.0798x - 6537.3289 x; y = -1545.8207 + 5029.4885X -3500.7892x.G grisescens preferred to high humidity than low humidity. The ability of enduring humidity for pupa was greater than egg and larva. The optimum range of humidity for the population growth was from 70%RH to 75%RH.4.1mpact of photoperiod on G grisescensDifferent photoperiod had no significant effect on developmental duration of egg and larva, but obviously affected developmental period of pupa, pre-oviposition period and generation. Under the photoperiod of 12L:12D, pupa period, pre-oviposition period andVIgeneration were lowest. The survival rate of egg and pupa kept in a high de...
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