Studies On The Pest Species In Apple Orchard Of Tianshui And The Biology Of Aphis Citricola Van Der Goot

This study investigated the pest species of Tianshui apple orchard, and the main pest species in apple orchard of Tianshui were identified. To study the biological characteristics of Aphis citricola Van der,laboratory population life tables were built under the constant temperatures 13℃,15℃,17℃,19℃,23℃,26℃,28℃,30℃and 32℃,and then the biological characteristics of experimental population were studied. The results were following:1. It indicated that there were 6 Orders,40 Families and 73 Species in Tianshui apple orchards,which Insecta have 8 Orders,38 Families and 68 Species,compared 1 Orders,2 Families and 5 Species in Arachnida. Five main pests were found in apple orchard of Tianshui. They were Tetranychus viennensis Zacher,Aphis citricola Van der Goot,Panonychus ulmi(Koch),Lithocolletis ringoniella Mats and Carposina nipponesis Walsingham. In this studied,we found 10 kinds of pest which have not been reported previously. The results are following: Psylla chinensis Yang et li,Aporia crataegi Linnaeus,Fixsenia pruni Linnaeus,Vespa mandarinia Smith , Epicauta chinensis Lap , Sucra jujuba Chu , Lycorma delicatula(White),Ostrinia furnacalis(Guene),Heliothis armigera Hübner and Rhynchites foveipennis Fairmaire。2. The optimum temperature for the development of Aphis citricola Van der Goot was 19℃,in which there was the highest Intrinsic growth rate(0.086) and shortest doubling time for population(8.086 days).The results indicated that there were a significant correlation between development and temperature. In a certain temperature range,the relation between development span (y) and temperature(t) could be described by the formulation y=471.3442/t -7.2753 (correlation coefficient r=0.9926,Significant level p=0.0001 ),and the relation between development rate (v) and temperature(t) could be descript by the formulation v=0.0046t-0.0287 (correlation coefficient r=0.9948,Significant level p<0.0001)With the increase of temperatures,the development durations of Aphis citricola Van der were shorten,when the development rates were accelerated. They could develop normally under the temperatures ranged from 15℃to 28℃. The generation was 24.69 days observed at 15℃,the shortest was 9.70 days at 28℃. If the temperature lower than 15℃or higher than 28℃, the die rate will raise sharply.3. The survival rate of Aphis citricola Van der has a significantly different under different temperatures. The nymph could not developed normally at 13℃and 32℃. The highest survival rate of each instars were 100%,100%,100%,83.33%at 19℃,while the lowest were 76.67%,53.33%,43.33%,26.67% at 15℃respectively .4. The development threshold temperatures and the effective accumulated temperatures required for 1-4 instars of nymphs and whole generation were 7.35℃,6.82℃,6.08℃,7.20℃,6.40℃respectively,and the effective accumulated temperatures for these stages are 46.85 d·℃,48.43 d·℃,49.66 d·℃,44.94d·℃and 214.41 d·℃respectively.