棉蚜种群季节性变异的生态条件

The ecological conditions related to seasonal population variation of cotton aphid,Aphis gossypii Glover

研究棉蚜在不同温度下取食不同生育期棉叶后种群的变动情况。通过 Weibull函数模拟、生命表分析和高氏距离分析比较表明 ,无论在苗期和蕾期 ,随着温度的升高棉蚜种群的死亡高峰日均提前 ,世代寿命明显缩短 ;然而 ,在 2 0～ 2 5℃范围内 ,相同温度时棉蚜生活在棉花蕾期叶上的繁殖力明显高于苗期叶上的繁殖力。在 30℃时繁殖力普遍明显下降 ,温度 2 0～ 2 5℃最适于棉蚜的生长与繁殖。且棉花生殖生长期比营养生长期更适于棉蚜的生存和繁殖 。

Cotton aphid,\%Aphis gossyipii\% is found on various plants with universal distribution.It causes serious damage on cotton and vegetable in China,especially in northwest droughty or semi-droughty areas.The population of cotton aphid differentiates obviously in types.On cotton,the population density usually have two peak periods.One occurs in spring with green or yellowish green body colour,infests the top tender leaves,it is usually called as seedling type;the other is in summer in blight yellow colour and small size but high population growth rate,it distributes mainly on the old leaves at middle or lower part of cotton plant,usually is called as dwarf type(summer type)and always causes serious damage at droughty season or areas.The ecological factors,temperature and cotton growth stages,were studied to define the effects on inducement of seasonal population type.Twelve applications in total have been applied,which included cotton leaves from four stage:seeding,bud,tender leaves of bud and old leaves of bud stages and three temperatures 20℃、25℃、30℃ in each growth stage.Data were calculated,compared and analysed under 3 parameters of life talbe;9 parameters of Weibull simulation model for survival and fecundity curves.The Gower distance was calculated in the combination of 6 main survival and fecundity parameters.The results showed that the date of maximum mortality of aphid population the four kinds of development status all shifted ahead along with the raising of temperature but no differences was found between different development status under the same temperature.The accumulated fecundity of the populations reared on four kind of leaves stages were all decreased along with the raising of temperature under same temperature 20℃ and 25℃,fecundity were much higher on dwarf type at bud stage,or old leaves of bud stage as compared with the seeding type or tender leaves of bud stage,but these differences reduced obviously as the temperature raised to 30℃.It was indicated that both temperature and development status of host plant were the exotic factors for leading differentiation of seeding and dwarf population type of cotton aphids.The level of differentiation might reach more than 68%.The DNA detection for polymorphism of these population phenotypes is to be further studied.