寄主龄期对可疑柄瘤蚜茧蜂寄生及其后代适合度的影响

采用单选试验，观察了可疑柄瘤蚜茧蜂（Tysiphlebus anbiguus）对不同发育时期黑豆蚜的寄生选择及其后代生长发育适合度相关特征，以检验寄主大小与其质量是否存在正相关关系。结果表明，黑豆蚜（Aphis fabae）1～4龄和成蚜均被寄生，但对2龄若蚜的寄生率最高（35．25％），对成蚜寄生率最低（14．75％）；寄生低龄蚜虫的羽化率显著高于高龄若蚜和成蚜。寄生2龄若蚜的发育历期（8．4d）最短，而寄生1龄若蚜最长（9．3d）；寄生2～4龄蚜虫的后代蜂体型显著大于寄生1龄和成蚜；寄生4龄若蚜的后代中，雌蜂比例（75．74％）显著高于1龄若蚜（62．89％）和成蚜（65．19％），但与寄生2～3龄若蚜无显著差异。寄主黑豆蚜的质量从高至低依次为2龄〉3龄=4龄〉成蚜〉1龄，因此，对可疑柄瘤蚜茧蜂而言。寄主大小与其质量并非存在正相关性。

Effects of Aphis fabae instars on Lysiphlebus ambiguus parasitism and its offspring fitness

Host size models assumed that the host quality for parasitoid growth and development is a linear function of host size.To test this assumption,a single-choice experiment was conducted to study the parasitism and offspring fitness performances of Lysiphlebus ambiguus developed on different nymphal instars of black bean aphis Aphis fabae.The results showed that all host instars and adults were susceptible to parasitism,but L_2 was most favored(35.25%) while adults were least attacked(14.75%).The eclosion rate of offspring wasps was significantly higher in young nymphs than in older hosts.The development duration of offspring was the shortest in L_2(8.4 d) and the longest in adults(9.3 d),while the body size of offspring was greater in L_2-L_4 than in L_1 and adult.The female proportion in offspring wasps was significantly greater in L_4(75.74%) than in L_1(62.89%) and adult(65.19%),but not statistically different from that in L_2 and L_3 hosts.Based on the fitness returns to the females of parasitoid,the quality of the host aphid varied in the order of L_2>L_3=L_4>adult>L_1,indicating that host quality was not a linear function of host size for the parasitization in L.ambiguus-A.fabae system.