烟蚜茧蜂生物学研究Ⅳ．──繁殖力、内禀增长力、功能反应及对桃蚜的抑制作用

在恒定的实验室条件下测定了寄生于桃蚜２～３龄若虫的烟蚜茧蜂的繁殖力和寿命。在２２℃下在寄主密度分别为５，１０，２５，１００或２００头／ｄ蚜虫时，寄生蜂平均寿命为３．６～６．８ｄ。试验证明雌蜂产卵量及寄生蚜虫数量为随寄主密度的增加而呈负加速上升，但当密度高于５０头／ｄ蚜虫时，两者均不再明显上升。分析证明烟蚜茧峰的内禀增长力随寄主密度增加而增加，在密度为２００头／ｄ蚜虫时达到最大值，为０．３６４１。当供蚜密度从５增加到２００时烟蚜茧蜂的净生殖力增加了１８倍，但平均世代长度则不受影响。烟蚜茧蜂对桃蚜的功能反应属于ＨｏｌｌｉｎｇⅡ型反应，经计算其ａ＝６．０３４１，Ｔｈ＝０．０１４。此外，还在７个不同起始密度下测定了烟蚜茧蜂对桃蚜种群的抑制作用。

Bionomics of Aphidius gifuensis Ⅳ.Fecundity,Intrinsic Rate of Increase,Functional Response and Population Suppresion of Peach Green Aphids

The fecundity,reproductive rates and adult survival of Aphidius gifuensis Ashmead parasitizing second and third instar nymphs of peach green aphids,Myzus persica (Sulzer) were measured under constant laboratory conditions.At host densities of 5, 10,25, 50, 100,or 200 aphids/day the parasite lived average of 3.6-5.8 days at 22℃. Both the number of eggs laid and the aphid parasitized the mean total numbers per female parasite increased with host density and were limited by the numbers of those available at the host density less than 50 aphids/day. Analysis of the data showed that the intrinsic rate of natural increase varied with the host density.It reached the maximum value at the density 200,calculated as 0.3641 female/female/day.The host density showed no significant effect on the mean generation time,but the net reproductive rate increased to 18 times as the density increased from 5 to 200. The parasite's functional response was a typical type Ⅱ response preposed Holling and decelerated with increasing density.The intrinsic attack rate(a') and handling time (Th)were estimated from functional response curve as a'=6.0314 days and Th=0.01474 day.The population suppression on peach green aphid by a pair of aphidian wasps within 30 days was examined present in seven different host densities.