瓜螟实验种群的年龄特征和年龄结构

Characteristics and Structures of Insect Ages in Population of Diaphania indica:

本文对瓜螟第2代和第3代实验种群的性比、取食量、年龄特征死亡率和年龄分布进行了分析。结果表明,幼虫的取食量与龄期呈如下指数关系:y_2=0.2172x_2^(3.2239)和y_3=0.3647x_3^(2.9216)。雌性幼虫个体的取食量明显大于雄性幼虫个体。实验种群中初期死亡率较低,5龄幼虫和蛹的死亡率较高。第2代和第3代的世代死亡率(K值)分别为0.59和0.44,种群趋势指数(Ⅰ)分别为33.68和30.75,以第2代为代表的瓜螟实验种群用广义Leslie矩阵模型模拟,表现出一个渐近稳定的种群年龄结构。种群中各虫态各年龄的相对数量分布呈圣诞树状。表明瓜螟的实验种群是一个世代间逐渐增长的种群。

This paper describes analyses of the sex ratio, feeding ratio, age mortality and age distributions in the experimental populations of the 2nd and 3rd generations of Diaphania indica. Results indicated that feedind ratios of its larvae increased with the progresses of instars. Relations between feeding ratios and instars are expressed with the formula below: y_2=0.2172x_2^(3.2239) and y_3=0.3647x_3^(2.9216), where y_2, y_3 and x_2, x_3 are the feeding ratios and the instars of the 2nd and 3rd generations, respectively. The feeding ratios of female larvae were higher than those of male ones. In experimental populations, mortalities of the 5th instar larvae and pupae were higher than those of instars at initial stages. The generation motalities (K) of the 2nd and 3rd generations were 0.59 and 0.44, respectively. Their population tendency indexes were 33.68 and 30.75, respectively. Simulation using the experimental population of its 2nd generation was taken with the generalized Leslie matrix model, showing that the age structure of its experimental population was stabilized gradually and the distribution of instars and morph appeared as the shape of a Christmas tree.