一种叶甲(Timarcha maritima)(鞘翅目:叶甲科)的种群变异性

本文研究了一种叶甲(Timarchamaritima)的种群变异性,在此物种的整个分布范围内,沿法国大西洋海岸取选10个种群,测定个体大小、生育力、寄生量、性比、交配模式几个变量,各变量在不同种群间呈现显著差异。我们的调查结果也表明:原生生物(簇虫,Gregarinamunieri)的寄生是影响T.maritima生态习性的主要因素;这种甲虫的交配模式与寄生量有关,这种交配模式3年前已在一个高寄生种群内发现;个体大小与交配的关联不显著,即便是在没有寄生的种群中也是这样;在不同种群间,寄生感染程度也是一个有力的指示量,可以预示雌性个体的生育力变化;相反,不管观察什么种群,外寄生种(蜱螨,Pseudamansiachrysomelinus)(Acari:Canestriniidae)的作用很小。这项研究表明:在研究种群生态学时,需要同时观察寄生物的影响。

Population variability in the beetle Timarcha maritima (Coleop-tera, Chrysomelidae)

We investigated variability between populations of the beetle Timarcha maritima over its geographic range by comparing several variables (size of individuals, fecundity, parasite load, sex ratio, pattern of pairing) in 10 populations along the French Atlantic coast. Populations exhibited significant differences for all variables considered. Our findings also indicate a major influence of the protozoan parasite Gregarina munieri on T. maritima ecology. Beetles paired assortatively according to the parasitic load, a pattern of pairing detected 3 years ago in a highly parasitized population. Size assortative pairing was never significant, even in parasite-free populations. The level of infection by gregarines was also a strong predictor of mean fecundity of females at the inter-population level. Conversely, the role of the external parasite Pseudamansia chrysomelinus (Acari: Canestriniidae) was weak whatever the population considered. This study underlines the need to consider parasites when studying population ecology.