快速区分沟眶象雌雄成虫的方法

 沟眶象Eucryptorrhynchus chinensis的雌雄成虫在外部形态上非常相似，目前还没有一种简单而快速的区分方法。通过对大量雌雄成虫外部形态进行比较，找出了可以仅靠肉眼区分的识别特征，即：雌雄间在成虫后胸腹板上有明显区别，雄虫腹中线贯穿后胸腹板，而雌虫的后胸腹板没有被贯穿，中断位置两侧后胸腹板凸起。经验证，该方法可以作为区分沟眶象雌雄虫的简易方法。与雌成虫相比沟眶象成虫雄虫腹部背板最后一节分为2节，因此，腹部背板雌虫为7节、雄虫为8节也是区分沟眶象雌雄成虫的稳定特征。另外，对臭椿沟眶象E. brandti的雌雄成虫的区分方法也做了相应的补充。图2表1参5

Rapid differentiation between male and female adults of Eucryptorrhynchus chinensis

The male and female adults of Eucryptorrhynchus chinensis （a weevil pest） have a very similar external morphology. Thus，to determine external morphological characteristics that could distinguish between the sexes，observation of a large number of E. chinensis adults was conducted. A random sample of 2 389 adults in Linhe town，Lingwu，Ningxia，then observation with the naked eye and anatomical lens. Results showed that the sexes differed in the shape of their metathoracic sternite where the medioventral line stretched over the metathoracic sternite in the male，but opposite in the female adult and both sides of interrupted position were convex. Also，compared with the female，male adults of E. chinensis had the last section of their abdominal webs divided into two sections for a total of 7 in the male and 8 in the female. Since the sexual dimorphism of the metathoracic sternite was readily seen with the naked eye，male and female adults of E. chinensis could be effectively determined.［Ch，2 fig. 1 tab. 5 ref.］