芒果切叶象甲虫体大小和形状的两性异形分析

为明确芒果切叶象甲虫体大小和形状的两性异形，我们基于多元统计和几何形态测量学定量分析了雌雄成虫的11个共有形态指标和胸、腹部形状两性间差异。结果显示：所有测量的形态指标中只有喙前段长分布范围在雌雄间不存在重叠；雌性喙后段长显著小于雄性(P<0.05),而鞘翅长、鞘翅宽、体高、腹长、前胸背板宽、头宽、喙前段长及喙全长皆显著大于雄性(P<0.05);前胸背板长与头长在两性间无显著差异(P>0.05);喙后段长、喙全长及腹部大小在两性中差异程度较大，而前胸及头部大小在两性间差异较小；雌性的腹部形状与雄性相比较为圆润，并有向外扩张的趋势。因此，该虫虫体大小和形状存在明显的两性异形。在实际应用中，我们可以通过肉眼观察雌性成虫的触角位于喙近基部1/4处而雄性成虫触角位于喙近基部约2/5处来100%准确地确定其性别。

Analysis of sexual dimorphism in the body size and shape of the mango leaf cutting weevil, Deporaus marginatus

In order to identify the sexual dimorphism of the body size and shape of Deporaus marginatus, we quantitatively analyzed the differences in the sizes of 11 shared morphological indexes and the shape of thorax and abdomen between male and female adults based on multivariate statistics and geometric morphometry. The results showed that there was no overlap in the distribution range of the length of front section of snout between male and female, while other morphological indexes were overlapped to different degrees. The length of rear section of snout in female was significantly smaller than that in male (P<0.05), while the length and width of elytra, the thorax depth, the widths of pronotum and head, the length of front section of snout and the total snout length in female were significantly larger than those in male (P<0.05). There was no significant difference in the length of the pronotum and head between female and male (P > 0.05). The length of rear section of snout, the total snout length and the abdomen size were quite different between male and female, while the length of pronotum and the head size were less different between male and female. Compared with the male, the female abdomen was round and tended to expand outward. Therefore, there was obvious sexual dimorphism in the body size and shape of D. marginatus. In practical application, we can use the naked eyes to definitely judge the sex of D. marginatus by observing the antennae: the antennae of female adults are located at 1/4 of the base of the snout, while the antennae of male adults are located at about 2/5 of the base of the snout.