椰心叶甲的生殖系统与繁殖力研究

The reproductive system and fecundity of the coconut leaf beetle,Brontispa longissima

为阐明椰心叶甲Brontispa longissima (Gestro)生殖密切相关的结构、卵巢发育以及繁殖特性,以显微解剖和室内观察的方法,对该虫的雌雄成虫的生殖系统构造、卵巢发育进度以及繁殖力进行了研究。结果表明,椰心叶甲雄性内生殖器包括精巢、贮精囊、输精管、附腺和射精管,其中贮精囊由侧输精管特化形成;雄性外生殖器由阳茎、阳茎基和阳基组成,无抱握器。雌性内生殖器包括卵巢、侧输卵管、中输卵管、受精囊和附腺,左右卵巢呈对称分布,每侧有5根卵巢管,为无滋式;雌性外生殖器由背产卵瓣、内产卵瓣和腹产卵瓣组成。根据相关形态特征,卵巢发育进度可分为发育初期(Ⅰ级)、成熟待产期(Ⅱ级)、产卵盛期(Ⅲ级)和产卵末期(Ⅳ级)4个级别,各等级在卵巢和卵巢管的分区长度及怀卵量上存在显著差异。椰心叶甲种群在椰子叶上的最高产卵量变化幅度最小(2.39粒/♀),但产卵期最长(348 d),推测应用椰子叶饲养椰心叶甲能确保获得稳定的卵量。由于椰心叶甲种群在鱼尾葵上具有较短的产卵前期(12.7 d)和雌成虫寿命(161.8 d),以及较高的产卵量(397.7粒/♀),表明了椰心叶甲种群在鱼尾葵上具有较强的繁殖力。

Laboratory observations were made on the reproductive system, progress of ovarian development and fecundity of coconut leaf beetle, Brontispa longissima （Gestro）. The adult male internal reproductive system was found to be composed of testes, seminal vesicle, vas deferens, accessory gland, and ejaculatory duct. The seminal vesicle is developed from a specialized vas deferens. The male external genitalia consists of three parts, the aedeagus, manubrium and tegmen, but there is no clasper. The adult female internal reproductive system consists of the ovaries, lateral and median oviduct, spermatheca, and bursa copulatrix. The two ovaries are symmetrical, each consisting of 5 panoistic ovarioles. The female external genitalia comprises a dorsovalvula, intervalvula, and ventrovalvula. Ovarian development can be divided into 4 stages based on the morphological characteristics of ovaries, namely the nooocyte stage, egg maturation stage, ovipositing stage, and post-ovipositing stage. Each stage shows significant differences in the length of the ovarian zones and the number of eggs carried. In addition, the daily fecundity of the coconut leaf beetle on Cocos nucifem is minimal （2.39 egg/female） and oviposition was prolonged （348 d） compared with that on other host plants, so stable egg production is expected when this species is raised on coconut leaf. However, on Caryota ochlandra, pre-oviposition and longevity of coconut leaf beetle are shorter, but egg production is higher, indicating that C. ochlandra is an ideal rearing material with respect to maximizing the fecundity of the coconut leaf beetle.