水椰八角铁甲和椰心叶甲对椰子和银海枣的寄主选择性

【目的】水椰八角铁甲和椰心叶甲均为棕榈科植物的重要入侵害虫,两者的外部形态、取食部位和危害特征相似。研究它们的寄主选择性有助于了解这2种害虫的扩散和成灾机制。【方法】在室内用椰子和银海枣2种寄主植物分别饲养水椰八角铁甲和椰心叶甲,研究在不同寄主植物上水椰八角铁甲和椰心叶甲的存活率、产卵率、发育历期等以及这2种害虫对不同寄主植物的选择性。【结果】水椰八角铁甲在2种寄主上的存活率差异显著,除了卵期和蛹期之外,幼虫期各虫态在银海枣上的存活率明显比在椰子上的存活率高;椰心叶甲在椰子上的存活率高于银海枣,各虫态平均存活率分别为95%和86%。取食银海枣的水椰八角铁甲达标准卵量概率为0.23,取食椰子不产卵,无法完成整个世代;取食椰子的椰心叶甲达标准卵量概率为0.86,取食银海枣不产卵,也无法完成整个世代;水椰八角铁甲取食银海枣完成世代的实验种群趋势指数为12.55,椰心叶甲取食椰子完成世代的实验种群趋势指数为66.55。【结论】水椰八角铁甲和椰心叶甲分别对银海枣和椰子这2种寄主植物具有明显的选择性。在海南椰子树的数量远远超过银海枣,该实验结果在一定程度上解释了椰心叶甲在海南岛广泛分布而水椰八角铁甲只是零星发生的原因。

Host preference of Octodonta nipae and Brontispa longissima to Cocos nucifera and Phoenix sylvestris

[Aim] Octodonta nipae and Brontispa longissima both are important invasive pests of palm trees; they both have similar morphologies, feeding sites and cause similar damage characteristics. The study of the host selectivity of these two pests can help understand the mechanisms of spread and outbreak.[Method] In the laboratory, two host plants, Cocos nucifera and Phoenix sylvestris, were used to rear O. nipae and B. longissim. Survival rate, egg production, developmental duration, and preference of the two kinds of host plants by O. nipae and B. longissim were studied.[Result] O. nipae survival on the two host plants significantly differ, expect at egg and pupal stages. Larval survival of each instar feeding on P. sylvestris was higher than on C. nucifera. B. longissim survival feeding on C. nucifera was higher than on P. sylvestris, with means values of 95% and 86%, respectively. The probability of eggs laid by of O. nipae feeding on P. sylvestris was 0.23, while no eggs were laid when feeding on C. nucifera and thus not completing a full generation. The probability eggs laid by B. longissim feeding on C. nucifera was 0.86 while no eggs were found on P. sylvestris. When O. nipae fed on P. sylvestris, the experimental index of population trend was 12.55, and B. longissim feeding on C. nucifera, the index was 66.55.[Conclusion] O. nipae and B. longissima have obvious preference between the two host plants. In Hainan, far more C. nucifera are available than P. sylvestris. Our results could explain the widespread outbreak of B. longissima in Hainan, as well as the occasional occurrence of O. nipae.