Effects of food plants on the geographic destribution and food habits of phytophagous ladybird beetles.

蓟属植物的分布。在北海道南部的大岛半岛调查了食蓟瓢虫(Epiachna pustlosa和E.niponica)。在卡里巴山脉以北的半岛北部采集到了脓疱艾美耳球虫，寄生在优势种卡姆茨卡氏菌上。另一方面，尼氏毛虫主要分布在奥诺平原及其南部邻近地区，主要发生在阿尔比科拉毛虫上。除了一个例外，这两种甲虫都不利用灰飞蓟，这是卡里巴山脉南部半岛上最常见的蓟类物种。因此，在半岛的颈部周围有一个区域，尽管有大量的蓟，但没有出现摄食蓟的瓢虫。实验室研究表明，这两种甲虫都不喜欢稻纵卷叶蝉，幼虫在该蓟种上的表现较差。此外，在温室内，尼波尼卡菲亚目幼虫在上述3种蓟中选择产卵时，产卵量达80%以上，孵化出的幼虫不以蓟叶为食而散布。这些结果表明，食蓟瓢虫在大岛半岛的分布是由当地优势种蓟的性质决定的。

The distribution of thistles (Cirsium spp.) and thistle feeding ladybird beetles (Epilachna pustlosa and E.niponica) was surveyed in Oshima Peninsula, southern Hokkaido. E.pustulosa was collected in the morthern part of the peninsula north of the Kariba mountains, occurring on predominant C.kamtschaticum. On the other hand, E.niponica was confined to Ohno Plain and its adjacent areas in the southern part, mainly occuring on C.alpicola. With only one exception, both beetle species did not utilize C.grayanum which was the commonest thistle species all over the peninsula south of the Kariba mountains. Thus there was a zone around the neck of the peninsula that lacked occurrence of thistle feeding ladybird beetles despite there was plenty thistles. Laboratory studies revealed that both beetle species did not prefer C.grayanumand the larvae performed less on that thistle species. Furthermore, E.niponicafemales laid more than 80% of eggs on C.alpicola when they were allowed tochoose between the above three species of thistles in a green house, and the larvae hatched from eggs occasionally laid on C.grayanum did not feed on laeaves of this thistle and dispersed. From these results it was concluded that the distribution of the thistle feedingladybird beetles in Oshima Peninsula was determined by the nature of locally predominant thistle species.