异色瓢虫与隐斑瓢虫的区别及其色斑型和横脊的频率

Identification of Harmonia axyridis and H.yedoensis with notes on the former' s color pattern and elytral ridge occurrence

异色瓢虫Harmonia axyridis(Pallas)和隐斑瓢虫H.yedoensis(Takizawa)是亲缘关系很近的姐妹种,在中国(北京到南岭,西至甘肃南部和西藏东部)、日本(北海道以南)和南韩等地同域分布,常常在松树等植物上共存。长期以来,隐斑瓢虫被认为是异色瓢虫的一个异名。有时从外形上很难区分这2种瓢虫,因此对于依据野外数据,分析异色瓢虫色斑型和鞘翅横脊的发生频率及小进化会产生一些错误。本文从没有隐斑瓢虫分布的东北地区的材料及其他数据,报道异色瓢虫的色斑型及鞘翅横脊发生频率。异色瓢虫的花斑型在我国东部地区(从东北至广东北部,西至甘肃和云南)发生率很低,而在新疆西北部发生率较高。鞘翅横脊的发生率从东北佳木斯的98.85%降低到云南大理的78.26%。本文列出了区分这2种瓢虫的形态特征及自然分布。如果鞘翅具横脊,则属于异色瓢虫,但如果标本来自2种瓢虫的共存区,鞘翅没有横脊,鞘翅的斑纹呈花斑型、四窗型或二窗型,则很难从外部形态上对它们进行鉴定。但这2种瓢虫的幼虫很容易区分。本文还提供了2种瓢虫的雄性外生殖器形态图、幼虫和成虫。

The two ladybird beetles,Harmonia axyridis（Pallas） and H.yedoensis（Takizawa）（Coleoptera：Coccinellidae） are sibling,often sympatric,species found in China（from Beijing in the north to northern part of Guangdong in the south,to eastern Xizang and southern Gansu in the west）,Japan（south of Hokkaido） and Korea.These insects occur simultaneously on some plants,most frequently on pine trees.H.yedoensis had long been regarded as a synonym of H.axyridis,including recently by Koch（2003）.Because adults of these two forms are difficult to distinguish in the field,there is potential to make wrong explanation for the variation of elytral color pattern,ridge occurrence and the microevolution in H.axyridis.This paper describes the color pattern and elytral ridge of H.axyridis in parts of North China lacking H.yedoensis.The axyridis form is very rare in the eastern part of China（from North China to north Guangdong in the south,to Gansu and Yunnan in the west） but is common in northwest Xinjiang.The frequency of elytral ridges ranges from 98.85% in North China（Jiamushi City,Helongjiang Province） to 78.26% in West China（Dali City,Yunnan Province）.The paper lists diagnostic characters for identifying these two species and details their natural distribution.Although the presence of an elytral ridge identifies specimens as H.axyridis,it is hard to determine from external characters if specimens lacking an elytral ridge and in forms of axyridis,spectabilis or conspicua.Fortunately,the mature larvae can easily be distinguished from each other.Illustrations of male genitalia and color photographs（including those of larvae） are provided.