早稻田发生的摇蚊种类及动态

摇蚊在各类水体中广泛分布且大量发生,在稻田生态系统中也有大量发生。目前我国关于稻田摇蚊的研究局限于种类描述和将摇蚊作为一类中性昆虫的调查。为了解稻田摇蚊的分布状况,利用笼罩对浙江省富阳市早稻田的摇蚊种类和动态进行了系统调查。结果表明,早稻田中共有4种摇蚊发生,分别是台湾长跗摇蚊(Tanytarsus formosanus)、中华摇蚊(Chironomus sinicus)、云足多集摇蚊(Polypedilum nubifer)和刺铗长足摇蚊(Tanypus punctipennis),均为常见种类,其中,前2种为稻田的优势种类。整个早稻大田期摇蚊发生量每1hm2可达4500万头,田间的摇蚊总体发生动态可分为前、后两个时期,前期发生数量大,后期发生数量小。优势种的发生动态也与总体动态相似,同时还发现台湾长跗摇蚊在稻田前期雌虫多于雌虫,而后期雄虫多于雌虫。中华摇蚊的雄虫数量在整个大田期均高于雌虫。

Occurrence and Population Dynamics of Chironomid Midges in Early Rice Field

The chironomid midge is one of world wide distribution insects and normally occurs in a great abundance among many kinds of water bodies. In rice field, chironomid midges are very abundant. Currently, our knowledge about chironomid midges in rice field is limited to the species survey as a neutral group. By using specially designed emergence traps, the occurrence of chironomid midges in rice field were studied throughout the early rice season in Fuyang, Zhejiang Province, China. Four species of chironomid, namely, Tanytarsus formosanus, Chironomus sinicus, Polypedilum nubifer and Tanypus punctipennis, were collected from rice fields. All of them are widely distributed species. T. formosanus and C. sinicus were the most dominant species in rice field. The dynamic of chironomid midges in early rice field could be divided into two phases, namely early and late phases. The abundance of chironomid midges was higher in the early phase than that in the late phase. It was estimated that there were 45 million chironomid midges emerged from the 1 hectare rice field throughout the early rice season. It was also found that the sex ratio of T. formosanus was female biased during the early phase, whereas it was male biased during the late phase. In contrast, the sex ratio of C. sinicus was male biased throughout the field season.