玉米螟微孢子虫病很早就被认为是玉米螟自然平衡的重要因素(Paillot,1928)。它对玉米螟的生存、繁殖和越冬都造成严重影响(zimmack等,1957;Kramer,1959;Frye等,1974;问锦曾,1975;Windels等,1976)。在室内饲养的玉米螟群体,常会因微孢子虫病的污染而毁灭。但在田间,玉米螟自然发病率一般仅0—40％(Weiser,1956;问锦曾.1975)。近年Lewis(1978)在田间小区玉米上人工接种螟虫的试验中发现,螟虫群体初始仅有25％染病,通过粪便传染,后期染病率可高达90％以上。显 Ostrinia furnacalis has long been considered an important factor in the natural balance of the corn borer (Paillot, 1928). It has a serious impact on the survival, reproduction and overwintering of the corn borer (zimmack et al., 1957; Kramer, 1959; Frye et al., 1974; Asking, 1975; Windels et al., 1976). Tilapia populations that are kept indoors are often destroyed by the infection of microsporidiosis. However, in the field, the natural incidence of corn borer is generally only 0-40% (Weiser, 1956; asked Kam was .1975). In recent years, Lewis (1978) experiment on the artificial inoculation of stem borers on corn in field plots found that the initial population of stem borers was only 25% infected, and the rate of late infection could reach over 90%. Significantly