耕作措施对江苏棉麦二熟田天敌种群数量影响的研究

INFLUENCE OF CULTIVATION METHODS ON THE NATURAL ENEMY POPULATIONS IN THE COTTON-BARLEY INTERCROPPING SYSTEMS IN JIANGSU

1987～1988年在江苏省盐城棉、麦二熟田研究的结果表明,大麦和棉花的收割及收割前后的耕作措施是影响害虫天敌种群数量的主要因素。夏季大麦收割后大量天敌随麦株运走,如将收割下来的麦株在田间放置一定时间,天敌就可逐渐转移到棉株上而保留下来,棉花收获后,原有捕食性天敌即大量转移或死亡。棉茬地种植越冬作物,增加地面覆盖是保护天敌越冬,大量增加来年天敌数量的有效措施。

Consecutive cotton-barley intercropping is a common practice in Jiangsu Province, where barley is interplanted in cotton fields in the autumn, and cotton is interplanted in barley in the following summer. Field studies during 1987-1988 in Yancheng, Jiangsu Province showed that harvesting of the crops and the cultivation practices pre- and after harvest were the major factors causing fluctuations of the natural enemy populations. Removal of the harvested barley in summer carried away a great number of parasites and predators. Also, dispersal and high mortality of predators occurred in the autumn after harvest of cotton plants. It was demonstrated that planting cotton in the barley fields in an earlier season or leaving the harvested plants in the field for a certain length of time would allow the natural enemies to transfer on to the interplanted cotton plants. Planting ground cover crops or green manure in the cotton fields protected the overwintering predators and significantly increased their population numbers in the following year.