植绥螨在桔树、藿香蓟和假臭草上的时空分布

Temporal and spatial distributions of phytoseiid mites on citrus, Ageratum conyzoides and Praxelis clematidea

【目的】植绥螨是柑桔园的重要天敌。桔园杂草假臭草常被误认为藿香蓟而被保留或种植,但其在维持植绥螨上的生态功能是否与藿香蓟相似,尚无报道。了解植绥螨在桔树和藿香蓟、假臭草上的时空分布,可为筛选果园杂草及其它合理保护和增殖桔园植绥螨措施提供参考。【方法】本文采用常规摘叶法调查植绥螨和柑桔全爪螨Panonychuscitri(McGregor)在桔树上的时空分布,以及采用整株取样法调查附近藿香蓟和假臭草上的植绥螨种群。【结果】发现植绥螨在桔树树冠外层的种群密度在夜晚23:30较高,而柑桔全爪螨正好相反,在白天15:30密度更高。在白天藿香蓟上的植绥螨显著多于假臭草上的,在夜晚两种草上的植绥螨无显著差异。植绥螨在白天多栖息于藿香蓟上,晚上则从藿香蓟转出至外面。【结论】藿香蓟对广谱性捕食螨天敌冲绳钝绥螨Amblyseius okinawanus增殖作用明显,建议果园留种藿香蓟;选择在桔树树冠外层植绥螨分布较少而全爪螨分布较多的白天时间段喷施安全性较高的农药,可以较好地达到控制全爪螨又保护捕食螨的效果。

[Objectives] To determine the temporal and spatial distribution of phytoseiid mites, important predators of citrus pests in citrus orchards, and particularly the relative importance of the weeds A. conyzoides and P. clematidea as habitat for these mites. The weed, Praxelis clematidea, is frequently confused with Ageatum conyzoides and consequently protected, or even planted. However, it is unclear if the ecological role of P. clematidea is similar to that of A. conyzoides in citrus orchards, especially with respect to providing habitat for predatory mites. [Methods] The regular leaf-picking method was used to investigate the temporal and spatial distributions of phytoseiid mites and Panonychus citri on citrus, and the whole-plant sampling method to survey phytoseiid mites on A. conyzoides and P. clematidea. [Results] The density of phytoseiid mites was highest at 23:30 on the periphery of the crown of citrus trees, whereas that of P. citri was highest at 15:30. During the day, phytoseiid mites were clearly more abundant on A. conyzoides than on P. clematidea, however at night there was no significant difference in phytoseiid mite abundance between these two plants. Phytoseiid mites preferred to inhabit at A. conyzoides during the daytime but left these plants at night. [Conclusion] Conserving A. conyzoides in citrus orchards and spraying citrus trees during the day when the density of phytoseiid mite on the trees is relatively low and that of P. citri is highest on the periphery of the crown, could help to both control P. citri and protect phytoseiid mites.