Hines R L, Hutchison W D
Department of Entomology, University of Minnesota, St. Paul 55108, USA.
J Econ Entomol. 2001 Feb;94(1):190-6. doi: 10.1603/0022-0493-94.1.190.
Action thresholds, based on the percentage of plants infested, for the lepidopteran pest complex in fresh-market cabbage Brassica oleracea variety capitata were evaluated in 1996 and 1997 in southern Minnesota. Three lepidopteran pests are common in Minnesota, including the imported cabbageworm, Pieris (=Artogeia) rapae (L.), diamondback moth, Plutella xylostella (L.), and the cabbage looper, Trichoplusia ni (Hübner). Most of the thresholds tested included all three pests. However, because T. ni is often the most consistent and damaging pest in Minnesota, two thresholds were based solely on the percentage of plants infested with T. ni eggs and larvae. Action thresholds were also evaluated for their compatibility with a recently labeled biologically based insecticide, spinosad, and a conventional pyrethroid, permethrin. Although all three lepidopteran pests were present in both years of the study, P. rapae provided most of the pest pressure in 1996, and T. ni was most abundant in 1997. Compared with the 0% larval infestation treatment (approximately weekly sprays from early heading to harvest), all action thresholds resulted in less insecticide use (17- 80%), while maintaining high levels of marketability. Despite variable pest pressure between years, one of the thresholds based solely on T. ni (10% of plants infested with eggs or larvae) performed as well as each of the thresholds based on all three species combined. For both years, and compared with a weekly spray schedule from early heading to harvest (average of 5.5 sprays per year), use of the 10% T. ni egg or larval threshold resulted in an average of 36.5% (3.5 sprays) and 65% (2.0 sprays) fewer applications of spinosad and permethrin, respectively, with no significant loss in marketability. The results indicate that a variety of incidence-based action thresholds can be used to ensure the production of high-quality cabbage in the midwestern United States with only minimal applications of spinosad or permethrin.
1996年和1997年，在明尼苏达州南部对鲜销甘蓝（芸苔属甘蓝变种结球甘蓝）中鳞翅目害虫复合体基于植株受害百分比的防治指标进行了评估。明尼苏达州常见三种鳞翅目害虫，包括菜青虫（粉蝶属（=菜粉蝶属）菜粉蝶）、小菜蛾（小菜蛾）和甘蓝夜蛾（甘蓝夜蛾）。测试的大多数防治指标涵盖了所有三种害虫。然而，由于甘蓝夜蛾通常是明尼苏达州最常见且危害最大的害虫，有两个防治指标仅基于甘蓝夜蛾卵和幼虫的植株受害百分比。还评估了防治指标与最近标注的生物源杀虫剂多杀菌素以及传统拟除虫菊酯氯菊酯的兼容性。尽管在研究的两年中都存在这三种鳞翅目害虫，但菜粉蝶在1996年造成了大部分害虫压力，而甘蓝夜蛾在1997年数量最多。与0%幼虫侵染处理（从结球初期到收获期大约每周喷雾一次）相比，所有防治指标都减少了杀虫剂的使用量（17 - 80%），同时保持了较高的商品率。尽管不同年份害虫压力有所变化，但仅基于甘蓝夜蛾的一个防治指标（10%的植株有卵或幼虫）与基于所有三种害虫综合的防治指标表现相当。在这两年中，与从结球初期到收获期每周喷雾一次的方案（每年平均5.5次喷雾）相比，使用10%甘蓝夜蛾卵或幼虫防治指标分别使多杀菌素和氯菊酯的施用量平均减少了36.5%（3.5次喷雾）和65%（2.0次喷雾），且商品率没有显著损失。结果表明，在美国中西部地区，多种基于发生率的防治指标可用于确保高质量甘蓝的生产，只需极少使用多杀菌素或氯菊酯。
