Showler Allan T, Robinson John R C
USDA-ARS APMRU 2413 East Highway 83, Weslaco, TX 78596, USA.
J Econ Entomol. 2005 Dec;98(6):1977-83. doi: 10.1603/0022-0493-98.6.1977.
The current standard practice of two to three preemptive insecticide applications at the start of pinhead (1-2-mm-diameter) squaring followed by threshold-triggered (whenever 10% of randomly selected squares have oviposition punctures) insecticide applications for boll weevil, Anthonomus grandis grandis Boheman, control does not provide a reliably positive impact on cotton, Gossypium hirsutum L., yields in subtropical conditions. This study showed that four fewer spray applications in a "proactive" approach, where spraying began at the start of large (5.5- 8-mm-diameter) square formation and continued at 7- to 8-d intervals while large squares were abundant, resulted in fewer infested squares and 46-56% more yield than the standard treatment at two locations during 2004. The combination of fewer sprays and increased yield made the proactive approach 115-130% more profitable than the standard. The proactive approach entails protection only at the crop's most vulnerable stage (large squares) that, as a source of food, accelerates boll weevil reproduction. In contrast, the standard approach protects early season small squares and later season bolls, both of which contribute less to boll weevil reproduction than large squares. Proaction is an in-season crop protection approach that can be used to increase yield in individual fields during the same season and that could be incorporated into boll weevil eradication strategy that involves later diapause sprays. Because proaction is based on an important relationship between the cotton plant and boll weevil reproduction, the tactic will probably be effective regardless of climate or region.
目前针对棉铃象甲（Anthonomus grandis grandis Boheman）防治的标准做法是，在棉蕾直径达1 - 2毫米（针头大小）初期进行两到三次预防性杀虫剂喷施，随后在阈值触发时（随机选取的棉蕾中有10%出现产卵孔时）进行杀虫剂喷施，但这种做法在亚热带条件下对棉花（Gossypium hirsutum L.）产量并未产生可靠的积极影响。本研究表明，在2004年的两个地点，采用“主动式”方法可减少四次喷施，即在棉蕾直径达5.5 - 8毫米（大蕾）初期开始喷施，并在大蕾数量充足时每隔7 - 8天持续喷施，结果是受侵染的棉蕾数量减少，产量比标准处理高46% - 56%。喷施次数减少且产量增加，使得主动式方法的利润比标准方法高出115% - 130%。主动式方法仅在作物最脆弱的阶段（大蕾期）进行保护，大蕾作为食物来源会加速棉铃象甲繁殖。相比之下，标准方法保护的是早期的小棉蕾和后期的棉铃，这两者对棉铃象甲繁殖的贡献都小于大蕾。主动式防治是一种季内作物保护方法，可用于在同一季节提高单个田块的产量，并且可以纳入涉及后期滞育期喷施的棉铃象甲根除策略。由于主动式防治基于棉花植株与棉铃象甲繁殖之间的重要关系，无论气候或地区如何，该策略可能都是有效的。
