NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Private Bag 4008, Menangle, Narellan, 2567, NSW, Australia.
Int J Parasitol Drugs Drug Resist. 2020 Dec;14:118-125. doi: 10.1016/j.ijpddr.2020.04.005. Epub 2020 May 11.
Late in 2017, field samples of the Australian sheep blowfly, Lucilia cuprina, were submitted by sheep producers from three states of Australia (South Australia, Victoria and New South Wales). Some were collected by submitters concerned about shortened periods of flystrike protection from dicyclanil based products. Neonate larval offspring from the NSW field samples survived and successfully completed their life cycles following exposure to dicyclanil and cyromazine at susceptible discriminating concentrations in vitro. The in vivo study reported here used dicyclanil resistant neonate larvae to assess the flystrike protection provided by a cyromazine jetting fluid and a number of dicyclanil based spray-on products, when applied to sheep six weeks after shearing. The two dicyclanil resistant blowfly strains used in this study showed in vitro resistance ratios, at the LC50, of approximately 13- and 25-fold relative to a dicyclanil and cyromazine susceptible strain. Compared to the levels of resistance that L. cuprina has developed to other insecticides these are relatively low, however, three dicyclanil based spray-on products (active ingredient 12.5 g/L, 50 g/L and 65 g/L) had protection periods reduced by 73%, 78% and 69% respectively when compared to the maximum protection periods claimed by the manufacturer. A 50% and a 33% reduction in protection period was also observed to a cyromazine and an ivermectin based jetting fluid respectively. In contrast, protection periods were attained or exceeded regardless of the treatment used against field derived dicyclanil susceptible neonate larvae. For the first time we confirm that dicyclanil resistance enables the completion of the L. cuprina life cycle following flystrike initiation on dicyclanil or cyromazine treated sheep when insecticide levels are considered high and protective. This study also provides in vivo information on the effect of dicyclanil resistance on the protection provided by a product with an active ingredient belonging to an unrelated insecticide group. Dicyclanil resistance is of major concern to the Australian sheep industry.
2017 年末，来自澳大利亚三个州（南澳大利亚州、维多利亚州和新南威尔士州）的绵羊养殖户提交了澳大利亚绵羊狂蝇的田间样本。一些样本是由关注基于双氯氰胺产品的蝇蛆病防治有效期缩短的提交者收集的。来自新南威尔士州田间样本的新生幼虫后代在体外暴露于双氯氰胺和环丙嗪的易感鉴别浓度下存活并成功完成了生命周期。本报告中的体内研究使用抗双氯氰胺的新生幼虫来评估在剪毛后六周给绵羊应用环丙嗪喷射液和几种基于双氯氰胺的喷雾产品时提供的蝇蛆病防治效果。本研究中使用的两种抗双氯氰胺的狂蝇品系在体外 LC50 时的抗性比值约为 13 倍和 25 倍，相对于双氯氰胺和环丙嗪敏感品系。与 L. cuprina 对其他杀虫剂产生的抗性水平相比，这些水平相对较低，然而，三种基于双氯氰胺的喷雾产品（有效成分 12.5 g/L、50 g/L 和 65 g/L）的有效期分别比制造商声称的最大有效期缩短了 73%、78%和 69%。与环丙嗪和伊维菌素喷射液相比，有效期也分别减少了 50%和 33%。相比之下，无论使用哪种处理方法，针对田间获得的抗双氯氰胺敏感的新生幼虫，都能达到或超过防治期。这是我们首次确认，在考虑到高水平和保护性的杀虫剂水平时，双氯氰胺抗性能够使狂蝇生命周期在对双氯氰胺或环丙嗪处理的绵羊上启动蝇蛆病后完成。本研究还提供了关于双氯氰胺抗性对属于不同杀虫剂组的活性成分产品提供的保护作用的体内信息。双氯氰胺抗性是澳大利亚绵羊产业的主要关注点。
