Daugherty M P, O'Neill S, Byrne F, Zeilinger A
Department of Entomology, University of California, Riverside, CA 92521.
Initiative for Global Change Biology, University of California, Berkeley, CA 94720.
Environ Entomol. 2015 Jun;44(3):789-97. doi: 10.1093/ee/nvv046. Epub 2015 Apr 20.
Vector control is widely viewed as an integral part of disease management. Yet epidemiological theory suggests that the effectiveness of control programs at limiting pathogen spread depends on a variety of intrinsic and extrinsic aspects of a pathosystem. Moreover, control programs rarely evaluate whether reductions in vector density or activity translate into reduced disease prevalence. In areas of California invaded by the glassy-winged sharpshooter (Homalodisca vitripennis Germar), Pierce's disease management relies heavily on chemical control of this vector, primarily via systemic conventional insecticides (i.e., imidacloprid). But, data are lacking that attribute reduced vector pressure and pathogen spread to sharpshooter control. We surveyed 34 vineyards over successive years to assess the epidemiological value of within-vineyard chemical control. The results showed that imidacloprid reduced vector pressure without clear nontarget effects or secondary pest outbreaks. Effects on disease prevalence were more nuanced. Treatment history over the preceding 5 yr affected disease prevalence, with significantly more diseased vines in untreated compared with regularly or intermittently treated vineyards. Yet, the change in disease prevalence between years was low, with no significant effects of insecticide treatment or vector abundance. Collectively, the results suggest that within-vineyard applications of imidacloprid can reduce pathogen spread, but with benefits that may take multiple seasons to become apparent. The relatively modest effect of vector control on disease prevalence in this system may be attributable in part to the currently low regional sharpshooter population densities stemming from area-wide control, without which the need for within-vineyard vector control would be more pronounced.
病媒控制被广泛视为疾病管理的一个组成部分。然而，流行病学理论表明，控制项目在限制病原体传播方面的有效性取决于病原系统的各种内在和外在因素。此外，控制项目很少评估病媒密度或活动的降低是否转化为疾病流行率的降低。在加利福尼亚州被玻璃翅叶蝉（Homalodisca vitripennis Germar）入侵的地区，梨火疫病的管理严重依赖于对这种病媒的化学控制，主要是通过系统性常规杀虫剂（即吡虫啉）。但是，缺乏将病媒压力降低和病原体传播归因于叶蝉控制的数据。我们连续多年对34个葡萄园进行了调查，以评估葡萄园内部化学控制的流行病学价值。结果表明，吡虫啉降低了病媒压力，没有明显的非靶标效应或次要害虫爆发。对疾病流行率的影响更为细微。前5年的处理历史影响疾病流行率，与定期或间歇性处理的葡萄园相比，未处理的葡萄园中有病葡萄藤明显更多。然而，不同年份之间疾病流行率的变化很小，杀虫剂处理或病媒数量没有显著影响。总体而言，结果表明，在葡萄园内部施用吡虫啉可以减少病原体传播，但益处可能需要多个季节才能显现出来。在这个系统中，病媒控制对疾病流行率的影响相对较小，这可能部分归因于目前由于区域范围控制导致的叶蝉种群密度较低，否则葡萄园内部病媒控制的需求会更加明显。
