Drummond Francis, Ballman Elissa, Collins Judith
School of Biology and Ecology, University of Maine, Orono, ME 04469, USA.
Cooperative Extension, University of Maine, Orono, ME 04469, USA.
Insects. 2019 Jul 13;10(7):205. doi: 10.3390/insects10070205.
A long-term investigation of dynamics in wild blueberry fields from 2012-2018 demonstrates relative abundance is either still increasing or exhibiting periodicity seven years after the initial invasion. Relative abundance is determined by physiological date of first detection and air temperatures the previous winter. Date of first detection of flies does not determine date of fruit infestation. The level of fruit infestation is determined by year, fly pressure, and insecticide application frequency. Frequency of insecticide application is determined by production system. Non-crop wild fruit and predation influences fly pressure; increased wild fruit abundance results in increased fly pressure. Increased predation rate reduces fly pressure, but only at high abundance of flies, or when high levels of wild fruit are present along field edges. Male sex ratio might be declining over the seven years. Action thresholds were developed from samples of 92 fields from 2012-2017 that related cumulative adult male trap capture to the following week likelihood of fruit infestation. A two-parameter gamma density function describing this probability was used to develop a risk-based gradient action threshold system. The action thresholds were validated from 2016-2018 in 35 fields and were shown to work well in two of three years (2016 and 2017).
对2012年至2018年野生蓝莓田动态的长期调查表明，在首次入侵七年后，相对丰度仍在增加或呈周期性变化。相对丰度由首次检测的生理日期和前一年冬季的气温决定。果蝇首次检测日期并不能决定果实受侵染的日期。果实受侵染程度由年份、果蝇压力和杀虫剂施用频率决定。杀虫剂施用频率由生产系统决定。非作物野生果实和捕食行为影响果蝇压力；野生果实丰度增加会导致果蝇压力增大。捕食率提高会降低果蝇压力，但仅在果蝇丰度较高或田边存在大量野生果实时才会如此。七年来雄性性别比可能在下降。行动阈值是根据2012年至2017年92个田地的样本制定的，这些样本将成年雄性诱捕器的累计捕获量与下周果实受侵染的可能性联系起来。使用描述这种概率的双参数伽马密度函数开发了一个基于风险的梯度行动阈值系统。2016年至2018年在35个田地对行动阈值进行了验证，结果表明在三年中的两年（2016年和2017年）效果良好。
