Pitfall traps baited with cattle dung are commonly used to characterize local assemblages of coprophilous insects. Baits can be made fresh or be prepared in advance and kept frozen until needed. Insect recoveries are expected to decline with the age of the bait and may be affected by the use of fresh vs. frozen baits. To assess the effect of these two factors on insect recoveries, we performed a pitfall trap experiment that was repeated in four trials spanning 2 years and two locations in southern Alberta, Canada. The experimental design allowed us to minimize the potential confounding effect of short-term weather events. For results combined across trials, baits aged >3 days were largely ineffective for attracting coprophilous species. Frozen baits attracted significantly more insects than did fresh dung for the first 3 days after placement in the field with no difference thereafter. Our findings suggest that insect recoveries in dung-baited pitfall traps can be maximized with the use of frozen baits with replacement every 3–4 days.

中文翻译：

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诱捕器中昆虫恢复的变化与放置时新鲜或冷冻牛粪诱饵的年龄有关

以牛粪为诱饵的陷阱通常用于表征当地的嗜粪昆虫组合。诱饵可以新鲜制作，也可以提前准备好并冷冻保存直到需要。预计昆虫的回收率会随着诱饵的老化而下降，并且可能会受到使用新鲜和冷冻诱饵的影响。为了评估这两个因素对昆虫恢复的影响，我们在加拿大阿尔伯塔省南部的两个地点进行了为期 2 年的四次试验中重复的陷阱陷阱实验。实验设计使我们能够最大限度地减少短期天气事件的潜在混杂影响。对于跨试验的综合结果，年龄 > 3 天的诱饵对于吸引嗜粪性物种在很大程度上是无效的。在放置在田间后的前 3 天，冷冻诱饵吸引的昆虫明显多于新鲜粪便，此后没有差异。我们的研究结果表明，使用每 3-4 天更换一次的冷冻诱饵可以最大限度地提高粪便诱饵陷阱中的昆虫回收率。