Kellermann Jherime L, Johnson Matthew D, Stercho Amy M, Hackett Steven C
Department of Wildlife, Humboldt State University, Arcata, CA 95521, USA.
Conserv Biol. 2008 Oct;22(5):1177-85. doi: 10.1111/j.1523-1739.2008.00968.x.
Coffee farms can support significant biodiversity, yet intensification of farming practices is degrading agricultural habitats and compromising ecosystem services such as biological pest control. The coffee berry borer (Hypothenemus hampei) is the world's primary coffee pest. Researchers have demonstrated that birds reduce insect abundance on coffee farms but have not documented avian control of the berry borer or quantified avian benefits to crop yield or farm income. We conducted a bird-exclosure experiment on coffee farms in the Blue Mountains, Jamaica, to measure avian pest control of berry borers, identify potential predator species, associate predator abundance and borer reductions with vegetation complexity, and quantify resulting increases in coffee yield. Coffee plants excluded from foraging birds had significantly higher borer infestation, more borer broods, and greater berry damage than control plants. We identified 17 potential predator species (73% were wintering Neotropical migrants), and 3 primary species composed 67% of migrant detections. Average relative bird abundance and diversity and relative resident predator abundance increased with greater shade-tree cover. Although migrant predators overall did not respond to vegetation complexity variables, the 3 primary species increased with proximity to noncoffee habitat patches. Lower infestation on control plants was correlated with higher total bird abundance, but not with predator abundance or vegetation complexity. Infestation of fruit was 1-14% lower on control plants, resulting in a greater quantity of saleable fruits that had a market value of US$44-$105/ha in 2005/2006. Landscape heterogeneity in this region may allow mobile predators to provide pest control broadly, despite localized farming intensities. These results provide the first evidence that birds control coffee berry borers and thus increase coffee yield and farm income, a potentially important conservation incentive for producers.
咖啡种植园能够支持丰富的生物多样性，然而农业生产方式的集约化正在破坏农业栖息地，并损害诸如生物虫害控制等生态系统服务。咖啡果小蠹（Hypothenemus hampei）是全球主要的咖啡害虫。研究人员已证明鸟类可减少咖啡种植园中的昆虫数量，但尚未记录鸟类对咖啡果小蠹的控制情况，也未对鸟类给作物产量或农场收入带来的益处进行量化。我们在牙买加蓝山的咖啡种植园开展了一项鸟类排除实验，以测定鸟类对咖啡果小蠹的虫害控制情况，识别潜在的捕食者物种，将捕食者数量和小蠹数量的减少与植被复杂性相关联，并量化由此带来的咖啡产量增加。与对照植株相比，排除觅食鸟类的咖啡植株遭受的小蠹侵害显著更高，有更多的小蠹虫窝，且浆果受损更严重。我们识别出17种潜在的捕食者物种（73%为越冬的新热带迁徙鸟类），其中3种主要物种占迁徙鸟类观测数量的67%。随着遮荫树覆盖度增加，鸟类的平均相对数量、多样性以及本地捕食者的相对数量均有所增加。尽管总体而言迁徙捕食者对植被复杂性变量没有反应，但3种主要物种的数量随着与非咖啡栖息地斑块距离的缩短而增加。对照植株上较低的侵害率与鸟类总数量较高相关，但与捕食者数量或植被复杂性无关。对照植株上果实的侵害率低1% - 14%，从而产生了更多可销售的果实，在2005/2006年其市场价值为44 - 105美元/公顷。尽管该地区存在局部农业集约化现象，但景观异质性可能使移动捕食者能够广泛地提供虫害控制。这些结果首次证明鸟类可控制咖啡果小蠹，从而提高咖啡产量和农场收入，这对生产者而言可能是一个重要的保护激励因素。
