Cowal Sanya, Morris Jonathan R, Jiménez-Soto Estelí, Philpott Stacy M
Department of Environmental Studies, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
School for Environment and Sustainability, University of Michigan, Ann Arbor, MI 48109, USA.
Insects. 2023 Nov 10;14(11):869. doi: 10.3390/insects14110869.
Vegetation connectivity is an essential aspect of the habitat complexity that impacts species interactions at local scales. However, agricultural intensification reduces connectivity in agroforestry systems, including coffee agroecosystems, which may hinder the movement of natural enemies and reduce the ecosystem services that they provide. Ants play an important role in regulating the coffee berry borer (CBB), which is the most damaging coffee pest. For arboreal ant communities, the connections between trees are important structures that facilitate ant mobility, resource recruitment, foraging success, and pest control ability. To better understand how connectivity impacts arboreal ants in coffee agroecosystems, we conducted an experiment to assess the impact of artificial (string) and naturally occurring vegetation (vines, leaves, branches) connectivity on behavior on coffee plants. We compared ant activity, resource recruitment, and CBB removal rates across three connectivity treatments connecting coffee plants to nest trees: vegetation connectivity, string, and control (not connected) treatments. We found higher rates of ant activity, resource recruitment, and CBB removal on plants with naturally occurring vegetation connections to nest trees. Artificial connectivity (string) increased the rates of resource recruitment and CBB removal but to a lesser extent than vegetation connectivity. Moreover, vegetation connectivity buffered reductions in ant activity with distance from the ant nest tree. These results reinforce how habitat complexity in the form of vegetation connectivity impacts interspecific interactions at the local scale. Our results also suggest that leaving some degree of vegetation connectivity between coffee plants and shade trees can promote ant-mediated biological pest control in coffee systems.
植被连通性是栖息地复杂性的一个重要方面，它在局部尺度上影响物种间的相互作用。然而，农业集约化降低了包括咖啡农业生态系统在内的农林业系统中的连通性，这可能会阻碍天敌的移动，并减少它们所提供的生态系统服务。蚂蚁在调控咖啡果小蠹（CBB）方面发挥着重要作用，咖啡果小蠹是对咖啡危害最大的害虫。对于树栖蚂蚁群落而言，树木之间的连接是重要的结构，有助于蚂蚁的移动、资源获取、觅食成功率以及害虫控制能力。为了更好地理解连通性如何影响咖啡农业生态系统中的树栖蚂蚁，我们进行了一项实验，以评估人工（绳子）和自然存在的植被（藤蔓、树叶、树枝）连通性对咖啡植株上蚂蚁行为的影响。我们比较了连接咖啡植株与蚁巢树的三种连通性处理方式下的蚂蚁活动、资源获取以及咖啡果小蠹清除率：植被连通性、绳子以及对照（不连接）处理方式。我们发现，与蚁巢树有自然植被连接的植株上，蚂蚁活动、资源获取以及咖啡果小蠹清除率更高。人工连通性（绳子）提高了资源获取和咖啡果小蠹清除率，但程度低于植被连通性。此外，植被连通性缓冲了随着与蚁巢树距离增加而导致的蚂蚁活动减少。这些结果强化了植被连通性形式的栖息地复杂性如何在局部尺度上影响种间相互作用。我们的结果还表明，在咖啡植株和遮荫树之间保留一定程度的植被连通性，可以促进咖啡系统中蚂蚁介导的生物害虫控制。
