Landscape potential for pollen provisioning for beneficial insects favours biological control in crop fields
Landscape potential for pollen provisioning for beneficial insects favours biological control in crop fields
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为有益昆虫提供花粉的景观潜力有利于农田的生物防治
作者：
A. Vialatte;Noelline Tsafack;D. A. Hassan;R. Duflot;M. Plantegenest;A. Ouin;J. Villenave;A. Ernoult
目的评价景观为益虫提供花卉资源的能力及其对田间生物防治的影响。方法对41个粮田采集的成虫肠道成分进行分析，以确定哪些植物被利用。通过植被调查评价了各生境在提供充足花粉资源方面的相对价值。然后按照景观复杂程度的梯度选择了15块麦田，监测了麦田中的蚜虫、飞蝇幼虫和蚜虫的寄生情况。以这些农田周围景观缓冲区中的生境比例作为景观描述符，评估花粉资源供给的潜在水平(LP指数)。结果随着草地带和田间杂草所支持的LP指数的增加，棉蚜的数量显著减少。然而，浮蝇幼虫的丰度也随着Lp指数的增加而降低。随着Lp指数的增加，棉铃虫的寄生率有所提高，这表明棉铃虫的寄生蜂可能与飞蝇具有相同的花卉资源。它们的作物生境特性可能使它们在蚜虫和花卉资源丰富的田野中具有竞争优势。结论参与生物防治的复杂相互作用网络可能扰乱对局部有益物种提供花卉资源的预期直接效果。我们强调，田野和草地是提供花卉资源的栖息地，LP指数对优化农业生态管理策略非常有帮助。
ContextThe importance of landscape complexity for biological control is well-known, but its functional roles are poorly understood.ObjectivesWe evaluated the landscape capacity to provide floral resources for beneficial insects and its consequences for biological control in fields.MethodsThe gut contents of adult hoverflies sampled in 41 cereal fields were analysed to determine which plant species are exploited. The relative value of each habitat in providing adequate pollen resources was evaluated by vegetation survey. Then 15 cereal fields were selected along a gradient of landscape complexity, where the abundance of aphids, hoverfly larvae and aphid parasitism was monitored. The habitat’s proportions in landscape buffers surrounding these fields were used as landscape descriptors and to assess the potential level of pollen resources provision (LP index).ResultsAphid abundance significantly decreased with an increase of the LP index mainly sustained by grassy strips and weeds in fields. However, hoverfly larvae abundance also decreased with the increasing LP index. The enhancement of the aphid parasitism rate with the LP index suggests that aphid parasitoids may benefit from the same floral resources as hoverflies. Their crop habitat specialism may give them a competitive advantage in fields where both aphid and floral resources are abundant.ConclusionsComplex interaction networks involved in biological control may disrupt the expected direct effects of floral resource provisioning for a focal beneficial species. We highlighted fields and grassy strips as habitats provisioning floral resources for which the LP index could be very helpful to optimize agroecological management strategies.