The conservation of pollinating insects in agriculture is a global concern since the diversity of such organisms may affect the productivity of pollination-dependent crops. In this study, we assessed (i) how distances from natural vegetation affect the diversity (guilds, richness, abundance) of flower-visiting insects within mustard crops in Nepal, (ii) how insect richness and abundance are related to mustard yields (weight of seeds) and (iii) the contribution of flower-visiting insects to mustard pollination by conducting pollinator exclusion experiments. To analyse these data, we carried out (i) hierarchical clustering followed by a Procrustes analysis as well as a generalized linear mixed model and (ii), (iii) linear mixed models. We found that the guild composition was not similar near and far from natural vegetation, indicating a tendency for Apis bees to displace in opposite directions relative to non-Apis bees. Nevertheless, while both richness and abundance were higher nearer natural vegetation, the former showed a stronger and more positive effect on mustard yields than the latter. Furthermore, we found that mustard flowers have a significant requirement for insect pollination since productivity increased by ~70% with insect visitation. Overall, our data suggest that the diversity of flower-visiting insects enlarges nearer to natural vegetation. However, the results indicate that species richness may be more relevant than abundance to mustard production. As such, we suggest that the maintenance of natural vegetation could be considered a strategy for ensuring the presence of multiple pollinator species within mustard fields to promote its long-term sustainability in Nepal.

中文翻译：

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接近自然植被的访花昆虫的丰富度和丰度对芥菜产量产生了对比影响

农业授粉昆虫的保护是全球关注的问题，因为此类生物的多样性可能会影响依赖授粉的作物的生产力。在这项研究中，我们评估了 (i) 与自然植被的距离如何影响尼泊尔芥菜作物中访花昆虫的多样性（行列、丰富度、丰度），（ii）昆虫丰富度和丰度如何与芥菜产量（重量种子）和（iii）通过进行传粉媒介排除实验，探花昆虫对芥菜授粉的贡献。为了分析这些数据，我们进行了 (i) 层次聚类，然后是 Procrustes 分析以及广义线性混合模型和 (ii)、(iii) 线性混合模型。我们发现公会组成在靠近和远离自然植被的地方并不相似，表明蜜蜂相对于非蜜蜂有向相反方向移动的趋势。然而，虽然丰富度和丰度都更高，更接近自然植被，但前者对芥菜产量的影响比后者更强，更积极。此外，我们发现芥菜花对昆虫授粉有重要的要求，因为昆虫的访问使生产力提高了约 70%。总体而言，我们的数据表明，访花昆虫的多样性在更接近自然植被的情况下扩大。然而，结果表明，物种丰富度可能比芥末产量更相关。因此，