Higher richness and abundance of flower-visiting insects close to natural vegetation provide contrasting effects on mustard yields

Abstract

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.

A Systematic review of flower-visiting insect community research on agricultural crops in Indonesia

“…The presence of butterflies on plantations could be caused by the attraction of several plant species in plantations that have the potential as a food source [11]. The natural habitats around plantations also could provide key resources to butterflies, such as perennial forage areas, nesting substrates, or breeding sites [12]. Based on articles that truly focused on flowervisiting insects, not only pollinators, our results showed that flower-visiting insects mostly belong to Hymenoptera.…”

Benefits of Insect Pollination in Brassicaceae: A Meta-Analysis of Self-Compatible and Self-Incompatible Crop Species

“…Some of the crops included in this review, such as B. rapa and S. alba, have also been used as insectary plants [176]. Proximity to natural habitats with natural vegetation and where wild bees can locate their nests can also enhance the abundance of wild bees [104,115,128]. The flowers of crucifer crops can also temporarily benefit wild bees because of the food resource boost [129].…”

Effects of selected management practices of gutenbergia cordifolia on insect flower visitation at Mwiba area, Tanzania

“…Other studies similar to this have shown that GLY treatment on weeds can have non-targeted negative effects on the richness and diversity of insects within a short or long time (Sharma et al, 2018), causing insect death, alteration in reproduction rates, and population size of numerous insect taxonomic group, including Hymenoptera, Coleoptera, and Orthoptera (Lins et al, 2007). In this study, results showed that GLY reduced insect diversity, which could negatively impact the ecological services as the productivity of > 88% of flowering plant species depend on diverse pollinators for sexual reproduction (Devkota et al, 2020). It can, therefore, be claimed that DUL can support insect diversity and richness and preserve a healthy ecosystem, while it ensures plant fertilization and maximizes plant genetic diversity (Siregar et al,2016).…”