Seasonal dynamics of plant pollinator networks in agricultural landscapes: how important is connector species identity in the network?

Farm habitat enrichment is crucial for sustainable production of pollinator-dependent crops. Correct choice of crop and non-crop plant species in habitat management support resilient pollinator fauna and effective pollination service delivery. We identify key network metrices to recognize suitable crop and non-crop plant species for farm habitat enrichment. We also highlight the importance of seasonal variation of the key plant and pollinator species that will crucially inform farm management. Crop species played a key role in maintaining plant-pollinator network integrity. In contrast to the conventional practice of focussing on non-crop plants for pollination service restoration, we find crop plants across seasons hold a key role in maintaining healthy plant-pollinator networks. Our study highlights the importance of non-bee pollinators especially, flies and butterflies in sustaining healthy plant-pollinator network. Bees were important as connector species and controlled other species in the network. Only 16.67% bees and 33.33% of plant species acted as connector species. Our study also shows that the identity of connector species in a plant-pollinator network can change drastically across seasons.

Structure, function and management of semi-natural habitats for conservation biological control: a review of European studies.

Different semi-natural habitats occur on farmland, and it is the vegetation's traits and structure that subsequently determine their ability to support natural enemies and their associated contribution to conservation biocontrol. New habitats can be created and existing ones improved with agri-environment scheme funding in all EU member states. Understanding the contribution of each habitat type can aid the development of conservation control strategies. Here we review the extent to which the predominant habitat types in Europe support natural enemies, whether this results in enhanced natural enemy densities in the adjacent crop and whether this leads to reduced pest densities. Considerable variation exists in the available information for the different habitat types and trophic levels. Natural enemies within each habitat were the most studied, with less information on whether they were enhanced in adjacent fields, while their impact on pests was rarely investigated. Most information was available for woody and herbaceous linear habitats, yet not for woodland which can be the most common semi-natural habitat in many regions. While the management and design of habitats offer potential to stimulate conservation biocontrol, we also identified knowledge gaps. A better understanding of the relationship between resource availability and arthropod communities across habitat types, the spatiotemporal distribution of resources in the landscape and interactions with other factors that play a role in pest regulation could contribute to an informed management of semi-natural habitats for biocontrol. © 2016 Society of Chemical Industry.