Wildfire alters the structure and seasonal dynamics of nocturnal pollen‐transport networks

Wildfires drive global biodiversity patterns and affect plant–pollinator interactions, and are expected to become more frequent and severe under climate change. Post-fire plant communities often have increased floral abundance and diversity, but the effects of wildfires on the ecological process of pollination are poorly understood. Nocturnal moths are globally important pollinators, but no previous study has examined the effects of wildfire on nocturnal pollination interactions. We investigated the effects of wildfire on nocturnal pollen-transport networks. We analysed the abundance and species richness of moths and flowers, and the structure of these networks, at three burned and three unburned sites in Portugal for two years, starting eight months after a large fire. Nocturnal pollen-transport networks had lower complexity and robustness following the fire than at nearby unburned sites. Overall, 70% of individual moths carried pollen, and moths were found to be transporting pollen from 83% of the flower species present. Burned sites had significantly more abundant flowers, but less abundant and species-rich moths. Individual moths transported more pollen in summer at burned sites, but less in winter; however, total pollen transport by the moth assemblage at burned sites was just 20% of that at unburned sites. Interaction turnover between burned and unburned networks was high. Negative effects of fire upon moths will likely permeate to other taxa through loss of mutualisms. Therefore, if wildfires become more frequent under climate change, community resilience may be eroded. Understanding the responses of ecological networks to wildfire can inform management that promotes resilience and facilitates whole-ecosystem conservation

Rapid transcriptional plasticity of duplicated gene clusters enables a clonally reproducing aphid to colonise diverse plant species

Background: The prevailing paradigm of host-parasite evolution is that arms races lead to increasing specialisation via genetic adaptation. Insect herbivores are no exception and the majority have evolved to colonise a small number of closely related host species. Remarkably, the green peach aphid, Myzus persicae, colonises plant species across 40 families and single M. persicae clonal lineages can colonise distantly related plants. This remarkable ability makes M. persicae a highly destructive pest of many important crop species. Results: To investigate the exceptional phenotypic plasticity of M. persicae, we sequenced the M. persicae genome and assessed how one clonal lineage responds to host plant species of different families. We show that genetically identical individuals are able to colonise distantly related host species through the differential regulation of genes belonging to aphid-expanded gene families. Multigene clusters collectively upregulate in single aphids within two days upon host switch. Furthermore, we demonstrate the functional significance of this rapid transcriptional change using RNA interference (RNAi)-mediated knock-down of genes belonging to the cathepsin B gene family. Knock-down of cathepsin B genes reduced aphid fitness, but only on the host that induced upregulation of these genes. Conclusions: Previous research has focused on the role of genetic adaptation of parasites to their hosts. Here we show that the generalist aphid pest M. persicae is able to colonise diverse host plant species in the absence of genetic specialisation. This is achieved through rapid transcriptional plasticity of genes that have duplicated during aphid evolution

Potentials and pitfalls in the analysis of bipartite networks to understand plant–microbe interactions in changing environments

Complex networks of interactions involving multiple plant and microbial species have consequences for ecosystem productivity and energy movement through higher trophic levels, but the sensitivity of these networks to environmental change is uncertain. The fast developing field focused on the construction of ecological networks involving multiple plant and microbial species allows the structure, complexity and robustness of these networks to be examined. However, the choice of methods used to generate data and construct networks can significantly influence network-level metrics. Here, we provide background and guidance on approaches for building and analysing bipartite networks of plant–microbe interactions. Researchers need to explore these methods (and their advantages and pitfalls) to create high quality and reproducible data that allow comparisons within and between systems. In particular, we highlight the significant advances of DNA-based approaches for characterising interactions between plants and microbes, while suggesting future work needed to help overcome their current limitations. As more studies embrace these approaches, these guidelines will allow robust characterisation and analysis of networks of plant and microbial interactions, and further enable our understanding of the influence of environmental change on species interactions and, ultimately, communities and ecosystem functioning

Data from: Determining plant – leaf miner – parasitoid interactions: a DNA barcoding approach

A major challenge in network ecology is to describe the full-range of species interactions in a community to create highly-resolved food-webs. We developed a molecular approach based on DNA full barcoding and mini-barcoding to describe difficult to observe plant – leaf miner – parasitoid interactions, consisting of animals commonly regarded as agricultural pests and their natural enemies. We tested the ability of universal primers to amplify the remaining DNA inside leaf miner mines after the emergence of the insect. We compared the results of a) morphological identification of adult specimens; b) identification based on the shape of the mines; c) the COI Mini-barcode (130 bp) and d) the COI full barcode (658 bp) fragments to accurately identify the leaf-miner species. We used the molecular approach to build and analyse a tri-partite ecological network of plant – leaf miner – parasitoid interactions. We were able to detect the DNA of leaf-mining insects within their feeding mines on a range of host plants using mini-barcoding primers: 6% for the leaves collected empty and 33% success after we observed the emergence of the leaf miner. We suggest that the low amplification success of leaf mines collected empty was mainly due to the time since the adult emerged and discuss methodological improvements. Nevertheless our approach provided new species-interaction data for the ecological network. We found that the 130 bp fragment is variable enough to identify all the species included in this study. Both COI fragments reveal that some leaf miner species could be composed of cryptic species. The network built using the molecular approach was more accurate in describing tri-partite interactions compared with traditional approaches based on morphological criteria

Farmer flexibility concerning future rotation planning is affected by the framing of climate predictions

International audienceArable crops are typically grown in annual rotations. Diverse rotations can deliver ecosystem services, provide economic resilience, and support adaptation to climate change. Our aim was to assess farmers' attitudes to planning and diversifying crop rotations, focusing on their responses in the face of contrasting climate viewpoints. We interviewed 75 farmers from four regions along a latitudinal gradient from the south of the UK to the south of France. We used a semi-structured questionnaire with face-to-face interviews and asked farmers to respond to two narrative viewpoints of climate change impacts: one viewpoint focused on opportunities, the other on constraints. We found in all four regions that farmers' use rotations, and the crops within rotations, to achieve their main objectives of financial stability and improved soil health. Most farmers (79-100% depending on region) said they had experienced climate change, and many (54-83%) had already implemented changes in their farming practices. We did not find a difference in these results based on latitude. However, farmers' self-reported outlook was mostly optimistic in southern UK and become progressively more pessimistic further south. When presented with a viewpoint of climate change impacts focusing on opportunities, more farmers were likely to diversify and lengthen rotations, and fewer were likely to shorten them, compared to a viewpoint presenting constraints from these impacts. Crucially, here we show that the presentation of climate change affects the ways in which farmers predict how they will respond to climate change. Diversified rotations align with multiple other economic and environmental benefits. Therefore, it is essential to consider the way in which climate change impacts are communicated, and the effect this has farmers' behavior, when designing measures to support environmentally sustainable adaptation to climate change

COI Minibarcode

Sequence alignement for COI Minibarcode (130 bp). This alignement has been used to build ML tree

Tri-partite interactions

Spreadsheet where all interactions described using molecular method and morphological approach are displayed. This file has been used to calculate the network metrics

COI Barcode

Sequence alignement for COI barcode (658bp). This alignement has been used to build ML tre

Number of leaves collected between the 13th June and the 19th September 2012.

<p>^a 147 leaves were still infested by a leaf mining insect when collected.</p><p>^b In 260 leaves, insects were already emerged when the leaves were collected.</p><p>Number of leaves collected between the 13th June and the 19th September 2012.</p

Amplification success for the three primers pairs used on the infested leaves collected.

<p>^a Leaves were still infested by a leaf mining insect</p><p>^b No insect has been found within the infested leaves.</p><p>Amplification success for the three primers pairs used on the infested leaves collected.</p