W3 Regenerative agriculture to improve
food quality and ecosystem services
I am starting a new postdoc about agroecology and regenerative agriculture as part of the the exciting UKRI-funded H3 project "Healthy Soil, Healthy Food, Healthy People". I will be contributing to the WP3:
Regenerative agriculture aims to enhance soil health (or function, eg nutrient availability, microbial activity, carbon sequestration, ...) while maintaining high yields. Less is known about the potential wider benefits of regenerative to the environment.
Objective 1: experimentally assess the impact of regenerative agriculture on biodiversity and ecosystem services (including biological pest control and pollination)
Objective 2: investigate the perception and uptake of regenerative agriculture by farmers (linking to Geography and Social Sciences).
Pollination in a drier world: how floral traits' alteration impacts pollination networks
In Europe and specifically in the Mediterranean Basin, climate change causes the intensification of droughts and fire events. Understanding the consequences on plant-pollinator interactions is key to help mitigate pollinator decline. We investigate how climate change alters floral traits - scent, color, nectar production and floral display - and the consequences on pollination networks and plant reproduction. Using the CLIMED facility in a typical Mediterranean
shrubland close to Marseille, France, we have shown that the 30 % reduction in precipitation caused an alteration of floral scent in all studied plant species, along with reduced nectar production in the most drought-sensitive species. This affected plant-pollinator interactions but had limited consequences on reproduction in our study (read more once our article in published). We are now pursuing this research in a UK grassland community, looking at how drought affects nectar productivity of the community.
Habitat management for conservation biological control
With colleagues in China (Prof Su Wang, Beijing Academy of Agricultural Sciences, and Dr Nicolas Desneux, INRAE Sophia-Antipolis, France), we are looking for solutions to enhance conservation biological pest control - the regulation of pest populations by their natural enemies locally and naturally present in the environment - by improving their environment. This means attracting them closest to crops and pest populations, and provide them alternative resources (such as pollen and nectar floral resources) to
enable them to build up populations prior to pest outbreaks. We have applied this strategy to greenhouse crops (Li et al. 2021 J Pest Sci) and orchards (Jaworski et al 2019 J Appl Ecol) and we are now testing the role of floral resources or banker plants in greenhouses to reduce intraguild predation - the attack of one natural enemy or biological control agent on another one - and improve biological control (Liang et al. 2021 accepted in J Pest Sci; Chen et al. in revisions for J Pest Sci).
Genome evolution in Drosophila mojavensis host races
Host races are different populations of a species undergoing some genetic isolation after a shift to a new host plant, and which may ultimately lead to speciation. Populations of the fly Drosophila mojavensis use different host cactus species depending on where they live I am studying how selection by host and adaptation of flies to their new environment (new host) may shape their evolution at the genome scale. I have optimized a de novo, hybrid (mixing short- and long-reads) genome assembly pipeline which produces highly contiguous (chromosome-size), high quality (low error rate and high completeness) genomes on non-model insects
(Jaworski et al. 2020 Mol Ecol Res), and I have used it to assemble genomes of seven species/populations closely related in the repleta Drosophila group. We are now using the genomes to study the evolution of genome structure evolution and the consequences for adaptation (eg, genes 'trapped' at breakpoints of chromosomic inversions), and of gene families involved in adaptation (eg, chemosensory genes, detoxication genes ...).
Plant-insect interactions: The Pyrenees snapdragon and its visiting insects
Species interactions play a major role in the structure and eco-evolutionary dynamics of communities, at different spatial scales. In an A. majus-based network, I studied (i) the regional metacommunity dynamics; (ii) how floral color and scent shape pollinator behaviour; and (iii) floral scent variation.
(i) Metacommunity dynamics A. majus network
Antirrhinum majus has a regional, patchy distribution, which provides an opportunity to study spatial processes likely to affect species interactions. I quantified biotic interactions in the field in the A. majus network composed of the plant, its cohort of pollinator, a specific seed-predator - a weevil Rhinusa vestita - and its associated parasitoid - a Cotesia wasp. I applied a model to empirical data to explore some mechanisms stabilizing this network. We predict that the A. majus metacommunity has a source-sink structure. This work has been published in Journal of Ecology.
(ii) How plant phenotypes alters pollinator behaviour
Antirrhinum majus is an interesting system to study speciation, because two subspecies grow naturally in the Pyrenees. They are distributed in parapatry and form a hybrid zone where they come into contact. Pollinators are assumed to cause the reproductive isolation between both subspecies, which have different colours. I conducted a behavioural experiment on bumblebees to explore how plant signals (colour vs. scent) may create constancy of bees toward one plant phenotype. This work has been published in PLoS ONE.
(iii) Floral scent variation
Floral scent is a major trait mediating plant-pollinator interactions. Understanding how floral scent varies is thus a key to predict the eco-evolutionary dynamics of plant-pollinator interactions. I grew plants grown in a common garden but issued from populations distributed across an elevational gradient, which is a proxy for a temperature gradient, and hence may also be used to predict the imapct of climate change. I measured floral scent variation at the individual level, at the population level, as well as across populations and across altitudes. I also compared these results to prior studies on floral scent. I found that floral scent is highly variable in A. majus, and the intra-individual and inter-individual variation within a population may hide differentiation of floral scent across populations and along the elevational range. More precise measures would be necessary to conclude on the spatio-temporal variability of floral scent in A. majus, and especially disentangle the conflicting results highlighted in our PLoS ONE paper. I also studied the variation of other floral traits, such as size and colour, based on the analysis of photographs using ImageJ, but no differentiation across populations was detected.
Generalist predators mediate indirect interactions between their prey. These indirect interactions may be positive if they favour both prey (apparent mutualism), or negative (apparent competition), and sometimes stronger than direct interactions like resource competition. Our aim was to experimentally measure the strength and nature of interactions between two tomato pests sharing a common predator. We highlighted resource competition (Bompard et al. 2013) and apparent competition between the whitefly Bemisia tabaci and the invasive tomato leafminer Tuta absoluta preyed upon by a generalist mirid bug Macrolophus pygmaeus in greenhouse experiments. Though this negative effect, the control of T. absoluta by M.pygmaeus appeared to be a poor biocontrol agent to ensure a correct crop productivity (Jaworski et al. 2015). We also highlighted the Switching behaviour of the predator M. pygmaeus between these prey in a laboratory experiment (Jaworski et al. 2013).
Trophic interactions in agro-ecosystems