Shortlisted for the 2024 Southwood Prize
Janina Heinen talks us through her and colleagues’ latest study which explores how agricultural practices impact predation pressure across prey taxa.
About the research
Overview
We explored predator-prey dynamics in agroecosystems by examining how carabid predator diet preferences shift throughout the crop growing season, and are influenced by the availability of prey under different agricultural management practices. By combining molecular gut content analysis with assessments of above- and belowground community composition, we reveal the pivotal role of early-season soil prey in supporting diverse and abundant predator communities.
Diverse and abundant predator communities, especially under diversified agricultural practices, are key to providing effective biological pest control, highlighting the importance of resource continuity in promoting pest regulation throughout the growing season.
Challenges
It was surprisingly challenging to get the beetles to regurgitate, especially considering the large number we collected. At times, I found myself questioning my day to day life in the fields—were we really making beetles vomit? But in the end, it is a great method since the beetles stay alive and can be safely returned to the fields.
Next steps and broader implications
There are many factors besides available prey determining the abundance, diversity, and the level of ecosystem services performed by arthropod predators. The next steps in this research should include replications of similar studies across a variety of management practices, but also investigate other aspects of arthropod community build up and sustenance, such as ability to overwinter and general habitat quality for arthropod predators and pests under contrasting management. Further, to enhance the impact of ecological research, we should assess the economic aspects of diversified management practices, demonstrating the economic and ecological trade-offs and benefits.
In practice, our paper underscores the need for holistic approaches when planning agricultural management, highlighting the important linkages between above- and belowground arthropod communities in fields. For policymakers, our study provides guidance on incentivising combined management practices, such as using organic fertilizers and perennial leys, which can enhance biological control compared to conventional management that relies solely on mineral fertilizers. By promoting these sustainable practices, we can support more resilient agricultural systems while reducing reliance on chemical inputs and fostering sustainable agriculture.
About the author
Current position
I am currently working as a researcher on the policy support project “Agrowise” for integrated pest management (IPM). While this has been quite a challenge, as it differs completely from ecological field research, it has given me valuable insights into how ecological research can inform actionable policies. Understanding the needs and perspectives of various stakeholders—farmers, advisors, national authorities, and policymakers—has been a key learning outcome for me.
However, soon, I’ll start a “classical” post doc at Aarhus University, where I’ll return to field research, exploring pest dynamics between autumn and spring sown brassica crops in the arable landscape.
Getting involved in ecology
I’ve always been excited to understand underlying patterns, which is probably why I ended up in ecology, as it is one of the most complex stories biology can tell. But to be very honest, ecology provides opportunities to travel the world, and see nature in ways only a few people will ever do. How many people can proudly say that they made beetles regurgitate?! Ecology never fails to surprise me, and challenges me to creatively tackle the complexities of single species, communities, up to entire ecosystems.
Current research focus
Currently, I am finalising remaining work from my PhD, looking at more detailed soil food webs including nematodes, bacteria and fungi in the same field study as the shortlisted paper. I am also examining the effects of tillage on above- and belowground communities, particularly how disturbance influences arthropod predator emergence, hence their community build up in fields. I am still trying to contribute to a better understanding of the mechanisms operating across the above and belowground interface that shape arthropod communities.
Advice for fellow ecologists
Collaboration is key, and I cannot stress this enough. For this paper, I had the opportunity to visit another lab, an experience that truly shaped the outcome of this work, and one I would not have wanted to miss. But also I want to tell every PhD student who doubts the significance of their research: it matters! Every piece of research contributes to the bigger picture and may even inspire someone else. Keep going—you’re making an impact.
Read the full article “Diversified cropping strengthens herbivore regulation by providing seasonal resource continuity to predators” in Journal of Applied Ecology.
Find the other early career researchers and their articles that have been shortlisted for the 2024 Southwood Prize here!
