PhD offer : The role of olfaction and feeding plasticity in resource exploitation by carabids related to crop pest regulation

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions, to address the major global challenges.

The IGEPP research unit (Institute of Genetics, Environment and Plant Protection) addresses major societal challenges in agronomy by promoting more resource-efficient agriculture with reduced use of fertilizers and pesticides, while preserving and enhancing biodiversity. You will join the "Insect Ecology and Genetics" (EGI) team, which focuses on: (i) describing and understanding interaction networks between phytophagous insects, host plants, natural enemies, and associated microbiota; (ii) identifying ecological, evolutionary, and molecular mechanisms underlying adaptive traits of phytophagous insects and their natural enemies with significant agronomic impact; (iii) assessing and predicting the influence of landscapes and agricultural practices on insect populations and communities in agroecosystems; and (iv) developing sustainable strategies based on integrated pest management and biological control.

 

Work environment, missions and activities

To reduce the use of chemical inputs, biological control is a key ecosystem service that limits pest damage and reduces reliance on pesticides. This service can be enhanced by conserving naturally occurring beneficial insects such as carabids (Carabidae). These diverse and abundant predators contribute to the regulation of crop pests and weeds by consuming seeds. While the effects of agricultural practices and landscape on carabid communities and their effectiveness are well documented, the role of the biotic context (prey diversity, intraguild interactions, competition) is still underexplored. In particular, studying the foraging behavior and dietary choices of carabids is essential to better understand their role in biological control within agricultural systems.
Many adult carabid species are generalist predators capable of consuming various prey types, including crop pests (insect pests, mollusks) and weed seeds. Their diets range from granivorous to omnivorous to strictly carnivorous, making them widely recognized as beneficial biological control agents. However, carabids also consume neutral prey and other beneficial organisms (e.g., other predators, earthworms, detritivorous arthropods), which serve as alternative food sources. Their food preferences are likely driven by the availability or profitability of exploitable resources and their physiological needs. The choices made when multiple prey types coexist may indirectly influence their pest control effectiveness. Our limited understanding of the trophic strategies of carabids — especially their ability to locate and select resources—hinders accurate prediction of their biological control potential. Advances in molecular tools now allow more precise identification of prey consumed in the field, offering new perspectives to understand their dietary flexibility, whether involving pests, competitors, or other service providers.

The ability of carabids to perceive various food resources in their environment and their capacity to adjust their foraging behavior (adaptive foraging) remain poorly documented. Olfaction appears to play a key role in detecting seeds and animal prey. However, it is still unclear whether olfaction influences choices between multiple simultaneously available resources (pests, weed seeds, springtails, etc.). Moreover, no electrophysiological studies have yet identified which volatile organic compounds (VOCs) are actually
detected by carabids at the antenna level. The presence or the perception of an alternative prey—especially via its odors—could trigger significant behavioral changes, influencing food choices by carabids. For example, detecting an alternative prey might reduce consumption of a less profitable, less abundant, or less accessible pest.

This PhD project aims to deepen our understanding of the resource exploitation strategies of carabids. Specifically, we will assess potential indirect competition between different resources: pests (e.g., aphids), weed seeds, and alternative prey (e.g., springtails, spiders), which are simultaneously present in the field and consumed by carabids. Based on the hypothesis that the resource exploitation by carabids is odor-mediated but varies with species, dietary type (strict carnivore to granivore), and individual status (sex, size, age, satiation, experience), the PhD will address three main questions:
• Work Package 1 (2025–2026): How do spatial and temporal variations in food resources affect dietary choices and predation in the field across different carabid species? This part will evaluate carabid dietary flexibility at both species and community levels, using data from 60 cereal fields across Europe (BioAware project). It will rely on multiplex PCR molecular data revealing field prey consumption and corresponding prey availability data.
• Work Package 2 (2026–2027): What role does olfaction play in selecting different types of food resources, and which volatile compounds are involved? This part will investigate the role of olfaction in perceiving, locating, and selecting resources. We will (i) characterize VOCs emitted by various resources, (ii) identify odor blends or individual compounds detected by carabids, and (iii) assess the importance of these odors for locating and selecting resources. Analytical chemistry will be used to characterize VOCs; electroantennography to assess antennal detection; and olfactometry to study behavioral responses to odors.
• Work Package 3 (2027–2028): Does the perception of alternative prey alter feeding behavior and affect pest control by carabids? This part will explore competition between different food resources in various carabid species. Under controlled conditions, we will test how the odor and/or actual presence of an alternative prey affects predation on pests (insect pests or weed seeds), impacting biological control. Behavioral observations (direct and video tracking) will be used to analyze the choices of carabids in resource choice/non-choice situations.

Doctoral School: VAAME No. 642

 

 

 

Training and skills

We seek a motivated student interested in insect ecology research, with a background in animal ecology, population biology, or chemistry applied to biological systems.
◾ Recommended background: Master’s degree or equivalent in Ecology or Agronomy.
◾ Desired knowledge:
- Basic knowledge of plant-insect and insect-insect interactions;
- Knowledge of chemical ecology and insect behavior, including associated methods (e.g., electroantennography, olfactometry);
- Understanding of trophic networks and natural pest regulation services.
◾ Specific skills:
- Literature review;
- Good data analysis skills and R programming.
◾ Transversal skills:
- Literature review;
- Good English skills (international collaboration foreseen);
- Strong presentation and synthesis abilities;
- Solid scientific writing skills.

The candidate should be autonomous, proactive, and capable of conducting lab experiments independently. Rigor, analytical thinking, patience, and a reflective attitude are essential. The candidate should be eager to acquire internal training in chemical and behavioral ecology methods. Good teamwork and willingness to collaborate and assist in supervising interns are also important.
This PhD is funded by the PARSADA ARDECO project and Institut Agro Rennes-Angers. The PhD student will be based at Angers, Institut Agro Rennes-Angers campus. The thesis will be supervised by Bruno Jaloux and Anne-Marie Cortesero, with co-supervision by Benjamin Carbonne. The PhD student will receive technical support
for insect rearing.

 

INRAE's life quality

By joining our teams, you benefit from (depending on the type of contract and its duration):

- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.

How to apply

◾ How to apply:

Please provide: (1) a motivation letter detailing your research interests, skills, and experience relevant to the position; (2) a CV; (3) two letters of recommendation along with the contact information of referees (e.g., academic supervisor, internship mentor); and (4) copies of degrees and transcripts (M1, M2).
Selected candidates will be invited for an interview (second half of June). In addition, candidates must apply for the PhD position directly via the Amethis platform. Shortlisted candidates will be asked to present an experimental proposal related to one of the thesis topics.