The role of the olfaction in the localisation of food resources and conspecifics by ground beetles.

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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.

Work environment, missions and activities

Biological control of pests is a key ecosystem service on agricultural fields, where it helps to reduce the pressure on crops and limit yield losses. This control can be enhanced by conserving or attracting predators naturally present in crops, such as ground beetles (Coleoptera: Carabidae). These beetles are capable of consuming a wide range of pests, such as weed seeds or aphids, as well as alternative prey such as springtails. A key challenge is therefore to gain a better understanding of their movements and their behaviour in foraging and exploiting food resources, in order to assess their role in these regulatory processes [1]. However, ground beetles’ decisions regarding movement may not depend solely on the search for food resources: the search for conspecifics, particularly sexual partners, may also influence their movements and spatial distribution.

The detection of and decision to head towards a food resource or a conspecific may involve various sensory modalities, such as olfaction, which plays an important role in insects [2]. In ground beetles, olfaction appears to be used for detecting both seeds [3] and animal prey [4]. However, very few studies have attempted to characterise how carabid beetles use odours to locate and select prey when confronted simultaneously with different types of resources. The presence of an alternative prey source, or its perception via associated odours, could lead to behavioural changes with significant implications for biological regulation. Similarly, olfaction appears to be involved in the aggregation behaviour observed in certain species of carabid beetles, as is notably the case with Brachinus sclopeta, Poecilus cupreus and Anchomenus dorsalis, which may utilise pheromones [5–6]. In both cases – whether involving food resources or conspecifics – the Volatile Organic Compounds (VOCs) emitted, detected and utilised by ground beetles for navigation remain largely unknown.

Furthermore, the response of individuals to a source of odour may vary from one species of ground beetle to another. For example, the species’ trophic specialisation (a greater or lesser tendency to consume a particular resource) may be linked to its olfactory ability and behavioural response. Furthermore, depending on the ecology and behaviour of the species, individuals may aggregate to benefit from better defence [5] or, conversely, avoid one another to reduce intraspecific competition [7]. Their response to the odours of their conspecifics may therefore vary greatly from one species to another.

The main objective of this internship will be to study the behavioural responses of different species of ground beetles to olfactory signals associated with their food sources and conspecifics. A secondary objective is to characterise the volatile organic compounds (VOCs) emitted by these different odour sources and to identify those involved in the behavioural responses observed.

The internship will take place within the EGI team at the UMR IGEPP, at the Angers site of the Institut Agro Rennes-Angers. It will be co-supervised by Benjamin CARBONNE (lecturer and researcher in entomology and plant protection) and Pierre GENDRON (PhD student in trophic and chemical ecology). This placement is funded by the PARSADA ARDECO research project (https://ardeco.hub.inrae.fr/).

Student's main missions:

Literature review and training in olfactometry

Capture of ground beetles in agricultural environments and their maintenance in the laboratory

Rearing and preparation of test food sources (e.g. springtails)

Definition of protocols, planning and conducting olfactometry tests

Analysis of movement patterns using video tracking

Statistical analysis of the data collected using R software

Secondary missions for the student: 

To test the antennal and behavioural responses to VOCs emitted by food sources and ground beetles.

This internship will build on the chemical ecology research carried out between 2024 and 2026, which led to the development of a passive olfactometry device and the characterisation of the olfactory responses of several species of ground beetles. In 2027, the student will continue this work by studying the behavioural responses of these species to the odours of food sources and conspecifics, with the possibility of video tracking their movements. This work will be complemented by the characterisation of the volatile organic compounds (VOCs) emitted (a study already underway in 2026), their detection by the antennae using electroantennography, and their role in the behavioural responses of ground beetles. As part of this work, occasional visits to the project’s partner laboratories are envisaged.

Training and skills

Recommended training: Master 2 in ecology or Last year in agronomic engineering.

Knowledge required: knowledge in entomology, ecology, and statistical analysis; Knowledge in R programming language and software

Skills sought: Interest in laboratory experimentation and the development of research experimental setups; Meticulosity, autonomy, interpersonal skills; Good writing skills.

How to apply

I send my CV and my motivation letter