Overview

Gastropods constitute a significant agricultural and horticultural pest around the world. Furthermore, some species are also known to act as disease vectors for parasites that can affect both livestock and humans. Current control methods are mainly focused on the extensive use of metaldehyde- or carbamate-based molluscicide baits, which have well-documented ecotoxicological effects, especially caused by their bio-accumulation in the food chain and their entry into adjacent waterways due to wash-off, as well as direct risks to the health of humans and pets (Barker, 2002). Molluscicide baits require active consumption, usually at multiple occasions, in order to be effective. However, terrestrial snails and slugs are generalised feeders with limited innate food preferences and highly adaptive feeding strategies.

For instance, once they encounter a nutritious food source, they have been shown to rapidly adapt their food preference (Figure 1; Peschel et al., 1996). This strategy makes them highly adaptive to changes in their environment and also very damaging as once they have 'acquired a taste' for a specific crop, they will feed selectively on that food source. This adaptive and flexible feeding strategy could also lead to active avoidance of molluscicide baits. As part of NERC's remit in the environmental physiology research area, we will study whether non-lethal doses of molluscide consumption can result in subsequent active avoidance reducing the effectiveness of molluscicide baits. We will also investigate which cues affect molluscicide bait attraction (smell, taste, nutrional value) as well as the underlying neurobiological mechanisms. Based on these findings, we will aim to develop improved control strategies for snails and slugs with less environmental impact, e.g. by attempting to develop hyper-attractive baits for snail/slug traps that avoid the need to spread molluscicides over large areas.

Methodology

The project will integrate field- and laboratory-based behavioural studies with neurobiological methods to study adaptive changes in feeding strategies and decision making processes in the grey field slug, Deroceras reticulatum that can compromise the effectiveness of molluscicide baits. This species was chosen as a model because of its worldwide economic impact as a pest. Results obtained with the grey field slug can be translated readily to other gastropods. We will specifically focus on the role of various cues (smell, taste and nutritional value) in the development of food preferences and food avoidance. Behavioural studies will be complemented by neurobiological studies to gain a better understanding of the interactions of various behavioural cues and the activation of the dopaminergic reward system.

Training and Skills

CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to CENTA research themes.

The student will also receive extensive training in behavioural, image analysis and statistical methods as well as neurophysiological and microscopy techniques. This will include:

Field- and laboratory-based behavioural studies on food preference and avoidance

Advanced image analysis for automatic behavioural scoring

Use of advanced multi-factorial statistical models for data analysis

Opportunity to acquire experience in neurophysiologial (extra- and intracellular recording techniques including state-of-the-art spike sorting techniques to extract information on the behaviour of single units) and electrochemical detection (dopamine) methods

Imaging of stained neurons and nerves to map neuronal signalling pathways

Timeline

Year 1: Field- and laboratory-based experiments to study whether non-lethal consumption of molluscicide baits can induce subsequent active bait avoidance. Investigation of the nature of cues that determine attractiveness of molluscicide baits (smell, taste, nutritional value).

Year 2: Study neurobiological basis of molluscicide bait attraction/avoidance with the aim to identify hyper-attractive cues.

Year 3: Integrate behavioural and neurobiological data to develop and test improved bait formulation that could be used in snail/slug traps. Prepare thesis.

There will be opportunities to attend international conferences in the UK and abroad throughout the project to present data and interact with other groups working in this research area.

Partners and collaboration (including CASE)

The primary supervisor Volko Straub has extensive experience studying behavioural and neuronal plasticity and food-related learning in gastropods including the study of chemosensory processing and learning in both terrestrial and aquatic snails (Peschel et al., 1996; Straub et al., 2004, 2006). He also actively interacts with various groups working in this area across the UK. The co-supervisor Jamie McCutcheon is a leading expert in using electrochemical methods for the detection of dopamine release in the nervous system (Cone et al., 2016) and the study of the role of dopamine as a food associated reward signal (McCutcheon, 2015).

Further Details

Any questions, please contact Volko Straub, Department of Neuroscience, Psychology & Behaviour, University of Leicester; vs64@le.ac.uk

https://www2.le.ac.uk/departments/npb/people/dr-volko-straub