Behavioural biomechanics of insect herbivory - a case study on leaf-cutter ants

ongoing

Insect herbivores are a dominant element in terrestrial ecosystems, and pose a continuing threat to global food security. However, little is known about a key determinant of insect herbivore success: the mechanics of plant-feeding. MechAnt proposes to transform our understanding of insect-plant relations by providing a rigorous biomechanical investigation into how insects cut leaves, using the major ecosystem engineers and principal insect pest of the New World, the leaf-cutter ants, as a model system. Specifically, MechAnt will combine the traditionally separate fields of behavioural ecology, mechanical engineering, materials science, computer vision and machine learning to investigate: (1) the mechanical and energetic constraints determining the cutting ability, and ontogeny of task choice of differently-sized workers, and hence the adaptive value of physical castes in eusocial insects; (2) the relationship between plant material properties, ease of cutting, and mandibular wear, which will reveal the key mechanical determinants of plant-herbivore species interactions; (3) the division of labour, ontogeny and demography of leaf-cutter colonies foraging on leaves of different “toughness”, testing the hypothesis that leaf-cutter colonies are organised according to ergonomic criteria. By integrating insights ranging from nano-scale mechanics up to whole-colony ecology, MechAnt will quantitatively link the mechanical properties of plants with the performance of individual foragers, the organisation of foraging parties, and the demography and social organisation of leaf-cutter ant colonies. The resulting understanding of the biomechanical innovations underpinning the success of the leaf-cutter ants will yield insights into the behavioural ecology of advanced plant-feeders, highlight the role of biomechanical constraints in the behaviour and evolution of herbivorous insects, and pave the way for the development of novel crop protection strategies.