Modelling locust foraging: How and why food affects group formation
Open Access
- 7 July 2021
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLoS Computational Biology
- Vol. 17 (7), e1008353
- https://doi.org/10.1371/journal.pcbi.1008353
Abstract
Locusts are short horned grasshoppers that exhibit two behaviour types depending on their local population density. These are: solitarious, where they will actively avoid other locusts, and gregarious where they will seek them out. It is in this gregarious state that locusts can form massive and destructive flying swarms or plagues. However, these swarms are usually preceded by the aggregation of juvenile wingless locust nymphs. In this paper we attempt to understand how the distribution of food resources affect the group formation process. We do this by introducing a multi-population partial differential equation model that includes non-local locust interactions, local locust and food interactions, and gregarisation. Our results suggest that, food acts to increase the maximum density of locust groups, lowers the percentage of the population that needs to be gregarious for group formation, and decreases both the required density of locusts and time for group formation around an optimal food width. Finally, by looking at foraging efficiency within the numerical experiments we find that there exists a foraging advantage to being gregarious. Locusts are short horned grass hoppers that live in two diametrically opposed behavioural states. In the first, solitarious, they will actively avoid other locusts, whereas the second, gregarious, they will actively seek them out. It is in this gregarious state that locusts form the recognisable and destructive flying adult swarms. However, prior to swarm formation juvenile flightless locusts will form marching hopper bands and make their way from food source to food source. Predicting where these hopper bands might form is key to controlling locust outbreaks. Research has shown that changes in food distributions can affect the transition from solitarious to gregarious. In this paper we construct a mathematical model of locust-locust and locust-food interactions to investigate how food distributions affect the aggregation of juvenile locusts, termed groups, an important precursor to hopper bands. Our findings suggest that there is an optimal food distribution for group formation and that being gregarious increases a locusts ability to forage when food becomes more patchy.Keywords
Funding Information
- School of Mathematical Sciences and the Faculty of Engineering, Computer and Mathematical Sciences, University of Adelaide
- University of Newcastle Australia (PhD scholarship)
- University of Newcastle Australia (start-up support)
This publication has 48 references indexed in Scilit:
- A new interaction potential for swarming modelsPhysica D: Nonlinear Phenomena, 2013
- Locust Dynamics: Behavioral Phase Change and SwarmingPLoS Computational Biology, 2012
- Role of social interactions in dynamic patterns of resource patches and forager aggregationProceedings of the National Academy of Sciences of the United States of America, 2012
- Non-local models for the formation of hepatocyte–stellate cell aggregatesJournal of Theoretical Biology, 2010
- Nutritional state and collective motion: from individuals to mass migrationProceedings Of The Royal Society B-Biological Sciences, 2010
- Random walk models in biologyJournal of The Royal Society Interface, 2008
- A model for rolling swarms of locustsThe European Physical Journal Special Topics, 2008
- From Disorder to Order in Marching LocustsScience, 2006
- An integro-differential equation arising as a limit of individual cell-based modelsJournal of Differential Equations, 2006
- Epidemic Diseases and Host Clustering: An Optimum Cluster Size Ensures Maximum SurvivalJournal of Theoretical Biology, 1997