Phase change the defining feature of locust biology

Phase change: the defining feature of locust biology Reared alone: Reared crowded: phase solitaria phase gregaria

Behaviour: the engine of phase change Temporal dynamics of behavioural change High resolution correlate for studying underlying mechanisms Basis for exploring population dynamics: individual-based models Environment

Step 1: Rearing locusts

Step 2: Measuring behavioural phase state

Behaviour 1 h Be Be ha v iou r 3 a u vio r 2

Multiple logistic regression model

Behaviour 1 ? p (solitary) = 1. 0 p(solitary) = 0. 5 h Be a u vio r 2 p(solitary) = 0 Be ha v iou r 3

Step 3: Quantifying the time-course of behavioural phase change A. Gregarisation of solitarious insects

Median p (solitary) B. Re-isolation of gregarised solitarious insects

Median p (solitary) C. Solitarisation of gregarious insects

p (solitary) 1. 0 F (time previously crowded) 0. 0 moult crowded isolated moult Time Also accumulates across generations: epigenetic maternal effect

What stimuli cause behavioural gregarisation? 1. Sight of other locusts? 2. Smell of other locusts? 3. Contact with other locusts? (4. Sound of other locusts)

Contact with others: 1. Mechanosensory 2. Contact chemosensory Millet seed Locust surface wax extract

Where on the body surface are the active sites? % gregarious 0 -25 26 -50 51 -75 76 -100

Neural pathways of gregarisation *

Correlated changes in CNS neuromodulators

Epigenetic transfer of phase-state

Dissecting the basis of epigenetic transfer Stage 1: Treat parents 1. Mother’s phase state: solitary- or crowd-reared 2. Father’s phase state: solitary- or crowd-reared 3. Mother alone or crowded from mating until oviposition Stage 2: test behavioural phase-state of hatchlings

% of hatchlings

What is the mother’s memory of crowding?

How does the mother influence hatchling phase-state? Egg laying locust

What is the gregarising agent? – extensive HPLC, MS and NMR analysis nearing completion Where is it produced?

Source of extracts for treatment of eggs Accessory gland extract Oviduct fluid

Ligaturing the accessory glands of gregarious females

Using behaviour as a means to explore population dynamics

Individual-based modelling RESOURCES CONCENTRATED RESOURCES DISPERSED

food dispersed food clumped

Interaction between spatial distribution and nutritional quality of food resources

Into the real world….

Effect of spatial distribution of food plants in adult environment on hatchling phase-state

The Oxford Desert Locust Phase Project Development of behavioural assay and description of time course of behavioural phase change Identification of gregarising stimuli Epigenetic transfer of phase-state to offspring Analysis of neural bases of behavioural phase change Discovery of maternal gregarising agent Molecular analysis of modulator/peptide profiles and testing of behavioural effects Identification of site of production Mode of action Interaction with resource distribution at small spatial scales Individual-based models Laboratory and field testing Interaction between spatial distribution and resource quality Chemical analysis Nutrients vs. allelochemicals Nutritional ecology: geometric analysis of nutrient balancing Evolution of colour forms: gut-mediated protection, aposematism Speciation within the genus Schistocerca and the ecological correlates of phase change Molecular developmental mechanisms Exploration of larger spatial scales (metapopulation responses, GIS) Synthesis Applied aim: Phase manipulation Applied aim: Swarm prediction Population genetics

The Oxford Desert Locust Phase Project Oxford group Steve Simpson Iain Couzin Peter Roessingh David Sumpter Saiful Islam Philip Maini Bouaichi Abdelghani Bernd Haegele Neil Oldham Emma Despland Matthew Collett (individual-based modelling) David Krakauer (individual-based modelling) Tim Dodgson Robin Aplin (foam chemistry MS; Dyson Perrins) Tim Claridge (NMR; Dyson Perrins) David Raubenheimer (geometry of nutrition) Spencer Behmer (geometry of nutrition) Steve Rogers (neurobiology, also Cambridge) Collaborators Alan Mc. Caffery (maternal effect; Reading) Greg Sword (colour morphs, aposematism, speciation; Austin, Texas) Arnold De Loof (peptide profiles; Leuven, Belgium) Paul Pener (stimuli eliciting non-behavioural phase characters) Frantisek Sehnal (ecdysteroids; Czech Republic) Bouaichi Abdelghani (field work; Morocco) Hans Wilps (field work; Mauritania) Jane Rosenberg (GIS modelling; NRI, Greenwich) Malcolm Burrows (neurobiology; Cambridge) Tom Matheson (neurobiology; Cambridge) Kamal Ibrahim (population genetics; East Anglia) Ian Wilson (foam chemistry MS-NMR; Astra. Zeneca, Maccelsfield) Eva Lentz (foam chemistry MS-NMR; Astra. Zeneca, Maccelsfield)