A behavioural analysis of phase change in the desert locust

  title={A behavioural analysis of phase change in the desert locust},
  author={Stephen James Simpson and Alan R. McCaffery and Bernd F. H{\"a}gele},
  journal={Biological Reviews},
A programme of research into phase change in the desert locust, Schistocerca gregaria, is described. The ability to change phase between solitarious and gregarious forms in response to population density is a key feature of locusts and is central to their occasional yet catastrophic impact on humans. Phase polymorphism is an extreme form of phenotypic plasticity. The most labile phase characteristic is behaviour. It is argued that a fully integrated study of behavioural phase change provides a… 
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Using an individual-based evolutionary model, it is revealed that cannibalism, a striking feature of locust ecology, could lead to the evolution of density-dependent behavioural phase-change in juvenile locusts and it is shown that this behavioural strategy minimizes risk associated with cannibalistic interactions and may account for the empirically observed persistence of locUST groups during outbreaks.
Innate phase behavior in the desert locust, Schistocerca gregaria
It seems that rather than emerging with a parentally derived and predetermined phase, hatchlings have an independent default or innate behavioral state, which reflects at least tolerance if not attraction to conspecifics and may later become dominant under the appropriate environmental conditions.
Small‐scale vegetation patterns in the parental environment influence the phase state of hatchlings of the desert locust
The offspring of locusts exposed to more clumped patterns of vegetation exhibited more gregarious behaviour when tested in a behavioural phase assay than did progeny from parents left in enclosures with more scattered vegetation.
Endocrinology of reproduction and phase transition in locusts.
Dopaminergic modulation of phase reversal in desert locusts
It is shown that dopaminergic modulation plays an important role in the plasticity underpinning phase transition and sets a context to deepen the understanding of the complementary role that distinct neuromodulators play in polyphenism in locusts.
Polyandry as a Signal of Phase Shift in Female Desert Locust Schistocerca gregaria
The results suggest that multiple mating is not associated with fitness benefits, and polyandry acts as a signal of phase shift through offspring in the gregarious desert locust.
The role of food distribution and nutritional quality in behavioural phase change in the desert locust
The effect of food distribution on locust phase depended on the nutritional quality of the food, and clumped resource distribution led to increased gregarization in the dilute and the complementary diet treatments.
Behavioural phase polyphenism in the Australian plague locust (Chortoicetes terminifera)
It is demonstrated that juvenile C. terminifera express extreme density-dependent behavioural phase polyphenism, which differs from other major locust species in that Isolated-reared juveniles are sedentary and repelled by conspecifics, whereas crowd- reared individuals are highly active and are attracted to conspespecifics.


Analysis of phase-related changes in behaviour of desert locust nymphs
An assay is developed in which the behavioural responses of an individual locust to a group of conspecifics are used to derive an index representing the ‘behavioural phase status’ of that insect. The
The influence of environmental microstructure on the behavioural phase state and distribution of the desert locust Schistocerca gregaria
It is shown that the fine‐scale distribution of food plants, perches and favourable microclimatic sites influences the spatial distribution of locusts, both in the laboratory and under semi‐field conditions.
The time‐course of behavioural phase change in nymphs of the desert locust, Schistocerca gregaria
Results indicate that, while behavioural gregarization is maximal within a few hours of crowding, solitarization is a two‐stage process, changing rapidly at first, then more slowly as a function of the period of previous crowding.
Spatial scales of desert locust gregarization.
Computer simulations and a laboratory experiment are presented that show how differences in resource distributions, conspicuous only at small spatial scales, can have significant effects on phase change at the population level; local spatial concentration of resource induces gregarization.
Primer pheromones and polymorphism in the desert locust
Solitarization in the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae)
It had been previously considered that S. gregaria nymphs lose very little of their gregarious tendency once it is acquired; this is now shown not to be the case.