Locust Physiology and Ecology

Locust Phase Change

Researchers: Fiona Clissold, Ekaterina Orlova, Katie Robinson, Tamara Pulpitel, Stephen Simpson

Locust species can change from the cryptic solitarious to the swarming gregarious phase in response to population density. Our programme of research investigates the neurological, physiological and ecological mechanisms involved in behavioural phase change. We contend that elucidating the behavioural processes involved in phase change provides: a) the best route to understanding underlying physiological and molecular mechanisms, and b) is the key to understanding the interactions between individual locusts and their environment that lead to population-level phenomena such as swarming.

Key Publications:

  • Simpson SJ, Sword GA, and Lo N. 2011. Insect polyphenism. Current Biology 21:R738-R749.
  • Cullen D, Sword GA, Dodgson T, and Simpson SJ. 2010. Behavioural phase change in the Australian plague locust, Chortoicetes terminifera, is triggered by tactile stimulation of the antennae. Journal of Insect Physiology 56:937-942.
  • Pener MP, and Simpson SJ. 2009. Locust phase polyphenism: an update. Advances in Insect Physiology 36:1-286.
  • Miller GA, Islam MS, Claridge DW, Dodgson T, and Simpson SJ. 2008. Swarm formation in the desert locust (Schistocerca gregaria): isolation and NMR analysis of the primary maternal gregarizing agent. Journal of Experimental Biology 211:370-376.
  • Rogers SM, Matheson T, Sasaki K, Kendrick K, Simpson SJ, and Burrows M. 2004. Substantial changes in central nervous neurotransmitters and neuromodulators accompany phase change in the locust. Journal of Experimental Biology 207:3603-3617.
  • Simpson SJ, Despland E, Haegele BF, and Dodgson T. 2001. Gregarious behaviour in desert locusts is evoked by touching their back legs. PNAS 98:3895-3897.

Locust Biological Control and Density Dependant Prophylaxis

Researchers: Tamara Pulpitel, Robert Graham, Stephen Simpson

A key principle in the evolutionary ecology of disease and immunity is the degree to which hosts invest in defence against parasites and pathogens. A clear prediction that arises from these concepts is that hosts living at high densities should invest more in defence than those living at low densities: a hypothesis known as “density-dependent prophylaxis” (DDP). The Australian Plague Locust Chortoicetes terminifera is an ideal model system to study the effects of crowding and migration, occurring in a socio-politically stable continent, allowing state-of-the-art field and laboratory experimentation. We are interested in three main objectives, a) to determine the spatial and temporal pattern of natural disease epizootics in APL populations, b) to compare immune function and disease resistance in gregarious and solitary locusts, and c) to quantify the impact of protein availability on immune function, host behaviour and disease resistance. Collaborations with the APL Commission (APLC) will endeavour to investigate the use of naturally-occurring microbes as novel biological control agents. This research will contribute to the knowledge-base in global food security and nutrition biology.

Key Publications:

  • Miller GA, and Simpson SJ. 2010. Isolation from a marching band increases haemocyte density in wild locusts (Chortoicetes terminifera). Ecological Entomology 35:236-239.
  • Miller GA, Pell JK, and Simpson SJ. 2009. Crowded locusts produce hatchlings vulnerable to fungal attack. Biology Letters 5:845-848.
  • Wilson K, Thomas MB, Blanford S, Dogett M, Simpson SJ, and Moore SL. 2002. Coping with crowds: density-dependent disease resistance in desert locusts. PNAS 99:5471-5475.