The locust foraging gene

Abstract

Our knowledge of how genes act on the nervous system in response to the environment to generate behavioral plasticity is limited. A number of recent advancements in this area concern food-related behaviors and a specific gene family called foraging (for), which encodes a cGMPdependent protein kinase (PKG). The desert locust (Schistocerca gregaria) is notorious for its destructive feeding and long-term migratory behavior. Locust phase polyphenism is an extreme example of environmentally induced behavioral plasticity. In response to changes in population density, locusts dramatically alter their behavior, from solitary and relatively sedentary behavior to active aggregation and swarming. Very little is known about the molecular and genetic basis of this striking behavioral phenomenon. Here we initiated studies into the locust for gene by identifying, cloning, and studying expression of the gene in the locust brain. We determined the phylogenetic relationships between the locust PKG and other known PKG proteins in insects. FOR expression was found to be confined to neurons of the anterior midline of the brain, the pars intercerebralis. Our results suggest that differences in PKG enzyme activity are correlated to well-established phase-related behavioral differences. These results lay the groundwork for functional studies of the locust for gene and its possible relations to locust phase polyphenism.

Critical role for protein kinase A in the acquisition of gregarious behavior in the desert locust

“…KT5823, an inhibitor of PKG previously used in S. gregaria (36,52), did not significantly affect behavioral phase state after acute crowding, nor did it cause long-term gregarious locusts to behave less gregariously. Injection of dsRNA against for was likewise ineffective despite causing a 60% reduction in FOR protein expression in the CNS.…”

“…We identified a 1,392-bp contig of the for gene orthologue (36) in an S. gregaria CNS GenBank Expressed Sequence Tags (EST) database (13) and used it as a template to generate a 271-bp dsRNA construct (SI Appendix, Fig. S2).…”

“…Phase change in locusts is a prime example of a nexus between the social and the nutritional domain, with intraspecific competition for ephemeral resources driving the transition to group living and foraging. The brains of long-term gregarious locusts contain more PKG activity than those of solitarious locusts (36), raising the possibility that the locust orthologue of for has been coopted into controlling behavioral phase state. Here we investigated whether PKA or PKG modulate the propensity of locusts to acquire and express gregarious behavior.…”

The complexity of learning, memory and neural processes in an evolutionary ecological context

“…Gregarious locusts are incapable of aversive taste learning, whereas they do show normal appetitive learning [28]. Remarkably, the gregarious phase correlates to higher PKG expression in the brain [29], again linking the foraging gene with variation in prepared learning. In the small cabbage white butterfly, Pieris rapae, a correlation between explorative behavior and learning was also demonstrated.…”

Food searching behaviour of a Lepidoptera pest species is modulated by the foraging gene polymorphism

“…This is because it is involved in modulating foraging strategies in a variety of invertebrate species (Ben-Shahar, 2005;Fitzpatrick and Sokolowski, 2004;Fitzpatrick et al, 2005;Kaun and Sokolowski, 2009;Lucas et al, 2010;Thamm and Scheiner, 2014). The phylogenetic analysis of this gene among metazoan taxa shows high conservation of its structure and suggests a strong evolutionarily conserved link between PKG I and food-related behaviours (Fitzpatrick et al, 2005).…”