Differential gene expression of density-dependent phenotypic plasticity in Schistocerca americana (Orthoptera: Acrididae)

The American Birdwing Grasshopper, Schistocerca americana, has been shown to express density-dependent phenotypic plasticity reminiscent of the desert locust, Schistocerca gregaria.  This process in the extreme form of locust phase polyphenism is the main driver in the desert locust’s ability to swarm.  S. americana does not swarm and rarely has outbreaks but still shows this trait more so than most other Schistocerca species.  The Schistocerca species that do express density-dependent phenotypic plasticity change from a solitary morph, where they are cryptic in color, and have solitary behavior to a crowded morph where they are conspicuous in color, much more active, and aggregate to each other in response to higher population density.  The first aspect to change in this transition is behavior.  It has been found in the desert locust that protein kinase A is involved in the behavioral transition and when its expression is knocked down, solitarious individuals remain solitarious even after exposure to high density.  I have found highly differential expressed transcripts between the isolated and crowded morph of S. americana.  In this study I quantify the expression level of PKA between these phases and another gene that is most likely involved in the phase transition process.  This work is in anticipation of knocking down these genes to verify if they also prevent the phase transition in S. americana.  This work is to inspire more work in revealing the molecular processes behind the density-dependent phenotypic plasticity phenomenon that remains largely unknown.