Protein Kinase A involved in locust swarming

Originally written January 2012

Protein Underlying Swarming Behavior in Locusts Discovered

A study published in the December 19 [2011] issue of Proceedings of the National Academy of Sciences has revealed a protein responsible for transforming desert locusts from solitary feeders into swarms of agricultural pests. 

Desert locusts ( Schistocera gregaria) are normally solitary, exhibiting cryptic coloration and behavior and avoiding conspecifics. Rain is sporadic in their barren habitat, supporting vegetation growth and the subsequent locust population explosion when it occurs. Once the rains stop, however, the locusts are funneled into dwindling islands of plants.  

These patches leave the locusts crowded, triggering a behavioral and physiological transformation. Within just four hours, they change from shy and cryptic into aposematically colored, fast, and desiring to seek out other locusts. This last point causes a positive feedback loop, resulting in increasingly larger swarms of locusts that can devastate crops and pastures.

A team headed by Dr. Swidbert Ott of the University of Cambridge showed that Protein Kinase A (PKA), a signal transduction protein involved in numerous forms of learning, underlies this initial behavioral transition. When the team injected a PKA inhibitor into solitary locusts, none changed into their ravenous counterparts when crowded for hours. RNA interference – essentially knocking out a gene by destroying the mRNA, and hence respective protein, it produces – on PKA-related genes also confirmed its role in the transformation.

The fact that PKA is involved in this transformation implies that locusts ‘learn’ to crowd in the sense that a social experience alters their future behavior. PKA’s role in physiological changes due to social experience has also been shown in clinical depression in humans. 

Defeating locust swarms, however, will not be as simple as spraying PKA inhibitor onto crops. Co-author Stephen Rogers wrote, “The viability of any such control measure would be highly dependent on finding a receptor or effector that is sufficiently distinct in locusts that it can be specifically targeted without affecting other animals or species. The universal nature of the mechanism we have discovered, whilst scientifically interesting, makes it more difficult to identify specific points of attack.” 

He added, “But it is possible, indeed likely, that somewhere in the chain of molecular signaling there is something that could be targeted by a possible anti-swarming agent.” 

The group is now identifying the central nervous system proteins PKA affects in the short term and which genes become differentially expressed in the long term.

Original article

Ott SR, Verlinden H, Rogers SM, Brighton CH, Quah PS, Vleugels RK, Verdonck R and Broeck JV. (2012). Critical role for protein kinase A in the acquisition of gregarious behavior in the desert locust. Proceedings of the National Academy of Sciences. 109: 381-387.