The insect cuticle is composed of several layers. One layer in particular called the wax layer, is composed of hydrocarbons (approximately 90%), which are molecules important in the communication between insects especially those that are social. In a study presented in a 2010 PLOS Biology publication, the hydrocarbons found on the cuticle of Drosophila were manipulated to test behavioral and pheromonal cues that cause aggression between males. In general, Drosophila use chemical cues to determine the sex of other individuals and behave accordingly based on these cues: they behave aggressively towards other males and compete to gain access to females, and do not attack females. Since the cues that cause aggression towards other males is not clearly understood, the authors of the publication decided to alter the genetic makeup of female Drosophila and de-feminize their pheromones and behavior. To de-feminize females, pheromone producing cell genes were targeted along with genes found in the nervous system that determine the behavior of both sexes.
The results of this study demonstrated that when female Drosophila are de-feminized and genetically made to be perceived as males, male Drosophila attack females. Males attacked females that only had their pheromone genes altered right after copulation, suggesting that chemical cues can overturn physical sensation. Males also attacked females that were genetically made to behave like males, despite of pheromone cues. When both genes were altered, males attacked females rather than trying to copulate first. Therefore, this study proves that aggression is not only mediated by pheromone cues, but by behavioral activity as well and demonstrates the importance of behavioral feedbacks.
Posted by: Nelson Milano