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
This is an interesting article because it makes me curious as to which other insects would response to pheromones or genetic cues in this way. It is interesting that males would attack the females (now genetically males) without trying to copulate, due to the behavioral responses. But I do not feel that this study proves that males act aggressively towards females that are genetically altered to act like males. There needs to be more research and variable testing done to make this study more substantial.
ReplyDeleteI understand what you are saying Liz, but the point of the study was to show that the chemicals on the cuticle and behavior of the male fruit flies were the cause of the aggression. They used female fruit flies to test this because males do not naturally behave aggressively towards them. By targeting certain genes in female fruit flies, they were able to make them (in simple terms) smell and behave like males to also show that the anatomy of both sexes does not affect male aggression.
ReplyDeletePosted by: Nelson Milano