Juvenile hormone and aggression in honey bees

Area of Science:

• Behavioral Ecology
• Insect Physiology
• Social Insects

Background:

• Individual defense behaviors in honey bees (Apis mellifera) are crucial for colony security.
• Juvenile hormone (JH) levels fluctuate developmentally and seasonally, influencing various physiological processes.
• Previous research indicates JH's role in modulating insect behavior.

Purpose of the Study:

• To investigate the correlation between individual honey bee aggression and juvenile hormone (JH) titers.
• To determine if JH levels differ between aggressive and non-aggressive individuals within colonies.
• To explore seasonal and task-related variations in aggression and JH titers.

Main Methods:

• Bioassaying winter and summer honey bees for aggressive and non-aggressive behaviors towards non-nestmates.
• Measuring juvenile hormone (JH) titers in individual bees.
• Analyzing aggression and JH levels in relation to bee age, season, and task group (nurses vs. guards).
• Conducting alarm pheromone tests to assess inter-colonial differences.

Main Results:

• Aggressive honey bees exhibited significantly higher JH titers than non-aggressive individuals within colonies.
• Summer guard bees, known for higher activity, displayed greater aggression and higher JH titers compared to nurses.
• Winter bees showed less aggression than summer guards, correlating with generally lower JH titers.
• While JH correlated with individual aggression, inter-colonial variation in aggressiveness was not directly explained by colony-level JH differences.

Conclusions:

• Juvenile hormone (JH) plays a regulatory role in individual honey bee aggression towards non-nestmates.
• Aggression levels are influenced by both individual JH titers and potentially other colony-specific factors.
• Seasonal and task-specific differences in aggression are associated with variations in JH levels.