Age- but not caste-related regulation of abdominal mechanisms underlying the sting reflex of the honey bee, Apis mellifera

Stinging behavior has been extensively studied in honey bees at the level of the individual, that is, in terms of stimuli that release stinging in adult bees, and in terms of integration of individual behavior into colony defense. Yet very little is known about the physiological basis for this behavior. Using an isolated abdominal preparation factors that influence peripheral control of the sting extension response are analyzed. Results show that: 1. Electromyogram activity released by severing the ventral nerve cord changed during the first few days of adult life but not later. Abdomens from older bees (nurses, guards, foragers) showed significantly higher EMG activity than newly emerged or 24 h-old bees. 2. The reflex "matured" over 5-7 days after emergence as an adult. 3. Younger bees (≤24h) had a lower threshold for initiating sting extension than older bees. However, the threshold for initiating the full sting response, i.e., extension and venom pumping, did not differ due to age. 4. Caste status was not correlated to any of the parameters of sting extension, indicating that any effect of caste on stinging behavior must arise in more anterior ganglia and/or in the brain.