Insulin effects on honeybee appetitive behaviour.

Area of Science:

• Insect neurobiology
• Behavioral endocrinology
• Social insect physiology

Background:

• Worker honeybees (Apis mellifera) exhibit age-dependent task specialization.
• The insulin/insulin-like signaling pathway is implicated in regulating behavioral maturation in social insects.
• Insulin signaling levels change as honeybees transition through nurse, food processor, and forager roles.

Purpose of the Study:

• To investigate the effects of insulin on olfactory and gustatory responsiveness in preforaging honeybee workers of different ages.
• To assess insulin's impact on olfactory learning in young honeybee workers.
• To understand age-dependent modulation of appetitive behaviors by insulin signaling.

Main Methods:

• Adult honeybees were reared in the laboratory or hive.
• Bees were injected with insulin or a vehicle control.
• The proboscis extension response was used to test spontaneous odor response, sucrose responsiveness, and olfactory conditioning for odor discrimination.

Main Results:

• Insulin injection increased spontaneous odor responses in honeybees.
• Insulin differentially affected sucrose responsiveness and odor discrimination based on age.
• Younger bees showed increased gustatory responsiveness but decreased learning abilities with insulin, while older bees exhibited the opposite effects.

Conclusions:

• Insulin signaling is active in young, pre-foraging honeybees.
• Insulin can enhance chemosensory responsiveness in young workers but impair their olfactory learning.
• Insulin exerts age-dependent effects on appetitive behavior, highlighting differential regulation of insulin signaling during adulthood.