Immune response in paper wasp workers: Task matters more than age

Area of Science:

• Insect immunology
• Social behavior in Hymenoptera
• Evolutionary biology

Background:

• Social insects like ants, bees, and wasps exhibit age-related task specialization (age polyethism).
• The interplay between behavioral tasks and immune function in these insects is not well understood.
• Immune responses, such as melanotic encapsulation, are crucial for disease resistance.

Purpose of the Study:

• To investigate whether task or age is the primary modulator of the melanotic encapsulation immune response in paper wasps.
• To compare immune strength between different worker tasks (guarding vs. foraging) and age groups.
• To determine the impact of experimental prevention of behavioral specialization on immune function.

Main Methods:

• Comparison of melanotic encapsulation strength in naturally behaving paper wasps (Polybia paulista) with different tasks and ages.
• Experimental manipulation to prevent behavioral specialization and assess the role of task versus age.
• Quantification of the encapsulation-melanization immune response.

Main Results:

• Foraging wasps exhibited significantly higher melanotic encapsulation than guarding wasps, irrespective of age.
• When behavioral specialization was experimentally blocked, melanotic encapsulation declined with increasing age.
• The findings suggest that task, rather than age, is the dominant factor influencing melanotic encapsulation in this species.

Conclusions:

• Worker immune function, specifically melanotic encapsulation, is more sensitive to behavioral tasks than chronological age in paper wasps.
• Upregulating immune responses in foragers, a high-risk behavior for pathogen exposure, likely enhances individual and colony-level disease resistance.
• This task-dependent immune modulation represents an adaptive strategy for social insect colonies.