Brood care by male bumble bees.

Area of Science:

• Entomology
• Behavioral Ecology
• Social Insects

Background:

• Brood care in social insects is crucial for colony survival.
• In Bombus griseocollis, brood care has primarily been attributed to females (workers and queens).
• The role of males in brood care, specifically pupal incubation, remains less understood.

Purpose of the Study:

• To investigate the involvement of male Bombus griseocollis in pupal incubation.
• To quantify the thermal contribution of male incubation to pupae.
• To assess the potential fitness implications for males participating in brood care.

Main Methods:

• Observational studies on male Bombus griseocollis behavior.
• Measurement of pupal temperatures during male incubation.
• Comparison of incubated versus unincubated pupal temperatures.

Main Results:

• Male Bombus griseocollis were observed to incubate pupae shortly after adult emergence.
• Male incubation posture is indistinguishable from that of females.
• Pupae incubated by males showed a temperature increase of 4-6°C compared to unincubated pupae.

Conclusions:

• Male Bombus griseocollis contribute to brood care through pupal incubation.
• Male incubation provides significant thermal benefits to developing nestmates.
• This behavior represents a form of incidental kin selection, benefiting the colony without direct fitness costs to males.