Brood Parasites That Care: Alternative Nesting Tactics in a Subsocial Wasp

Area of Science:

• Behavioral Ecology
• Evolutionary Biology
• Insect Behavior

Background:

• Brood parasitism is a classic example of host-parasite conflict, where parasites lay eggs in host nests, imposing costs.
• Subsocial wasps (Ammophila pubescens) display a unique form of brood parasitism, alternating between nest initiation and egg replacement in conspecific nests.
• Intruder wasps often provision offspring in host nests, a deviation from typical brood parasite behavior.

Purpose of the Study:

• To investigate the reasons behind intruder provisioning behavior in Ammophila pubescens.
• To understand the dynamics and fitness consequences of these unusual brood parasitic interactions.
• To explore the evolutionary implications of egg replacement strategies in this species.

Main Methods:

• Field data collection on Ammophila pubescens behavior.
• Analysis of provisioning strategies and fitness payoffs for both hosts and intruders.
• Comparative analysis of egg replacement tactics and outcomes.

Main Results:

• Intruder wasps could not improve fitness by adopting a non-provisioning brood parasite strategy; offspring survival depended on host provisioning.
• While some hosts benefited from intruder provisioning, the overall interaction represented parasitism, with hosts bearing costs and intruders benefiting.
• Intruders were more likely to lay the final egg in replacement sequences, suggesting an advantage in this tactic.

Conclusions:

• The provisioning behavior of intruder wasps in Ammophila pubescens is a complex adaptation driven by uncertain host provisioning.
• This form of conspecific brood parasitism imposes net costs on hosts, highlighting the intricate nature of social conflicts.
• Selection may favor enhanced offspring discrimination, potentially driving cycles of costly egg replacement and counter-adaptation.