Big maggots dig deeper: size-dependent larval dispersal in flies

Area of Science:

• Zoology
• Ecology
• Animal Behavior

Background:

• Animal habitat selection is crucial for survival and development.
• Movement costs, such as burrowing energy, can constrain habitat choices.
• Overwintering strategies in insects are vital for population persistence.

Purpose of the Study:

• To investigate the relationship between individual size and overwintering site selection in tephritid flies (Rhagoletis juglandis and Rhagoletis suavis).
• To assess the impact of overwintering site selection on pupal mortality, parasitism, and emergence.
• To understand the trade-offs involved in overwintering site selection for these fly species.

Main Methods:

• Field and laboratory studies were conducted on Rhagoletis juglandis and Rhagoletis suavis.
• Individual size and pupal depth were measured in both lab and field settings.
• Survival rates, parasitism levels, and emergence success from different soil depths were analyzed.

Main Results:

• Larger pupae of both fly species were consistently found at deeper soil depths.
• Pupae in deeper overwintering sites showed a trend towards higher survival rates (48% increase).
• Larger individuals had higher emergence rates at a given depth, but deep sites reduced overall emergence success.

Conclusions:

• Overwintering site selection in tephritid flies involves a trade-off between avoiding shallow-site predators/parasites and the costs of deep-site burrowing and emergence.
• Size-dependent overwintering behavior influences population dynamics.
• Pest control strategies relying on natural enemies may be less effective against larger individuals in deeper, less accessible overwintering sites.