Does Size Matter? Mate Choice in Two Lekking Flies.

Area of Science:

• Entomology
• Pest Management
• Behavioral Ecology

Background:

• The Sterile Insect Technique (SIT) relies on sterile male mating success to reduce pest populations.
• Male size is often assumed to influence mating success in SIT, but empirical evidence is limited.

Purpose of the Study:

• To evaluate the effect of male size and origin (laboratory-reared vs. wild) on female mating choice in two key pest species.
• To determine if male size is a critical factor for mating competitiveness in SIT programs for Anastrepha obliqua and Anastrepha ludens.

Main Methods:

• Field cage experiments were conducted with wild females of A. obliqua and A. ludens.
• Females were presented with competing males of varying sizes and origins (wild or laboratory-reared/sterile).
• Mating success was quantified based on copulation events.

Main Results:

• A significant advantage for larger males was observed in Anastrepha obliqua.
• Male size did not influence mating competitiveness in Anastrepha ludens.
• For A. obliqua, large wild males outperformed small laboratory males, but large laboratory males performed similarly to small wild males.

Conclusions:

• Male size is a relevant factor for mating success in A. obliqua, but not A. ludens, within SIT contexts.
• SIT programs should not universally assume male size is critical; species-specific data are essential.
• When male size confers an advantage, mass-rearing protocols should prioritize producing larger males.