Experimental evidence for chemical mate guarding in a moth

Area of Science:

• Chemical ecology
• Behavioral ecology
• Insect reproductive strategies

Background:

• In polyandrous species, males often use chemical signals for mate guarding, suppressing female receptivity or deterring rivals.
• While moths extensively use pheromones for long-range communication, post-copulatory, odor-based mate guarding has not been previously documented.

Purpose of the Study:

• To investigate if male sex pheromones in the noctuid moth Heliothis virescens function as an anti-aphrodisiac after copulation.
• To determine if this chemical mate guarding impacts female mating behavior and subsequent reproductive output.

Main Methods:

• Virgin female Heliothis virescens were treated with male pheromone extract or its primary component.
• Mating frequency of treated females was compared to control virgin females.
• Reproductive output of once-mated versus twice-mated females was assessed.

Main Results:

• Females treated with male pheromone extract or its main component mated significantly less than control females.
• This anti-aphrodisiac effect persisted for at least two nights post-treatment.
• Twice-mated females exhibited significantly higher reproductive output than once-mated females, indicating a disadvantage of the male’s strategy.

Conclusions:

• The male sex pheromone of Heliothis virescens acts as an anti-aphrodisiac, representing a novel form of post-copulatory chemical mate guarding in moths.
• This strategy may influence the evolution of female sex pheromones due to their shared biosynthetic pathways.
• The findings highlight the complex interplay between chemical communication and reproductive strategies in insects.