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Updated: Jun 4, 2026
Measuring and Altering Mating Drive in Male Drosophila melanogaster
Published on: February 15, 2017
Post-mating sexual abstinence in a male moth
Romina B Barrozo1, Christophe Gadenne, Sylvia Anton
1INRA; UMR 1272 Physiologie de l'Insecte; Signalisation et Communication; Versailles, France.
Abstract:
In most animals, male copulation is dependent on the detection and processing of female-produced sex pheromones. In males, a refractory postejaculatory interval (PEI) follows copulation, allowing them to avoid direct remating until they have replenished their reproductive tracts. In the moth Agrotis ipsilon, newly mated males show a transient inhibition of behavioral and central nervous responses to sex pheromone. Using non-pheromonal (plant) odors, pheromones and their mixture, we now show that the observed lack of pheromone response originates from differential post-mating odor processing in the brain. Although mated males still respond to plant odors alone, their response to mixtures depends on the added pheromone concentration. Below a specific threshold, sex pheromone is not detected at the brain level; above this threshold, it becomes inhibitory. This PEI can thus be interpreted as a «refusal to respond», which contradicts the generally accepted paradigm of sleep-like/exhaustion behavior during PEI.
Insights
Male moths exhibit a postejaculatory interval (PEI) where they temporarily stop responding to female sex pheromones. This study reveals this "refusal to respond" is due to altered brain processing of odors, not exhaustion.
Area of Science:
- Neuroethology
- Insect Behavior
- Chemical Ecology
Background:
- Male animals typically enter a refractory postejaculatory interval (PEI) after mating to avoid immediate remating.
- This PEI is generally attributed to physiological exhaustion or a sleep-like state.
- In the moth Agrotis ipsilon, males show reduced responses to sex pheromones after mating.
Purpose of the Study:
- To investigate the neural mechanisms underlying the postejaculatory interval (PEI) in male Agrotis ipsilon moths.
- To determine if the lack of response to sex pheromones during PEI is due to altered odor processing in the brain.
Main Methods:
- Exposure of newly mated male moths to non-pheromonal odors, sex pheromones, and mixtures of both.
- Behavioral assays and central nervous system recordings to assess odor detection and processing.
- Varying pheromone concentrations in odor mixtures to analyze response thresholds.
Main Results:
- Mated male moths still responded to non-pheromonal plant odors presented alone.
- Responses to odor-pheromone mixtures were dependent on pheromone concentration.
- Below a specific threshold, sex pheromone was not detected centrally; above it, the pheromone had an inhibitory effect.
Conclusions:
- The postejaculatory interval (PEI) in male moths is characterized by a 'refusal to respond' to sex pheromones.
- This refusal is mediated by differential odor processing in the brain, challenging the exhaustion paradigm.
- Altered pheromone detection thresholds during PEI represent a novel mechanism for regulating mating behavior.
