Dispersal From Natal Patch Correlates With the Volatility of Female Sex Pheromones in Parasitoid Wasps

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Böttinger, Lea ; Stökl, Johannes:
Dispersal From Natal Patch Correlates With the Volatility of Female Sex Pheromones in Parasitoid Wasps.
In: Frontiers in Ecology and Evolution. Bd. 8 (2020) . - 557527.
ISSN 2296-701X
DOI: https://doi.org/10.3389/fevo.2020.557527

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Abstract

Chemical communication via pheromones is considered the oldest and most
widespread form of communication in nature. However, the way that the enormous
diversity of species-specific pheromones evolved is still of debate. One possible process
driving pheromone evolution is the mate-finding and dispersal behavior, as long-distance
mate-finding requires highly volatile compounds. In contrast, less volatile compounds
might be sufficient attractants in species that search for mates within proximity. In the
parasitoid wasp genus Leptopilina, the composition of species-specific sex pheromones
ranges from highly volatile iridoid compounds through combinations of iridoids with
low volatile cuticular hydrocarbons (CHCs) to only CHCs. To study the selective forces
shaping the composition of sex pheromones in Leptopilina, we examined the dispersal
behavior, i.e., the proportion of male and female wasps dispersing after emergence, in
four species with known sex pheromone compositions. If males and females disperse
immediately, long-range mate attraction might become necessary, favoring volatile
iridoids over CHCs. If mating occurs directly on the host patch, short-range mate
attraction by low volatile CHCs might suffice. Our analyses have revealed that the
dispersal behavior of Leptopilina males and females after emergence does indeed
differ between species with differently volatile sex pheromones. Specifically, males of
species with iridoid sex pheromones start to disperse immediately before their females’
emergence, whereas males of species with CHC sex pheromones delay dispersal until
their conspecific females emerge. While the differences in female dispersal behavior
turned out to be species-specific, differences in male dispersal correlated with the
volatility of female-produced sex pheromones of each species. This study significantly
contributes to our understanding of the evolution of sex pheromones by differences in
dispersal behavior.