Temperature Influences Gender of Offspring, Study Finds
Whether an insect will have male or female offspring depends on the temperature, according to a new study.
Researchers experimented on the species of oophagous parasitoid (Trichogramma euproctidis) - an insect that lays its eggs inside a host insect that will be consumed by the future larvae.
"We know that climate affects the reproductive behavior of insects. But we never clearly demonstrated the effects of climate change on sex allocation in parasitoids," said Joffrey Moiroux of the University of Montreal's Department of Biological Sciences, who led the study, in the press release.
In bees, wasps and ants, the gender determination of Trichogramma parasitoids is called "haplodiploid," that is, fertilized eggs produce female offspring while unfertilized eggs produce male offspring, researchers said.
"It is possible to predict whether the parasitoid will lay a son or daughter by observing the presence or absence of a pause in its abdominal contractions at the time of spawning," he added. "A pause means the egg will be fertilized. Conversely, the absence of a pause means the egg will not be fertilized."
To test if the particular behavior was modified by climate, researchers exposed female Trichogramma to three different temperatures. They found that when it was hot, females deliberately produced more males than at medium temperature - at 34°C, the number of males produced increased by 80%.
"There was a physiological stress that was not related to the females' choice," Moiroux noted in the press release. "They intended to spawn as many females as during medium temperature, but the eggs were not fertilized after all. There were therefore more males produced at low temperature."
The study will be published in the May issue of the journal Animal Behavior.