From drastic changes in the Earth's climate, global warming seems to touch on the biological facet of the planet, too. A recent study revealed that the gender of insects' offspring can be largely influenced by the weather.
This is what a team of researchers from the Department of Biological Sciences of University of Montreal, Horticulture Research and Development and Centre of Agriculture and Agri-Food Canada found out after observing a particular type of insect called Trichogramma euproctidis, an oophagous parasitoid that injects its small eggs inside another insect to serve as host for the offspring that will soon be eaten up when they hatch.
"We know that climate affects the reproductive behavior of insects," said Joffrey Moiroux of the University of Montreal. "But we never clearly demonstrated the effects of climate change on sex allocation in parasitoids."
Like other insects such as bees, spider mites, ants and wasps, the gender of Trichogramma euproctidis can be determined through a system called "haplodiploidy." If the insect hatches from a fertilized egg, the offspring is a female or diploid. If it comes from an unfertilized egg, the offspring is a male or haploid.
Similarly, if there is a gap in the abdominal contractions of the female Trichogramma, the egg is a fertilized one. If there is no pause detected, then an unfertilized egg will likely come out, Moiroux explained.
In the study, which came out in the journal Animal Behaviour, the researchers exposed female Trichogramma into three temperatures ranging from 34°C, 24°C and 14°C in order to find out if changes in climate could influence the fertilization of the insects' eggs. The results were interesting.
The insects exposed to hot temperatures around 34°C were more likely to produce males 80 percent of the time but the offspring were smaller in size. However, the gender of the Trichogramma is "compromised," said Moiroux, whenever cold temperature settles in. "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," he said.
The weather also influences how these parasitic insects choose their host for their eggs. During hot weather, they tend to look for their usual hosts to lay its male offspring while they choose "reserve hosts," such as the shade of hedges to lay its eggs carrying female newborns.
"It is therefore advantageous for mothers to have the largest female offspring possible and use hosts that will produce smaller offspring for males," Moiroux concluded.
