November 9th, 2015
Brazilian researchers from the University of Sao Paulo unveiled changes in courting and mating in insects in response to changes in air pressure. They found that bugs have the ability to predict a storm, by modifying their behaviour to reduce the risk of injuries and in this way ultimately save their lives.
Under changing air pressure, the team studied the mating behaviour of three unrelated insects, the curcurbit beetle (Diabrotica speciosa), the true armyworm moth (Pseudaletia unipuncta) and the potato aphid (Macrosiphum euphorbiae).
A drop in air pressure – a condition associated with rain, wind and possible storms – caused male curcurbit beetles simply to ignore females’ sex pheromones. While they continued to mate with a few females in the proximity, the vast majority dispensed with foreplay and accelerated their mating behaviour. Surprisingly, females accepted this lack of romance, perhaps recognising the emergency of the situation. In contrast, with a stable or increasing air pressure, males responded to every female scent and took their time to woo the ladies, displaying the full mating behaviour.
Similarly, under decreasing air pressure, both female armworms and female potato aphids refused to call for mates. This is easy to understand, as this would mean dangerously balancing on the edge of a leaf in the host plant to disseminate their pheromones. Seemingly more sensitive, female potato aphids were able to detect increasing air pressure as well. Since this is also associated with high winds it has a similar obstructive effect on their mating rituals.
Results show that three very different insect species can modify their mating behaviour in anticipation of a storm. However, according to results published in the open-access journal PLOS ONE “there is a great deal of interspecific variability in their responses that can be related to differences in size, flight ability and the diel periodicity of mating”.
“Changes in foraging and mating behaviours in response to changing barometric pressure are common in insects”, conclude the authors, and continue to say that it would be very interesting to “determine exactly how changes in atmospheric pressure are detected and integrated”.
Photo: Flickr, Norby
Pellegrino AC, Penaflor MFGV, Nardi C, Bezner-Kerr W, & Guglielmo CG (2013). Weather Forecasting by Insects: Modified Sexual Behaviour in Response to Atmospheric Pressure Changes PloS ONE DOI: 10.1371/journal.pone.0075004
storm, insects, mating, mate, air pressure, detect, adapt