Fruit fly study offers clues to insect survival in a hotter, drier world

Researchers at the Francis Crick Institute have discovered a unique lipid barrier in fruit fly pupae that helps protect them from dehydration in hot and dry conditions. This internal barrier, made of hyper-long hydrocarbons, is formed during the larval stage and stored in the larval fat reserve until needed. The team analyzed the chemical composition of these hydrocarbons, which are similar to those found in crude oil, using methods adapted from the petroleum industry and advanced molecular imaging techniques.

They found that while adult fruit flies have a lipid barrier made of medium-length hydrocarbons that also serve as sex pheromones, the pupae have a specialized internal barrier of hyper-long hydrocarbons. This barrier enables the pupa to resist dehydration, but exposure to high temperatures and low humidity significantly reduces its water content and accelerates dehydration.

The absence of the hyper-long hydrocarbon-producing enzyme in adult flies leads to higher dehydration levels, which are incompatible with survival. Interestingly, a desert species of fruit fly called Drosophila mojavensis retains hyper-long hydrocarbons as an adult, rather than switching to shorter ones like other Drosophila species.

This adaptation suggests that hyper-long hydrocarbons may be more important for survival in desert environments than airborne sex pheromones. The study, published in Science Advances, highlights the importance of understanding insect resilience to climate change, particularly in the context of increasing aridity and temperature.