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How do fruit flies find my kitchen?

Fruit flies have invaded our kitchen. How did they find their way into our kitchen?Home sweet home

We may have inadvertently brought home some fruit flies on our produce. They live off and on fresh fruits and vegetables and fermenting liquids, such as wine or vinegar. The larvae feed on yeast in rotting fruit. They have a high tolerance for the alcohol in these environments, which helps them defend against parasites.

The nose knows
But they also good at sniffing out clues. The nose of a fruit fly is a pair of pill-shaped antennae on the front of its face. The antennae contain specialized smelling nerves called "olfactory receptor neurons" that respond to particular chemicals that enable it to find food. 

Smell blindness
Scientists isolated a gene that control smell in fruit flies and created "odor blind" strains. In these larvae, the odor sensing neurons do not develop as much as in regular fruit flies and they do not survive as well in environments where they need to find new food sources. This could become useful as an insecticide or repellent. 

Olfactory settings
A fruit fly has a brain no bigger than a poppy seed. By messing with the connections, scientists were also able to make flies that could "smell" blue light (the frequency of electromagnetic radiation, not the beer).

Follow its nose
A fruit fly flies around in search of good smells. If the area does not make good scents, the fruit fly does not linger. When a fruit fly finds a "good" smell connected with food, it can tell which side to move toward and react quickly. When a fruit fly is hungry, its insulin level drops and the olfactory receptor neurons become extra sensitive.

Smells to avoid
Fruit flies also avoid certain smells. Soil bacteria produce a chemical called geosmin, which gives results in the smell of fresh soil, beets, and corked wine. It is also deadly to fruit flies. They have receptors for it and lead to avoidance behaviour. Perhaps another repellent idea.

Now that I have a better appreciation for the fruit fly's fine sense of smell, I'll have to keep my peelings to myself or at least make better use of my new green bucket.

More on fruit flies
Life
Odor senses
Smell and survival
Location
Way finding
Receptor system
Smell of blue light
Alcohol as antibiotic