Determining Whether Drosophila melanogaster Have an Innate Directional Preference Based on the Ambient Magnetic Field of the Earth

The status of the fruit fly Drosophila melanogaster as a model organism for behavioral and genetic research makes it an attractive candidate for investigations of the genetic basis of magnetoreception. There are two main hypotheses for how animals detect Earth-strength magnetic fields. One hypothesis is that animals use magnetite, which forms long chains and serves as a magnetic dipole, while the other hypothesis is that animals have a light-dependent magnetic response utilizing cryptochrome. Several studies have found that Drosophila can orient to Earth-strength magnetic fields using a mechanism consistent with a cryptochrome-based magnetoreceptor, but the specifics of the findings have varied. For example, two studies found that Drosophila have an innate directional preference, while two studies found that Drosophila need to be trained in order to have a directional preference. Additionally, one study found that only male flies orient to magnetic fields, while the other studies found that both male and female flied orient to magnetic fields. To help resolve the conflicting results of these studies, we aimed to determine if Drosophila melanogaster have an innate directional preference and if orientation differs between males and females. We used a sequential Y-maze housed within a Faraday cage, the purpose of which was to block out any radio frequency (RF) fields that mat affect the choices of the flies

Using Artificial Selection to Understand Orientation Behavior in Drosophila

Several studies suggest that the fruit fly Drosophila melanogaster can use magnetic fields for orientation1-4; however, the responses to magnetic fields are not consistent across studies and experiments investigating the mechanism of magnetoreception rely on magnetic fields that are at least 10 times stronger than the magnetic field of the Earth5-6. We are attempting to determine whether Drosophila have the ability to detect Earth-strength magnetic fields by running flies through a progressive Y-maze and then selectively breeding the flies based on their choices in the maze. There are two main hypotheses about the mechanism of magnetoreception in animals. The first is based on the use of magnetite, which forms long chains and serves as a magnetic dipole and has been found in organisms such as bats7. The other hypothesis is based on a light-dependent magnetic response utilizing the cryptochromephotoreceptor8. While the predominant hypothesis is that fruit flies use cryptochrome to detect magnetic fields1-6, experimental results have shown that most invertebrates use magnetite or both magnetite and cryptochrome