Rhodamine B: A New Tool for Monitoring Mosquito Mating
Tuesday, November 21, 2017
We are very excited to announce the Debug Project’s first publication, which explores tracking mosquito movement and mating in the wild, a collaborative effort between Verily’s Debug team, The Australian ...Read More
We are very excited to announce the Debug Project’s first publication, which explores tracking mosquito movement and mating in the wild, a collaborative effort between Verily’s Debug team, The Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) and James Cook University (JCU) in Australia. The study demonstrated that rhodamine B can be utilized to successfully perform mark-release-recapture (MRR) experiments and observe mating in the field.
Rhodamine B is a red dye that fluoresces when exposed to certain wavelengths of light. When fed to mosquitoes, it binds to internal proteins and stains them bright red. Rhodamine B staining is observable in adult mosquitoes by eye or by a microscope when looking at small tissues, which can be useful when studying mosquitoes in the wild. Mosquitoes can be tracked in the wild using an approach known as mark-release-recapture (MRR) where insects are marked (in our research, with rhodamine B), released into the wild, and then recaptured for marking examination. MRRs provide information on how far mosquitoes move across the landscape, as well as their lifespan, and can help us estimate the wild population size by comparing the ratio of marked recaptured individuals to unmarked insects.
Traditional methods for MRR labeling rely on dusting mosquitoes with fluorescent powders, however, these powders can be difficult to detect and can impair a mosquito's ability to fly. Rhodamine B, on the other hand, can be easily visualized and evidence suggests it does not impact a mosquito’s activity or health.
Rhodamine B has another useful property: it can stain the male mosquito’s semen, which females store in dedicated capsules called spermathecae. After mating with a rhodamine B fed male, stained semen can be observed in the female’s spermatheca using a microscope. So not only can rhodamine B be used to track males in the wild, it can also be used to measure how successfully they mate with wild females.
In our paper, we demonstrate that rhodamine B is a very effective label when mixed into the honey normally fed to male mosquitoes, with the stain visible up to three days after males are released. We performed several small scale MRR experiments in Cairns, Australia and were able to successfully detect mating between our lab reared males and wild females through rhodamine B fluorescence.
For future sterile male releases rhodamine B labeling will be a useful tool allowing us to easily and efficiently assess the dispersal, fitness and mating ability of the males we rear in our Debug factory. We are excited to continue this research and further demonstrate rhodamine B’s utility.
Sara Mitchell, PhD, Senior Scientist, Verily
Rhodamine B is a red dye that fluoresces when exposed to certain wavelengths of light. When fed to mosquitoes, it binds to internal proteins and stains them bright red. Rhodamine B staining is observable in adult mosquitoes by eye or by a microscope when looking at small tissues, which can be useful when studying mosquitoes in the wild. Mosquitoes can be tracked in the wild using an approach known as mark-release-recapture (MRR) where insects are marked (in our research, with rhodamine B), released into the wild, and then recaptured for marking examination. MRRs provide information on how far mosquitoes move across the landscape, as well as their lifespan, and can help us estimate the wild population size by comparing the ratio of marked recaptured individuals to unmarked insects.
A male Aedes aegypti mosquito fed on a mixture of rhodamine B and honey is stained visibly red (A) compared to males fed on honey alone (B).
Traditional methods for MRR labeling rely on dusting mosquitoes with fluorescent powders, however, these powders can be difficult to detect and can impair a mosquito's ability to fly. Rhodamine B, on the other hand, can be easily visualized and evidence suggests it does not impact a mosquito’s activity or health.
Rhodamine B labeled males will seek out wild females. During mating males transfer their labelled semen to females, which can be detected by its red fluorescent properties.
Rhodamine B has another useful property: it can stain the male mosquito’s semen, which females store in dedicated capsules called spermathecae. After mating with a rhodamine B fed male, stained semen can be observed in the female’s spermatheca using a microscope. So not only can rhodamine B be used to track males in the wild, it can also be used to measure how successfully they mate with wild females.
Rhodamine B labeled sperm within the female spermathcal capsules after mating.
In our paper, we demonstrate that rhodamine B is a very effective label when mixed into the honey normally fed to male mosquitoes, with the stain visible up to three days after males are released. We performed several small scale MRR experiments in Cairns, Australia and were able to successfully detect mating between our lab reared males and wild females through rhodamine B fluorescence.
For future sterile male releases rhodamine B labeling will be a useful tool allowing us to easily and efficiently assess the dispersal, fitness and mating ability of the males we rear in our Debug factory. We are excited to continue this research and further demonstrate rhodamine B’s utility.
Sara Mitchell, PhD, Senior Scientist, Verily
