Rainy conditions typically result in plenty of sites for mosquito breeding and development and signal the need to keep mosquito repellent handy and in some cases, to consider the use of an insecticide as a control measure. In addition to their general annoyance, mosquitoes can transmit diseases, affect livestock performance, and spoil outdoor enjoyment. As mosquitoes develop resistance to commonly used insecticides, public health officials are looking for alternative mosquito control options. Two Ohio State University scientists have recently delivered some hope on the mosquito control front.
Peter Piermarini, an entomology professor based on the Wooster OARDC campus and an expert on the biology of mosquitos, along with Liva Rakotondraibe, an assistant professor in Ohio State’s College of Pharmacy, teamed up to test a bark extract from a small, fragrant tree native to Madagascar and found that it has successfully controlled mosquitoes. The bark extract repelled the flying adults from a distance, which kept them from landing and feeding on blood. In addition, the extract killed the larvae and adults upon contact. If developed, this represents a natural product that could be used on mosquito populations that are resistant to common insecticides as well as non-resistant mosquitos.
The bark extract came from the mandravasarotra tree grown naturally only in Madagascar. Folk medicine in Madagascar has long used parts of the tree, and more recently, as a source of essential oil for aromatherapy. The tree has a fragrant, black pepper-like scent. Through their research, the scientists found that mandravasarotra bark contains a chemical called cinnamodial, and that’s what affected the mosquitoes. Cinnamodial is a sesquiterpene, a group of plant chemicals common in resins and in essential oils.
Don’t go looking for a new mosquito control product on the shelves just yet. Think potential, not product. According to Rakotondraibe, the fact that the compound showed good activity and positive results means that this is a strong candidate for further development to improve the compound. Stay tuned.