2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Yellow fever mosquito (Aedes aegypti).
The bacterium Xenorhabdus budapestensis synthesizes substances that repel mosquitoes more than DEET or picaridin-based repellents, Science Advances reports. They turned out to be Fabclavins, a class of substances that have so far been found only in Xenorhabdus. Researchers tested their effectiveness on three types of mosquitoes, carriers of malaria, yellow fever and other dangerous diseases.
Bacteria from the genus Xenorhabdus have a symbiotic relationship with the insect-parasitic nematode Steinernema. The bacteria live in the intestines of worms. When the nematode enters the host organism, it releases xenoradus. These, in turn, produce substances that destroy cells and immunosuppressants, which as a result leads to the death of the insect. After the death of the host, bacteria synthesize antimicrobial and antifungal substances that suppress the activity of other microorganisms. In addition, it is known that some species of xenoradus synthesize substances that repel ants, crickets and wasps.
Biologists from the University of Wisconsin at Madison, led by Susan Paskewitz, decided to study the bacteria Xenorhabdus budapestensis and see if they synthesize substances that repel mosquitoes. Nowadays, formulations based on diethyltoluene amide (DEET), a toxic substance that pollute fresh water and can be dangerous for some fish species, are often used as repellents. Researchers are analyzing plant metabolites as biological alternatives, while bacterial substances have not yet been paid attention to.
The authors tested the effect of bacterial metabolites on three species of mosquitoes - vectors of Anopheles gambiae malaria, vectors of yellow fever, dengue and Zika fevers Aedes aegypti, and common mosquitoes, Culex pipiens. Female mosquitoes were fed through a gauze membrane that had been soaked in a solution of bacterial metabolites, water (control), or DEET or picaridin, another popular repellent.
It turned out that in order to scare off half of the mosquitoes, comparable concentrations of bacterial substances and DEET were needed, and six times more picaridin. In order to starve 90 percent of mosquitoes, DEET and picaridin were required three and eight times more than bacterial metabolites, respectively.
To find out which substances turned out to be mosquito repellents, the scientists conducted a mass spectrometric analysis of the fraction of metabolites that repelled insects. It turned out that this is a mixture of two fabclavins - peptide-polyketide hybrids with insecticidal and antimicrobial activity. Researchers discovered this class of substances relatively recently, and so far it is known that it is only synthesized by xenoradus.
In the future, the authors plan to identify other substances in the "repellent" fraction and find out whether they act separately or in combination. They also plan to study the efficacy and toxicity of these substances to see if they can be used as a repellent.
Researchers recently defeated a dengue fever pathogen in an Australian city using the Wolbachia bacteria. This microorganism is a symbiont of insects, including mosquitoes, and is able to suppress the activity of viruses. Mosquitoes stop carrying them, and, accordingly, infect people.
