Cannabis extract against mosquito larvae

The cannabis extract results in 100% destruction of pesticide-resistant mosquito larvae

New global research into combating insecticide resistance has found that a cannabis plant extract—commonly used for a variety of health conditions—is highly effective at killing mosquito larvae.

Mosquitoes and insecticide resistance: a global threat and potential solutions

Mosquitoes affect the lives of millions, as these tiny insects spread malaria, dengue fever, Zika virus, and other serious diseases. In recent decades, insecticides have been a key tool in fighting mosquitoes across many parts of the world. However, mosquitoes are increasingly developing resistance to various insecticides, posing a significant public health challenge.

What exactly is insecticide resistance and how did it develop?

Insecticide resistance occurs when a mosquito population undergoes genetic changes that enable them to survive exposure to chemicals that once killed them. This is an evolutionary process similar to the antibiotic resistance we now see in humans.

Mosquitoes have short lifespans and reproduce quickly, allowing rapid adaptation to their environments. When the same insecticide is used repeatedly in a given area, genetic resistance to that chemical develops. The insects that survive the poisoning pass their resistance on to their offspring, and over time, an increasing portion of the population becomes resistant.

The global situation

According to World Health Organization (WHO) reports, an increasing proportion of mosquito populations worldwide are becoming resistant to insecticides, especially in regions where chemicals are heavily used to prevent disease. In Africa, where malaria is a major public health issue, the mosquitoes that spread the disease have developed significant resistance to pyrethroid-based insecticides, which are also used to treat mosquito nets. Similar trends have been observed in parts of Asia and South America.

Why is insecticide resistance dangerous?

The declining effectiveness of insecticides poses a serious problem for controlling disease outbreaks. When spraying loses effectiveness, controlling the spread of illnesses becomes much harder. This is especially critical in the fight against malaria, which claims more than 400,000 lives annually, most of them children.

Insecticide resistance in mosquitoes presents a major global challenge, but advances in science and technology offer hope for effective solutions. Integrated approaches and new technologies can help reduce disease transmission and preserve the public health gains achieved in recent decades.

Latest research points to cannabis extract and its CBD content as playing a key role in this fight

CBD, or cannabidiol, is a natural component of the cannabis plant. Known for its calming properties, it’s increasingly popular for pain relief, anxiety reduction, anti-inflammatory purposes, and treating sleep disorders. CBD Oils, capsules, and creams are widely used, as many experience improvements in various health issues without worrying about side effects. Although CBD is popular as a natural therapeutic option, surprisingly, a research finding highlights an entirely different application.

A study published in the Insects journal found that cannabis extract kills mosquito larvae of two different strains of the yellow fever mosquito within 48 hours, one of which was resistant to conventional insecticides.

To test cannabis’s toxic effect on mosquito larvae, the research team dried cannabis leaves in air, ground them into a fine powder, and soaked them in methanol for several weeks. The methanol was later removed from the solution, yielding a crude extract that was then mixed into the larvae's food.

The extract proved potent enough to be equally toxic to larvae of both mosquito strains. However, the surprising part—said Martinez Rodriguez, the lead researcher—was how little was needed to achieve such lethal effects.

“When comparing the amount of hemp extract required to kill the population with that needed for traditional synthetic insecticides, it’s right at the top, but compared to other natural extracts, only relatively small amounts are necessary to achieve high mortality rates,” Martinez Rodriguez said.

The benefits of cannabis and future research directions

While it’s still unclear exactly how the extract biologically affects mosquito larvae, results show that CBD was the primary active compound in the cannabis extract, effectively overcoming the larvae’s resistance mechanisms to other insecticides.

One advantage of cannabis is that it can be grown sustainably compared to other plant alternatives, so cannabis-based insecticides could potentially be produced relatively cheaply.

Peter Piermarini, co-author of the study and professor at the Ohio State Entomology Institute, said that while this discovery bodes well for developing future natural mosquito control products, further research is needed to determine how safe cannabis and CBD are for honeybees and other pollinators—creatures that scientists want to protect rather than harm.

“CBD is a compound that’s safe for humans and most animals,” Piermarini said. “It will be interesting to learn more about how CBD interacts with different insect proteins to understand why it’s safe for people but not for mosquito larvae.”

Reference: Erick J. Martínez Rodríguez, P. Larry Phelan, Luis Canas, Nuris Acosta, Harinantenaina L. Rakotondraibe, and Peter M. Piermarini29: “Larvicidal Effects of Hemp Extracts and Cannabidiol Against the Yellow Fever Mosquito Aedes aegypti”