The Van Trump Report

Hemp Finding New Market as Natural Insecticide

Mosquitoes have absolutely no tolerance for hemp, according to a new study. The active ingredient in hemp, cannabidiol (CBD) causes 100% mortality against mosquito larvae, including ones known to be resistant to typical insecticides.

The study comes from researchers at Ohio State University investigating whether extracts of hemp leaves were toxic to the larvae from two different strains of the yellow fever mosquito, one that was resistant to typical insecticides and another that was not. Unlike adult mosquitoes, mosquito larvae are aquatic organisms often found in standing water. Insecticides are critical for killing mosquito larvae and keeping adult populations under control. However, rampant overuse has led to widespread insecticide resistance.

“Mosquitoes are one of the deadliest animals in the world, mainly because as adults they serve as vectors of disease,” said Erick Martinez Rodriguez, lead author of the study and a graduate student in entomology at The Ohio State University. “It’s very important to be able to control these pests at an early stage, when they are at the most vulnerable.”

Depending on the concentration of hemp extract used, the team discovered that the hemp leaf was potent enough to be equally toxic to both strains of mosquito larvae. What was surprising, though, said Martinez Rodriguez, was the small amount needed to be so deadly. While CBD eventually led to 100% mortality for the larvae, different concentrations of the hemp extract caused different mortality rates in the hours leading up to that time.

Researchers still aren’t clear how the extracts work but the team’s findings showed that CBD was the primary active ingredient in the extract used and that it can successfully bypass the larvae’s metabolic resistance to other insecticides. The findings support other research showing that CBD deters pests.

A recent study from Cornell AgriTech researchers found evidence that “cannabinoids” found in hemp may have evolved to deter pests from chewing on them. Cannabinoids are naturally produced by hemp plants and convert to more commonly known CBD, THC, and CBG when heated.

In controlled feeding studies of cabbage looper larvae in the lab, the researchers isolated CBDA and CBGA, and painted the extracts on to an artificial insect diet in a range of concentrations. Larvae grew less and had lower rates of survival as cannabinoid concentration increased, according to the paper. Future work will investigate if sap-sucking insects, such as aphids, are also inhibited by cannabinoids.

The findings are somewhat curious when coupled with other research that finds insects do not have cannabinoid receptors. The biological effects that humans and other animals experience from cannabinoid compounds are mediated by these receptors. However, insects have other receptors capable of interacting with cannabinoids, particularly CBD, which is known for binding with a range of receptors beyond the classic cannabinoid receptors.

In a previous paper, the same authors showed that tobacco hornworm caterpillars, considered a major pest on tobacco and tomato crops, preferred low-CBD over high-CBD cannabis plants, supporting the hypothesis that cannabis produces the compound at least in part to protect itself from insect herbivores.

The research is all relatively new – within the past two years – so scientists have a ways to go before a commercial hemp-derived insecticide might be available. One of the key questions that needs to be answered is whether CBD and other cannabinoid compounds are safe for use on human food crops. Researchers also need to determine how these compounds might impact beneficial insects, such as bees and other pollinators. (Sources: OSU, International Journal of Molecular Science, Project CBC)

Leave a Comment

Your email address will not be published. Required fields are marked *