Cannabis has been one of the most studied subjects in recent times with much of the focus placed on its medicinal and recreational properties. However, in what has been described as ‘exciting new research’, cannabis is now being investigated for its potential use in pesticides.
Working from the hypothesis that all plants have evolved to produce defence systems that help to prevent them from being eaten by insects and herbivores, such as greenflies and caterpillars, researchers at Cornell University assessed the ability of cannabinoids found in cannabis plants to protect against pests.
Smart, the senior researcher on this study explained the role cannabinoids may play, “It has been speculated that they are defensive compounds because they primarily accumulate in female flowers to protect seeds, which is a fairly common concept in plants.”
Published in Horticulture Research in October the team used cultivars of the cannabis plant containing different ratios of cannabinoids, the compounds found in cannabis that include THC and CBD, to test their resilience to chewing herbivores.
At two separate sites in New York State, the team planted two crops. One crop contained cannabis plants which were a cross between Carmagnola, a hemp plant used for its high CBD content, and USO-13, which is also hemp and grown for its high CBG. The other crop contained cannabinoid-free plants.
A team of raters assessed a total of 240 plants, 140 in each crop. The raters were tasked with visually observing each plant and recording how much plant matter had been eaten by chewing herbivores.
The results showed that plants in the crop containing the high CBD and high CBG cultivar suffered less damage from pests than the crop with cannabinoid-free plants, suggesting that cannabinoids play a role in defending its plant host.
This phenomenon was also evident when the team contrasted fallen leaves which contained fewer cannabinoids and had been eaten more, to leaves still attached to the plant that contained higher levels of CBD and CBG.
The study explains, “In the field, foliar cannabinoid concentration was inversely correlated with chewing herbivore damage. On detached leaves, Trichoplusia ni larvae consumed less leaf area and grew less when feeding on leaves with greater concentrations of cannabinoids.”
To check their results the team fed insects they reared with a diet high in cannabinoids and found them to grow less and to live shorter lives.
Reaching a conclusion the study author wrote, “The results reported here demonstrate that CBDA and CBGA, two of the most abundant phytocannabinoids produced by C. sativa, can reduce growth and survival of chewing herbivores independent of other biochemical or physical factors.”
