Tag Archives: hemp research

Toxic and repellent effects of hemp leaf extracts and cannabidiol against adult female yellow fever mosquitoes, Aedes aegypti

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A 2026 study published in PLOS ONE found that hemp leaf extracts were both toxic and repellent to adult female Aedes aegypti mosquitoes, the species responsible for transmitting diseases including yellow fever, dengue and chikungunya. Researchers observed dose-dependent mosquito mortality within 24 hours after direct exposure to the hemp extract.

The hemp extract also reduced blood-feeding and produced strong contact-repellent effects. Importantly, isolated cannabidiol (CBD) did not reproduce the full activity of the whole extract, suggesting that other cannabinoids, terpenes or additional hemp compounds may contribute to the effect.

The findings add to growing research into hemp-derived compounds as potential plant-based tools for insect and mosquito control. The authors concluded that hemp leaf extracts showed both topical toxicity and repellency against yellow fever mosquitoes, with effects that could not be duplicated by CBD alone.

“Hemp (Cannabis sativa) derived products have emerged as potential sources of novel biopesticides.

We recently demonstrated that a hemp leaf extract was toxic to larvae of the yellow fever mosquito Aedes aegypti, and that cannabidiol (CBD) was the primary larvicidal component of the extract.

Here we evaluated the toxic and repellent effects of a hemp leaf extract and CBD against adult female Ae. aegypti.

Toxicity was assessed using an acute topical assay in which mosquitoes received a 500 nL application to the thorax and mortality was recorded at 24 h. Repellency was then evaluated using two complementary bioassays: (i) a no-choice membrane blood-feeding assay to quantify feeding deterrence, and (ii) a mosquito airborne repellency test (MART) to assess spatial repellency.

Topical application of CBD-rich hemp leaf extract induced dose-dependent mortality in adult Ae. aegypti with a LD50 of 22.13 µg/mosquito at 24 h. When CBD isolate was tested at its equivalent doses in the extract, it caused significantly lower mortality than the hemp extract.

In the membrane blood-feeding repellency assay, the hemp leaf extract repelled mosquitoes in a dose-dependent manner, whereas CBD produced weaker effects even at higher equivalent doses. In the MART assay, the hemp extract did not elicit spatial repellency, suggesting low volatility of the repellent compounds.

Taken together, our results demonstrate that CBD does not fully explain the adulticidal or repellent effects of the CBD-rich hemp leaf extract against adult female Ae. aegypti suggesting that other compounds contribute to the bioactivity of hemp leaf extracts against adult female mosquitoes.”

https://pubmed.ncbi.nlm.nih.gov/42743102

“This study demonstrates that hemp leaf extracts exhibit topical toxicity and repellency against the yellow fever mosquito, Ae. aegypti, and that these effects cannot be duplicated by CBD alone. The greater toxicity of the hemp leaf extract compared to the CBD isolate suggests important contributions by other compounds in the extracts. When repellency of the extract or CBD was evaluated, mosquitoes were only repelled when direct contact with the treated surface was allowed. Nevertheless, the hemp leaf extract was more effective than the CBD isolate, again pointing to the involvement of other compounds in adult repellency.

Our findings advance our understanding of the potential uses of hemp and CBD against adult female Ae. aegypti. Identifying the additional components of the leaf extract that contribute to toxicity and repellency in adult female mosquitoes will be essential for evaluating the potential of hemp-based products in integrated mosquito management strategies. In addition, future research evaluating the human and environmental safety of using hemp-derived products as biopesticides is needed.”

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0354696

Bioactive Compounds and In Vitro Antibacterial Activity of Hemp Leaves and Inflorescences as Potential Functional Feed Ingredients for Canine Nutrition

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Hemp may have value far beyond its traditional uses. A 2026 study examining hemp leaves and inflorescences found that both plant parts contain bioactive compounds with potential nutritional value, while extracts from the plants also demonstrated antibacterial activity against several important bacterial species.

Researchers found that hemp flowers were especially rich in cannabinoids and terpenes, while the leaves offered a favorable fatty-acid profile. In laboratory testing, hemp extracts showed activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, highlighting another potential use for compounds naturally produced by the cannabis plant.

The researchers suggest that hemp leaves and flowers deserve further investigation as functional ingredients in canine nutrition. The findings add to growing evidence that parts of the cannabis plant often treated as agricultural byproducts may contain valuable nutritional and biologically active compounds.

“Hemp (Cannabis sativa L.) inflorescences have been extensively characterized for their bioactive compounds, whereas less information is available on hemp leaves despite their potential as a source of nutrients and phytochemicals.

This study compared leaves and inflorescences of four organically grown hemp cultivars (Finola, Futura 75, Dioica, and Kompolti) in terms of cannabinoid, terpene, and fatty acid profiles, lipid quality indices, and in vitro antibacterial activity.

Antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa was evaluated using MIC, MBC, and time-kill assays. Total cannabinoid content was approximately 2.7-fold higher in inflorescences than in leaves, which were also generally richer in terpenes. Leaves showed a more favorable fatty acid profile, with higher n-3 polyunsaturated fatty acid proportions and a lower n-6/n-3 ratio.

All extracts exhibited antibacterial activity. Among the tested bacteria, S. aureus was the most susceptible to the hemp extracts, with both growth inhibition and bactericidal activity observed at the lowest tested concentration (MIC/MBC = 0.005%), compared with 0.625% for E. coli and 1.25-2.5% for P. aeruginosa, depending on the extract. Finola and Kompolti inflorescence extracts showed the fastest bactericidal activity against S. aureus. 

These findings demonstrate distinct and complementary characteristics of hemp leaves and inflorescences and provide a basis for further investigation of their potential relevance to canine nutrition.”

https://pubmed.ncbi.nlm.nih.gov/42738424

“The pet food industry is increasingly looking for natural ingredients that can improve both the nutritional value and microbiological safety of dog diets while making better use of agricultural resources. Industrial hemp cultivation generates large amounts of leaves that are often underutilized, although they contain valuable natural compounds. This study compared hemp leaves and inflorescences from four industrial hemp cultivars to determine whether these plant materials could be useful in canine nutrition.

The results showed that leaves provide a favorable fatty acid profile, whereas inflorescences are richer in naturally occurring plant compounds such as cannabinoids and terpenes. Extracts from both plant parts also inhibited the growth of bacteria under laboratory conditions. These findings suggest that different hemp plant parts may have complementary roles as functional ingredients in dog foods while supporting more sustainable use of hemp biomass. Further studies in complete diets and feeding trials are needed before practical application.”

https://www.mdpi.com/2076-2615/16/17/2635