Assessment of Genetic Diversity, Micromorphology and Antimicrobial Activity in Nepeta cataria L.

The mosquito repellent Nepetalactone rich Nepeta cataria L. (catmint) plant has a variety of therapeutic and industrial potential. Reports on the genetic diversity of N. cataria germplasm are minimal globally and need attention for adding a new variety into commercial cultivation. The present study, therefore, assessed the genetic diversity among thirteen half-sib genotypes of N. cataria using agro economic and phytochemical traits. The experimental set has shown substantial variation for agro economic traits studied. Among all the studied populations, fresh herb-based essential oil content ranged from 0.1 % to 0.3 %, with a grand mean of 1.67 %. However, the estimated oil yield ranged from 44.4 kg/h to 120.73 kg/h with an average of 71.34 kg/h. Among the eleven phytochemical constituents detected in different concentrations in the essential oil of experimental sets, 4aα,7α,7aα-Nepetalactone (67.9-87.5 %) constituted the significant proportion of essential oil. Altogether, based on mean comparison, the population NC8 was found to be promising for estimated oil yield and 4aα,7α,7aα-Nepetalactone content. The greater heritability estimates (h2 bs) and genetic advance as percent of mean (GAM) were observed for important economic parameters, i. e., oil content, herb yield, and oil yield. The cluster analysis revealed the least interactions between various agro economic and phytochemical variables. The microscopic study of trichome showed a positive correlation of abaxial leaf surface with essential oil content. The promising antimicrobial potential of catmint oil was also observed against human health-related pathogens. The results infer from our study provide valuable insight for genetic improvement and product development in the catmint germplasm.

Repellency Assessment of Nepeta cataria Essential Oils and Isolated Nepetalactones on Aedes aegypti.

There is an increased need for improved and affordable insect repellents to reduce transmission of rapidly spreading diseases with high mortality rates. Natural products are often used when DEET cannot be afforded or accessed and when consumers choose not to use a synthetic repellent. The essential oils from two newly bred Nepeta cataria (catnip) plants representing two different chemotypes and their respective isolated nepetalactone isomers were evaluated as mosquito repellents against Aedes aegypti mosquitoes that transmit the Zika and Dengue virus in a one choice landing rate inhibition assay. A dose response curve was generated for each treatment and a time course analysis of repellency was performed over 24 hours with a N. cataria essential oil sample. The results indicate that all essential oil samples and their respective purified nepetalactone isomers were able to achieve greater than 95% repellency. Between two and four hours, the ability to repel more than 95% of the mosquitoes diminished. At the lowest concentrations tested, the nepetalactones and crude essential oil samples were more effective than DEET at reducing the number of mosquito landings.