Wounding of the plant has been employed as a method to increase resin production (Emboden 1972). This increase may be a response to desiccation above the point of vascular disruption. Under natural circumstances, wounding most often occurs as a result of insect attack. This is a source of environmental stress which the production of terpenes and cannabinoids may be able to minimize. Cannabis is subject to few predators (Smith and Haney 1973, Stannard et al. 1970) and has even been utilized in powdered or extract form as an insecticide (Bouquet 1950) or repellent (Khare et al. 1974). Its apparent defensive mechanisms include a generous covering of non-glandular trichomes, emission of volatile terpenoid substances, and exudation of the sticky cannabinoids. Cannabis is often noted for its aromatic quality and many of the terpenes produced are known to possess insect-repellent properties. Among these are alpha and beta pinene, limonene, terpineol and borneol. Pinenes and limonene comprise over 75% of the volatiles detected in the surrounding atmosphere, but account for only 7% of the essential oil (Hood et al. 1973). Consistent with glandular trichome density and cannabinoid content, more of these terpenes are produced by the inflorescences than the leaves, and their occurrence is also greater in the female plant (Martin et al. 1961).

No insect toxicity studies using isolated cannabinoids have been published to date. Rothschild et al. (1977) found THC-rich Mexican (vs. CBD-rich Turkish) Cannabis fatal to tiger moth (Arctia caja) larvae, but not Nigerian grasshopper (Zonocerus elegans) nymphs. Rothschild and Fairbairn (1980) later found that pure THC (vs. CBD) sprayed on cabbage leaves, does repel the large white cabbage butterfly (Pieris brassicae).

The cannabinoids may also serve as a purely mechanical defense. A tiny creature crossing the leaf surface could rupture the tenuously attached globular resin reservoirs of the glandular trichomes (Ledbetter and Krikorian 1975) and become ensnared in resin. A sizable chewing insect, if able to overcome these defenses, would still have difficulty chewing the gummy resin, along with the cystolithic trichomes and silicified covering trichomes also present on the leaf. The utility of these epidermal features as insect antifeedants is also inferable from their predominant occurrence on the insect-favored abaxial leaf surface. Although the above strategies represent a seemingly sophisticated system, many other plants (Levin 1973) and even arthropods (Eisner 1970) utilize similar defense mechanisms, often employing identical terpenes!
HARDDON Reviewed by HARDDON on . humidity & Smell It seems to me that if I lower the humidity of my growroom I can lower the smell considerably. I know the lower the humidity the more protective sap the plant excretes to protect the seeds to maintain viability until the next growing season. This sticky sap is the base for THC production. Rember that THC resin deters germination. That is part of the reason that seeds which have been dried for a month germinate much better seeds out of fresh wet buds. So my question is that if I have a good Rating: 5