Solidago nemoralis

Diterpenoids have a wide range of biological activities. Their role in plant-insect interactions, both as antifeedants and growth inhibitors, is reviewed. Four ent-kauranes, kaur-16-en-19-oic acid, (-)-kauran-l > -ol, 15 t-hydroxy-(-)-kaur-16-en-19-oic acid, and 17-hydroxy-(-)-kaur-15-en-19-oic acid, have recently been isolated from the leaves of Solidago nemoralis.These compounds were found to have antifeedant activity against Trirhabda canadensis. 

Solidago nemoralis is a plant which grows from Quebec to the North-West Territory, south to Florida and west to Texas and Arizona. A sample of the oil obtained from this species was examined by Schimmel Co. It was bright olive-green in colour, and had a peculiar odour, reminding somewhat of cypress oil. It bad a specific gravity 0 8799, optical rotation - 23 10, ester number 14 4, ester number after acetylation 38 2, and formed a cloudy solution in about seven or more volumes of 95 per cent, alcohol. 

The role of diterpenes in the resistance of four Solidago (Astereae) species to the beetle Trirhabda (Coleoptera) is under investigation (368). Preliminary results indicate that three of the four kauranoids isolated from the leaves of S. nemoralis and S. altissima, ew/-kauran-16a-ol (720), 15a-hydroxy-eA2/-kaur-16-en-19-oic acid (646), and 17-hydroxy-e /-kaur-15-en-19-oic acid reduced Trirhabda larval growth by 40 percent and adult growth by 32 to 49 percent. The fourth, ew/-kaur-16-en-19-oic acid (625), had no deterrent effect on the larvae and actually stimulated feeding by adults. 

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