NATURAL AND SYNTHETIC MATERIALS WITH INSECT HORMONE ACTIVITY. 5. SPECIFIC JUVENILE HORMONE EFFECTS IN ALIPHATIC...

The juvenile hormone activity of ethyl or methyl esters of aliphatic sesquiterpenic acids with 0 to 4 double bonds was tested on 8 species of insects belonging to 5 families of Hemiptera and Coleoptera. Special attention was paid to the addition of hydrogen chloride or epoxide groups on or across the double bonds. Certain chemical changes in the molecule appear to cause a general increase of the activity in all species studied. These are: the presence of 2,3 unsaturation conjugated with the carboxyl group; the trans stereochemical position of the C-3 methyl; an introduction of 10,11 epoxide or hydrochloride; and esterification with ethyl rather than with methyl. There are also chemical changes which lead to genus- or family-specific variations in juvenile hormone activity. With increasing amount of unsaturation the activity either remains almost unaffected (pyrrhocorid bugs) or increases (pentatomid bugs) or decreases considerably (tenebrionid and dermestid beetles). The addition of hydrogen chloride or epoxide to the 6,7 double bond causes enormous increase in the activity in the Pyrrhocoridae and Lygaeidae, no considerable change in the Pentatomidae, and great decreases in the beetles and Lepidoptera.