Bioefficacy of compounds from Dittrichia viscosa (Asteraceae) as protectant of chickpea seeds against the cowpea seed beetle Callosobruchus maculatus (Coleoptera: Chrysomelidae)

The efficacy of four bi- and tri-cyclic sesquiterpenes, namely inuloxins A, B and C and alpha-costic acid, extracted from aerial parts of Dittrichia viscosa collected in Algeria was assessed against the cowpea seed beetle Callosobruchus maculatus. The compounds were evaluated for their effect on adult mortality, oviposition and adult emergence. Three concentrations (100, 50 and 25 mu g/ml) of each compound were tested with chickpea being used as the test plant. Complete adult mortality (100%) was achieved at only 1 day after exposure to inuloxins B and C and alpha-costic acid with LC50s less than 36 mu g/ml. Lethal concentration values (LC50) were determined as 30.4, 35.2, 31.6 and 29.4 mu g/ml, respectively, for inuloxins A, B and C and alpha-costic acid. Oviposition and F1 progeny emergence were significantly reduced (27% and 73%, respectively) after treatment with D. viscosa compounds. Our results also revealed that oviposition, adult emergence and sex ratio varied with the sex of the treated mating partner suggesting that the test compounds may have acted as male (or indirect female) chemosterilants resulting in reduced fecundity and fertility of untreated females that mated with treated males.