Pantnagar Journal of Research

Abstract

Fumigant toxicity of essential oil of Ageratum houstonianum Mill. (Asteraceae) was studied against five major insect pests of stored grain, namely, Rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Lesser Grain Borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), Red Flour Beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Pulse Beetle, Callosobruchus chinensis (L.) (Coleoptera: Bruchidae). Essential oil of A. houstonianum was extracted in Clevenger apparatus by hydro-distillation technique. GCMS analysis of essential oil revealed that ageratochromene (precocene II) (32.02), trans β-caryophyllene (23.06), precocene I (8.5), E-β-farnesene (6.49), β -cubebene (4.33), sesquisabinene (4.04), D-germacrene (3.05), benzyl nitrile (2.11), α-humulene (1.36), camphene (1.24), amorphene-gamma (1.22), α-farnesene (1.2), γ-cadinene (1.13), β- geraniolene (1.1), and α-phellandrene (0.27) are major component of it. Fumigation toxicity of essential oil was studied at 0.2, 0.1 0.05, 0.025 % V/W in airtight plastic vials. Ten adults of test insect were released in treated food and observation was recorded on emergence of F1 generation to calculate per cent inhibition as compared to untreated control. Fumigation of grain resulted in 91.42 per cent inhibition of F1 progeny of S. oryzae at 0.20 per cent while 100 per cent inhibition was recorded in case of R. dominica and C. chinensis at this level. As compared to these insects, the essential oil was less effective against T. castaneum and S. cerealella, respectively, against whom only 78.50 and 55.78 per cent inhibition was observed at 0.20 per cent. In almost all cases, the fumigant toxicity increased with increasing concentrations. The results indicated that essential oil of A. houstonianum may be explored for ecofriendly management of R. dominica, S. oryzae in cereals and C. chinensis in pulses.