Antifeedant effect of essential oils of five indigenous medicinal plants against stored grain insect pests

The present study aims at assessing the antifeeding effects of azadirachta indica,melia azedarach,colocynthis citrullus,nicotiana tabacum and eucalyptus camaldulensis against tribolium castaneum,ryzopertha dominica and trogoderma granarium under laboratory conditions. all treatments showed the prominent feeding deterrence activities. the most potent essential oil against all insect pests was found in a. indica,with maximum reduction in weight loss (0.56,1.02,1.69%) and feeding deterrence index (75.44,54.57 and 39.21%) against t. castaneum,t. granarium and r. dominica,respectively followed by m. azedarach (0.63,1.05 and 1.76%) (67.59,50.85 and 34.92%),c. citrullus (0.65,1.17 and 1.76%) (65.35,43.57 and 33.94%),n. tabacum (0.7,1.22 and 1.84) (58.43,38.87 and 30.28%) and e. camaldulensis (0.84,1.32 and 1.97%) (45.11,38.98 and 23.18),respectively. it was also observed that weight loss and feeding deterrence index increases with increasing concentration of toxin. weight loss was (0.37,0.85 and1.50%) (0.48,0.96 and 1.61%) (1.26,1.09 and 1.74%) and (1.72 and 2.39%) at the dose rate of 6%,4%,2% and controls against t. castaneum,t. granarium and r. dominica,respectively. feeding deterrence index was 71.74,50.41 and 37.22%,at 6% concentration of toxicant,62.83,44.18 and 32.54% at 4% concentration of toxicant and 52.59,36.65 and 27.17% at 2% concentration of toxicant. copyright 2015 zoological society of pakistan.