Effect of Rhizomes Essential Oil of Cyperus rotundus L. on Feeding Indices of Sawtoothed Grain Beetle, Oryzaephilus surinamensis L. and the Khapra Beetle Trogoderma granarium Everts

In recent years, the use of plant derivatives including essential oils and plant extracts has been taken into consideration as an alternative to chemical pesticides for pest control. In this study, antifeedant activity of purple nutsedge, Cyperus rotundus L. essential oil was investigated against sawtoothed grain beetle, Oryzaephilus surinamensis L. and khapra beetle, Trogoderma granarium Everts by using flour disc method, under laboratory conditions (27±2°C, 65±5% RH and continuous darkness). Results showed that feeding indices were affected by essential oil and the relative growth rate, relative consumption rate and efficacy of conversion of ingested food decreased for both insects with increasing concentration. The efficacy of conversion of ingested food decreased from 7.80% and 6.18% at control to 3.05% and 3.68% at highest concentration for O. surinamensis and T. granarium, respectively. The feeding deterrence index for both insects increased from 32.57% and 39.02% at the lowest concentration to 46.85% and 49.33% at highest concentration, respectively. According to these results, the essential oil affected test insects in two ways; feeding deterrence and post ingestive toxicity. The results demonstrated that C. rotundus essential oil could be used as a probable substitution to chemical pesticides for stored products protection against storage pests.