مشخصات پژوهش

Plants metabolites contain complex compounds that have adverse effects on insect’s feeding or oviposition behaviors. In some cases these compounds completely repel insects or may force them to starve over long periods. In this study, effects of 18 different extracts of some plants were investigated on behavior of last larval instars of Alfalfa weevil, Hypera postica (Gyllenhal) (Col.: Curculionidae), Carob moth Ectomyelois ceratoniae (Zeller) (Lep.: Pyralidae) and Khapra beetle Trogoderma granarium Everts (Col.: Dermestidae) at 25 ± 2 °C, 50 ± 5 RH % and 16:8 (L:D) h. Insects starved for 24 h before tests. A standard choice test conducted with a rectangle Plexiglas box (30 × 10 × 1.5 cm) covered with fine mesh net. For repellency tests, 100 μl of extracts (dilution of 10 % in acetone) was loaded on a piece of filter paper (3 cm in diameter). Papers were air dried for 3 h and placed into the test box. Papers loaded with acetone were used as control located in opposite position with treatment. Ten larvae were introduced to the center of boxes. Position of insects in the box, was recorded every 1, 3, 6, 12 and 24 h. The repellency effects of a treatment were calculated by comparing number of insects in control and treatment sites of test box. A Chi-square test was used for comparing the observed and expected data (df=1). The results revealed that hexane extract of Xanthium strumarium (X2=28.88, P<0.05) and Ageratum houstonianum (X2=6.48, P<0.01), methanol extract of Achillea millefolium (X2=25.92, P<0.001) and Falcaria vulgaris (X2=6.48, P<0.05) repelled E. ceratoniae larvae by 38, 18, 36 and 18 %, respectively. Hexane extract of A. houstonianum (X2=5.12, P<0.05), ethylacetate extracts of Apium graveolens (X2=6.48, P<0.05), F. vulgaris(X2=6.48, P<0.05) and Artemisia abrotanum (X2=9.68, P<0.01) had repellent activity by 16, 18, 18 and 22 %, respectively on last larval stage of T. granarium. Similarly, methanol extract of F. vulgaris (X2=9.68, P<0.01) and A. millefolium