Nutritional indices of Tribolium castaneum (Herbst) (Col.; Tenebrionidae) affected by ethanolic extract from Euphorbia helioscopia
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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران
نویسندگان
Shahid Bakeri High Education Center of Miandoab, Urmia University, Urmia, Iran,
چکیده
The genus Euphorbia is the largest genus in the Euphorbiaceae family. All contain latex and have a medicinal importance. Ethanolic extract from aerial parts of Euphorbia helioscopia L. was evaluated on nutritional indices of the stored product insect, Tribolium castaneum (Herbst). Relative growth rate (RGR), relative consumption rate (RCR), efficiency of conversion of ingested food (ECI) and feeding deterrence index (FDI) were measured. Experiments were done in total darkness at 27±1°C and 60±5% R.H. Several concentrations of the plant extract (0.25, 0.5, 0.75, 1.0, 1.5 and 2.0%) with control were used evenly on the flour discs. After 72 h, nutritional indices of adults were calculated. Data was analyzed using one-way analysis of variance and Duncan's multiple range tests (P<0.05) was employed to determine differences between means. Also correlations between measured factors were calculated. Results showed that the values of RGR, RCR and ECI were reduced significantly with increasing E. helioscopia extract concentration. At 0.5% concentration, the RGR index reduced about 50% (0.27 mg/mg/day) compared to that of control (0.53 mg/mg/day). The higher concentration treatment (2%) of E. helioscopia caused 91% (0.04 mg/mg/day) reduction in relative growth rate of adults. Although at 2% concentration, FDI was 69.78% but ECI decreased by 25.73% compared to that of control. These results showed that the ethanolic extract of E. helioscopia, in addition to its feeding deterrence, affected the pest nutrition considerably through post-ingestive toxicity. There were significant positive correlations (P<0.05, r2>0.9) between RGR and RCR or ECI, however, there was a significant negative correlation between RGR and FDI. Generally, total mean values of RGR, RCR, ECI and FDI of the extract were 0.26 mg/mg/day, 0.56 mg/mg/day, 46.40% and 43.37%, respectively. Our findings suggest that using ethanolic extract of E. helioscopia could be a significant method for reducing population of T. castaneum.
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