Spatial distribution of Rhopalosiphum padi (L.) (Hemiptera: Aphididae) on corn in Shahrekord
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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران
نویسندگان
1Department of Plant Protection, University of Mohaghegh Ardabili, Ardabil, Iran,
2Department of Plant Protection, Faculty of Agriculture, Yasouj University, Yasouj, Iran,
3Department of Plant Protection, Chahar Mahal and Bakhtiari Agricultural, and Natural Resources Research Center, AREEO, Shahrekord, Iran,
4Department of Plant Protection, Faculty of Agriculture, Yasouj University, Yasouj, Iran
چکیده
The bird cherry-oat aphid, Rhopalosiphum padi L. is a polyphagous pest of agriculture plants, especially cereals as corn. In this study, three corn fields (2 ha) was studied in Chahartakhte Agriculture Research Station in Shahrekord. To determine the sample size based on statistical calculations a sampling operation was carried with 20 samples. For sampling unit (bush), 120 samples from each field were selected randomly by weekly in the year 2011. The determination of spatial distribution was described by mathematical analyses viz. the variance to mean ratio (S2 / m) and Taylor’s power law, and Iwao’s regression. To calculate the ratio of variance to mean, all data collected on different dates were used altogether in the Taylor regression method mean and variance related to each date after taking logarithms and the linear regression was obtained. The calculations were done using the Minitab software. Results showed that the spatial distribution of alata aphid was randomized in all three fields (S2/x ̅ =1.11, 0.8, 1.12; ID=65.77, 47.2, 65.92; Z=0.56,-1.19, 0.57). In contrast, it was cumulative for apterous aphidsin the same farms according to the variance to mean ratio (S2/x ̅ =173.43, 258.54, 146.35; ID=1023.83, 152.54, 56.35; Z=132.15, 163.75, 120.51). Using the Taylor method revealed that the slope of the regression line (b) was greater than one. Therefore, the cumulative distribution of spatial distribution was confirmed (P=0.00, b=1.84, 1.96, 1.86, SE=0.10, 0.10, 1.36 R2=98.2, 98.2, 99.7 for apterous). However, for alata aphids, the regression between data collected in the three studied farms was not significant (P> 0.05). Also, there was no significant difference between m and m* in the Iwao's method for both alata and apterous aphids. Therefore, it was not possible to calculate the slope of the regression line. These results can be used to determine the sampling program and the IPM
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