| Spatial distribution pattern of Arboridia kermanshah Dlabola (Hemiptera: Cicadellidae) immature stages, on grape in Kermanshah region |
| Paper ID : 1096-3IICE (R1) |
| Authors: |
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Shabnam Dehpahni *1, Hassan Ali Vahedi2, Maryam Darbemamieh3 1Department of plant protection. Compus of Agriculture and Natural Resources, Rzi university 2Department of Plant Protection, Campus Agriculture and Natural Resources, Razi University 3Department of plant protection, Campus of Agriculture and Natural Resources, Razi University |
| Abstract: |
| Grape, Vitis vinifera L., is one of the most important horticultural products in Iran. Arboridia kermanshah Dlabola (Hemiptera: Cicadellidae), grape leafhopper, is a serious pest in vineyards in Kermanshah region. Adults and nymphs of the pest feed on leaves and develop white spots on their upper surface resulting in early loss of leaves. In this research, the spatial distribution pattern of the immature stages of A. kermanshah was investigated in a vineyard (Kermanshah region) during two growing seasons (2017-18). Five different methods including: index of dispersion, Morisita’s index, Lloyd’s mean crowding, Iwao’s patchiness regression and Taylor’s power law were used to calculate distribution pattern of the pest. Due to the establishment of nymphs on the lower surface of leaves, a grape leaf was selected as a sampling unit. Sample size was determined according to a primary sampling and corrected according to the previous sampling data. Data analysis was performed using Minitab 16 and Microsoft Office Excel 2016 softwares. Most used methods revealed an aggregated spatial distribution pattern (b>1, Pvalue<0.05) for the pest in both seasons. For Taylor's method in 2017, distribution pattern of the 3rd instar (b=0.941, r2=0.772, Pvalue<0.05), 4thinstar (b=0.892, r2=0.676, Pvalue<0.05) and 5thinstar nymphs (b=0.36, r2=0.629, Pvalue<0.05) were observed regular. Also, by using the Iwao’s patchiness regression in 2018, spatial distribution pattern of the 2nd instar nymph (b=1.14, r2=0.208, Pvalue= 0.05) was calculated as random. Using the Morisita’s index, it was found that in year 2017, the 4th instar nymph on 13 July, 20 July and 11 August and the 5th instar nymph on 13 July, 18 August and 6 October and in year 2018, 4th instar nymph on 20 July and 17 August and the 5th instar nymphs on 20 July, 24 August and 12 October had regular distribution pattern (Z<-1.96). These changes showed that the spatial distribution could change during a season. In both sampling years, Taylor’s method was more accurate comapred with other methods for determining the spatial distribution pattern of the pest. The lowest optimum sample size was calculated by Taylor’s power law (N= 464.58 in 2017, N= 385.36 in 2018). Knowledge of the spatial distribution pattern for a pest can be used in designing appropriate sampling program. |
| Keywords: |
| Sampling, Optimum sample size, Grape leafhopper, Taylor’s power law, Iwao’s patchiness regression, Morisita index. |
| Status : Paper Accepted (Poster Presentation) |
