Determination of different sampling patterns and selection of the suitable method for estimating the population of wheat thrips (Haplothrips tritici) in wheat fields

Wheat thrips, Haplothrips tritici (Kurdjumov) (Thysanoptera: Phlaeothripidae) is one of the most important sucking pests in wheat fields. In this study, in order to select different sampling patterns as well as the most suitable method for estimating wheat thrips population, regularly sampling was done during wheat growing period in the wheat fields in Eyvan city (Ilam province, west of Iran) during years 2017-2018.After the start of wheat growth, wheat thrips was sampled once in a week by using four sampling methods i.e. X- shaped movement, zig-zag, U and S shape.In each sampling, 100 wheat plants were selected randomly in each field and wheat thrips was counted and recorded.Relative variation (RV) and relative net precision (RNP) were compared to determine the best sampling methods.Comparison of the four sampling methods showed that the X- shaped movement was more precise than the other three patterns.Also, the analysis of variance and comparing the average of the density of wheat thrips between different shaped and growth stages of wheat were used to determine the best sampling space.The results showed that there was a significant difference between the sampling patterns and growth stages and based on these results, the highest density of wheat thrips was observed in X- shaped pattern in the flowering stage. Therefore, according to the results, the flowering stage was determined as the most suitable space for wheat thrips.