Population fluctuations and spatial distribution of the canola false chinch bug, Nysius cymoides (Hem., Lygaeidae) in Kermanshah

The false chinch bugs, Nysius cymoides (Spinola) (Hem., Lygaeidae) is a polyphagous and cosmopolitan distributed and it causes damage as the most important pest in canola fields in Kermanshah province in the recent years. In the present study, population fluctuations and spatial distribution of the pest were investigated in canola fields of Kermanshah province during 2020 and 2021 years. The results of this study showed that the first group of the false chinch bugs populations in 2020 and 2021 were observed on the 8 and 11th of April, respectively.The second population peak of the pest in 2020 and 2021 with an average of 372.22 ± 66.31 and 126.45 ± 4.58 was obtained on 22 and 19th June, respectively. The highest population density of nymphs in 2020 and 2021 with an average of 1263.50 ± 125.19 and 206.00 ± 3.91 was obtained on 23th June. The results of spatial distribution showed that in 2020, the spatial distribution of males, females and adults of the N. cymoides was recognized as aggregated based on Taylor’s power law method and as random based on Iwao’s patchiness regression method. In general, the results of this study showed that N. cymoides had two population peaks. Also, based on goodness of fit, the Iwao’s patchiness method was more suitable than the Taylor’s power law method for estimating the spatial distribution of the pest.