Spatio-temporal distribution and association of cabbage stem weevil (Ceutorhynchus pallidactylus Marsham, 1802) and pollen beetle (Meligethes aeneus Fabricius, 1775) in winter oilseed rape

Abstract: The within-field spatio-temporal distributions and relationships of Ceutorhynchus pallidactylus (Marsham) (Coleoptera: Curculionidae) and Meligethes aeneus (Fabricius) (Coleoptera: Nitidulidae) in a crop of winter oilseed rape [Brassica napus L. (Brassicaceae)] were assessed in the Olomouc region (northern Moravia, Czech Republic) over the course of 2013-2015. Distributions were analysed using SADIE analysis (Spatial Analysis by Distance IndicEs), for associations we used Quick association analysis. In 2013, males and females of C. pallidactylus were within-field associated during the period of higher flight activity when beetles were rather edge distributed. The similar character of distribution patterns and significant association of both sexes of C. pallidactylus was recorded in mid-April 2015. Despite a random distribution of females of C. pallidactylus in the crop on April 22 2013 there was a significant spatial association between the adults of M. aeneus and the females that date. Significant association between non-randomly distributed females of C. pallidactylus and adults of M. aeneus was recorded on 21 April in 2015. In all years, adults of M. aeneus showed stronger tendency to aggregation in crops mostly during their higher flight activity. When populations of the assessed insects were non-randomly distributed in crops (Ia > 1 for p < 0.05), they were usually aggregated into one major and one adjacent patch clusters localized along the edge of field with tendencies to spread to central parts of crop, too.