Pea leaf weevil (Coleoptera : Curculionidae) spatial distribution in peas

The effects of tillage, location within a plot, and date of sampling on the spatial distribution of adult Sitona lineatus (L.) in peas, Pisum sativum L., were evaluated using geostatistical analyses. The geostatistics procedu re uses spatial variation to determine the degree and type of spatial assoc iation and dependence of spatially related data. These analyses showed that 88% of the locations sampled had aggregated spatial distribution for adult S. lineatus. The variation that was spatially dependent was only 11.5%. Of the 2 types of aggregated spatial distributions, the spherical spatial dis tribution was most common on the Ist sampling date under conventional tilla ge, whereas the check-mark spatial distribution was most common on the 2nd sampling date in the outside edge locations of the pea plots. The smoother soil surface and reduced plant residue of the conventional tillage plot may have increased weevil movement and facilitated aggregation development. Th e spatial dynamics of this insect changed over time and was probably affect ed by the physical environment, as represented by the 2 tillage regimes and location within the pea plots. The geostatistical analyses provided insigh ts into the spatial distribution of this insect and potential relationship with agronomic practices.