Changes in flower thrips spatial distribution over time on a southern highbush blueberry field in North Central Florida

During 2008, Florida produced 4.45 million kg of fresh market southern highbush blueberries (SHB) at an average of $11.67 per kg. Flower thrips are the key pest of SHB because feeding and ovipostion damage to the ovaries produces fruit scarring. They have a clumped distribution and tend to form small areas of high population termed ‘hot spots’. Geostatistics are used to model spatial variation. Kriging then uses these models, called variograms, to interpolate values at unsampled locations. The purposes of this study were to examine flower thrips’ distribution using kriging and to examine environmental factors that may influence thrips’ distribution. One hundred white sticky traps were distributed throughout a regular grid, with an additional 30 traps placed randomly throughout the gridded area. Traps were changed out weekly over a period of 5 weeks and the number of thrips per trap was recorded. SGeMS and ArcMap were used to construct and analyze semivariograms and to perform ordinary kriging. All five variograms have a range of spatial autocorrelation between 18 and 29m. One large ‘hot spot’ formed in the middle of the sampling area stretching through the north end. There were very few thrips collected during the second week because of an extreme cold front. Temperature appears to be a major factor influencing thrips’ distribution.