Analysis of the Spatial Distribution and Development of Sequential Sampling Plans for Heteropteran-Associated Fruit Injury in Florida Peaches

Abstract

Catfacing and gummosis/sap-type injury associated with a heteropteran pest complex were sampled at five peach orchards in southern Florida during two consecutive growing seasons. Trapping and visual surveys indicate that Euschistus servuis (Say) (Hemiptera: Pentatomidae) was the dominant heteropteran pest in the study orchards. The spatial arrangement of injury indicated a random distribution, as determined by Taylor's power law. Spatial analysis by distance indices indicated a random arrangement of fruit injury in a majority of the sample site × date combinations and analysis of local clustering did not provide evidence of patches of fruit injury occurring near orchard borders. The coefficients from Taylor's power law were used to develop sequential sampling plans based on hypothetical injury thresholds. Sequential sampling plans were compared to a simple random sample of 15 sample units using a simulation approach. The sequential sampling plan was able to achieve equivalent levels of accuracy when compared to the 15-unit fixed sampling plan while reducing the number of sample units required to an average of 7.99. The sequential sampling plans developed in this study are an improvement over simple random sampling; however, further research is needed to determine how to best implement sequential sampling of fruit injury in Florida peach orchards to better inform management decisions.

Keywords: Euschistus servus; SADIE; catfacing; integrated pest management.