Spatial distribution and sequential sampling plan for Oligonychus punicae (Acari: Trombidiformes: Tetranychidae) on grapevine.

Abstract

Sequential sampling plans are employed for the rapid characterization of infestations to facilitate decision-making. This study aimed to (i) investigate the spatial distribution of Oligonychus punicae (Hirst) in grapevine crops, (ii) determine the most representative branch, leaf, and leaf region for monitoring, and (iii) develop a sequential sampling plan for decision-making to control O. punicae in the table grape varieties Arra 15, BRS Vitória, Cotton Candy, Sugar Crisp, and Timpson at different phenological stages. O. punicae distribution was analyzed across all varieties and developmental stages. Notably, O. punicae distribution varied among the tested varieties, with no consistent pattern observed in branches and leaves. However, a distinct distribution pattern was evident within leaves, with larger populations concentrated in the central regions. The lower and upper economic thresholds implement control measures varied according to the phenological stage, with the lower thresholds (economic threshold) set at 36% and the upper thresholds (economic injury level) at 40%. Consequently, a minimum of 3 and maximum of 20 plants were sampled. Overall, this study provides a robust approach to optimizing resource allocation and minimizing the environmental impact of O. punicae management.