Spatial distribution and fixed-precision sequential sampling plan for the cotton mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcidae), on Chinese hibiscus in Southwestern Iran

Abstract

The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), has emerged as a key pest of ornamental plants, yet effective monitoring tools for its management remain limited. This study investigated the spatial distribution and developed fixed-precision sequential sampling plans for P. solenopsis populations on Chinese hibiscus (Hibiscus rosa-sinensis L.) under urban landscape conditions in Khuzestan province, southwest Iran. Spatial distribution analyses using Taylor's power law and Iwao's patchiness regression revealed significant aggregation across developmental stages, with nymphs exhibiting the highest degree of clumping and adults showing weaker aggregation due to greater dispersal ability. Based on these aggregation parameters, sequential sampling plans were generated for nymphs, adults, and combined populations at 3 precision levels (D = 0.25, 0.15, and 0.10). Optimum sample size requirements were density-dependent and consistently higher for nymphs than for adults. Validation through resampling confirmed that achieved precision closely matched target levels, with mean sample sizes for combined stages (nymphs and adults) ranging from 47 (D = 0.25) to 294 (D = 0.10). The D = 0.25 plan provided robust accuracy while substantially reducing sampling effort, making it most suitable for practical pest management. By contrast, the D = 0.10 plan is recommended for research requiring high precision. These findings provide the first validated sequential sampling framework for P. solenopsis on hibiscus, offering an efficient and reliable basis for integrated pest management in urban green spaces.

Keywords: IPM; Iwao’s patchiness regression; Taylor’s power law; hibiscus; mealybug.