Sampling Strategies for Diceraeus melacanthus in Early Maize: A Decision-Support Framework

The green-belly stink bug (GBB), Diceraeus melacanthus (Dallas, 1851) (Heteroptera: Pentatomidae) is a key South American maize (Zea mays L.) pest, feeding on seedlings and causing physiological disorders. Understanding D. melacanthus population distribution and establishing sampling plans is essential to manage this species. Hence, the objective was to determine a distribution pattern, recommend a sampling unit size and develop sampling plans for the GBB, covering maize pre-sow period up to the maize V4 stage. Assessments were carried out in an experimental field and nine crop fields in northern Paraná State. In the experimental field, quadrants of n, 2n, 4n, 8n and 16n (n = 0.25 × 0.25 m²) were tested, thus determining an aggregated distribution with a recommended sampling unit size of 0.5 × 0.5 m². After the nine crop field samplings, a negative binomial distribution was deemed fit to represent GBB in field conditions. Two sampling plans were developed, highlighted is the sequential presence-absence plan, which recommends a maximum of 60 sample points, and a minimum of 25, with at least six presences to make control decisions. For a more assertive sampling, divide the evaluated area into glebes with distinct natural characteristics and employ the sampling plan to each glebe. These sampling plans must be validated before IPM recommendation.