LAUSR

Abstract The common blossom thrips, Frankliniella schultzei (Thysanoptera: Thripidae) (Trybom), is an important pest of melons (Cucumis melo). This species is found on all continents, but especially in tropical and subtropical regions. Decision-making systems are essential parts of Integrated Pest Management (IPM) programs. Sampling plans and decision-making indices are two critical components for an effective and successful IPM program. Sequential sampling plans have a variable number of samples as a function of pest density. Economic Injury Level (EIL) is the most commonly used decision-making index in IPM programs. Despite the importance of the impact of Frankliniella schultzei on Cucumis melo, economic injury levels and sequential sampling plans for this pest have not yet been determined. Thus, this study aimed to determine the control decision-making system for F. schultzei. To this end, research was conducted over two years in 39 commercial melon fields. The EIL was calculated based on control costs and melon production value as a function of F. schultzei density. The sequential sampling plan was developed based on the binomial sequential probability ratio test. Attack up to 9 thrips. sample−1 reduced the yield of melon fields by 46%. The cost of thrips control represented 1.85% of the production value of the melon fields. The EIL for F. schultzei was 0.36 thrips per sample. The sequential sampling plan made correct decisions in 100% of situations and saved more than 85% of sampling time and cost. In conclusion, this decision-making system can be incorporated into melon field IPM programs to help farmers make correct decisions when the monitoring this pest, as well as reduce the costs and sampling times.