Economic injury level and sequential sampling plan for Liriomyza huidobrensis management in tomato crops

Abstract Decision-making systems, comprised of sampling plans and decision indices, are essential components of integrated pest management (IPM) programs. Sampling plans allow the manager to verify if the pest reached the economic injury level (EIL). Although conventional sampling plans are reliable, they generally require more samples and the related cost can discourage their use. Sequential sampling plans usually require fewer samples to reach a decision, reducing the time and cost of sampling. Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) is one of the major pests of tomato crops. Despite the importance of L. huidobrensis , to date, no decision-making system has been established for this pest in tomato. This study aimed to determine the EIL and a sequential sampling plan for L. huidobrensis in fresh-market tomato crops. The EIL was calculated based on control costs and tomato production value as a function of L. huidobrensis density. The sequential sampling plan was developed based on the binomial sequential probability ratio test. The cost of L. huidobrensis control in tomato crops was US$ 335.38 per hectare. Liriomyza huidobrensis reduced the productivity of tomato crops by up to 15%. The EIL was estimated at 3.24 larvae per leaf. The sequential sampling plan was validated using field-collected data (providing correct decisions in 100% of the fields and an average time saving of 86.75%), and operational characteristic (OC) and average sample number (ASN) curves. This study provides relevant insights into the decision-making process of L. huidobrensis control in tomato crops by providing a formal criterion (EIL) to reduce economic losses coupled with an accurate and highly cost-effective sampling plan.