Feasible sampling plan for Tuta absoluta egg densities evaluation in commercial field tomato

Tomato leaf miner Tuta absoluta (Lepidoptera: Gelechiidae) is a main tomato crop pest in the Americas, Europe, and Africa and can cause up to 100% yield loss in tomato crops. The larvae feed on the leaf mesophyll, which makes their control difficult. Therefore, it is essential to detect this pest before it starts to feed, which can be done by assessing egg density. Sampling plans are an essential part of integrated pest management programs, and despite the importance of T. absoluta to tomato crops and the need for early decision making to control it. The aim of this study was to determine a conventional sampling plan to assess the density of T. absoluta eggs in commercial tomato fields, allowing farmers to manage the pest before it causes economic losses. To establish a sampling plan, the sampling unit, the number of samples, the time required to sample, and the cost of sampling was determined. For this purpose, the number of eggs of T. absoluta in 24 commercial tomato fields was counted. The sampling unit for the assessment of the eggs of the pest were the two leaves located in the transition between the apical and middle sections of tomato plants (relative variance <25%). The data of the egg densities were adjusted to the negative binomial distribution and presented a common aggregation parameter (Kcommon = 0.4460), which allows us to generate a sampling plan that can be used for both vegetative and reproductive plant stages. The sampling plans consisted of evaluating T. absoluta egg density in 64 plants per field. The time required for sampling varied from 49 min to 1 h 21 min, depending on the field size (i.e. fields from 1 to 10 ha). The cost of sampling was less than US $3.00 for different field sizes. In conclusion, the sampling plan determined in this study is feasible because it is fast and affordable, and it can be used in tomato fields of different sizes and phenological stages.