Tomato plants host various herbivores, including the Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), recently introduced into South and Central America. It is a harmful pest for tomato crops, damaging mainly the flowers and fruits. The assessment of losses and the establishment of economic injury level (EIL) and economic threshold (ET) are core steps toward establishing a control program. We determined losses caused by H. armigera on processing tomato and estimated EIL/ET values. Trials were run during two growing seasons using tomato plants caged in the field. The field cage experiment consisted of six densities of H. armigera second instar larvae (0, 1, 3, 6, 12, and 24 larvae per row meter) at two infestations periods spaced 15 d apart with the first infestation done 90 d after transplanting. The larvae were placed individually on the third upper fully developed leaf. The number of healthy and damaged fruits, size, and weight of the fruits were measured. Yield losses as a function of infestation of 1–24 larvae per row meter ranged from 4 to 34% and resulted in a yield reduction of 1.22–12.77 kg per row meter. The EIL ranged from 1.41 to 1.72 and from 2.11 to 2.58 larvae per row meter of plants in 2017 and 2018 cropping seasons, respectively. Helicoverpa armigera causes significant reduction of tomato yield. These EIL values will enable better control decision-making in processing tomato.
Helicoverpa armigera (Hübner) regularly requires quick deployment of control practices due to its potential of causing yield loss of processing tomatoes. The monitoring of H. armigera adults using stick traps lured with sex pheromone was correlated to egg densities, larvae, and percentage of damaged fruits, aiming to subsidize control decisions only using the number of males caught in the traps since surveying pest stages or damaged fruits is laborious and costly. Surveys were carried out on 11 tomato fields (ca. 80 to 120 hectares each) for processing during the 2015 and 2016 crop seasons. The survey was initiated at the flowering stage with traps set up along the field borders 100 m distant each. Evaluations of adult male capture in the traps were conducted twice a week for 14 and 10 weeks during the 2015 and 2016 seasons, respectively. Simultaneously, 70 tomato plants were fully inspected for eggs, larvae, and damaged fruits per area using a rate of 10 plants per point of trap setting in each area. Overall capture of male moths correlated to subsequent eggs, larvae, and damaged fruits. Based on the outcome of the regression analysis between male moths captured and percentage of damaged fruits, the control decision is suggested when three to six male moths are captured per trap during one week. The monitoring of adults using pheromone traps help deploy chemical or biological control methods to restrain H. armigera population reaching economic threshold levels.
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