Investigations on Tuta absoluta (Lepidoptera: Gelechiidae): larval infestation on the tomato cultivated in open field and evaluation of five essential oils against larvae in laboratory

Abstract

Abstract The tomato miner Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is a Neotropical species, which cause serious damages to tomato in spread areas. It appeared in 2008 in Italy, where it seriously threatened tomato production both in greenhouse and open field cultivations. In this work a study on infestation by this leafminer on leaves was conducted in an organic cultivation of tomato (Lycopersicon esculentum Mill.) "Pizzutello" variety in Sicily (Italy), and the insecticidal activity of 5 essential oils (EOs) on T. absoluta was evaluated in laboratory. EOs of basil, cypress, laurel, peppermint and Spanish oregano were used against 3rd- and 4th-instar larvae to assess contact effects and, only for oregano and laurel, inhalation effects. Results showed that the infestation in field had a variable trend showing peaks in two periods, in the months of July and October. Larvae of T. absoluta developed on leaves for most of the growing season of tomato showing a peak of 1.5 larva per leaf in the first part of July decreasing in the subsequent months. Results on the use of essential oils against the leafminer showed a good larvicidal effects confirming their use as potential alternative for pest control. Basil, cypress and laurel oils showed major contact efficacy. Inhalation effects of the oils of oregano and laurel increased with increasing their doses with a positive correlation. Oregano oil was effective at lower doses than laurel.