EFFECTS ON TWO IMPORTANT AGRICULTURAL PESTS OF ESSENTIAL OILS RICH IN (E)-NEROLIDOL FROM Melaleuca leucadendra

Abstract

Tetranychus urticae is a polyphagous pest that attacks tomato and cucumber crops in protected environments and on organic farms in the region of the lower-middle São Francisco Valley in the state of Pernambuco, Brazil. Plutella xylostella is another pest that causes serious damage to vegetable crops around the world, particularly cabbage, cauliflower and broccoli. Control with synthetic products is still the most widely used method to minimize the damage caused by these pests. However, even when employed correctly, large amounts of synthetic pesticides cause ecological imbalances, leading to arthropod populations that are resistant to the active ingredients. As an alternative to synthetic products, essential oils are promising in the control of several arthropods due to their known biological properties, causing death and acting on the behavior of different agricultural pests. Essential oils from the leaves, stems, flowers and fruit of M. leucadendra growing in the state of Pernambuco, Brazil, were analyzed using GC-MS. The effects of the oils and their major constituent were evaluated on the agricultural pests T. urticae and P. xylostella in different stages of development. Analysis show a new chemotype of M. leucadendra rich in (E)-nerolidol (81.78 ± 0.90% to 95.78 ± 1.20%). P. xylostella was more susceptible to the oils and major constituent than T. urticae. The fruit oil was 1.5-fold more toxic than the leaf oil to T. urticae eggs. (E)-Nerolidol was 5.5-fold and 4.5-fold more toxic to T. urticae adults than the leaf and fruit oils, respectively. Azamax® used as the positive control was more efficient than the oils and (E)-nerolidol against T. urticae. However, for P. xylostella, the oils and (E)-nerolidol were more toxic than Azamax®.