Toxicidade de óleos essenciais de anonáceas para Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) e seletividade para Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae)

Abstract

The indiscriminate use of synthetic chemical insecticides and genetically modified plants in economic importance crops has led to the selection of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) resistance populations. Since, S. frugiperda is a polyphagous insect, capable of causing great economic damage, there is a need to search for new molecules that can be used in its management. One of the sources of new molecules are secondary metabolites of plant origin. In this work, species of plants of the family Annonaceae were selected: Annona neolaurifolia H. Rainer (leaves), Duguetia lanceolata A. St.-Hil (leaves and stem barks) and Xylopia brasiliensis (branches and stem barks), with the objective of studying the toxicity of its essential oils (OEs) for S. frugiperda, as well as evaluating the physiological selectivity for the oophagus parasitoid Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae), an important natural enemy of S. frugiperda. In the present work, it was found toxic activity of OEs from D. lanceolata (leaves and stem bark) and X. brasiliensis (stem bark) against S. frugiperda, in a topical application test. The OEs of the leaves and stem barks of D. lanceolata were selected for the next stages of the work, due to the higher yield obtained in the extraction process. The OE of D. lanceolata leaves (DL90 70.76 µg/insect) showed greater toxicity than the OE of stem bark (DL90 127.14 µg/insect). Thus, the major compounds of the OE from leaves of D. lanceolata (beta-caryophyllene and caryophyllene oxide) had their toxicity assessed for S. frugiperda, but the biological activity was not pronounced when tested in isolation. However, the mixture of beta-caryophyllene and caryophyllene oxide was active for S. frugiperda. In a test with the natural enemy T. pretiosum, the EOs from D. lanceolata (leaves and stem barks) were not selective for this insect. Thus, although OEs from D. lanceolata (leaves and stem barks) presented potential as sources of toxic substances for S. frugiperda, more information is needed on how to make the use these OEs in integrated pest management programs with T. pretiosum.