Estudo dos compostos orgânicos voláteis e dos agentes microbianos para o controle de Rhynchophorus spp. (Coleoptera: curculionidae) em Arecaceae

Abstract

The Arecaceae family, consisting of 250 genera and 2,600 species, with worldwide distribution and grown in different countries with tropical climate and adapted to a variety of climates and soils. In Brazil, 37 native genera are catalog, with 288 species, where 123 are endemic, among the commercial species Cocos nucifera L. (1758) and Eleais guinenses. One of the limitations in the production of coconut in Brasil, is the incidence of pests and diseases in coconut trees, which are a problem in the farm and provide low productivity, and can be observed the presence of insects considered pests initially in the beginning of plantation, the seedlings until harvest. During the growth stage, between 4 and 5 years, the action of insect borers is intense, whose larvae feed on the internal tissues of the plant. Among the main pests of economic interest, we mention Rhynchophorus palmarum and the quarantine pest A1 to Brasil Rhynchophorus ferrugineus, belonging to family Curculionidae and order Coleoptera, feed and oviposit on plants of the family Arecaceae, their usual hosts. To mitigate the damage caused by these insects, several agronomic methods are associated, among which are mention: the use of aggregation pheromone with food attractive used in trap-type buckets; of entomopathogenic fungi like Beauveria bassiana and Metharizium anisopliae as biological controllers to decrease insect populations. Aiming at the search for sustainable control methods for palm cultures, a bibliographic analysis was carried out in order to map scientific and technological developments for the control of R. palmarum and R. ferrugineus. The main objective of this research was to characterize the VOCs of entomotogenic fungi for the control of R. plamarum as a preventive model for R. ferrugineus in Arecaceae. For the extraction of volatiles from Entomopathogenic Fungi (EFs) an aeration system was used for a period of 24 hours. After desorption with hexane the extracts were analyzed by GC-DID, GC-EM, GC-EAG and bioassays performed. The morphological identification of the EFs was based on the microculture technique in medium PDA and for the molecular technique, the isolates were submitted to the DNA extraction, amplification and sequencing protocol, using the ITS-rDNA (Internal Transcript Spacer) and α-TEF (Translation Elongation Factor-1α). In the pathogenicity bioassays, native isolates called CVAD01, CVAD02, CVAD06 were used in relation to B. bassiana CPATC/032 and B. bassiana commercial isolate, in a fungal suspension of 1.0 x 109 conidia/mL. The morphological and phylogenetic analyzes allowed the identification of native EFs belonging to the species B. bassiana. Pathogenicity tests caused high mortality for R. palmarum compared to controls. The extract of the isolate CVAD01 showed no activity in the olfactometer, while CVAD02 was active, but both extracts were bioactive in the electrophysiological test. The chromatographic analyzes of the extracts indicated the presence of two alcohols, three aromatic and aliphatic hydrocarbons, two monoterpenes and three ketones. It is concluded that native B. bassiana isolates and the identified compounds can be bioproducts with potential for use in the control of these beetles.