Avaliação e caracterização química de substratos vegetais para atração e monitoramento de Sphenophorus levis Vaurie, 1978 (Coleoptera: Curculionidae)

Abstract

Brazil is the world leader in sugarcane production, a crop of extreme relevance to the agribusiness sector. However, Sphenophorus levis, one of the main pests of this crop, has affected production in some regions of the country. Therefore, it is necessary to improve monitoring and control methods, as the underground habitat of the pest is a limiting factor. The aim of this study was to evaluate whether different plant substrates (sugarcane, sugarcane with 10% molasses, pineapple peel, banana pseudostem, and coconut fiber) and their volatile compounds have attractive potential for S. levis adults. Samples of these plant substrates were subjected to different periods of natural degradation (0, 24, 48, and 72 hours) in a B.O.D. at 26°C, and subsequently processed and stored in a freezer. Next, the pH, total and soluble solids, carbon, and total nitrogen of the samples were characterized, and the organic volatile compounds were identified and quantified by gas chromatography with flame ionization detection (GC-FID). To test the attractiveness of the substrates, assays were performed in choice arenas containing four treatments (plant substrates) and 30 repetitions (15 female and 15 male S. levis adults), with the duration of permanence on the substrate evaluated for 30 minutes. The most frequently occurring volatile compounds in the physicochemical characterization were selected to evaluate their attractiveness to S. levis adults. The results showed variations in pH and total and soluble solids over time for all plant substrates, as well as ethanol and acetic acid contents, the main volatile compounds present in the natural degradation of the substrates. The degree of substrate degradation did not interfere with attractiveness; however, the concentration of volatile compounds influenced insect attraction. The exploration of S. levis' perception and attraction behavior to these different substrates and volatile compounds provided insights and promising perspectives to improve monitoring techniques for this insect pest.