Semioquímicos envolvidos na interação cana-de-açúcar versus broca gigante e mandioca versus percevejo-de-renda versus mosca-branca

Abstract

Brazil is known worldwide for its natural vocation for agriculture. Among the main crops is the sugarcane and cassava that are cultures with strong socioeconomic influence cassava being the main crop in small-scale farming and family agriculture, and sugarcane historically more relevant to agro-industry and agribusiness. Despite the high agricultural production in these two cultures, both suffer greatly with the incidence of pests which results in considerable production losses. Pest control is usually performed by insecticides, which is undesirable both for economic and environmental reasons, it eliminates natural enemies, and increase the possibility of insecticide resistance. The use of semiochemicals provide a more viable and environmental friendly approach to control these pests. Thus, this study aimed to identify volatile organic compounds (VOCs) from a resistant cassava cultivar (Manihot esculenta), and to evaluate the repellency of its VOCs to white flies that attack cassava. In addition we aimed to identify the epicuticular compounds (EC) of the larvae and adult giant sugarcane borer (Telchin licus) and to evaluate the antimicrobial activity of these compounds against endophytic microorganism isolated from sugarcane. VOCs were identified using gas chromatography coupled mass spectrometry. The resistant cultivar in uninfested plants emitted several compounds that may be involved in plant defense, while maintaining a high emission of trans-β-ocimene monoterpene, which showed repellency against the whitefly. The epicuticular compounds of larvae and adults of giant sugarcane borer were identified using chromatography coupled mass spectrometry. The ECs from the larvae showed in particularly, long-chain esters, reaching a 98% of its total composition. These compounds showed antimicrobial activity against the isolated endophytic "G" (unidentified) and isolated "O" (Bacillus cereus). ECs of the adult male and female giant sugarcane borer showed similar profiles, mostly n-alkanes (C-23 to C-30), however the ECs from males have three unique compounds that may be related to communication between genders.