Composição química e repelência de óleos essenciais de Drimys angustifolia Miers e Drimys brasiliensis Miers em cupins de madeira Cryptotermes brevis (Isoptera: Kalotermitidae) / Chemical composition of essential oils of Drimys angustifolia Miers and Drimys brasiliensis Miers and their repellency to drywood termite Cryptotermes brevis (Isoptera: Kalotermitidae)

ABSTRACT

The essential oils extracted from leaves of the Southern Brazilian native species Drimys angustifolia Miers (DA) and Drimys brasiliensis Miers (DB) by Clevenger distillation were analyzed by gas chromatography/mass spectrometry (GC/MS). The oils of DA and DB consisted predominantly of monoterpenoids and sesquiterpenoids. The largest components of DA oil were bicyclogermacrene (19.6%), sabinene (9.7%)and myrcene (5.2%), while DB oil was characterized by cyclocolorenone (18.2%), followed by terpinen-4-ol (8.7%) and alpha-gurjunene (6.9%). Laboratory tests were carried out to determine the repellency of the essential oils to the drywood termite Cryptotermes brevis (Isoptera Kalotermitidae). It was observed that the oil showed repellency at the concentrations 25, 12.5, and 6.25 μg/mL. The oils of both species exhibited a negative repellency index, which represents repellent activity, except for DA oil at the highest concentration, which was attractive. Five deaths (11% of the termitesample) were observed at 25 μg/mL DA, in the fourhour repellency test, while four deaths occurred at 12.5 μg/mL (approximately 9%). The essential oil of DB did not cause any termite deaths...

RESUMO

Os óleos essenciais obtidos das folhas das árvores nativas do sul do Brasil Drimys angustifolia Miers (DA)e Drimys brasiliensis Miers (DB) foram analisados por cromatografia gasosa acoplada a espectrometria de massas (CG/EM). O óleo de DA foi caracterizado pela presença de monoterpenóides e sesquiterpenóides, biciclogermacreno (19,6%), seguido por sabineno (9,7%) e mirceno (5,2%). O óleo de DB foi caracterizado por sesquiterpenóides e monoterpenóides, ciclocolorenona (18,2%), seguido por terpinen-4-ol (8,7%) e alfagurjuneno(6,9%). Os testes foram realizados a fim de se determinar o potencial repelente dos óleos essenciais contra o cupim de madeira seca Cryptotermes brevis (Isoptera Kalotermitidae) nas doses de 25, 12,5, e 6,25 μg/mL. Ambas as espécies mostraram índice de repelência negativo, o que representa a ocorrência da atividade repelente, exceto na maior concentração de DA, na qual o óleo mostrou-se atraente. Cinco mortes foram observadas na concentração de 25 μg/mL de DA, correspondendo a 11% do total em quatro horas de análise, sendo que 9% ocorreram na concentração de 12,5 μg/mL. No caso do óleo essencial de DB não foram observadas mortes de cupins...