Evaluation of essential oils of Eucalyptus spp. for the control of the subterranean termite Coptotermes gestroi (WASMAN)

Abstract

The subterranean termite Coptotermes gestroi (Wasman) (Isoptera: Rhinotermitidae) is considered one of the main pest species in urban areas in the Southeast Region of Brazil. For the control of this pest, the use of chemical insecticides is recommended, but this method is problematic in urban areas because of the risks of intoxication in the population and environmental contamination along with difficulties in isolating the treated areas. Therefore, it is necessary to find alternative methods aimed at minimizing the undesirable effects on the human population and the environment caused by termite control measures. The objective of this research was to evaluate the toxicity of several essential oils of Eucalyptus (E. camaldulensis, E. citriodora, E. tereticornis, E. pseudoglobulus, and E. maidenii) to the termite C. gestroi, under laboratory conditions. The oils were applied on filter papers that were infested with C. gestroi immediately after the treatment. The most toxic oil to the termite was E. citriodora, with the lowest lethal concentration (LC50: 0.63%) and the shortest lethal time (LT50: <1 h at 10%, LT50: 42.4 h at 1.25%). The least toxic oil was E. pseudoglobulus, with the highest lethal concentration (LC50: 3.66%) and the longest lethal time (LT50: 11.1 h at 10%; LT50: 473 h at 1.25%). These results indicate the potential for use of eucalyptus essential oils, especially for E. citriodora, for the control of C. gestroi. This article also provides information on the yield from essential oil extraction for different eucalyptus species.