Chemical composition of the essential oil of Eucalyptus genotypes susceptible or resistant to the gall-forming wasp Leptocybe invasa Fisher & La-Salle, 2004 (Hymenoptera: Eulophidae)

Abstract

Eucalyptus are trees native to Australia and have been cultivated in various regions of the world. In its worldwide expansion, several native and exotic insects began to use these plants for their survival. Leptocybe invasa Fisher & La-Salle, 2004 (Hymenoptera: Eulophidae) is a gall wasp that lay eggs into leaves, young branches, and petioles causing galls; however, there are resistant and susceptible eucalyptus genotypes to gall formation. This study aimed to compare the chemical composition of eucalyptus genotypes and relate it to resistance and susceptibility to gall formation. Leaf oils were extracted by steam distillation and oil compositions were analyzed. The essential oils of eucalyptus genotypes resistant to gall formation had 12 constituents, which do not occur in susceptible genotypes, probably one of the factors that contributes to the resistance of these plants to gall formation. Thus, we suggest an early evaluation of resistant or susceptible eucalyptus genotypes, based on the chemical composition of the essential oils of these plants, avoiding economic losses of planting susceptible genotypes.