The eucalypt defoliator Thyrinteina arnobia (Lepidoptera: Geometridae) protects its eggs from parasitism

Eucalyptus plantations in Brazil can be damaged by insect pests from the native Myrtaceae, such as the moth Thyrinteina arnobia (Lepidoptera: Geometridae), which is considered the main defoliating caterpillar of this plant in Brazil. Eggs of T. arnobia reared with E. grandis, guava or mulberry plants were collected and offered to the parasitoid Trichogramma maxacalii (Hymenoptera: Trichogrammatidae). All individuals of this parasitoid died within 24 h after contact with unwashed eggs of this moth, independent of its rearing host. Most parasitoids survived when exposed to solvent-washed eggs, but still could not parasitize them. This means that the moth covers its eggs with some compounds that are toxic to the parasitoid T. maxacalii. This phenomenon helps to explain the population explosion of this pest in eucalypt plantations and the fact that egg parasitism was not recorded in Thyrinteina†arnobia.