Bioactivity of ten essential oils on the biological parameters of Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) adults

Abstract

Trichogrammatidae are biological control agents of agricultural and forest pests. However, chemicals can affect their biological aspects. Essential oils (EOs) are an alternative for pest control, but their effect on biological control agents are not fully known. The objective was to evaluate the effects of EOs of Allium sativum, Carapa guianensis, Citrus sinensis, Mentha piperita, Origanum vulgare, Piper nigrum, Syzygium aromarticum, Thymus vulgaris, Zingiber officinale and Azadirachta indica on the female longevity, parasitism and emergence rates and sex ratio of Trichogramma pretiosum (Riley) (Hymenoptera: Trichogrammatidae) adults of parental, F1 and F2 generations. The longevity of T. pretiosum females in the parental and F1 generations was reduced ∼50% by the EOs of A. sativum and M. piperita in comparison to controls (∼10 days). Eggs of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) treated with Z. officinale were not parasitized, evidencing a strong repellent activity of this EO. Allium sativum and C. guianensis EOs reduced the parasitism rate in 33 and 70%, respectively, of females from the parental T. pretiosum generation. These EOs were classified as slightly harmful (class 2) in relation to parasitism. Carapa guianensis caused the greatest reduction in the emergence rate of the F1 generation (27%); however, this EO continued to be classified as innocuous to T. pretiosum. Sex ratio of the F1 and F2T. pretiosum generations was no affect by these ten EOs. Zingiber officinale was not compatible for T. pretiosum; and A. sativum, C. guianensis and M. piperita are poorly compatible with this parasitoid. The EOs of the other six plant species are promising for integrated pest management with T. pretiosum.