Abstract
Biological control of Oebalus insularis eggs is considered an important strategy in the control of this rice “stink bug”. Effects of essential oils (EOs) from Piper jacquemontianum Kunth and Piper marginatum Jacq. (Piperaceae) on the viability of parasitized and unparasitized eggs by Telenomus podisi, in concentrations of 0.5 to 2.0%, were evaluated. EOs from both species at a concentration of 2% affected the development of embryons of O. insularis as well as of T. podisi after 24 and 48h of their administration. In both species, P. jacquemontanium and P. marginatum LC50, 24 h before the application of treatments on eggs of O. insularis was 3.835 y 3.037, respectively. LC50 after 48 h of treatment with EOs showed contrasting results which varied from 2.207 and 1.811. for P. jacquemontianum and P. marginatum, respectively. LC50 calculated before 24 h in parasitized eggs of O. insularis by T. podisi, was 3.037 and 2.171 for P. jacquemontianum y P. marginatum, respectively, while after 48h of treatment it was 1.166 y 1.935, respectively. Absorption of the EO components by the unparasitized and parasitized eggs of O. insularis by T. podisi was higher after 48 h of exposition. This is due to the longer exposure time, which allows higher penetration of the EOs into the interior of insect eggs by microscopic pores and micropyle.