| Abstrakt: |
Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is the most devastating pest of tomato crops worldwide. Various biorational management options, such as the application of botanical pesticides, have been deployed to reduce crop damage caused by this invasive pest in Tunisia. In this context, the chemical composition of five plant essential oils (EOs) was explored and their fumigant insecticidal toxicity was evaluated toward larvae of Tuta absoluta and adults of its mirid predator Macrolophus pygmaeus. Gas chromatography coupled with mass spectrometry analysis showed the dominance of monoterpene hydrocarbons and oxygenated monoterpenes in Cymbopogon citratus, Rosmarinus officinalis, Eucalyptus globulus and Salvia officinalis EOs. Ketones are abundant only in Mentha pulegium and S. officinalis EOs. Sesquiterpene hydrocarbons were present in all EOs, while oxygenated sesquiterpenes were found only in C. citratus, R. officinalis and E. globulus. The EOs of C. citratus, R. officinalis, E. globulus, S. officinalis and M. pulegium applied at either 1.25, 2.5, 5, 7.5, 10 or 20 μL/L air at three exposure times (4, 24 and 48 h) were tested against T. absoluta, while the EOs of C. citratus and R. officinalis were assessed on M. pygmaeus. All EOs were toxic toward T. absoluta larvae, causing high mortalities (> 97%) at the highest concentration (20 μL/L air) at 72 h after treatment. Lethal concentration (LC50) values were 20.53, 10.02 and 7.77 μL/L air for C. citratus; 7.53, 5.74 and 5.59 for R. officinalis; 11.09, 5.62 and 5.62 for E. globulus; 11.78, 4.35 and 4.05 for S. officinalis and 10.62, 3.59 and 3.59 for M. pulegium, after 4, 24 and 48 h of exposure, respectively. The highest mortality rates of M. pygmaeus adults exceeded 95% at either 10 or 20 μL/L for either C. citratus or R. officinalis EOs at the three exposure times. These EOs applied at lower concentrations with promising insecticidal potential could be incorporated in integrated pest management programs of T. absoluta, taking into account their possible side effects on M. pygmaeus individuals. [ABSTRACT FROM AUTHOR] |
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