The Tuta absoluta species represents a significant threat to solanaceous crops globally and has developed resistance to conventional synthetic insecticides. This study investigated the insecticidal properties of essential oils (EOs) from Melaleuca alternifolia and Eucalyptus staigeriana against T. absoluta using the age-stage, two-sex life table methodology. Initially, the EOs of M. alternifolia and E. staigeriana were chemically characterized by gas chromatography (GC) techniques. In this analysis, we identified 19 compounds in M. alternifolia essential oil, with terpinen-4-ol, γ-terpinene, and α-terpinene as the predominant constituents. Eucalyptus staigeriana essential oil contained 25 identified compounds, predominantly limonene, terpinolene, geranial, and neral. Essential oils were dissolved in acetone and applied topically to larval stages. Both treatments significantly reduced pest longevity and adversely affected key demographic parameters. Melaleuca alternifolia treatment resulted in a substantial decrease in the intrinsic rate of population increase, indicating potential for population suppression. These findings support the potential application of M. alternifolia and E. staigeriana EOs as biological control agents against T. absoluta in integrated pest management programs.

The tomato leafminer Phthorimaea absoluta is an important pest of solanaceous plants and is considered a key pest of tomato plants. This pest is rapidly dispersed, difficult to con-trol, and resistant to the main synthetic insecticides. The objective was to determine the lethal and sublethal effects of three essential oils (Eos) of Melaleuca alternifolia and Euca-lyptus staigeriana against P. absoluta. We evaluated the effects of the EOs during the life cy-cle of the pest using an age-stage, two-sex life table. The treatments were solubilized in ac-etone and applied to the back of the caterpillars. The EOs of M. alternifolia and E. staigeriana reduced P. absoluta longevity to 22.2 and 15.9 days and negatively impacted demographic parameters. Melaleuca alternifolia notably decreased the intrinsic rate of increase. Chroma-tographic findings revealed the presence of 19 compounds in the M. alternifolia EO, with terpinen-4-ol, γ-terpinene and α-terpinene being the most abundant. On the other hand, E. staigeriana presented 25 constituents, with the compounds limonene, geranial and neral being the most abundant. The results obtained demonstrate the insecticidal potential of M. alternifolia and E. staigeriana EOs in the control of P. absoluta.

Spodoptera frugiperda (Lepidoptera: Noctuidae) causes significant losses in major crops and is mainly controlled with chemical insecticides and genetically modified plants; however, improper use of these strategies has led to the development of resistant populations. We evaluated the insecticidal activity of essential oils (EOs) and major compounds of Syzygium aromaticum (Myrtaceae) and Foeniculum vulgare var. dulce (Apiaceae) against S. frugiperda, and their selectivity toward Trichogramma pretiosum (Hymenoptera: Trichogrammatidae). EOs and major compounds were topically applied to caterpillars using a microsyringe. Chromatographic analysis revealed that the major compounds of S. aromaticum were eugenol (76.2%) and (E)-caryophyllene (19.9%), while (E)-anethole (83.35%) was the major compound of F. vulgare var. dulce. The EOs of S. aromaticum and F. vulgare var. dulce were toxic to S. frugiperda (LD₅₀ = 54.2 and 41 µg/caterpillar, respectively), compared with 0.03 µg a.i./caterpillar for chlorpyrifos, with (E)-anethole accounting for most of its insecticidal activity. The EOs also adversely affected larval development, fecundity, and life table parameters. Additionally, the EO of S. aromaticum was harmful to adult T. pretiosum females, whereas F. vulgare var. dulce EO and (E)-anethole were harmless to slightly harmful to the parasitoid’s immature stages, highlighting their potential for selective control of S. frugiperda.