Assessments were made of fumigant and contact toxicities of 6 Myrtaceae plant essential oils (EOs) and their components against spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). Median lethal dose (LD50;mg/L) values of Leptospermum citratum EO for fumigant activity were 2.39 and 3.24 for males and females, respectively. All tested EOs except Kunzea ambigua EO exhibited effective contact toxicity. LD50(μg/fly) values for contact toxicity of manuka and kanuka were 0.60 and 0.71, respectively, for males and 1.10 and 1.23, respectively, for females. β-Triketone fractions, composed of flavesone, isoleptospermone and leptospermone, exhibited efficient activity with the LD50 values of 0.13–0.37and0.22–0.57μg/fly for males and females, respective

Fumigant and contact toxicities of 11 Myrtaceae plant essential oils and their constituents against adult male and female Blattella germanica were evaluated. Of 11 Myrtaceae plant essential oils, Eucalyptus polybractea, E. smithii, E. radiata, E. dives, E. globulus, and Melaleuca uncinata, showed 100% fumigant toxicity against adult male German cockroaches at a concentration of 7.5 mg/liter air concentration. In contact toxicity tests, E. polybractea, E. smithii, E. radiata, E. dives, E. globulus, M. dissitiflora, and M. uncinata produced strong insecticidal activity against adult male and female German cockroaches. Of the essential oil constituents, terpinolene, α-terpinene, and terpinen-4-ol demonstrated strong fumigant toxicity against adult male and female B. germanica. Eugenol, isoeugenol, methyl eugenol, and terpinen-4-ol showed strong contact toxicity against adult male B. germanica. The toxicity of the constituent blends identified from M. dissitiflora essential oils indicated that terpinen-4-ol were major contributor to the fumigant activity or contact toxicity of the artificial blend. Only isoeugenol exhibited inhibition activity against male acetylcholinesterase. IC50values of isoeugenol were 0.22 mg/mL against male acetylcholinesterase.

The larvicidal activities of 11 Myrtaceae essential oils and their components against Aedes aegypti were tested by the immersion method. We also tested the acute toxicity of 4 active oils and their components against the water flea, Daphnia magna. Further, the aqueous residues of these oils and their components were determined at 2 and 7 days after suspending in water. Among the 11 oils tested, 0.1 mg/mL of Melaleucalinariifolia, M. dissitiflora, M. quinquenervia, and Eucalyptus globulus oils showed strong larvicidal activity against A. aegypti. Among the test compounds, allyl isothiocyanate, γ-terpinene, p-cymene, (+)-limonene, (-)-limonene, γ-terpinene, and (E)-nerolidol showed strong larvicidal activity against A. aegypti. The acute toxicity test revealed M. linariifolia was the most toxic to D. magna. Among test compounds, allyl isothiocyanate was the most toxic to D. magna. Two days after treatment, the residues of M. dissitiflora, M. linariifolia, M. quinquenervia, and E. globulus oils in water were 55.4, 46.6, 32.4, and 14.8%, respectively. Low concentrations of allyl isothiocyanate, γ -terpinene, p-cymene, (-)-limonene, (+)-limonene, and γ-terpinene were detected in the water at 2 days after treatment. Therefore, Myrtaceae essential oils and their components could be developed as control agents against mosquito larvae.