Most studies on the essential oil of nutmeg (Myristica fragrans Houtt,; Myristicaceae) have been laboratory based. To our knowledge, this is the first study describing the practical application of the essential oil of this species in the greenhouse for controlling the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Three concentrations (10, 5, and 2.5 mg/mL) of the ethanol-extracted essential oil of M. fragrans were prepared. In laboratory experiments, fumigation toxicity was evaluated by applying 0.1 mL of extracted oil onto a filter paper (6 cm diameter) that was attached to the inside of the cap of a 100 mL glass jar containing 20 whiteflies; mortality was recorded 1, 2, 4, and 8 h after application. For assessment of contact toxicity, a tomato leaf was treated with 0.1 mL of the essential oil extract solutions and placed in cages containing 20 whiteflies each; the mortality was recorded at 3, 6, 12, and 24 h of the bioassay. For determination of the repellency effect, 2 leaves, 1 treated with extracted oil and another with the control solution, were placed in cages, and 20 insects were released into each cage; repellency was observed after 24, 48, and 72 h. In the greenhouse, 2 potted plants were placed in a cage; 1 was treated with extracted oil and the other was treated with a control solution; 100 whiteflies were released into the cage, and repellency and anti-oviposition effects were observed at 24 and 48 h of the bioassay. Maximum fumigation toxicity (79.17 ± 3.00%), contact toxicity (72.50 ± 4.23%), and repellency (76.67 ± 7.15%) were observed at 10 mg/mL in the laboratory experiments. The maximum repellency (58.33 ± 3.50%) and anti-oviposition (46.11 ± 5.38%) effects were observed at 24 h of exposure in greenhouse tests. These results suggest that the essential oil of M. fragrans was toxic, repellent, and prevented whitefly oviposition in laboratory and greenhouse tests. Further studies are recommended to assess the bioactivity of the chemical components of the essential oil on other insect species.
