The insecticide properties of mineral oils have not been fully exploited especially for use during the vegetative period. New trends in crop protection are encouraging the search for harmless pesticides that have renewed the interest for the use of oils in agriculture.

Several trials have been done to assess the repellency and toxicity of different oils on Myzus persicae and Franklinella occidentalis: a summer mineral oil, refined oils of soya and rapeseed, and a crude fish oil. In the laboratory the results obtained suggest that tested oils, in particular fish oil, are feeding deterrents for both insect species. Oils also showed some toxicity for the aphids settled on sprayed pepper leaves and for the thrips settled on sprayed green beans. The oil showing the strongest insecticidal activity on the aphids was soya oil (40% mortality at 72 h), followed by the fish oil and the rapeseed oil (over 30% mortality at 72 h). On the thrips, the strongest insecticidal activity was showed by fish oil (over 60% mortality at 96 h).

In a trial in which alate aphids were released into a cage that contained sprayed pepper plants, the plants sprayed with fish oil and mineral oil were less colonized by the aphids than the plants sprayed with the vegetable oils and the untreated plants.

In a field trial conducted in a pepper greenhouse showed that oils reduce the number of thrips on the flowers in the sprayed plots. The vegetable oils and the fish oil reached higher control efficiency and persistence than mineral oil.