Essential Oils for the Control of Stored Product Insect Pests in Dry Food
Dr. Kostyukovsky M.*, Prof. Shaaya E. and Prof. Ravid U.
E-mail: inspect@volcani.agri.gov.il
The Volcani Center, Bet Dagan, Israel, 50250
The protection of stored agricultural products against insect attack is essential for safe and steady supply of high quality food. Insect damage in stored grains and pulses may amount to 10-40% in countries where modern storage technologies have not been introduced. Currently, the measures to control pest infestation in grain and dry food products rely heavily upon the use of toxic fumigants and contact insecticides, which pose possible health hazards and risk of environmental contamination. This situation has led to the search for potential safe phytochemicals as alternatives to the toxic fumigants mainly methyl bromide and other pesticides for insect control.
In the search for safe natural alternatives, the fumigant activity of a large number of essential oils and essential oil components extracted from aromatic plants was evaluated on the major stored product insects Sitophilus oryzae, Rhizopertha dominica, Tribolium castaneum, Oryzaephilus surinamensis, Ephestia cautella For space fumigation, 3.4 liter glass chambers were used. Exposure time was 24 h. For pilot tests simulation columns (10 120 cm) filled to 70% volume by grain were used. Exposure time was 1-7 days depends on the activity of the test materials. Final adult and larvae mortality was calculated 72 h from the end of the treatment period. Egg mortality was calculated as percent of unhatched eggs. All experiments were conducted at a temperature of 270.5C.
Several compounds were found to be active fumigants at low concentrations. The most active compound extracted from Labiatae spp. has proved to have similar potency as methyl bromide against major insect pests of dry stored food. In space fumigation, all adult insects were killed at a mere concentration of 1.8 mg/l air which is equivalent to 1.8 g/m3 after a 24-h exposure. In pilot tests, using wheat grains, low concentrations of 50-70 g oil/m3 grain, is needed to obtain effective control of the test insects, compared with the recommended concentration of the methyl bromide 30-50 g/m3. The tested essential oils showed also great promise as natural fumigants against some other pests.