The need for food commodities that are free of synthetic pesticides and the increase of insecticide resistance in pest insect populations present challenges for stored-product pest management. Presently the only botanical insecticide registered for use in storage systems is pyrethrum. More research is needed to develop natural products for storage insect pest control. The neem tree, Azadirachta indica, contains natural insecticides, but their utility for storage pests has not been fully realized. Neem, pyrethrins from chrysanthemum flowers, Chrysanthemum cineraraefolium, and essential oils of many plants will kill storage pests when applied at high levels, but low levels are not as effective as synthetic insecticides. Initial experiments with proprietary materials suggest that diatomaceous earth (DE), a naturally occurring insecticidal desiccant, can act as a synergist for botanical insecticides. Here we conducted a series of laboratory experiments in which wheat was treated with either a commercial neem extract (Amazin 3% EC; AMVAC), a natural extract of pyrethrins (Evergreen Grower's Spray, MGK), or essential oils from eastern red cedar, Juniperus virginiana, either alone or in combination with DE. Treated wheat was challenged with infestation by Indian meal moth, red flour beetle, rice weevil and lesser grain borer, and the effects of treatment on infesting adults and progeny survival were determined. Adult beetles were unaffected by low concentrations of any of the botanicals applied alone to wheat. However, progeny production by the Indian meal moth and the red flour beetle was suppressed by the neem extract alone at levels less than 1.0 ppm. These species have externally feeding larvae and thus may have experienced the insect growth regulating activity of neem. Results to date show that combinations of DE at 80, 100 and 150 ppm with the three botanicals hold promise as grain protecants.
Species 1: Lepidoptera Pyralidae Plodia interpunctela (Indian meal moth)
Species 2: Coleoptera Bostrichidea Rhyzopertha dominica (lesser grain borer)
Species 3: Coleoptera Tenebrionidae Tribolium castneum (red flour beetle)
Keywords: Botanicals, Diatomaceous earth
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA