Toxicological Studies of the Thiourea Diafenthiuron in Diamondback Moths (Lepidoptera: Yponomeutidae), Twospotted Spider Mites (Acari: Tetranychidae), and Bulb Mites (Acari: Acaridae)
Authors: KADIR, HABSAH A.; KNOWLES, CHARLES O.
Source: Journal of Economic Entomology, Volume 84, Number 3, June 1991 , pp. 780-784(5)
Publisher: Entomological Society of America
Abstract:Diafenthiuron possessed moderate toxicity to adult diamondback moths, Plutella Xylostella(L.) (LD• 269.4 fJ.g/g), low toxicity to twospotted spider mites, TetTanychus uTticae Koch (41.7% mortality at 500 ppm), and was inactive against bulb mites, Rhizoglyphus echinopus (Fumouze and Robin) (0% mortality at 1,000 ppm). However, 3-(2,6-diisopropyl)- 4-phenoxyphenyl)-1-teTt-butylcarbodiimide (DFCD), a diafenthiuron photodegradation product, was highly toxic to diamondback moths (LD• 29.7 fJ.g/g), twospotted spider mites (LC• 8.9 ppm), and bulb mites (LC50 106.6 ppm). The toxicity of diafenthiuron to diamondback moths was antagonized by the mixed function oxidase inhibitor piperonyl butoxide, but the toxicity of DFCD was unaffected by the same treatment. Moreover, bulb mites converted diafenthiuron-14C to DFCD and to 3-(2,6-diisopropyl-4-phenoxyphenyl)-1-teTtbutyl urea, which was nontoxic. Symptoms in moths treated with diafenthiuron or DFCD were time and dose dependent. These symptoms appeared earlier and with greater intensity in moths treated with the carbodiimide. Symptoms included hyperreflexia and marked hyperactivity manifested chiefly by jumping, increased movement of antennae and mouthparts, spinning, and wing flutter. They were strikingly similar to those manifested by moths treated with N'-(4-chloro-o-tolyl)-N-methylformamidine, a known octopaminergic agonist, and markedly different from symptoms displayed by moths treated with dicyclohexylcarbodiimide and with insecticides and acaricides known to attack cholinergic, GABA-ergic, and other systems. These data suggest that diafenthiuron is a propesticide with lethal action in insects and mites that depends on the carbodiimide metabolite. This metabolite functions as a neurotoxicant, possibly by interfering with a biogenic amine (octopamine) mediated mechanism(s).
Document Type: Research Article
Publication date: June 1991
- Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.
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