Development of Agrochemicals Regulating Metamorphosis and Diapause

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Since juvenile hormone (JH) and ecdysteroids are involved in many physiological functions in insects such as metamorphosis, reproductive and embryogenic events, diapause, and behavior, compounds with anti-JH and anti-ecdysteroid activity, insect growth regulators, offer a prospective method for selective insect control as well as an effective tool in studies of insect biochemistry and physiology. In this research project, the design and synthesis of a novel series of insect growth regulators were carried out. Various 1,5-disubstituted imidazoles inhibited in vitro JH III biosynthesis in isolated corpora allata from the cockroach, Diploptera punctata, and caused a significant accumulation of methyl farnesoate, suggesting an inhibition of methyl farnesoate epoxidase. Among the compounds tested, 1-Isobutyl-5-(3-benzyloxyphenyl)-imidazole showed the highest activity. A large number of 1-substituted imidazoles and 3-pyridyl etheres as well as 1,5-disubstituted imidazoles induced precocious … More metamorphosis in the larvae of the silkworm, Bombyxmori. The activity of these compounds to cause precocious pupation was completely counteracted by the simultaneous application of tebufenozide, a non-steroidal ecdysteroid agonist, indicating that these compounds temporarily depressed the ecdysteroid titer in the larval hemolymph to induce precocious pupation. A variety of 1,5-disubstituted imidazoles-have been found to show delayd toxicity against the larvae of the brown rice planthopper, Nilaparvata lugens and Laodelphax striatellus. Of the series of compounds tested, 1-isobutyl-and 1-neopentyl-5-(3-trifluoroethoxyphenyl) imidazoles showed the highest activity. 1-Substituted imidazoles terminated the diapause in the pharate first-instar larvae of the silkmoth, Antheraea yamamai. 1-[5-(4-Ethylphenoxy) pentyl] imidazole showed activity comparable to that of KK-42, the most effective compound so far. The injection of KK-42 into fifth instar larvae of the silkworm (Daizo strain), which had been destined to produce diapause eggs, induced the moths to lay non-diapause eggs. Less