Diflubenzuron, 1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl)urea, possesses larvicidal and ovicidal activities. On larvae it acts mainly as a stomach poison, yet it sometimes exhibits important contact activity. Though all instars can be controlled, older instars are generally less susceptible than younger ones. Histological inspections of Leptinotarsa decemlineata larvae revealed that after ending exposure to the compound, distortions in newly deposited cuticular layers decreased gradually. Ovicidal effects resulted from direct contact of diflubenzuron with eggs or from contamination of females by contact or feeding. Electron microscopic observations of embryos of Leptinotarsa decemlineata, contaminated via the female, also showed disturbed cuticule formation, suggesting a similar activity of the compound in larvae and in eggs. Spraying the eggs of Leucoptera scitella shows the compound to be mainly ovidical at a rate of 100 mg litre−1, whilst with lower concentrations (10 and 1 mg litre−1) the young larval instar will be killed. The levels of cross‐resistance to diflubenzuron as a larvicide are low and the compound can be used effectively in the field against populations that are highly resistant to conventional insecticides. Laboratory and field results, based on larvicidal and ovicidal activities of diflubenzuron, are discussed in respect of species belonging to the Diptera, Lepidoptera, Coleoptera, Acarina (Phyllocoptruta oleivora) and Hemiptera (Eurydema oleraceum and Psylla piri).

Mention of a brand name or proprietary product is for identification only and does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of others which may also be suitable.

Upon the discovery of the powerful insecticidal properties of 3-(4-chlorophenyl)-l-(4-chlorophenylcarbamoyl)-2-pyrazoline (PH 60-41), a large number of analogues was prepared. The structures of these compounds were confirmed by NMR. Their insecticidal properties were evaluated with larval stages of Aédes aegypti L., Pieris brassicae L., and Leptinotarsa decemlineata Say. Many of these compounds proved to be excellent insecticides, bringing about the same symptoms as PH 60-41. From the point of view of biological activity and of economic aspects, PH 60-41 appeared to be the most promising compound for several fields of application.

No abstract

No abstract