Persistence of the Insecticide Dimilin 45 ODC on Conifer Forest Foliage in an Atlantic-Climate Ecosystem

Abstract

The oil formulation of diflubenzuron (Dimilin 45 ODC) persisted for 10-12 weeks on the foliage of a conifer forest in an Atlantic-climate ecosystem. Within 22-30 days following treatment, 55-80% of the insecticide had been removed from the foliage. During this period, the concentration of diflubenzuron was higher than 370 ng g(-1). Aerial application at 56.3 g of Al ha(-1) resulted in deposition levels of the insecticide ranging from 867.5 to 1824.4 ng g(-1), depending upon forest characteristics. The results showed that aerial application is only a suitable technique for the treatment of forest areas with dense foliage and/or high tree density and no more than 15% of tree-free area. The only metabolite detected was 2,6-difluorobenzamide, and this persisted on foliage until the first rainfalls occurred. An empirical mathematical correlation was found to express the influence of meteorological variables--rainfall, solar radiation and temperature--on the persistence of the insecticide. These results suggested that degradation of diflubenzuron on foliage could be due to photodegradation. Some recommendations were made to optimize the deposition of the insecticide on foliage and to minimize its persistence and the off-site spray drift.

Experimental Study on Diflubenzuron: Degradation in Freshwater and Bioconcentration in Mosquitofish Following Chronic Exposure

“…HPLC was found to be one of the best methods due to its sensitivity [17]. Dimilin is degraded in the environment mainly by photodegradation and hydrolysis [40], producing as major metabolites: 2,6-diflurobenzamide, 4-chlorophenylurea, 4-chloroacetanilide, 4-chloroaniline and N-methyl-4-chloroaniline [45]. Among them, 4-chloroaniline shows a higher toxicity to fish than the original product [46].…”

The tissue distribution, metabolism and hepatotoxicity of benzoylurea pesticides in male Eremias argus after a single oral administration

“…Diflubenzuron is one of the early used BPUs, which could persistent in the grassland for two months (Symmons, 1992). The aerial application of diflubenzuron resulted in deposition levels ranging from 867.5 to 1824.4 ng g À1 (Rodriguez et al, 2001). Diflubenzuron has limited impact on the non-target invertebrate populations (Soltanimazouni, 1994) and low toxicity to birds (Whitmore et al, 1993).…”

Residues of diflubenzuron on horse chestnut (Aesculus hippocastanum) leaves and their efficacy against the horse chestnut leafminer, Cameraria ohridella

“…No data are available in the literature on the possible persistence of DFB on/in horse chestnut foliage. The stability of DFB has been studied on other deciduous as well as coniferous trees;9–11 in these cases, DFB was reported to remain stable over extended periods. As the horse chestnut is one of the favourite ornamental trees in parks and other public areas, the environmental impact of DFB formulations should be carefully assessed.…”