A field study on the possible impact of the insecticide diflubenzuron on insectivorous birds

This study examined the possibility that great tits (Parus major), blue tits (Parus caeruleus), and tree sparrows (Passer montanus) might be poisoned by the application of diflubenzuron (Dimilin) used to control insects in woodland and roadside trees. Breeding results were compared in nestboxes in sprayed and unsprayed orchards, and in ash coppices. Diflubenzuron was found to have no significant effect on the breeding results or on the growth of nestlings. The composition of the nestlings' food and the quantity of diflubenzuron found in leaf-feeding insects in the food was measured. On this basis the maximum possible daily intake of diflubenzuron by the nestlings was estimated. These amounts were compared with the daily toxic intake by captive birds, on which dietary feeding tests were carried out.