No abstract

No abstract

No abstract

The efficacy of a fungicidal preparation, natamycin, for the effective control of Dermatophagoides pteronyssinus (Trouessart), was determined at different concentrations on mattress-dust microsites, including ticking. One treatment with the commercially available natamycin concentration (Tymasil) resulted in a 65% reduction of house-dust mite populations within 4 weeks of treatment. The acaricidal control could be proven despite the protective role of mattress fibres such as ticking. However, mite fecundity was much more affected after treatment with twice the commercial concentration, which then assured a long-term control. Concentrations below the commercially available one were not effective. In a maritime climate, six sequential treatments three times a year would be effective for an adequate long-term control because of the high growth of house-dust fungi and the close interaction between the mite and the mould Aspergillus penicilloides.

The potential ovicidal activity of natamycin and four imidazoles was investigated with levilite-diatom powder and water as controls. All products tested prevented larval hatching, but not embryonic development. Irregular distribution of the products on the sprayed eggs was noted, except for natamycin. The eggs appeared surrounded in crystal formations or particle clusters. The random nature of these phenomena explains the greatly varied resuits. Its superior dispersion gives natamycin a clear advantage over the other antifungal preparations.