The efficacy of antifungal azole and antiprotozoal compounds in protection of wool from keratin-digesting insect larvae

Abstract

The seven azole compounds, econazole nitrate, sulconazole nitrate, miconazole nitrate, thiabendazole, epoxiconazole, propiconazole, and tebuconazole, were applied to wool fabrics at 3.0% on mass of wool and the protection from wool-digesting Tineola bisselliella (common clothes moth) larvae was assessed in bioassays. Econazole nitrate gave the greatest protection according to Wools of New Zealand Test Method 25, easily passing the bioassay. Other good results with sulconazole and epoxiconazole led to further bioassays being performed with Australian carpet beetle larvae Anthrenocerus australis. Propiconazole provided the most effective protection of wool from this species, with a concentration of approximately 0.4% on mass of wool predicted to give adequate insect resistance. A combination of propiconazole and isoniazid was trialed against Anthrenocerus australis, without any synergistic effect. The antiprotozoal compound pentamidine isethionate had no measurable effect on Anthrenocerus australis larvae, but provided a moderate anti-feeding effect on Tineola bisselliella. Antimicrobial compounds could affect the digestive process of wool-digesting insects either directly or by their effects on any gut flora and/or fauna. Azoles are antifungal compounds, and are likely to disrupt the insect utilisation of cholesterol by inhibiting the cytochrome P450 enzymes. Propiconazole was trialed as a dyebath-applied insect-proofing agent on piece-dyed carpet, showing inefficient uptake onto wool, but good fastness to carpet shampooing and light exposure.