Susceptibility of the multi-resistant strains of the house fly and the german cockroach to fluralaner and fipronil

The comparative insecticidal activity of fluralaner and fipronil against resistant strains of the house fly and the German cockroach was studied upon contact and ingestion. Topical application revealed extremely high resistance of flies to fluralaner (300–2100?) and resistance of various levels to fipronil (5–75?). All strains of the German cockroach were resistant to fluralaner (5–50?), resistance to fipronil was higher (8–192?). Insecticidal activity of fluralaner increased within 72 hours when applied topically to M. domestica ranged from 2.8 to 10 times, fipronil from 2.5 to 13.1 times, while for the B. germanica this activity increased from 6.5 to 50 times for fluralaner, and from 1.7 to 15 times for fipronil. For houseflies, the intestinal effect of fluralaner is 1.7–17.0 times higher, and that of fipronil is 1.2–2.4 times higher than that by contact. Keywords: Musca domestica, Blattella germanica, proinsecticide, resistance.