Intestinal effects of modern insecticides on multiresistant strains of the housefly Musca domestica

Under laboratory conditions, resistance to insecticides in several strains of the housefly, Musca domestica, obtained from populations collected at various facilities in the Moscow and Kaluga regions, was assessed by intestinal ingestion of insecticidal baits. The insects of the strains Krasnogorsk and Kaluga had the highest resistance ratios to fipronil (23.3–76.7x), while those of the KSK-1 and KSK-2 strains were tolerant (6.3–7.7x). The strains Krasnogorsk, KSK-1, KSK-2 and Kaluga are highly resistant to neonicotinoids (thiamethoxam 80.4–104.8x and clothianidin 79.5–97.9x), weakly tolerant to chlorfenapyr (1.8–2.8x) and highly susceptible to indoxacarb (0.22–0.54x). A comparison was made of the contact and intestinal effects of insecticides against the housefly. The resistance factor of the housefly to fipronil, thiamethoxam, and clothianidin upon contact is 1.5–4.4 times higher than those after feeding with the similar insecticide dose. Possible mechanisms of insect multiresistance to insecticides are discussed. Comparative evaluation using three strains of the housefly showed that a number of industrially produced baits are effective for control of the field populations of the house fly. Physiological resistance of the housefly of Krasnogorsk and Kaluga strains to baits based on methomyl was shown.