Treatment with a combination of the insecticides imidacloprid and permethrin successfully inhibits blood feeding by adult female mosquitoes in dogs raised under outdoor conditions, a new study suggests.

To evaluate the inhibitory effects on blood-feeding activity of mosquitoes Dr. Hiroyuki Machida from Bayer Medical Ltd.’s Animal Health Division in Tokyo and colleagues used a combination of 10% (w/v) of imidacloprid and 50% (w/v) of permethrin as spot-on form.

Dr. Machida’s team compared a group of treated dogs with a control group of untreated dogs. After treatment, dogs in the control and treated groups were kept separately from the evening (17:00) to the morning of the following day (09:00) in two different kennels installed outdoors to mimic realistic dog-raising conditions

Mosquitoes were collected by light traps placed in the kennels and a sweep net to determine evidence of blood feeding, and for species identification. The researchers collected mosquitos at days 5, 3 and 1 before agent treatment, the day of treatment, and days 3, 7, 14, 21, 28, 35 and 42 after treatment.

Analysis of the collected mosquitos showed that the percentages of blood-fed mosquitoes measured at days 0, 3, 21, 28 and 42 after treatment were statistically significantly lower in the treated group than in the control group, the team notes in Veterinary Parasitology.

The most commonly collected mosquito, Culex tritaeniorhynchus, revealed statistically significant lower percentages of blood-fed mosquitoes in the treated group than in the control group at the day of treatment, and days 3, 7, 21, 28 and 42 after treatment.

It appeared “that the test agent was effective in inhibiting blood feeding by adult female mosquitoes, and the efficacy lasts for 42 days after treatment under outdoor conditions”.

References

• Veterinary Parasitology, July 2008, Volume 154, Issues 3-4, Pages 318-324