Residual Activity of Pyriproxyfen Against Mosquitoes in Catch Basins in Northwestern Riverside County, Southern...

Area of Science:

• Environmental Entomology
• Pest Management
• Public Health Entomology

Background:

• Mosquitoes in catch basins pose a public health risk, necessitating effective control strategies.
• Insect growth regulators (IGRs) offer a targeted approach to mosquito population management.
• Understanding the residual activity of IGRs is crucial for optimizing treatment schedules.

Purpose of the Study:

• To evaluate the year-long residual efficacy of pyriproxyfen compared to methoprene against mosquito larvae in catch basins.
• To determine the optimal application rates of pyriproxyfen for sustained mosquito control.

Main Methods:

• A field study was conducted in 80 catch basins in Riverside County, California.
• Pyriproxyfen was applied at rates of 75-175 g, and methoprene at 3.5 g per catch basin.
• Mosquito developmental stages were monitored weekly, with pupae reared to adults to assess adult emergence inhibition (% IAE).

Main Results:

• Both pyriproxyfen and methoprene provided complete mosquito control at certain application rates.
• Pyriproxyfen achieved 48-50 weeks of residual activity, with higher rates (125g, 175g) showing sustained efficacy.
• Post-study bioassays confirmed significant inhibition of adult emergence by pyriproxyfen at higher rates.

Conclusions:

• Pyriproxyfen is an effective IGR for long-term mosquito control in catch basins, with efficacy dependent on application rate.
• Optimal application rates of pyriproxyfen can provide residual control for up to 50 weeks.
• This study supports the use of pyriproxyfen as a valuable tool in integrated mosquito management programs.