Insecticidal sugar baits for adult biting midges

Area of Science:

• Entomology
• Pest Management
• Veterinary Entomology

Background:

• Insecticidal sugar baits (ISBs) are a method for controlling adult insect populations by mixing insecticides with sugar solutions.
• Biting midges, such as *Culicoides sonorensis*, are significant vectors of animal diseases, including bluetongue virus, epizootic hemorrhagic disease, and vesicular stomatitis viruses.
• Effective control strategies for these disease vectors are crucial for animal health and agricultural economics.

Purpose of the Study:

• To evaluate the efficacy of various commercial insecticide formulations in insecticidal sugar baits (ISBs) against the biting midge *Culicoides sonorensis*.
• To determine the mortality rates of *C. sonorensis* exposed to different concentrations of insecticides in sugar baits.
• To assess the feeding behavior of *C. sonorensis* when presented with ISBs versus an insecticide-free sugar source.

Main Methods:

• Laboratory assays were conducted using reared *C. sonorensis*.
• Midges were exposed to ISBs containing various concentrations (0.01% to 3%) of eight commercial insecticide formulations: bifenthrin, cyfluthrin, deltamethrin, permethrin, dinotefuran, imidacloprid, thiamethoxam, and spinosad.
• Mortality was recorded at 1, 4, 10, and 24 hours post-exposure. A competitive feeding assay was also performed, offering both ISB and plain sugar solutions.

Main Results:

• Pyrethroid-based ISBs (bifenthrin, cyfluthrin, deltamethrin, permethrin) demonstrated the highest mortality rates within the first hour of exposure, even at low concentrations.
• Spinosad-based ISBs resulted in the lowest mortality rates among the tested insecticides.
• A significant finding was that *C. sonorensis* midges did not avoid feeding on 1% ISB solutions, even when a non-insecticidal sugar source was available.

Conclusions:

• Insecticidal sugar baits, particularly those containing pyrethroids, show potential for controlling populations of the biting midge *Culicoides sonorensis*.
• The choice of insecticide active ingredient significantly impacts the efficacy of ISBs against this vector.
• The lack of feeding deterrence suggests ISBs could be a viable tool for integrated pest management strategies targeting disease-carrying midges.