Topical Testing Assay: A Technique to Evaluate the Insecticidal Potential of Dopamine Receptor Antagonists on Adult Female Mosquitoes by Topical Application

Topical testing assay in mosquitoes depends on the direct deposition of an active test compound on the dorsal thorax of adult mosquitoes to test its insecticidal property.

To begin, anesthetize adult female mosquitoes by exposing them to the critical thermal minimum - a low temperature which ceases their neuromuscular activity.

Place individual anesthetized female mosquitoes under a dissecting microscope. Take a micro-applicator-connected glass syringe filled with the test compound - a dopamine receptor antagonist - in a non-polar solvent. Position the needle near the thorax and use the micro-applicator to carefully deposit a drop of the test compound on the dorsal surface.

Post application, transfer the treated mosquitoes to a growth chamber with controlled environmental conditions for a determined period.

The non-polar solvent in the droplet solubilizes lipids in the cuticle - an outer covering - allowing the compound to penetrate inside. The compound diffuses through the epidermal layer underneath and reaches the thoracic ganglia - a dense group of nerve cells connected to the nervous system.

Upon reaching the nerve cells, the compound binds to an allosteric site - an additional binding site for regulatory molecules - on the dopamine receptor. The allosteric binding hinders the downstream signaling cascade upon binding to dopamine - a neurotransmitter controlling critical biological processes - leading to death.

Following the experimental duration, record the number of dead mosquitoes - treated individuals lacking any movement - to assess the test compound's insecticidal potential.