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10-Minute Presentation

Medical, Urban, and Veterinary Entomology

10-min: MUVE, Mosquito Physiology, Surveillance, and Control

The antihistamine pyrilamine negatively impacts behavior and infection outcomes in Anopheles stephensi

Tuesday, November 11, 2025
11:24 AM - 11:36 AM Pacific
Location: Oregon Convention Center, B114, OCC
Oral Presentation
Evolutionarily ancient histaminergic signaling regulates a wide diversity of biological processes in animals, including behavior and immunity. To this effect, we have demonstrated that ingestion of the biogenic amine histamine at concentrations present in the blood from individuals with severe malaria (10 nM) alters the biology of the invasive vector mosquito Anopheles stephensi in a manner predicted to enhance malaria parasite transmission. Antihistamines have been shown to affect arthropod biology, so we asked whether the histamine H1 receptor antagonist pyrilamine could reverse the effects of 10 nM histamine on A. stephensi. To evaluate this, we orally provisioned 0.1 µM pyrilamine, 10 nM histamine, or histamine and pyrilamine to A. stephensi for 3 days; controls received diluent only. We monitored diel locomotor activity and infection status in control and treated females at 10- and 14-days post-infection with the mouse parasite Plasmodium yoelii. Compared to treatment with histamine alone, treatment with pyrilamine and histamine significantly reduced the activity of uninfected mosquitoes across the entire active period from 1600 hours–0800 hours. Relative to histamine treatment alone, treatment with pyrilamine and histamine also significantly reduced infection with P. yoelii midgut oocysts at 10 days and P. yoelii salivary gland sporozoites at 14 days. These findings underscore pyrilamine as a potential candidate for use in attractive bait stations to alter mosquito behavior and reduce parasite transmission.