Modeling shows that painting with organophosphate microcapsules would be a highly efficient strategy for <i>Triatoma infestans</i> control

The eradication of Triatoma infestans and similar vector species has been the focus of the fight against Chagas disease for several decades. The standard control method continues to be the fumigation with pyrethroids, which has led to the emergence of resistant bug populations in many regions of South America and, especially, in the Gran Chaco. It is therefore essential to develop alternative methods of T. infestans control. Paint with microcapsules containing organophosphate substances has been shown to have a positive impact on the reduction of house infestation. In this study, we investigate the effects of the application of organophosphate-based insecticidal paints on a T. infestans population in a chicken coop, the recovery of this population, and the frequencies of application required to control the insect under realistic conditions. We extended a recently proposed model of all stages of T. infestans populations in chicken coops to include paint-induced mortality. Considering climate and bug migration variations, we find the paint application frequencies that guarantee low levels of infestation. A strong and stable decrease in the triatomine population can be achieved by paint applications separated by 4 years or more. This work, taken together with previous experimental results, strongly suggests that painting with organophosphate microcapsules would be a highly efficient method to control T. infestans in regions where it has developed immunity to pyrethroids.