Work

Implication of long-term use of unilateral mosquito control in Hungary – the assessment of pyrethroid resistance in disease vectors Culex pipiens and Aedes albopictus

Year: 2025

Type: article

Abstract: Nowadays, vector-borne diseases cause major problem worldwide. To stop their spread, beside the chemical treatment –using mostly pyrethroid substances– several alternative methods are available. Nevertheless, the mosquito control in most places still relies predominantly on chemical treatments using only one substance, as the use of delthametrin in Hungary. However, pyrethroids are non-selective, so they can cause major damage to the ecosystem and the targeted mosquitoes can develop resistance against it. Our aim is to highlight the presence of knockdown mutation caused by the long-term, unilateral application of pyrethroid substances. To achieve this, we investigated Culex pipiens as the major vector of West Nile virus and Aedes albopictus as the vector of several arboviruses, including Dengue virus. The mosquitoes (n=208) were collected from 3 different regions of Hungary, in 2022 and 2023. 128 specimens of Culex pipiens and 80 of Aedes albopictus were collected with CO2 baiting traps. To detect the knockdown mutation, an allele-specific PCR was used (described previously by Martinez-Torres et al. (1999) and Pichler et al. (2022)), followed by gel electrophoresis. Our analysis revealed the presence of the allele associated with pyrethroid resistance in Cx. pipiens specimens in 60% of the individuals, while 40% showed the susceptible genotype. Pyrethroid resistant mosquitoes were identified both from 2022 and 2023 at all the collection sites. In the case of Ae. albopictus, all the investigated specimens showed the susceptible genotype, the resistant allele was not present. Although our study revealed only susceptible individuals of Ae. albopictus, the resistance allele has been identified in other European populations of the species (Spain, France, Italy, Romania etc.), necessitating proactive measures in Hungary. This species was initially identified in Hungary in 2014, potentially indicating insufficient time for the development of pyrethroid- resistance. On the other hand, in Cx. pipiens species the presence of the resistance allele was expected since this species is endemic in Hungary, and has been the primary target of the chemical treatments, leading to the development of pyrethroid resistance. Based on our research, we are advocating for an integrated vector control program in Hungary, focusing on vector-borne disease prevention, minimizing the ecological harm of chemical treatments and enhancing communication between the stakeholders. Furthermore, we aim to expand resistance testing to other vector species as well. Our study shows the presence of pyrethroid resistance in Cx. pipiens populations in Hungary, highlighting the urgent need to reconsider the local mosquito control methods. The presence of resistance in Ae. albopictus in the neighbouring countries emphasizes the importance of preventive measures. Continued reliance on pyrethroid-based products could exacerbate ecological damage without effectively reduce the targeted mosquito populations. Thus, shifting towards alternative strategies is crucial for a sustainable vector control in Hungary.

Source: International Journal of Infectious Diseases

DOI: 10.1016/j.ijid.2024.107629