Advancements in knowledge and approaches towards pyrethroid-free control of mosquitoes, vectors of arboviruses

The emergence and re-emergence of arboviruses (arthropod-borne viruses) with pandemic potential have escalated as a global public health threat also in Europe, driven by factors such as increased human mobility and trade, urbanization, climate change, and uncontrolled mosquito vector populations. This trend is expected to persist and increase in future years. The aim of this PhD project was to advance knowledge and strategies for pyrethroid-free mosquito management, focusing on vectors of arboviruses in Italy. The research was carried out in collaboration with three institutions: Sapienza University of Rome, Entostudio srl, and the University of Queensland, in Australia. The project explored three main topics: i) the evaluation of insecticide resistance, ii) the optimization of pyrethroid-free innovative mosquito control approaches, and iii) the development of new monitoring methods for adult mosquitoes. In collaboration with Entostudio, I assessed the susceptibility of Italian Culex pipiens populations to the larvicide Diflubenzuron, identifying widespread resistance, especially in the Venetian lagoon. This highlighted the need for insecticide resistance monitoring and rotation of larvicide active ingredients to reduce resistance. At the University of Queensland, I contributed to optimize the Incompatible Insect Technique for Aedes aegypti control, focusing on male longevity and dispersal through Mark-Release-Recapture experiments. The results suggested that releasing males at night – rather than during day-hours, as usually done - could improve control effectiveness due to their increased longevity. At Sapienza University, I tested two innovative tools (i.e., 1- an optical sensor coupled with machine learning technologies for automatic counting and identification of mosquito species, and 2- a Mid-Infrared spectroscopy coupled with a supervised machine learning approach for Aedes albopictus age-grading) and evaluated their potential for optimized monitoring and consequently control interventions. Additionally, I contributed to studies on various topics, including: the use of Citizen Science (within the framework of Mosquito Alert Italia) for mosquito monitoring; the effectiveness of conventional and novel bio-larvicides in catch basin treatments in urban sites; the genotyping of pyrethroid resistance mutations in Ae. albopictus; the impact of extreme temperatures on vector dynamics, and the effectiveness of Sterile Insect Technique (SIT)-based mosquito control interventions. Overall, the results obtained provided valuable insights which could help in promoting advanced mosquito monitoring and control, while raising awareness on spreading of resistance to pesticides in Italian mosquito populations, and consequently on their environmental impact.