An easier life to come for mosquito researchers: field-testing across Italy supports VECTRACK system for automatic count, identification and capture rate estimation of Aedes albopicts and Culex pipiens adult females and males.

Abstract

Background. Monitoring of mosquito vectors of human and zoonotic diseases is an essential prerequisite to optimize control interventions and for evidence-based risk predictions. However, conventional entomological monitoring methods are labor- and time-consuming and do not allow high temporal/spatial resolution. In 2022, a novel system coupling an optical sensor with machine learning technologies (VECTRACK) was proven effective in counting and identifying Aedes albopictus and Culex pipiens adult females and males. Here, we carried out the first extensive field evaluation of the VECTRACK system to assess: i) whether the catching capacity of a commercial BG-Mosquitaire trap (BGM) for adult mosquito equipped with VECTRACK (BGM+VECT) was affected by the sensor; ii) the accuracy of the VECTRACK algorithm in correctly classifying the target mosquito species genus and sex; iii) Ae. albopictus capture rate of BGM with or without VECTRACK. Methods. The same experimental design was implemented in four areas in Northern (Bergamo and Padua districts), Central (Rome) and Southern (Procida Island, Naples) Italy. In each area, three types of traps - a BGM, a BGM+VECT, and Sticky Trap (N=4) were rotated each 48h in three different sites. Each sampling scheme was replicated three times/area. Collected mosquitoes were counted and identified both by the VECTRACK algorithm and by operator-mediated morphological examination. The performance of the VECTRACK system was assessed by generalized linear mixed and linear regression models. Aedes albopictus capture rates of BGMs were calculated based on the known capture rate of ST. Results. A total of 3,829 mosquitoes (90.2% Ae. albopictus) were captured in 18 collection-days/trap type/site. The performance of BGM+VECT in collecting target mosquitoes and the VECTRACK algorithm performance in identifying Ae. albopictus and Cx. pipiens females and males were overall satisfactory, although with some inaccuracies. Moreover, the results allowed to quantify the heterogeneous effectiveness associated with different trap types in collecting Ae. albopictus and to predict estimates of its absolute density. Conclusions. Obtained results strongly support the VECTRACK system as a powerful tool for mosquito monitoring and research, and its applicability over a range of ecological conditions, accounting for its high potential for continuous monitoring with minimal human effort.