Background: The exotic invasive tiger mosquito, Aedes albopictus, appeared in southern Switzerland in 2003. The spread of the mosquito has been surveyed constantly since then, and an integrated vector management (IVM) has been implemented to control its numbers. The control measures focus on the aquatic phase of the mosquito with removal of breeding sites and applications of larvicides in public areas whereas private areas are reached through extensive public information campaigns. Here, we evaluated the efficacy of the IVM. Methods: Since all the municipalities with Ae. albopictus in southern Switzerland are currently implementing the IVM, Italian municipalities just across the Swiss-Italian border, where Ae. albopictus is present but no coordinated intervention programme is in place, served as control. Ovitraps and adult female traps were used to measure mosquito abundance in 2019. Generalised mixed-effects models were used to model the numbers of Ae. albopictus eggs and adult females collected. These numbers of Ae. albopictus eggs were compared to the numbers of eggs collected in 2012 and 2013 in a previous assessment of the IVM, using a hurdle model. Results: Mean numbers of Ae. albopictus eggs and adult females in 2019 were consistently higher in the municipalities not following an IVM programme. In these municipalities, there were about four times (3.8) more eggs than in the municipalities implementing an IVM programme. Also, the numbers of eggs and adult females increased steadily from the beginning of the Ae. albopictus reproductive season, reaching a peak in August. In contrast, the increase in numbers of Ae. albopictus was much more contained in the municipalities implementing an IVM programme, without reaching an evident peak. Comparison with data from 2012 and 2013 indicates that the gap between intervention and non-intervention areas may have almost doubled in the past 6 years. Conclusions: The results of the survey strongly support the efficacy of the IVM programme implemented in southern Switzerland compared to municipalities without defined control measures. With the constant implementation of an IVM, it appears possible to contain the numbers of Ae. albopictus at a manageable level, reducing the nuisance for the human population and the risk of arbovirus epidemics. Graphical

The invasive Asian tiger mosquito Aedes albopictus appeared in southern Switzerland in 2003 and is currently well established in most of its urban regions. In public areas, the control measures against the mosquito focus on its aquatic phase with removal of breeding sites and applications of larvicides at sites that cannot be eliminated. Larvicidal products are applied mainly to catch basins, one of the major sites of oviposition for both Ae. albopictus and Culex pipiens in urban areas. We evaluated the efficacy of a larvicidal formulation (i.e. VectoMax® FG), combing the action of spore-forming bacteria Bacillus thuringiensis var. israelensis and Lysinibacillus sphaericus, against Ae. albopictus, Cx. pipiens and non-target organisms present in urban catch basins. We used floating adult emergence traps to compare the number of adults emerging from 38 catch basins treated once during the study period with ten untreated (control) catch basins. The catch basins were monitored for 21 weeks and the efficacy was evaluated fitting a Generalised Additive Mixed Model (GAMM). The efficacy of the treatment varied among species. It was high against Cx. pipiens (100% reduction in emerging adults at maximal efficacy) and lower against Ae. albopictus (60% reduction). This suggests that it is important to examine target species separately when evaluating the efficacy of larvicidal products. The product showed a long residual larvicidal activity with the number of emerging adults still being reduced by 75% for Cx. pipiens and 60% for Ae. albopictus at ten weeks after the treatment. We also observed that the maximal efficacy of the product was reached about two weeks after the treatment. The effect on non-target organisms, specifically, chironomids, was also strong (80% reduction). However, their numbers raised again rather quickly (i.e. after two weeks), and the effect vanished around week 11.

Although Switzerland is currently not endemic for canine leishmaniosis (CanL), imported cases of this emerging zoonosis are regularly detected. Also, phlebotomine sand flies, vectors of the causative agent Leishmania infantum, are present in the southern part of the country, in Canton Ticino, and endemic foci of CanL have been recently described in neighboring Italian municipalities. In 2022 and 2023, we evaluated the distribution of phlebotomine sand flies and the presence of antibodies against L. infantum in domestic dogs and cats in Ticino and Mesolcina (Canton of Grisons). An entomological survey was also carried out in the northwest of Switzerland (cantons Basel-Stadt and Basel-Landschaft) close to an area in Germany where potential vectors are present. No sand flies were caught there. In Ticino, 15 out of 20 sites surveyed (75%) were positive for phlebotomine sand flies. Phlebotomus perniciosus, a potential vector of L. infantum, was the most abundant species, with site densities ranging from 0.1 to 5.3. The parasite was not detected in females. Leishmania infantum seroprevalences of 3.0% and 1.6% were observed in 101 and 126 dog and cat sera, respectively. Although, at this time, the risk of endemic CanL is extremely low, integrated surveillance and prevention measures should be considered.

The Asian tiger mosquito, Aedes albopictus, a vector of arboviruses such as dengue and chikungunya, has become established in southern Switzerland since 2003. Here, effective control of the mosquito in public areas relies primarily on larvicidal treatment of stormwater catch basins. Recently, the biological larvicide VectoMax ^® FG, a combination of Bacillus thuringiensis israelensis and Lysinibacillus sphaericus, was introduced as a more persistent and ecologically safer alternative to previously used larvicides. This study aimed to determine the optimal reapplication frequency of VectoMax FG (fixed dose: 10 g per basin) to maximise efficacy while minimising environmental impact and operational costs. We conducted a field experiment in 2022 across 60 catch basins in Ticino, comparing six-week and eight-week reapplication regimens against untreated controls over a 22-week monitoring period. Using floating emergence traps, we assessed adult emergence of Ae. albopictus, Culex pipiens, and non-target chironomids. Data were analysed using generalised additive mixed-effects models (GAMMs), controlling for seasonal and spatial variation. Both regimens significantly reduced mosquito emergence, with similar average efficacy. Notably, repeated applications showed increasing effectiveness over time, particularly against Ae. albopictus, suggesting cumulative larvicidal effects. Culex pipiens and chironomids showed similar trends. Non-target impact on chironomids was evident but temporary. Sensitivity analyses confirmed consistent treatment effects across geographical regions and mosquito density levels. Given the comparable efficacy and reduced treatment frequency, an eight-week reapplication schedule is recommended. This strategy offers a cost-effective, environmentally conscious approach to Ae. albopictus control, suitable for municipalities across southern Switzerland and potentially other temperate urban areas where this invasive mosquito is present.

The sterile insect technique (SIT) is considered a promising and environmentally sustainable tool for controlling Aedes albopictus. While current guidelines address its implementation in moderately large and partially isolated areas, evidence from small, fully urban and spatially connected environments remains limited. In 2025, we evaluated SIT in two municipalities in southern Switzerland, releasing sterile males in small (≈12 ha), non-isolated urban areas representing contrasting operational contexts within ongoing integrated vector management programs. Entomological responses were assessed using a spatial, distance-based framework integrating ovitrap-derived egg abundance and hatching rates from treated and surrounding zones, alongside adult female monitoring. Following releases, egg abundance declined within treated areas relative to surrounding zones, with model-based peak reductions of approximately 57% in Ascona and 67% in Losone. Egg hatching rates were also lower within treated areas, with estimated reductions of approximately 9% and 22%, respectively. For both indicators, spatial analyses revealed gradual distance-dependent patterns rather than abrupt boundary effects. No consistent pattern was detected for adult female abundance, likely reflecting limited sampling intensity. The spatial and temporal responses observed across the two study sites suggest that SIT may contribute to modifying local reproductive dynamics of Ae. albopictus even in small, non-isolated urban areas under operational conditions.

The expanding distribution of theAedes albopictus mosquito (also known as the Asian tiger mosquito) throughout Europe is a health and safety threat due to its potential to spread tropical and sub-tropical arboviruses to temperate climate regions. Therefore, it is becoming increasingly important to broaden the use of all tools within integrated pest management systems to control this threat. Since this mosquito species in Europe breeds mainly in manhole drains, managing them is therefore essential. The UNFO-Pest Lock System (UNFO-PLS) mechanical control device fits in siphoned manholes and prevents mosquitoes from entering the manhole and breeding in the water below. We tested and quantified the efficacy of these UNFO-PLS devices against standard control manholes (no mechanical devices attached) in Balerna, Switzerland (Canton Ticino). Weekly counts of five developmental stages (larval stages L1-L4 and the pupal stage) were conducted at 12 experimental and 12 standard control manholes during the mosquito breeding and activity periods of 2020 and 2021. For each developmental stage, we compared the counts of mosquitoes in manholes fitted with and without the UNFO-PLS devices using generalised mixed-effect models. Results show that these devices reduced the presence of mosquitoes at all developmental stages between 92.6-97.2%. The use of the UNFO-PLS mechanical control device, or similar devices, should be considered for use in integrated mosquito pest management plans, especially in places that might present challenges for maintaining adequate larvicide applications, such as around schools and secondary homes.