Aedes albopictus, an invasive mosquito species, is currently well established in many European countries, posing high risks to human health. A preliminary trial using repetitive releases of irradiated sterile male mosquitoes was designed, implemented and evaluated for the first time in Greece. The main scope of this trial was to investigate the efficacy of sterile insect technique (SIT) on wild population egg hatch rate in Greece using mass-produced sterile male mosquitoes from another country (Italy). The study was conducted in Vravrona area, close to Athens International Airport (Attica Region). The number of eggs laid in ovitraps was similar in all intervention and control plots. However, a significant reduction in egg hatch rate was recorded in the SIT plot in comparison with both control plots starting two weeks after the first release. This trial validates the logistics (transportation, releases handling and monitoring) as a major step towards implementing efficient, environmentally safe control approaches as an additional tool against the invasive Aedes species in Greece and more widely in Europe.

Community involvement in Aedes albopictus management can be very efficient and result in raising awareness among citizens. Toward this end, a door-to-door campaign can encourage active community participation in vector control. The current study describes the results of an intervention where a KAP (knowledge, attitude, practices) survey tool was paired with a door-to-door campaign and was implemented as an intervention method in Vravrona area (Attica, Greece) before the release of sterile males (sterile insect technique, SIT) against Aedes albopictus. The KAP tool was used to shed light on the knowledge, practices, and attitudes of local community members in order to better prepare and motivate participation in household mosquito control and to assess current understanding of SIT. Each household also received specific information about mosquito source habitat in their own yards at the time of the initial KAP survey. These household data were complemented by standardized mosquito trapping in the municipality. Our findings indicate that citizens’ attitude toward SIT ranged from indecisive to fully supportive, while 77.5% of the respondents agreed that the SIT has many advantages over chemical control methods. Furthermore, the results demonstrate that using the door-to-door campaign as an intervention and prerelease method before SIT can suppress the initial mosquito population and potentially improve its efficacy. Lastly, we show that the presence of local municipality officials during door-to-door visits was associated with increased willingness from the residents to participate in the intervention.

Negative impacts on the environment from the continuous use of synthetic insecticides against mosquitoes has driven research towards more ecofriendly products. Phytochemicals, classified as low-risk substances, have been recognized as potential larvicides of mosquitoes; however, problems related to water solubility and stability are limiting factors for their use in mosquito control programs in the field. In this context, many researchers have focused on formulating essential oils in nanoemulsions, exploiting innovative nanotechnology. In the current study, we prepared 4 (R)-(+)-limonene oil-in-water nanoemulsions using low and high energy methods, and we evaluated their physicochemical characteristics (e.g., viscosity, stability, mean droplet diameter, polydispersity index) and their bioactivity against larvae of two mosquito species of great medical importance, namely, Cx. pipiens molestus and Ae. albopictus. According to the dose–response bioassays with the limonene-based nanoemulsions and pure limonene (dissolved in organic solvent), the tested nanoformulations improved the activity of limonene against Ae. albopictus larvae, while the performance of limonene was either the same or better than limonene against Cx. pipiens molestus, depending on the applied system. Overall, we achieved the production of limonene-based delivery nanosystems, with sufficient lethal properties against mosquito larvae to consider them promising larvicidal formulations applicable to mosquito breeding sites.

Seasonal patterns of mosquito population density and their vectorial capacity constitute major elements to understand the epidemiology of mosquito-borne diseases. Using adult mosquito traps, we compared the population dynamics of major mosquito species (Culex pipiens, Aedes albopictus, Anopheles spp.) in an urban and a wetland rural area of Attica Greece. Pools of the captured Cx. pipiens were analyzed to determine infection rates of the West Nile virus (WNV) and the Usutu virus (USUV). The data provided were collected under the frame of the surveillance program carried out in two regional units (RUs) of the Attica region (East Attica and South Sector of Attica), during the period 2017–2018. The entomological surveillance of adult mosquitoes was performed on a weekly basis using a network of BG-sentinel traps (BGs), baited with CO₂ and BG-Lure, in selected, fixed sampling sites. A total of 46,726 adult mosquitoes were collected, with larger variety and number of species in East Attica (n = 37,810), followed by the South Sector of Attica (n = 8916). The collected mosquitoes were morphologically identified to species level and evaluated for their public health importance. Collected Cx. pipiens adults were pooled and tested for West Nile virus (WNV) and Usutu virus (USUV) presence by implementation of a targeted molecular methodology (real-time PCR). A total of 366 mosquito pools were analyzed for WNV and USUV, respectively, and 38 (10.4%) positive samples were recorded for WNV, while no positive pool was detected for USUV. The majority of positive samples for WNV were detected in the East Attica region, followed by the South Sector of Attica, respectively. The findings of the current study highlight the WNV circulation in the region of Attica and the concomitant risk for the country, rendering mosquito surveillance actions and integrated mosquito management programs as imperative public health interventions.

Mosquito management programs in the urban environment of Italian cities mainly rely on larval control with conventional insecticides, primarily targeting the road drains that constitute the principal mosquito breeding sites encountered in public. The repeated utilization of synthetic insecticides may have adverse effects on non-targets and lead to resistance development issues, while the performance of biopesticides encounters limitations in field use. Botanical insecticides as single larval control agents or in binary mixtures with conventional insecticides have been extensively studied in the laboratory as an effective and eco-friendly alternative mosquito control method with promising results. The study herein concerns the investigation, for the first time under realistic conditions in the field, of the joint action of a carvacrol-rich oregano Essential Oil (EO) with two conventional insecticides, namely, the insect growth regulator diflubenzuron and the bio-insecticide Bacillus thuringiensis israelensis (B.t.i.), in road drains in Crevalcore city, Italy, against Culex pipiens and Aedes albopictus. According to the obtained results, the application of both plain EO and its mixtures with diflubenzuron and B.t.i. exerted very high efficacy in terms of immature mosquito population reduction over a two-week period. Three weeks after treatment, the performance of the oil and its mixtures diminished but remained high, while the addition of diflubenzuron potentiated the persistent action of the oil against Cx. pipiens. These findings are indicative of the potential of mixing carvacrol-rich EO with diflubenzuron and B.t.i. as an efficient eco-friendly alternative to mono-insecticide applications in road drains against Cx. pipiens and Ae. albopictus larvae.

This manuscript compiles all the available information on the presence of the native mosquito species Aedes cretinus in Greece, before and after the invasion of Aedes albopictus. Mosquito survey data particularly from the Region of Attica, as well as other areas in Greece indicate Ae. cretinus has become scarce since the invasion of Ae. albopictus, which is now widespread. This mini review on Ae. cretinus occurrence in Greece over the years indicates a marked decline in its populations that seems to be related to the prevalence of the invasive mosquito Ae. albopictus, and a need for more comprehensive entomological surveys in areas where these species co-occur.