Stomoxys flies are mechanical vectors of pathogens present in the blood and skin of their animal hosts, especially livestock, but occasionally humans. In livestock, their direct effects are disturbance, skin lesions, reduction of food intake, stress, blood loss, and a global immunosuppressive effect. They also induce the gathering of animals for mutual protection; meanwhile they favor development of pathogens in the hosts and their transmission. Their indirect effect is the mechanical transmission of pathogens. In case of interrupted feeding, Stomoxys can re-start their blood meal on another host. When injecting saliva prior to blood-sucking, they can inoculate some infected blood remaining on their mouthparts. Beside this immediate transmission, it was observed that Stomoxys may keep some blood in their crop, which offers a friendly environment for pathogens that could be regurgitated during the next blood meal; thus a delayed transmission by Stomoxys seems possible. Such a mechanism has a considerable epidemiological impact since it allows inter-herd transmission of pathogens. Equine infectious anemia, African swine fever, West Nile, and Rift Valley viruses are known to be transmitted by Stomoxys, while others are suspected. Rickettsia (Anaplasma, Coxiella), other bacteria and parasites (Trypanosoma spp., Besnoitia spp.) are also transmitted by Stomoxys. Finally, Stomoxys was also found to act as an intermediate host of the helminth Habronema microstoma and may be involved in the transmission of some Onchocerca and Dirofilaria species. Being cosmopolite, Stomoxys calcitrans might have a worldwide and greater impact than previously thought on animal and human pathogen transmission.

No abstract

Five species of invasive Aedes mosquitoes have recently become established in Europe: Ae. albopictus, Ae. aegypti, Ae. japonicus japonicus, Ae. koreicus and Ae. atropalpus. These mosquitoes are a serious nuisance for people and are also competent vectors for several exotic pathogens such as dengue and chikungunya viruses. As they are a growing public health concern, methods to control these mosquitoes need to be implemented to reduce their biting and their potential for disease transmission. There is a crucial need to evaluate methods as part of an integrated invasive mosquito species control strategy in different European countries, taking into account local Aedes infestations and European regulations. This review presents the control methods available or in development against invasive Aedes mosquitoes, with a particular focus on those that can be implemented in Europe. These control methods are divided into five categories: environmental (source reduction), mechanical (trapping), biological (e.g. copepods, Bacillus thuringiensis var. israelensis, Wolbachia), chemical (insect growth regulators, pyrethroids) and genetic (sterile insect technique and genetically modified mosquitoes). We discuss the effectiveness, ecological impact, sustainability and stage of development of each control method.

BackgroundThe invasive species Aedes (Finlaya) koreicus was first identified in north-eastern Italy in 2011, during the ongoing surveillance activity of Aedes albopictus. Following this finding, a more intensive monitoring was carried out to assess the distribution of the species and to collect biological data. Herein, we report the new records obtained by four years of surveillance.FindingsThe presence of Ae. koreicus was checked using ovitraps, adults traps and by larval collections in all possible breeding sites from May 2011 to July 2015. The monitoring started in the site of the first detection (Province of Belluno) and was then extended in the neighbouring Provinces belonging to four Regions. Aedes koreicus was found in 73 municipalities out of 155 monitored (47.1 %), including 23 municipalities (14.8 %) previously not infested. The area of first detection of Ae. koreicus (Province of Belluno) was also the most infested (68 %). However the mosquito has also been found to the west (Province of Trento) and to the south and south-west (Provinces of Vicenza and Treviso) of the initially infested area.ConclusionsThe spread of Ae. koreicus is directed towards south and west from the original infested area, likely due to the dense road connections and the habitat suitability of the new areas. According to these records, northern Italy has a high probability to be invaded by Ae. koreicus in the next decade. These data can be useful to validate predictive models of potential distribution and dispersal of this species in Italy or in Europe.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1208-4) contains supplementary material, which is available to authorized users.

Background Aedes albopictus and Culex pipiens larvae reared in the same breeding site compete for resources, with an asymmetrical outcome that disadvantages only the latter species. The impact of these interactions on the overall ecology of these two species has not yet been assessed in the natural environment. In the present study, the temporal patterns of adult female mosquitoes from both species were analysed in north-eastern Italy, and substantial temporal shifts between abundance curves of Cx. pipiens and Ae. albopictus were observed in several sites. To understand which factors can drive the observed temporal shifts, we developed a mechanistic model that takes explicitly into account the effect of temperature on the development and survival of all mosquito stages. We also included into the model the effect of asymmetric interspecific competition, by adding a mortality term for Cx. pipiens larvae proportional to the larval abundance of Ae. albopictus within the same breeding site. Model calibration was performed through a Markov Chain Monte Carlo approach using weekly capture data collected in our study sites during 2014 and 2015.ResultsIn almost half of observation sites, temporal shifts were due to competition, with an early decline of Cx. pipiens caused by the concurrent rise in abundance of its competitor, and this effect was enhanced by higher abundance of both species. We estimate that competition may reduce Cx. pipiens abundance in some sites by up to about 70%. However, in some cases temporal shifts can also be explained in the absence of competition between species resulting from a “temporal niche” effect, when the optimal fitness to environmental conditions for the two species are reached at different times of the year.ConclusionsOur findings demonstrate the importance of considering ecological interactions and, in particular, competition between mosquito species in temperate climates, with important implications for risk assessment of mosquito transmitted pathogens, as well as the implementation of effective control measures.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2041-8) contains supplementary material, which is available to authorized users.

Aedes mosquitoes are considered highly successful global invasive species and vectors of several pathogens of relevance for public health. Their midgut’s microbiota can play an important role in affecting not only their vectorial competence but also their fitness, physiology, food digestion, metabolism, immunity and adaptation to new environmental conditions. Using high-throughput sequencing we compared the microbiota of Aedes albopictus collected in Italy with those reported in populations from France and Vietnam. We also analysed Aedes koreicus gut microbiota for the first time. We found remarkable individual difference along with common bacterial taxa in both species. Ae. albopictus collected in Italy had a lower richness and a different composition of microbiota in respect to specimens collected in France and Vietnam. It also showed a core microbiota formed mainly of bacteria of the genus Pseudomonas. Overall, the two Aedes species (Ae. albopictus and Ae. koreicus) collected in Italy, showed a large core microbiota with 75.98% of the identified Operational Taxonomic Units. Furthermore, Ae. albopictus had 2.5% prevalence of Wolbachia and 0.07% of Asaia spp, while Ae. koreicus had 14.42% of Asaia spp. and no Wolbachia. This study provides new informations on the spatial variation of the midgut bacterial communities in mosquitoes of medical relevance within areas of recent invasion and provide the basis for further studies aimed at assessing the effects of such variation on vectorial capacity for a range of pathogens.

The rapid invasion and spread of Aedes albopictus (Skuse, 1894) within new continents and climatic ranges has created favorable conditions for the emergence of tropical arboviral diseases in the invaded areas. We used mosquito abundance data from 2014 collected across ten sites in northern Italy to calibrate a population model for Aedes albopictus and estimate the potential of imported human cases of chikungunya or dengue to generate the condition for their autochthonous transmission in the absence of control interventions. The model captured intra-year seasonality and heterogeneity across sites in mosquito abundance, based on local temperature patterns and the estimated site-specific mosquito habitat suitability. A robust negative correlation was found between the latter and local late spring precipitations, indicating a possible washout effect on larval breeding sites. The model predicts a significant risk of chikungunya outbreaks in most sites if a case is imported between the beginning of summer and up to mid-November, with an average outbreak probability between 4.9% and 25%, depending on the site. A lower risk is predicted for dengue, with an average probability between 4.2% and 10.8% for cases imported between mid-July and mid-September. This study shows the importance of an integrated entomological and medical surveillance for the evaluation of arboviral disease risk, which is a precondition for designing cost-effective vector control programs.

Based on 2015 abundance of Aedes albopictus in nine northern Italian municipalities with temperate continental/oceanic climate, we estimated the basic reproductive number R 0 for Zika virus (ZIKV) to be systematically below the epidemic threshold in most scenarios. Results were sensitive to the value of the probability of mosquito infection after biting a viraemic host. Therefore, further studies are required to improve models and predictions, namely evaluating vector competence and potential non-vector transmissions.In 2015, the largest recorded epidemic of Zika virus (ZIKV) started in Brazil and has since then expanded progressively to most countries in Central and South America [1]. We provide estimates of the basic reproduction number (R 0 ) of ZIKV in northern Italy, based on estimates of the mosquito abundance from entomological surveillance data. Entomological surveillance in northern ItalyMosquito monitoring was carried out fortnightly from May to October 2015 in the provinces of Belluno and Trento, Italy (Figure 1).Aedes albopictus mosquitoes were collected using 54 Biogents Sentinel traps (Biogents AG, Regensburg, Germany, hereafter abbreviated as BG) baited with BG lures and CO 2 from dry ice, running for 24 hours and placed by entomologists at selected locations in nine municipalities (Figure 1 Mosquito population dynamicsWe developed a population model representing the developmental cycle of mosquitoes by means of temperature-dependent parameters (Figure 3) and fitted it to capture data in order to estimate the density of female adult mosquitoes per hectare over time at each municipality. For two towns (Belluno and Feltre), human landing captures were carried out (seven and five sessions, respectively) where BG traps were positioned. Two experts performed the catches, rotating between the two sites, acting as human baits and collectors. The mosquitoes were collected by a handheld aspirator during the three hours preceding sunset. Human landing data were used for independent validation of the local mosquito abundance predicted by the model.The four main stages of the Aedes albopictus life cycle (eggs, larvae, pupae and adults) are modelled. Biological parameters encoding mortalities, developmental rates and the length of the gonotrophic cycle depend on the average daily temperature recorded at the site of capture, according to equations provided in [6] and based on experimental data [20]. The sitespecific density-dependent factors and the capture rate (common to all sites) are free model parameters estimated by fitting model outputs to experimental capture data.Given the model-predicted daily number of mosquitoes N V and the number of bites per mosquito per day k, the following relation should hold: k N V = HLR T,