Aedes albopictus in recently invaded areas of Spain: effects of trap type, region and season on mosquito capture

This study is a field investigation aimed at determining the role of key factors potentially influencing the capture of the invasive Asian tiger mosquito. ah.Aedes albopictusin the recently invaded areas of Granada and Málaga (southern Spain).^{twenty three}.For this purpose, we conducted regular sampling. ah.Aedes albopictus From May to November 2022, we surveyed other indigenous mosquito species in five different regions categorized as natural, urban, and peri-urban. These results provide valuable information for public health-related invasive mosquito surveillance and control.

Effects of trap type and gender on mosquito capture

Our study highlights the higher effectiveness of BG-Sentinel traps than CDC-UV traps in capturing mosquitoes in the study area. BG-Sentinel trap effectively captured ah.Aedes albopictus Almost 50% of trap events were successful, whereas the CDC trap success rate was 5%. Although the overall capture efficiency of both traps was high, Cx.pipiens than ah.Aedes albopictus, large differences between trap types persisted. Indeed, the higher effectiveness of BG sentinel traps compared to other trapping methods has been widely demonstrated in different environments and different mosquito species.^{26, 27, 28, 29, 30}. Certain widely used mosquito traps (such as the CDC Miniature Light Trap, Gravid Trap, and New Jersey Light Trap) have been found to have low capture efficiency. ah.Aedes albopictus^{26, 27, 29}. This may be because this invasive species is primarily diurnal and seeks hosts close to the surface.^31,32. Here, the CDC-UV trap was installed approximately 1.5 m above the ground (but e.g.^30,33an alternative setting), may increase the effectiveness of capturing mosquitoes with more crepuscular or nocturnal activity patterns. Cx.pipiens³⁰.Additionally, the use of visual and olfactory attractants such as BG-Lure and CO₂BG-Sentinel traps have the potential to further improve the capture of female mosquitoes of both species.^26,29. Therefore, these results support the need to consider trapping methods to compare mosquito trapping between different studies. Interestingly, both types of traps showed comparable performance in capture. Cx.pipiens male, while male ah.Aedes albopictus It was more commonly captured using BG-sentinel traps. This difference can be attributed to certain behaviors, such as: ah.Aedes albopictus To increase their chances of mating, males skillfully distinguish between chemical and olfactory signals emitted by their hosts and predict the presence of females.³⁴. Finally, our findings confirm the general pattern previously reported in various mosquito species, where female mosquitoes outnumber male mosquitoes in number of catches.^{26, 27, 28, 29, 35}.

Effects of regionality and seasonality on mosquito BG capture

rich in both ah.Aedes albopictus and Cx.pipiens Mosquitoes were determined by sampling location, with variations in effects observed between sexes of the latter species (Fig. 2, Table 1). The Bioparc Zoo in the city center of Fuengirola (Málaga province) had the largest number of animals. ah.Aedes albopictus. Zoos can provide suitable habitat for mosquitoes, especially invasive species such as: ah.Aedes albopictus. This is due to the availability of breeding sites (ground puddles or small waterholes on the surface of the plant, such as the cut ends of Lucky Bamboo), and the presence of exotic plants that mimic the landscapes of Southeast Asia where this species inhabits. Abundance of native species and potential hosts. These factors allow for the continuation and proliferation of mosquito populations in the area.^36,37. Aedes albopictus They can suck blood from a variety of creatures, including fish, reptiles, and birds. However, the majority of its blood meal comes from mammals, and humans are recognized as a common host for this species.^38,39. This fact supports the role of. ah.Aedes albopictus It is not only an important nuisance for humans, but also a vector that can be involved in the transmission of pathogens, including those that affect wildlife and humans. Dirofilaria^{13, 14}. Furthermore, the difference in abundance is ah.Aedes albopictus Mosquitoes between Fuengirola (elevation 11, Table 3) and the region of Granada (range 642 to 762 elevation, Table 3), located by the sea, may be due to differences in climate. The former is characterized by more moderate environmental conditions, in contrast to the more extreme and variable conditions that exist in the Granada region.^31,40,41,42. Considering that the mosquito trapping period in the zoo was short (due to the presence of visitors, trap operation time was shorter than in other areas; see Methods), if mosquitoes were captured over a 24-h period; A much larger difference could be expected. . Finally, we recorded the presence of . ah.Aedes albopictus It is present in all regions of Granada, with significantly higher numbers in the peri-urban area of ​​Gojal compared to the natural area of ​​La Vega.

In a previous study conducted in Andalusia (Spain), Cx.pipiens Although it is the predominant mosquito species in urbanized areas, it is also more abundant in rural and natural areas.⁴³.We found that there were significant differences in the number of women Cx.pipiens Distance between the natural area of ​​La Vega, the area with the highest number of catches of this species, and the peri-urban areas of Cartuja and Gojar (Fig. 2, Table 1). La Vega, a wastewater treatment plant, is surrounded by agricultural land that provides a suitable breeding habitat for this mosquito. In urban areas such as Fuengirola and Fuente Nueva, Cx.pipiens It was similar to sites near cities.

For males, the lowest abundance is Cx.pipiens It was also detected in Cartuja, an open and highly exposed sampling point in the peri-urban area of ​​Granada.Lack of correlation between male and female regions Cx.pipiens The abundance may be explained by differences in the ecological requirements and behavior of these sexes.Man Cx.pipiensThey tend to stay close to their breeding grounds and have lower dispersal than females that actively search for hosts.⁴⁴. Nevertheless, the results obtained are Cx.pipienstogether with what was found in ah.Aedes albopictuslocal-scale environmental characteristics, such as microhabitat characteristics, temperature, and rainfall, are suggested to be suitable for mosquito breeding.^{40,41,42,45,46}, may strongly determine the presence and abundance of these mosquito species.meanwhile Cx.pipiens It is a common species in urban areas, but reaches its maximum abundance in natural habitats^43,45,46,47on the other hand ah.Aedes albopictus They tend to prefer urban areas with mild winters and water infrastructure.^31,40,41,42.

Finally, we did not find any significant differences in capture. ah.Aedes albopictus Capture mosquitoes between trapping sessions. However, the population of this species reached its maximum from mid-July to late September (sessions 4–7, Fig. 2), with almost 75% of captured females (100/135) and 72% of males (46 /64). . This seasonality is similar to that previously reported in field studies in other parts of southern Europe.^29,35,48. For example, a study conducted in 2019 in the Algarve region of Portugal, geographically close to our study area, observed that the number of adults peaked between mid-July and mid-September. .³⁵. In such a study, two short peaks were detected in early October and early November 2019, but these were not registered in our field sampling.Differences in experimental design and the extreme weather conditions observed in October and November 2022 in Malaga and Granada provinces, which were the driest and hottest on record, may explain these results.⁴⁹.relatively few ah.Aedes albopictus Mosquitoes captured during the study period, especially those captured in the first and last sampling sessions, may partly explain the lack of variation in overall mosquito captures.

Culex pipiens Seasonality has been extensively documented. We observed that demographic trends are consistent with previous field studies conducted in Spain and other countries of the Mediterranean basin.^{45, 46, 47}.compared to ah.Aedes albopictuswe identified a more consistent and stable seasonal pattern. Cx.pipiens, there are more subtle changes depending on the season. Two abundant peaks were identified. one from May to early June (Sessions 1–2, Figure 2) and the other a slightly larger peak from September to the end of November, excluding the hottest summer (Sessions 7–10, Figure 2) is. A few months. therefore, Cx.pipiens Although it exhibits a wide range of tolerance to environmental factors, our findings indicate that its populations can thrive during wet and warm seasons but face constraints under conditions of extreme heat. suggests that there is a possibility^{45, 46, 47}.

There are some differences in the temporal dynamics observed for both species (Fig. 2), with their abundance peaks occurring at different times. These differences in temporal variation may be due to niche differences related to climate and local breeding habitat availability.⁵⁰. However, these results may be due to other factors such as interspecific competition between these species. ah.Aedes albopictus May compete effectively with other species. Cx.pipiensin the larval stage⁵¹. His previous studies on two species of mosquitoes in the natural environment of northern Italy support the important influence of interspecific competition and temporal niche effects on the abundance patterns of both species.⁵⁰.This asymmetric interspecific competition may lead to temporary changes in the dynamics of both species.⁵⁰. Nevertheless, complementary field studies are needed to determine the relative contributions of niche differentiation and interspecific competition to the temporal dynamics observed in our study.

The conclusion is ah.Aedes albopictus It is an important nuisance to humans in the invaded area and may also act as a potential vector for locally circulating and imported pathogens.⁴⁰. This species has been introduced to southern Spain in recent decades and its population is currently increasing.native Cx.pipiens They also pose a serious concern to wildlife and public health because they transmit pathogens such as West Nile virus.^47,52. The virus has caused outbreaks in several Mediterranean countries in recent years, including the southern Iberian Peninsula. Our findings indicate that trap type, sex, and location are important factors influencing the capture of both exotic and native mosquitoes. These findings have implications for recently established community surveillance and monitoring. ah.Aedes albopictus and indigenous Cx.pipiens and subsequently to prevent the potential contribution to transmission of locally circulating or imported pathogens in southern Spain.