Mosquitoes are important vectors of disease pathogens and multiple species are undergoing geographical shifts due to global changes. As such, there is a growing need for accurate distribution predictions. Ecological niche modelling (ENM) is an effective tool to assess mosquito distribution patterns and link these to underlying environmental preferences. Typically, macroclimatic variables are used as primary predictors of mosquito distributions. However, they likely undervalue local conditions and intraspecific variation in environmental preferences. This is problematic, as mosquito control takes place at the local scale. Utilising high-resolution (10 × 10 m) Maxent ENMs on the island of Bonaire as model system, we explore the influence of local environmental variables on mosquito distributions. Our results show a distinct set of environmental variables shape distribution patterns across ecologically-distinct species, with urban variables strongly associated with introduced species like Aedes aegypti and Culex quinquefasciatus, while native species show habitat preferences for either mangroves, forests, or ephemeral water habitats. These findings underscore the importance of distinct local environmental factors in shaping distributions of different mosquitoes, even on a small island. As such, these findings warrant further studies aimed at predicting high-resolution mosquito distributions, opening avenues for preventative management of vector-borne disease risks amidst ongoing global change and ecosystem degradation.
- MeSH
- Aedes fyziologie MeSH
- Culex fyziologie MeSH
- Culicidae * fyziologie MeSH
- ekosystém * MeSH
- komáří přenašeči * fyziologie MeSH
- rozšíření zvířat MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The risks of depletion of energy reserves and encountering lethally low temperatures are considered as two important mortality factors that may limit winter survival of mosquito, Culex pipiens f. pipiens populations. Here we show that the autumn females carry lipid reserves, which are safely sufficient for at least two overwintering periods, provided the females diapausing at temperatures typical for underground spaces (0 °C - 8 °C) would continuously rest at a standard metabolic rate (SMR). The overwintering females, however, switch from SMR to much higher metabolic rate during flight, either seeking for optimal microhabitat within the shelter or in response to disturbances by air current or predator attack. These behaviors result in fast oxidation of lipid reserves and, therefore, the autumn load of energy reserves may actually limit winter survival under specific circumstances. Next, we show that the level of females' cold hardiness is physiologically set relatively weak for overwintering in open field, above-ground habitats, but is ecologically entirely sufficient for overwintering in most underground spaces. The characteristics of suitable overwintering shelters are: no or limited risk of contact with ice crystals, no or limited air movements, winter temperatures relatively stable between +2 and + 6 °C, winter minimum does not drop below -4 °C for longer than one week, or below -8 °C for longer than 1 day.
- Klíčová slova
- Cold tolerance, Culex pipiens, Energy reserves, Insects, Overwintering,
- MeSH
- Culex metabolismus fyziologie MeSH
- diapauza MeSH
- energetický metabolismus * MeSH
- metabolismus lipidů MeSH
- nízká teplota * MeSH
- roční období * MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The overwintering strategy of the mosquito Culex modestus, an important West Nile virus (WNV) vector in Europe, was explored under field conditions in reedbed (Phragmites australis) ecosystems in early 2019. A total of 30 Cx. modestus females were found in a BG-Sentinel trap placed in a plastic greenhouse as well as in a reference BG-Sentinel trap placed under the open sky, both set up within the reedbeds and inspected every 2-3 days from February 27 to April 10, 2019. Moreover, 186 females of Cx. pipiens, 3 females of Anopheles hyrcanus, and 3 females of Culiseta annulata were trapped in the monitored time span. While all Cx. modestus females tested negative for the presence of WNV and other arboviruses circulating in Central Europe, we confirmed WNV lineage 2 and Ťahyna virus infection in several pools of the collected Cx. pipiens, demonstrating arbovirus overwintering. This pilot study highlights the need for large-scale monitoring activities covering different regions to identify the overwintering strategy of both mosquito-borne viruses and their vectors in Central Europe.
- Klíčová slova
- Anopheles hyrcanus, Culex modestus, Culex pipiens, Culiseta annulata, arboviruses, overwintering,
- MeSH
- Culex fyziologie virologie MeSH
- ekosystém * MeSH
- roční období MeSH
- virus západního Nilu izolace a purifikace MeSH
- viry kalifornské encefalitidy izolace a purifikace MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
We observed instances of cannibalism (intraspecific predation) among intra-instar larvae of Culex pipiens Linnaeus, 1758 while performing a bioassay of Lysinibacillus sphaericus (formerly named Bacillus sphaericus) larvicide, when the larvae were exposed to the larvicide for 48 h in the absence of food. Larvae without symptoms of poisoning attacked and devoured those visibly affected. Cannibalism was more prevalent in 1st-2nd instar larvae than in 3rd-4th instar. This phenomenon should be taken into account when interpreting the results of larvicide bioassays, especially when the exposure lasts over 24 h. The necessity of creating optimal conditions for organisms tested is emphasised.
- Klíčová slova
- Culex pipiens, Lysinibacillus sphaericus (Bacillus sphaericus), bioassay, intraspecific predation, larval feeding, larval starvation,
- MeSH
- Bacillaceae chemie MeSH
- Culex účinky léků růst a vývoj fyziologie MeSH
- insekticidy aplikace a dávkování chemie MeSH
- kanibalismus MeSH
- larva účinky léků růst a vývoj fyziologie MeSH
- věkové faktory MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- insekticidy MeSH
The efficacy of 30 aromatic compounds and their mutual binary combinations was assessed for acute toxicity against the larvae Culex quinquefasciatus. Based on comparison of the lethal doses, thymol and p-cymene were selected as the most effective (LD50 = 18 and 21 mg L(-1), respectively, and LD90 = 25 and 30 mg L(-1), respectively). Although the LD50 for terpinolene and trans-anethole was also estimated at 21 mg L(-1), their LD90 was significantly higher compared to the substances above (245 and 34 mg L(-1), respectively). In total, 435 binary combinations were tested, of which 249 combinations showed a significant synergistic effect, while 74 combinations showed a significant antagonistic effect on mortality. Only nine substances were identified as being able to create a synergistic effect with more than 20 substances: limonene, trans-anethole, 4-allylanisole, carvacrol, isoeugenol, menthone, carvone, borneol, and camphor. The highest synergistic effect on larval mortality was achieved for the combinations: eugenol and isoeugenol, carvone and carvacrol, carvone and 4-allylanisole, carvone and α-terpineol, carvone and menthone, limonene and trans-anethole, limonene and menthone, α-pinene and menthone, β-citronellol and menthone, carvacrol and 4-allylanisole, carvacrol and terpineol, α-terpinene and trans-anethole, camphor and menthone, camphene and menthone, and 4-allylanisole and menthone. Significant differences between achieved mortality and the mutual mixing ratio were found for the five selected binary mixtures that had shown the most significant synergistic effect in the previous tests. The mixture of limonene and trans-anethole showed the highest mortality, with the mixing ratio 1:1; the mixture of eugenol and isoeugenol caused 90.2% mortality, with the mixing ratio 1:3. One hundred percent mortality was achieved if carvacrol was contained in a mixture with carvone in a ratio >2. After a comparison of all our results, based on our experiments, we can choose two pairs that caused mortality higher than 90% in concentrations lower than 20 mg L(-1): limonene and trans-anethole (with the mixing ratio 1:1), and carvone and carvacrol (with the mixing ratio 1:2-3). The information gained can thus be used in the development of new botanical insecticides based on essential oils (EOs) and particularly in the creation of formulations.
- MeSH
- Culex účinky léků růst a vývoj fyziologie MeSH
- insekticidy farmakologie toxicita MeSH
- larva účinky léků fyziologie MeSH
- lékové interakce MeSH
- oleje prchavé farmakologie toxicita MeSH
- synergismus léků MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- insekticidy MeSH
- oleje prchavé MeSH
Mosquito feeding behavior determines the degree of vector-host contact and may have a serious impact on the risk of pathogen transmission, including that of the West Nile virus (WNV). To measure the role of Culex mosquitoes as WNV vectors, host-seeking females were collected using animal-baited traps containing live birds (quail) or mammals (rabbits) and CO2-baited Center for Disease Control and Prevention traps placed in several wetland areas in the Czech Republic. Culex pipiens (L.) and Culex modestus (F.) were the most frequently collected species. Although Cx. modestus did not distinguish between baits, Cx. pipiens was collected significantly more frequently in bird-baited traps. Based on mitochondrial DNA analysis of bloodmeals from engorged females collected by CO2-baited traps situated within reed beds, a diverse group of birds were the predominant hosts (93.7%), followed by mammals (4.2%) including humans, and amphibians (2.1%). Among birds, Anseriformes were fed upon most frequently by Cx. modestus, whereas Cx. pipiens fed most frequently on Passeriformes. To measure the infection risk and confirm the distribution of mosquito species in various biotopes, transects of CO2-baited CDC traps were operated from wetland reed beds into upland vegetated areas. Even though both Culex species occurred in all biotopes sampled and frequently dispersed hundreds of meters away from fishpond shore vegetation, the spatial distribution of Cx. modestus was significantly associated with reed beds at wetlands. The first detection of WNV (subtype RabV) in Cx. modestus in Bohemia and confirmation of WNV presence in Cx. pipiens in Moravia together with observed feeding behavior supports the presumed role of both Culex species in the avian-to-avian enzootic WNV cycle and in avian-to-mammal transmission in the Czech Republic.
- MeSH
- Culex fyziologie virologie MeSH
- druhová specificita MeSH
- hmyz - vektory fyziologie virologie MeSH
- lidé MeSH
- mokřady MeSH
- obojživelníci fyziologie MeSH
- ptáci fyziologie MeSH
- rozšíření zvířat MeSH
- savci fyziologie MeSH
- stravovací zvyklosti MeSH
- virus západního Nilu izolace a purifikace fyziologie MeSH
- západonilská horečka přenos MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Mosquito faunal studies were carried out in five separate wetland regions in the Czech Republic during 2004-2007, sampling with dry ice-baited and sentinel host-baited CDC traps. A total of 79,245 adults was identified, representing 23 mosquito species that belonged to the genera Anopheles, Culiseta, Coquillettidia, Aedes, and Culex. Our findings reveal that the mosquito fauna is enriched by new elements in the Mediterranean region. Historical and CDC trap data suggest that the newly-emerging potential malaria vector, Anopheles hyrcanus, has reached the northern limit of its distribution in the Czech Republic, and the important West Nile virus (WNV) vector, Culex modestus, has widened its distribution in the Czech Republic. No significant differences were observed in a total number of mosquitoes collected by traps baited with either the sentinel animals or with CO2, although species abundance differed. A relatively higher proportion of Cx. modestus was collected in the sentinel-baited traps, while the proportion of Cx. pipiens was higher in the CO2-baited traps.
- MeSH
- Anopheles fyziologie MeSH
- časové faktory MeSH
- Culex fyziologie MeSH
- demografie MeSH
- hmyz - vektory fyziologie virologie MeSH
- malárie přenos MeSH
- mokřady MeSH
- virus západního Nilu fyziologie MeSH
- západonilská horečka přenos MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Effects of methoprene and 20-hydroxyecdysone on the development and hemagglutination activity (HA) were studied in both sexes of two members of the Culex pipiens complex-anautogenous C. p. quinquefasciatus and autogenous C. p. molestus. Juvenile hormone analogue (methoprene) and 20-hydroxyecdysone caused developmental changes in both mosquito strains. High larval mortality, prolongation of intermolt period in each larval instar and in the pupal stage, and morphological changes in the larval-pupal and pupal-adult transformations were also observed. Developmental changes were accompanied with some differences in the HA. HA was found in both sexes of both experimental mosquito strains. The juvenile hormone analogue used in the larval stage caused significant decrease of HA in the gut of adults of both sexes. On the other hand, 20-hydroxyecdysone decreased HA only in the female gut. Results obtained indicate that HA depends on the sex, the studied organ, and the level of hormones.
- MeSH
- Culex účinky léků fyziologie MeSH
- ekdysteron farmakologie MeSH
- hemaglutinace účinky léků MeSH
- methopren farmakologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- ekdysteron MeSH
- methopren MeSH
Two strains of Culex pipiens molestus of different geographical origin were reared for more than five years under the same laboratory conditions in order to study to what extent the reactions of these strains to constant temperature and density become similar. Lower temperature and higher densities caused not only the prolongation of developmental time of preimaginal stages and increasing mortality of larvae and pupae in both strains but also the extension of the rate between the first and last emerging imago in both sexes of both strains. Absolute time spent in the preimaginal stage was also influenced by genetic factors. Both strains displayed different values, although both strains were for reared in the laboratory under identical conditions.
- MeSH
- časové faktory MeSH
- Culex fyziologie MeSH
- hmyz - vektory fyziologie MeSH
- hustota populace MeSH
- larva růst a vývoj MeSH
- teplota * MeSH
- zvířata MeSH
- zygota MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Autogeny was observed in a laboratory colony of Culex pipiens quinquefasciatus Say originating from Hyderabad, India. In a strain selected for an autogeny for 15 generations, all females, both mated and unmated, were able to mature eggs although the unmated females were unable to oviposit them. Ingesting glucose had little effect on the expression of autogeny and on the number of eggs in rafts in the laboratory experiments. Most autogenous females can ingest blood during first gonotrophic cycle, if the host is available. The blood feeding that occurred during the first cycle to initiate the second cycle was not confirmed, however, we cannot exclude this possibility.
- MeSH
- Culex fyziologie MeSH
- kladení vajíček MeSH
- krev MeSH
- larva MeSH
- myši MeSH
- rozmnožování fyziologie MeSH
- stravovací zvyklosti MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Indie MeSH
