Responses of Amblyomma americanum and Dermacentor variabilis to odorants that attract haematophagous insects

Carbon dioxide (CO₂), 1‐octen‐3‐ol, acetone, ammonium hydroxide, L‐lactic‐acid, dimethyl trisulphide and isobutyric acid were tested as attractants for two tick species, Amblyomma americanum and Dermacentor variabilis (Acari: Ixodidae), in dose–response bioassays using Y‐tube olfactometers. Only CO₂, acetone, 1‐octen‐3‐ol and ammonium hydroxide elicited significant preferences from adult A. americanum, and only CO₂ was attractive to adult D. variabilis. Acetone, 1‐octen‐3‐ol and ammonium hydroxide were separately evaluated at three doses against CO₂ (from dry ice) at a field site supporting a natural population of A. americanum nymphs and adults. Carbon dioxide consistently attracted the highest number of host‐seeking ticks. However, for the first time, acetone, 1‐octen‐3‐ol and ammonium hydroxide were shown to attract high numbers of A. americanum. Further research is needed to determine the utility of these semiochemicals as attractants in tick surveillance and area‐wide management programmes.     

Seasonal dynamics of mosquitoes (Diptera: Culicidae) in Osijek (Croatia) for the period 1995–2004

The ten year research (1995–2004) of adult mosquitoes in the area of Osijek by dry ice baited CDC traps has provided significant information on mosquito species, species prevalence, their dynamics and seasonal activity. A total of 207,136 adult mosquitoes comprising twenty species belonging to the following genera: Anopheles, Ochlerotatus, Aedes, Culex, Coquillettidia, Culiseta and Uranotaenia were collected. The seven most common species collected during this study were: Aedes vexans (75.6%), Ochlerotatus sticticus (13.3%), Culex pipiens complex (5.9%), Anopheles maculipennis complex (1.9%), Oc. cantans (0.9%), Oc. caspius (0.6%) and Oc. excrucians (0.6%). The temporal changes in the relative abundance of the twenty mosquito species in the Osijek area were reflected in three peaks: in May, July and September. Seasonal population dynamics differed between years and between mosquito species in relation to wetland, urban and forest habitats and was influenced by water level of the Drava and the Danube rivers.     

Temporal and spatial habitat preferences and biotic interactions between mosquito larvae and antagonistic crustaceans in the field

Investigations on natural antagonists of mosquito larvae found that micro‐crustaceans (e.g., Cladocera) control mosquito populations under experimental conditions. However, their relevance for mosquito control under field situations remains widely unclear because important information about habitat preferences and time of occurrence of crustaceans and mosquito larvae are still missing. In order to fill this knowledge gap, a field study was undertaken in different wetland areas of Saxony, Germany, in different habitats (i.e., grassland, forest, and reed‐covered wetlands). We found negative interactions between larvae of Ae. vexans and predatory Cyclopoida (Crustacean: Copepoda), which both were dominant during the first two weeks of hydroperiod, at ponds located at grassland habitats. Larvae of Cx. pipiens were spatially associated with competing Cladocera, but they colonized ponds more rapidly. Populations of Cladocera established from the third week of hydroperiod and prevented Cx. pipiens colonization thereafter. Ostracoda were highly abundant during the whole hydroperiod, but their presence was restricted to habitats of reed‐covered wetland at one geographical area. Mosquito larvae hardly occurred at those ponds. In general, we found that ponds at the reed‐covered wetlands provided better conditions for the initial development of crustaceans and hence, mosquito larval colonization was strongly inhibited. Grassland habitat, in contrast, favored early development of mosquito larvae. This study showed that micro‐crustaceans are relevant for mosquito management but their impact on mosquito larvae varies between species and depends on environmental conditions.     

Specific detection of the floodwater mosquitoes Aedes sticticus and Aedes vexans DNA in predatory diving beetles

Floodwater mosquitoes (Diptera: Culicidae) are associated with periodically flooded wet meadows, marshes, and swamps in floodplains of major rivers worldwide, and their larvae are abundant in the shallow parts of flooded areas. The nuisance caused by the blood‐seeking adult female mosquitoes motivates mosquito control. Larviciding with Bacillus thuringiensis israelensis is considered the most environmentally safe method. However, some concern has been raised whether aquatic predatory insects could be indirectly affected by this reduction in a potential vital prey. Top predators in the temporary wetlands in the River Dalälven floodplains are diving beetles (Coleoptera: Dytiscidae), and Aedes sticticus and Ae. vexans are the target species for mosquito control. For detailed studies on this aquatic predator–prey system, we developed a polymerase chain reaction (PCR) assay for detection of mosquito DNA in the guts of medium‐sized diving beetles. Primers were designed for amplifying short mitochondrial DNA fragments of the cytochrome C oxidase subunit I (COI) gene in Ae. sticticus and Ae. vexans, respectively. Primer specificity was confirmed and half‐life detectability of Ae. sticticus DNA in diving beetle guts was derived from a feeding and digestion experiment. The Ae. sticticus DNA within diving beetle guts was detected up to 12 h postfeeding, and half‐life detectability was estimated to 5.6 h. In addition, field caught diving beetles were screened for Ae. sticticus and Ae. vexans DNA and in 14% of the diving beetles one or both mosquito species were detected, showing that these mosquito species are utilized as food by the diving beetles.     

Species assemblages of cyclopoid Copepoda from Mantecal,Venezuela

A 14 year monitoring of species composition and abundance of cyclopoid copepods throughout the rainy and dry seasons in a flooded savanna at Mantecal, Apure State, Venezuela, is presented. Two characteristic habitats within these water bodies were selected: the open center of small ponds free of emergent vegetation and the surrounding flooded grassland. In total, 13 species were registered, all of which appeared in the flooded grassland and 11 of which occurred in the open water. Ten species were common for the two habitats during the dry season. The highest abundance was found in flooded grassland during the dry season. Eight species showed abundances greater than 1.0 individual per liter in flooded grassland during both seasons; 3 and 7 species were this abundant in the open water during rainy and dry seasons, respectively. Mesocyclops meridianus and Microcyclops varicans were the most abundant species in both habitats and seasons, while Thermocyclops decipiens was the dominant species during rainy season in open water. Principal component analysis indicates that the important species were positively correlated between them (sharing habitat and season).     

Peruvian Red Uakaris (<Emphasis Type="Italic">Cacajao calvus ucayalii</Emphasis>) Are Not Flooded-Forest Specialists

In the literature, particularly in primatological books, the Peruvian red uakari (Cacajao calvus ucayalii) is generally considered as a species that is specialized on living in flooded forest, despite existing evidence to the contrary. Here we review all available information on habitats where Cacajao calvus ucayalii have been observed. Most sightings are from terra firme, including palm swamps, or from mixed habitats, including terra firme and flooded forest. Therefore, we conclude that the species is not a flooded-forest specialist, but is flexible in its habitat requirements and generally uses terra firme forests or a mixture of habitats. Proper recognition of habitat requirements is important for understanding the ecoethological adaptations of a species and for appropriate conservation measures.     

Habitat Preferences of Ungulates in Hunted and Nonhunted Areas in the Calakmul Forest, Campeche, Mexico1

We investigated habitat preference in the community of ungulates in the Calakmul Forest of Southern Mexico through systematically counting the tracks of six species in randomly placed transects. Tracks were associated with one of four major forest types according to Pennington and Sarukhan (1998) . Forest type availability was estimated through 393 independent points on the same transects. We surveyed 90 transects in three hunted areas and one large nonhunted area, with a total of 206 km walked. A total of 1672 tracks of the six species were found. Brocket deer (Mazama americana and Mazama pandora) preferred low‐dry forest in the nonhunted area and low‐flooded forest in the hunted areas. Collared peccary (Pecari tajacu) was a generalist species in the nonhunted area, whereas in the hunted areas, it preferred the subperennial forest. White‐lipped peccary (Tayassu pecari) was found only in subperennial forest in the nonhunted area and favored low‐flooded forest in the hunted areas. White‐tailed deer (Odocoileus virginianus) preferred low‐flooded forest in the hunted areas, while it was a generalist in the nonhunted area. Tapir (Tapirus bairdii) preferred low‐flooded forest in the hunted areas. The most evident habitat difference among hunted and nonhunted areas was a major use of low‐flooded forest in the hunted areas for the species. Conservation of ungulate species in the Calakmul region requires protection of all major habitat types in hunted and nonhunted areas.     

Forest plant community changes in the Spačva lowland area (E Croatia)

The forests in the Spa?va Basin are a complex of lowland forests in the region of Slavonia (eastern Croatia). The present state of the forests is strongly influenced by intensive exploitation and hydro-ameliorative activities carried out in the past. The aim of this study was to consider the extent of changes in species composition, and the extent of environmental changes in forest communities of the Spa?va Basin in relation to research conducted between 1969 and 1971. The species composition of four communities (Carpino betuli-Quercetum roboris, Genisto elatae-Quercetum roboris aceretosum tatarici, and caricetosum remotae, and Leucojo-Fraxinetum angustifoliae) is studied by comparing 41 old and 57 new relevés. Changes were estimated using ordinations (RDA, CCA, DCA) and changes in species frequency and cover. A general trend of moisture reduction was noticeable among all communities. All vegetation types are becoming floristically more similar. An increase in frequency and cover of flood intolerant woody species (such as Carpinus betulus, Cornus sanguinea, Tilia tomentosa, and Acer tataricum) as well as a decrease of vernal species related to wet habitats are particularly evident. The succession of all studied communities is resulting in loss of the mosaic community pattern characteristic of lowland alluvial forests.     

Environmental factors associated with the distribution of floodwater mosquito eggs in irrigated fields in Wrocław,Poland

A survey of distribution patterns of floodwater mosquito eggs related to environmental conditions such as moisture and plant associations was conducted by using soil samples from irrigated fields in Wroc?aw, Poland. Mosquito egg distribution was determined by repeatedly flooding the soil samples with aerated water at a temperature of 25° C. Under laboratory conditions, hatching in installments of Aedes caspius (Pallas) and Aedes vexans (Meigen) were commonly observed. The results show that ～75% of the larvae of Ae. caspius and Ae. vexans hatched after the first flooding under summer‐like conditions, whereas, following the second and third flooding, the numbers of hatched larvae were significantly lower. In our study, within one intermediate flooded field, a total of 66 plant species was identified and classified into six communities. All vegetation types were associated by varied egg densities and showed differences both in richness and Shannon‐Wiener diversity index as well as in ecological indices for moisture, soil reaction, and nutrient level. Small changes in elevation along the slope within the study area showed a large difference in the distribution of mosquito eggs. The highest average egg density was observed in zones with high occurrence of Phalaris arundinacea, usually prevalent in intermediate flooded and fertile areas. Knowledge of the indicators for the distribution of floodwater mosquito eggs in temporary breeding sites may be essential for organizing a successful, integrated mosquito control program with special regard to microbial control agents.     

Juxtaposition and Disturbance: Disentangling the Determinants of Lizard Community Structure

Disturbance alters the structure and dynamics of communities. Here, we examined the effects of seasonal flooding on the lizard community structure by comparing two adjacent habitats, a seasonally flooded and a non‐flooded forest, in a Cerrado–Amazon ecotone area, the Cantão State Park, Tocantins state, Brazil. Despite the strong potential impact of seasonal flooding, the only significant environmental difference detected was more termite mounds in non‐flooded forests. Species richness was significantly higher in the non‐flooded forest. Colobosaura modesta, followed by Mabuya frenata and Anolis brasiliensis, were the only species that differed in number of captures between sites. Colobosaura modesta was exclusively found in the non‐flooded forest, while Anolis brasiliensis was the most captured in the flooded forest. Mabuya frenata is indicated as an indicator species in the flooded forest, and Colobosaura modesta in the non‐flooded forest. We found a significant association between lizard abundances and habitat characteristics, with flooding, canopy cover, and logs being the best predictors. A phylogenetic community structure analysis indicated a lack of structure in both lizard assemblages. Overall, we show that seasonal flooding can strongly impact species richness and species occurrence patterns, but not phylogenetic community structure. The Amazon–Cerrado transition is undergoing pronounced transformations due to deforestation and climate change. Despite being species‐poor compared with central areas in Amazon or Cerrado, this ecotone harbors species with important adaptations that could hold the key to persistence in human‐disturbed landscapes or during periods of climate change.     

Effects of flash flooding on mosquito and community dynamics in experimental pools

Pulsed disturbances of larval mosquito sites are likely to have a direct negative effect on mosquitoes but may also have indirect effects due to the alteration of community structure. These altered communities may become attractive to gravid mosquitoes searching for oviposition sites when the disturbances decrease the abundance of mosquito antagonists such as competitors, which often results in an increase in mosquito food resources. However, flash flood disturbances in intermittent riverbeds can also remove mosquito food resources such as algae, so that the net effect of flash floods could be either to increase or decrease mosquito abundance. We conducted an outdoor mesocosm experiment to assess the effects of flash floods on mosquito oviposition habitat selection and larval abundance during the post‐disturbance period of community recovery. Mesocosms were artificially flooded. Mosquito oviposition, immature abundance, invertebrate species diversity, chlorophyll a, and abiotic parameters were monitored. Our results showed that the flash flood negatively affected phytoplankton and zooplankton, leading to a decrease of mosquito oviposition in flooded mesocosms compared to non‐flooded mesocosms. More broadly, this study indicates how disturbances influence mosquito oviposition habitat selection due to the loss of food resources in ephemeral pools, and it highlights the importance of considering the effects of disturbances in management, habitat restoration, and biodiversity conservation in temporary aquatic habitats.     

Mosquito (Diptera: Culicidae) fauna in an area endemic for West Nile virus

Mosquito collections with CDC light traps using dry ice and pigeon‐baited traps were carried out in south Moravia (Czech Republic) from April to October in 2007 and 2008 at two study sites. In 2007, 11 two‐day captures were carried out in two‐week intervals, and 1,490 female mosquitoes of nine species were caught. In 2008, 15 two‐day trappings of mosquitoes were carried out: 6,778 females of 22 species of mosquitoes were trapped. The results showed marked differences in abundance and species composition of mosquitoes between both study sites and between the trapping methods. In the floodplain forest ecosystem of the Soutok study area, Aedes vexans predominated. The species composition in the Nesyt study site was more varied and the most common species was Culex pipiens. At the latter study site, Anopheles hyrcanus (var. pseudopictus) and Uranotaenia unguiculata, mosquito species with largely southern Eurasian distribution, were repeatedly demonstrated. The largest capture of mosquitoes was in traps with CO₂ placed at a height 1 m above the ground. The capture of mosquitoes in the pigeon‐baited traps as well as in the traps with CO₂ placed in the canopy of trees was markedly lower in both study sites, with the predominant species being Culex pipiens.     

Comparison of sampling tabanids (Diptera: Tabanidae) by four different potential attractants

Synthetic and natural attractants in traps are used in many parts of the world to attract female tabanids. Certain attractants in different geographic regions may be ineffective or effective under different environmental conditions for horseflies. One‐octen‐3‐ol, as a compound present in bovine emanations, has a behavioural effect on many horsefly species and together with other phenolic compounds makes very effective attractant for this group of insects. As the attractiveness of the mixture of three chemicals (1‐octen‐3‐ol, acetone and ammonia solution in the proportions 5 : 3 : 2), aged donkey urine, lactic acid and fresh human urine is not yet known, it was studied in Eastern Croatia. The combination of those three chemicals and efficiency of natural attractants offers promising results. Tabanus was the most represented genus with 83% of the total collected tabanids. The chi‐squared analyses of the trapping data for canopy traps revealed that each of the attractants (mixture of three chemicals, aged donkey urine, lactic acid and fresh human urine) significantly increased the number of collected horseflies in comparison to those collected in unbaited canopy traps. Some species differences in relative response to different attractants were noted. Significantly, more specimens of Haematopota pluvialis were collected from canopy traps baited with the mixture of three chemicals when compared with traps baited with other attractants. Canopy traps baited with aged donkey urine collected significantly more Atylotus loewianus females than did traps baited with the mixture. The F‐test analysis of the trapping data for the genus Tabanus showed that there is significant difference between average number of collected specimens between mixture of three chemicals and other used attractants (lactic acid and human urine) except aged donkey urine. Finally, traps baited with the mixture of three chemicals (1‐octen‐3‐ol, acetone and ammonia solution) collected 14.5 times more tabanids than unbaited traps, whereas aged donkey urine, lactic acid, and fresh human urine‐baited traps collected 12, 3.9 and 2.5 times as many tabanids, respectively, than did unbaited traps. The mixture of three chemicals (1‐octen‐3‐ol, acetone and ammonia solution) and aged donkey urine appear to be very effective attractants for tabanids.     

Comparison of novel and conventional methods of trapping ixodid ticks in the southeastern U.S.A.

Tick‐borne disease surveillance and research rely on resource‐effective methods for tick collection. This study compared the respective performances of several trapping methods in a mixed grassland–forest habitat in western Tennessee. To test for temporal differences in effectiveness, sites were sampled monthly (April–August 2013) using dry ice, dragging, flagging, sweep netting, carbon dioxide (CO₂) dragging and CO₂ flagging methods. To evaluate the effect of habitat on method effectiveness, four methods (dragging, CO₂ dragging, CO₂ flagging and dry ice) were compared in four habitat types (bottomland deciduous, upland deciduous, coniferous and grassland) in June 2014. In the temporal comparison, ticks were found to be most abundant in April and May, and there was a significant sampling period and method interaction, such that method effectiveness varied across sampling period. Sweep netting was significantly less effective than the other methods. In the habitat comparison, dry ice trap collections represented the most effective method in upland deciduous and coniferous habitats. Flagging using CO₂ was significantly less effective than CO₂ dragging and dragging in bottomland deciduous habitats. The success of the various collection methods did not differ significantly within grassland habitats. Overall, dry ice trapping and dragging were the most effective methods for tick collection across time and habitat.     

Nestedness patterns of container-dwelling mosquitoes: effects of larval habitat within variable terrestrial matrices

Distributions of mosquito larvae likely are a consequence of multiple factors, although two commonly studied factors (quality of the larval environment and the terrestrial matrix in which these habitats reside) have rarely and simultaneously been varied in the field to understand distributions of larvae. We monitored aquatic containers of two leaf detritus levels within a forest, prairie, and industrial habitat across five months to understand the temporal and spatial colonization of aquatic invertebrates in Northcentral Illinois, USA. Data were collected monthly on mosquito populations and the composition of other invertebrates colonizing containers. Overall, six species of mosquitoes colonized containers, with Culex restuans and Aedes triseriatus having the highest relative abundances. There were strong seasonal abundance patterns for these two mosquito species, with the dominant species changing over time in the forest habitat. The responses of other mosquito taxa were more variable, with abundances reflective of either the terrestrial matrix or larval habitat quality. High detritus containers supported the highest abundances of most species encountered, regardless of habitat. Non-mosquito taxa were less common numerically, but analyses suggested that some taxa, such as syrphid larvae, often co-occurred with mosquitoes. Nested subset analysis indicated communities were strongly nested, and that both habitat type and detritus level were important in explaining nested patterns of aquatic invertebrates. Our data show that both the larval habitat and the surrounding terrestrial matrix shape patterns of container mosquitoes, and that other container invertebrates vary in similar ways as mosquitoes. Handling editor: K. Martens     

Vertebrate responses to fruit production in Amazonian flooded and unflooded forests

We document patterns of fruit and vertebrate abundance within an extensive, virtually undisturbed mosaic of seasonally flooded (várzea and igapó) and unflooded (terra firme) forests of central Amazonia. Using phenological surveys and a standardised series of line-transect censuses we investigate the spatial and temporal patterns of immature and mature fruit availability and how this may affect patterns of habitat use by vertebrates in the landscape. All habitats showed marked peaks in fruiting activity, and vertebrate detection rates varied over time for most species both within and between forest types. Many arboreal and terrestrial vertebrates used both types of flooded forest on a seasonal basis, and fluctuations in the abundance of terrestrial species in várzea forest were correlated with fruit availability. Similarly, the abundance of arboreal seed predators such as buffy saki monkeys (Pithecia albicans) and macaws (Ara spp.) were closely linked with immature fruit availability in terra firme forest. We conclude that highly heterogeneous landscapes consisting of terra firme, várzea and igapó forest appear to play an important role in the dynamics of many vertebrate species in lowland Amazonia, but the extent to which different forest types are used is highly variable in both space and time.     

A review of vertebrate community composition in seasonal forest pools of the northeastern United States

Seasonally-flooded wetlands occur throughout the world and provide important foraging, resting, and breeding habitat for a broad array of organisms. This review summarizes our current understanding of vertebrate community composition at seasonal forest pools in the northeastern United States. These wetlands typically have hydroperiods that range from temporarily flooded to intermittently exposed, which reduces densities of many potential predators (e.g., fish). Current research has shown that pool hydroperiod, canopy closure, vegetation structure within pools, presence of potential predators, and landscape structure surrounding pools are the key factors determining vertebrate diversity at seasonal forest pools. Of 25 species of amphibians in the region, frogs (10 of 12 species) are more likely to breed in seasonal forest pools than salamanders (6 of 13 species). Seven of 10 amphibian species that breed in seasonal forest pools are state-listed as threatened or endangered. Among 27 species of reptiles, 3 of 15 species of snakes, and 6 of 12 species of turtles utilize seasonal pools during at least one stage of their annual cycle. Seasonal forest pools are important foraging and basking habitat for three species of turtles listed as threatened or endangered. Compared to other vertebrate taxa, most species of mammals are habitat generalists, with 50 of 63 mammal species potentially foraging at seasonal pools during part of their annual cycle. Chiroptera (bats; all 9 species) are believed to actively forage at seasonal pools and some Insectivora, particularly Sorex palustris Richardson and S. fumeus (Miller) and Condylura cristata (L.), are detected regularly at seasonal pools. Breeding birds are less likely to utilize seasonal pools than other vertebrate taxa, although 92 of 233 species might forage or breed near seasonal pools. Several species of Anatidae, Rallidae, and some Passeriformes use seasonally flooded pools. All vertebrates that use seasonal forest pools use other habitats during some stage in their life cycle; thus gaining a clear understanding of their habitat requirements is critical to their long-term persistence.