Aquatic Mites Research Articles

Observations on the life history of giant water bugs Lethocerus Mayr, 1853 (Heteroptera: Nepomorpha: Belostomatidae) in the Gangetic plains of India and Nepal

Two species of giant water bugs Lethocerus were found in the Gangetic plains of northern India and Nepal. Lethocerus indicus is widespread, whereas a single record of Lethocerus patruelis confirms the eastern distribution range in Bihar. Four instars of aquatic nymphs occur exclusively in temporary shallow stagnant water bodies which harbor rich amphibian populations but lack permanent fish fauna. From mid-August to the first week of November adults fly. Later they live submerged in aquatic habitats of large rivers and permanent stagnant water bodies which harbor diverse fish fauna. Repeated findings of adults with ventrally attached egg-shaped pupae of aquatic mites (Hydracarina) suggest that these are host-specific ones of Lethocerus. Thus, the occurrence of protelean parasites on giant water bugs in the Gangetic plains is a previously unknown unique finding since apparently mites have been noticed only from other Nepomorpha families.

Freshwater halacarid mites (Acari: Halacaridae) from Madagascar. New records and the description of a new species

In recent years the numbers of aquatic mite species from Madagascar has increased considerably (Gerecke 2004a, b, 2006, 2009; Goldschmidt 2008; Tuzovski and Gerecke 2009), but the area is still a white spot with respect to knowledge of its freshwater halacarid (Halacaridae) fauna. Recently, some halacarid specimens were extracted from sandy deposits of the banks of streams and creeks. These samples included four species, namely Limnohalacarus cultellatus Viets, 1940, Limnohalacarus novus Bartsch, 2013, Lobohalacarus weberi (Romijn and Viets, 1924), and a new species of the genus Ropohalacarus. The new species, Ropohalacarus pallidus n. sp., is described, and the characters of the other species are outlined. The three genera collected in Madagascar are cosmopolitan and the Lobohalacarus and Limnohalacarus species are wide-spread. The halacarid fauna of Madagascar seems to be poor in endemic species, which is contrary to the situation for the freshwater Hydrachnidia mites. Future studies will certainly increase the number of halacarid species but not the percentage of endemics.

Larval aquatic and terrestrial mites infesting parthenogenetic Ischnura hastata (Odonata: Coenagrionidae) from the Azores islands

We report here the prevalence of parasitism by water mites (Arrenurus sp.) and terrestrial mites (Leptus killingtoni) on parthenogenetic Ischnura hastata (Odonata: Coenagrionidae) from the Azores islands. Leptus killingtoni was only found on the island of Pico, and the prevalence of infestation was highly variable among the different ponds studied, ranging from 0 to 41%. Leptus killingtoni was observed on three of the four odonate species from the archipelago: I. hastata, I. pumilio, and Sympetrum fonscolombii, all of them new hosts for this species. Aquatic mites have been found parasitizing I. hastata females on the island of São Miguel. The prevalence of mite parasitism by Arrenurus sp. on I. hastata was very low, ranging from 12% (2003) to 1% (2008), and in most of the studied ponds, no mites were found attached to females. Although I. hastata coexists with a sexual congener species in the Azores (I. pumilio), they are syntopic in only a small fraction of ponds. Therefore, a comparison between I. hastata and I. pumilio was insufficient to test the predictions of the Red Queen Hypothesis, and further research on parasitism rates in both species needs to be done. In any case, the low prevalence of mite parasitism found in the Azores, coupled with the fact that most of the populations in the archipelago are almost free from competitors and predators, could explain the persistence of these I. hastata parthenogenetic populations, despite their low levels of genetic variation.

Morphological Confocal Microscopy in Arthropods and the Enhancement of Autofluorescence after Proteinase K Extraction

Procedures to study the molecular and morphological characteristics of microscopic organisms are often incompatible with each other. Therein, the realization of alternatives that make the characterization of these features compatible and simultaneously permit the deposition of the original material as a voucher sample into a reference collection is one of the foremost goals of biodiversity studies. In this study, we show that genomic extraction does not necessarily compromise the detailed study of the external morphology of microscopic organisms, and to do so, we used a group of aquatic mites (Acari, Hydrachnidia) as a test group. Hydrachnidia morphology is difficult to study when specimens have been stored in pure ethanol; however, proteinase K extraction leaves them flexible and easy to dissect, while, at the same time, maintaining all of their diagnostic features intact. Furthermore, autofluorescence is significantly enhanced after proteinase extraction. Our study was conducted with aquatic mites that were stored in absolute ethanol in the field and processed for DNA extraction using a Qiagen QIAamp minikit. Before and after molecular extraction, a laser scanning confocal microscopy morphological examination was carried out.

Trophic ecology of an aquatic mite (Piona carnea) preying on Daphnia pulex: effects of predator density, nutrient supply and a second predator (Chaoborus americanus)

As compared to other aquatic invertebrates, relatively little is known about the ecology of predaceous, pelagic water mites. Studies to date do, however, show that water mites can be important components of aquatic food webs. Here, we used manipulative field experiments to better understand the trophic ecology of a predaceous water mite (Piona carnea). Three experiments were conducted that examined (i) the effect of P. carnea density on the per-capita interaction strength (PCIS) of P. carnea preying on zooplankton; (ii) how the effects of P. carnea predation change with prey productivity; and (iii) how P. carnea interacts with another pelagic predator (Chaoborus americanus) to affect a shared prey species (Daphnia pulex). Results from the first experiment showed that P. carnea can strongly impact D. pulex populations, and that the PCIS of P. carnea decreases with an increase in P. carnea density. The second experiment showed that the effects of P. carnea on D. pulex populations depend on bottom-up factors that influence D. pulex population biomass and the reproductive potential of a D. pulex population relative to its size. The third experiment uncovered a non-additive interaction between P. carnea and C. americanus that resulted in a risk reducing situation for D. pulex in the presence of both predators. Together these experiments show that P. carnea imposes a strong negative impact on D. pulex, that the magnitude of this negative impact is dependent on the P. carnea density and the productivity of the system, and that the trophic ecology of P. carnea is modified by coexisting predator species.

Can freshwater mites act as forensic tools?

Determination of post-mortem interval often employs analysis of age structure and diversity of saprophilic arthropods (including mites) that have colonized corpses. The majority of research has focused on decomposition processes in terrestrial situations, with relatively few studies on the utility of freshwater invertebrates as forensic agents. Most freshwater mites are predators, detritivores or algivores, and hence seem unlikely candidates as tools for aging or determining original placement of corpses or other bodily remains. The main exceptions to this are some aquatic Astigmata, which have occasionally been observed feeding on the tissues of moribund aquatic animals. Here I investigate Canadian law literature and published forensic research to determine how frequently freshwater mites are included in court cases or are found attending dead bodies. I found only one questionable report of aquatic mites in over 30 years of material from legal databases. Three published research papers reported mites associated with vertebrate flesh in fresh water. Only one paper provided an identification of mites finer than 'Acari' or 'water mites'. In this case, the mites were identified as Hydrozetes (Oribatida). In none of these papers were mites reported to be high in abundance or biomass, and in two of the three publications methodological problems and/or poor reporting of data raised doubts about interpretation of results. I conclude that based on their biology, there is little expectation that freshwater mites should be of great value as forensic tools, and this survey of legal and scientific literature supports my argument.

Larval aquatic and terrestrial mites infesting a temperate assemblage of mosquitoes

We collected 22,769 adult female mosquitoes, representing 27 species, from light traps in Norfolk, Virginia (2006-2007) and examined them to assess infestation by larval mites. Mosquitoes were parasitized by two species of aquatic (Acari: Arrenuridae: Arrenurus) and three species of terrestrial mites (Acari: Erythraeidae). The prevalence of infestation varied from 0.55% (2006) to 0.17% (2007). The mean intensity of parasitism ranged from 3.6 mites per host (2006) to 1.8 mites per host (2007). The most common host species for aquatic mites was Culex erraticus, while the most common host for terrestrial mites was Anopheles quadrimaculatus. Relationships between biotic and abiotic factors were investigated in an attempt to provide insight into temporal, spatial, and interspecific variation in mite-mosquito interactions. Scanning electron microscopy was used to examine the mode of attachment for larval mites. While the prevalence of aquatic mite parasitism was correlated for Culex erraticus, the invasive mosquito, Aedes albopictus, was never parasitized through the duration of the study.

Predation efficiency of indigenous larvivorous fish species on Culex pipiens L. larvae (Diptera: Culicidae) in drainage ditches in Argentina

Two neotropical freshwater fish species, Cnesterodom decemmaculatus (Poeciliidae) and Jenynsia multidentata (Anablepidae), were collected from human-made ditches, a common habitat of the house mosquito Culex pipiens in La Plata, Argentina. Cnesterodom decemmaculatus was recorded in 62 of the 100 examined ditches, whereas J. multidentata was collected from only 21 ditches sympatrically with C. decemmaculatus. Culex pipiens was the only mosquito species collected, and its larvae and pupae were found in 38 of the 100 ditches. Fish and mosquito larvae and pupae were collected together in only two ditches and were significantly negatively correlated. Siphons of larval Culex and remnants of chironomid larvae, copepods, aquatic mites, and fish were present in the gut contents of two C. decemmaculatus from mosquito-positive ditches, while diatoms and filamentous algae were recorded in every fish dissected. Adult C. decemmaculatus and J. multidentata needed approximately 6.2 h to completely digest one Cx. pipiens 4th instar larva under laboratory conditions. When fish were confined with a density of 60 or fewer Cx. pipiens 4th instar larvae, C. decemmaculatus and J. multidentata adults consumed 100% of them in one day but only 35% and 42%, respectively, when confined with 150 larvae. Eradication of Cx. pipiens from a ditch, where densities had averaged 250 immatures per dip, was achieved 17 days after the introduction of 1,700 C. decemmaculatus.

Recapture of male and female dragonflies in relation to parasitism by mites, time of season, wing length and wing cell symmetry

For aquatic mites parasitic on dragonflies, completion of their life cycle depends on their being returned to appropriate water bodies by their hosts, after completion of engorgement. We examined whether differences among hosts in timing of emergence or phenotypic attributes might affect their probability of return to an emergence pond, and hence success of mites. Parasitized males and females of the dragonfly Sympetrum obtrusum (Hagen) did not differ in overall recapture rates. Females that had wing cell symmetry and emerged early were more likely to be recaptured than females that emerged later or had wing cell asymmetry, but there were no consistent relations between these variables and parasitism by mites. No such relations between wing cell asymmetry, emergence date, and recapture likelihood were found for males. Using randomization tests, we found that mean intensities of Arrenurus planus (Marshall) mites at host emergence were the same for recaptured females and females not recaptured; however, males that were recaptured had lower mean intensities of mites at emergence than males not recaptured. Further, mature females carried more mites than mature males, and the latter had fewer mites than newlyemerged males not recaptured. Biases in detachment of engorging mites do not explain the differences in parasitism between mature males and females, nor the differences in mite numbers between mature males and newly emerged males that were not recaptured. Rather, heavily parasitized males appear to disperse or die and are not recaptured, which should have implications for dispersal of mites and fitness of male hosts.

Experimental evidence for a female sex pheromone in Arrenurus manubriator (Acari: Hydrachnida; Arrenuridae).

We present experimental evidence for a water-borne female-produced sex pheromone in aquatic parasitengonine mites. Water that has contained adult female Arrenurus manubriator Marshall will elicit arrestant behaviour in conspecific adult males, and if the cue is sufficiently strong, the males will assume a readiness posture (with 4th pair of legs held over the back, bent anteromedially at the genuotibial joint) that is typically a precursor to coupling. Water that has not been exposed to female mites does not induce any behavioural response from male mites. Female-conditioned water that has been passed through a C-18 column does not elicit any response from male A. manubriator, while the rehydrated residue from the column does induce arrestant behaviour and may result in the readiness posture. The results from the C-18 extraction indicate that the pheromone is nonpolar in nature.

Temporary ponds and their invertebrate communities

1. Temporary waters are bodies of water that experience a recurrent dry phase of varying length that is sometimes predictable in its onset and duration. The maximum number of temporary and permanent ponds in England and Wales in 1880 is estimated to be >1 million. A 1920s survey showed lowest densities in mountainous areas (0.12 km−2) and highest densities in ancient woodland and ancient agriculture areas (115 km−2). 2. The most important physical and chemical influences on the biota of temporary ponds are the length of the aquatic phase, pattern of disappearance of the water, and whether the latter is predictable or unpredictable. Biological influences include the degree of inter/intraspecific competition and predation, and the seasonal influx of aerial colonizers. 3. Temporary ponds from Britain, northeastern North America and northwestern Australia are compared and, despite large differences in climate and zoogeography, considerable similarity is evident amongst their faunas. Snails, microcrustaceans, aquatic mites, springtails, odonates, chironomids, and a high diversity of Hemiptera and Coleoptera are characteristic of these habitats. British ponds share at least 33 genera and three species with their North American counterparts. The three main evolved strategies by which invertebrates survive in temporary ponds are physiological tolerance, life history modification, and migration. 4. The cyclical nature of the temporary pond environment creates a habitat that is distinctive enough to support species either not found in any other habitat type or that attain their greatest populations in these ponds. 5. Agricultural drainage and pond ‘improvement’ schemes are seen as distinct threats to the survival of temporary ponds and should be reviewed in the context that these water bodies are not ‘wasted’ areas of land but natural features of the environment. It is recommended that the management of wetlands in Britain should be directed towards maintaining a high diversity of natural water bodies, including a variety of temporary pond types. © 1997 John Wiley & Sons, Ltd.

Temporary ponds and their invertebrate communities

1. Temporary waters are bodies of water that experience a recurrent dry phase of varying length that is sometimes predictable in its onset and duration. The maximum number of temporary and permanent ponds in England and Wales in 1880 is estimated to be >1 million. A 1920s survey showed lowest densities in mountainous areas (0.12 km−2) and highest densities in ancient woodland and ancient agriculture areas (115 km−2). 2. The most important physical and chemical influences on the biota of temporary ponds are the length of the aquatic phase, pattern of disappearance of the water, and whether the latter is predictable or unpredictable. Biological influences include the degree of inter/intraspecific competition and predation, and the seasonal influx of aerial colonizers. 3. Temporary ponds from Britain, northeastern North America and northwestern Australia are compared and, despite large differences in climate and zoogeography, considerable similarity is evident amongst their faunas. Snails, microcrustaceans, aquatic mites, springtails, odonates, chironomids, and a high diversity of Hemiptera and Coleoptera are characteristic of these habitats. British ponds share at least 33 genera and three species with their North American counterparts. The three main evolved strategies by which invertebrates survive in temporary ponds are physiological tolerance, life history modification, and migration. 4. The cyclical nature of the temporary pond environment creates a habitat that is distinctive enough to support species either not found in any other habitat type or that attain their greatest populations in these ponds. 5. Agricultural drainage and pond ‘improvement’ schemes are seen as distinct threats to the survival of temporary ponds and should be reviewed in the context that these water bodies are not ‘wasted’ areas of land but natural features of the environment. It is recommended that the management of wetlands in Britain should be directed towards maintaining a high diversity of natural water bodies, including a variety of temporary pond types. © 1997 John Wiley & Sons, Ltd.

Description of a new microsporidium of the water mite Limnochares aquatica and establishment of the new genus Napamichum (Microspora, Thelohaniidae)

The new microsporidium Napamichum aequifilum, a parasite of the aquatic mite Limnochares aquatica in Sweden, is described based on an ultrastructural investigation. The fusiform sporophorous vesicles, the pyriform spores, the unique plurilayered exospore, and the characteristic crystalline inclusions of the episporontal space are characteristics shared by Chapmanium dispersus ( R. Larsson, 1984, Protistologica, 20, 547–563). The polar filament and the polaroplast differ in some ways. Some traits of ultrastructural cytology are discussed, with comments on two possible cases of reductions of an anisofilar polar filament. The taxonomic position of the species is discussed, and the new genus Napamichum is established for this species and for C. dispersus.

Neglected Predators: Water Mites (Acari:Parasitengona:Hydrachnellae) in Freshwater Communities

Despite the abundance and ubiquity of water mites, their importance as predators in freshwater communities is seldom investigated. This neglect is likely due both to the perceived difficulty in identifying aquatic mites, and to the lack of easily available information on the feeding habits of these animals. We review the literature on water mite feeding, translating (from German) the only previous compendium of predator-prey relationships, and adding recent reports and unpublished observations. Diets of 38 genera in 21 families are described. Reports of herbivory, detritivory, and saprophagy are dismissed and several trends are noted. Mites that eat insect eggs as adults tend to parasitize the same insect taxa during their parasitic larval stage. Lentic mites can be grouped into egg-specialists, those that concentrate on crustaceans, those that concentrate on insect larvae, and generalists. Lotic mites appear to feed primarily on chironomid larvae. A discussion of the predatory behaviour of water mites follows the compendium.

Attachment sites, phenology, and growth of larvae of Eylais sp. (Acari) on Dytiscus alaskanus J. Balfour-Browne (Coleoptera: Dytiscidae)

Larvae of aquatic mites are common ectoparasites of aquatic beetles. A population of Dytiscus alaskanus (Coleoptera: Dytiscidae) studied in a central Alberta lake was parasitized by members of the genus Eylais (Acari: Hydrachnellae). Mites attached preferentially in the costal–subcostal region of the ventral surface of the hindwings. Afferent blood flow in the costa and subcosta and the numerous blood sinuses in this region provide an abundant food source. The smallest (= youngest) larvae were taken on the first beetles caught in early spring, indicating that some mite larvae overwinter on the host. Mites grow rapidly, reach maximum size in late June and July, and then enter the nonparasitic phase of the life cycle. Rates of parasitism (proportion of beetles with parasites) was highest in early spring, declined throughout the summer, and rose again in the fall. In this way, the parasitic phase of the mites life cycle occurs at the same time as the peak in the population of adult beetles. There was constant recruitment throughout the year into the population of larval mites indicating asynchronous cohorts or more than one mite species.

Stable swimming by diagonal phase synchrony in arthropods

The aquatic mite, Limnochares americana Ldbld., in common with several types of insects which are also secondary invaders of fresh water, can swim only by stroking the legs on opposite sides of successive segments in phase (diagonal phase synchrony). A planar model developed to analyse the distribution of forces generated during this type of swimming demonstrates that there is a substantial potential for lateral instability (yaw) inherent in the locomotory pattern. The model also suggests morphological adaptations that could minimize the instability. Substitution of measured variables for L. americana and for the beetle Hydrophilus piceus in the model indicate that, consistent with observations, the mite has been considerably more successful than the beetle in minimizing lateral instability. It is concluded that diagonal phase synchrony represents an ancestral coordination pattern which is less efficient than the more derived method of coordination by transverse phase synchrony.

Observations on the integument of the water mite Arrenurus major (Acari: Parasitengona).

A study of the integument of the aquatic mite Arrenurus major Marshall is presented. When the cuticle is examined with the unaided eye and the light microscope, it appears to possess numerous tiny pits. However, scanning electron micrographs of the cuticle reveal that it is a solid surface with topographical sculpturing of the epicuticle, indicating that the "pits" are an internal phenomenon. In cuticle which has been sectioned, areas devoid of cuticular material beneath the thin exocuticle are revealed. These areas are the pits which are goblet-shaped. The integument consists of five major strata. These are from the outside to the inside: (1) a superficial layer with a maximum observed thickness of 725 Å, (2) an epicuticle with a thickness of about 900 Å and composed of at least four sublayers, (3) an exocuticle with a thickness of about 1.5 Å. Fibers of the exocuticle are arranged in a Bouligand pattern and exhibit a regularly occurring discontinuity with a spacing of 200 Å. (4) An endocuticle ranging from 15 to 20 μ in thickness. The endocuticle is characterized by bandings which superficially resemble the lamellae of insects but are not homologous, microfibers which exhibit a preferred orientation, and the presence of the pits; and (5) an epidermis lying beneath the endocuticle and extending into the pits. Pore canals are present only in the exocuticle and have their origin at the apices of the pits. The pore canals contain a central filament, and a plug is present just beneath the epicuticle.

The Arthropod Enemies of Mollusks, with Description of a New Dipterous Parasite from Brazil

The Mollusca are, next to the Arthropoda, the largest phylum of the Animal Kingdom. They exist in innumerable species in the sea, in fresh waters, and on land, where they frequently occur in populous colonies. It might therefore seem that their soft and succulent bodies would be an important item in the diet of the many carnivorous arthropods. Yet such is not the case. In the light of our present knowledge rapacious snails appear to be the most formidable predaceous enemies of mollusks. Against predatory arthropods, snails and bivalves are generally well protected by a calcareous shell, the aperture of which is frequently obstructed by folds or teeth, or in some species may be completely closed with an operculum. In the case of the bare-bodied slugs, the violent contractions of the body and the abundant slimy secretion of the skin seemingly are quite effective repellents. Moreover, the secretive habits of snails and slugs contribute much to their personal safety. Many species are strictly nocturnal or crawl about during rainstorms only, that is when most of their potential enemies are inactive. At other times they are safely hidden in inaccessible recesses or buried in the soil, often at great depth. Among lower arthropods several species of mites (Acarina) infest land mollusks. Thus Erynetes limaceum Koch is commonly found in Europe on the slug Limax maxinmus Linnaeus and some of the Helicidae, retiring upon occasion into the pulmonary chamber (Cooke, 1895:62). In North America a mite (Hypopus concolor Haldeman) has been recorded by Binney as found upon a snail; it may have been a nymphal form of Erynetes. I have observed minute, ectoparasitic mites on a living Achatina in the Semliki forest of the Belgian Congo. Stuhlmann (1894: 313) had found them before in the same region with Achatina schweinfurthi v. Martens and A. stuhlmanni v. Martens. The acarids that parasitize fresh-water mollusks are much better known. They are aquatic mites (Hydrachnidae) of the genus Unionicola Haldeman (= Atax Fabricius) and are most frequently found in the naiads or Unionidae, where they often are fixed on the gills. They are said to feed on the microscopic animals drawn in by the mussel. Kiichenmeister (1856) has shown that they may become the center of a pearl growth, although this more commonly is formed around an