Water mite parasitism in damselflies during emergence: two hosts, one pattern

The infections of emerging damselfly cohorts by ectoparasitic water mites Arrenurus cuspidator were followed closely over two years in two populations. In one pond Coenagrion puella was the single host species, whereas in the second pond C. hastulatum co-occurred. The prevalences found were close to 100%. The mean daily abundance of mites ranged from I to 45 mites per host with a peak after roughly one third of the emergence period.
The water mites displayed a clumped distribution on their hosts measured by the variance/mean ratio. No differences in parasite abundance due to host sex, head width, or host species could be detected. The abundance of mites was synchronised with host's emergence patterns. This was stronger in the system with two host species. Shaw and Dobson recently showed a generalised relationship of variance/mean of parasite abundance combining data from 269 host parasite systems. The data presented here and some other water mite associations show a significant deviation from this general rule.     

Characteristics of dispersing Ischnura elegans and Coenagrion puella (Odonata): age, sex, size, morph and ectoparasitism

In this study we assessed whether individuals of the damselfly species Ischnura elegans and Coenagrion puella that moved between ponds differed in their mean characteristics from individuals that did not move. Overall, the sex (female) and species ( C. puella ) that spent the most time away from the breeding site was more likely to move between ponds. Ischnura elegans males that dispersed had significantly longer forewings than males that did not, while male C. puella parasitised by water mites were more likely to disperse than unparasitised males. There was no evidence for differences in dispersal rates among the female colour forms of either I. elegans or C. puella . In general, the differences in dispersal characteristics between sexes and species could be explained by underlying variation in activity and mobility. The majority of dispersal between breeding sites by C. puella and I. elegans did not appear to be directed, but probably arose from chance movements occasionally taking individuals to a different pond from which they emerged.     

Co-occurrence of ectoparasites on rodent hosts: null model analyses of data from three continents

We studied patterns of species co-occurrence in communities of ectoparasitic arthropods (ixodid ticks, mesostigmate mites and fleas) harboured by rodent hosts from South Africa ( Rhabdomys pumilio ), South America ( Scapteromys aquaticus and Oxymycterus rufus ) and west Siberia ( Apodemus agrarius , Microtus gregalis , Microtus oeconomus and Myodes rutilus ) using null models. We compared frequencies of co-occurrences of parasite species or higher taxa across host individuals with those expected by chance. When non-randomness of parasite co-occurrences was detected, positive but not negative co-occurrences of parasite species or higher taxa prevailed (except for a single sample of mesostigmate mites from O. rufus ). Frequency of detection of non-randomness of parasite co-occurrences differed among parasite taxa, being higher in fleas and lower in mites and ticks. This frequency differed also among host species independent of parasite taxon, being highest in Microtus species and lowest in O. rufus and S. aquaticus . We concluded that the pattern of species co-occurrence in ectoparasite communities on rodent hosts is predominantly positive, depends on life history of parasites and may be affected to a great extent by life history of a host.     

Species and sex biases in ectoparasitism of dragonflies by mites

An important problem in understanding the evolution of parasite host range is determining the extent to which parasite fitness varies among host species and the factors affecting that fitness variation. We present a detailed investigation on the patterns of host use and successful parasitism of two dragonfly species by the ectoparasitic water mite, Limnochares americana Lundblad. In our field surveys, we found both species biases and sex biases in parasitism by mites, which appear explained by differences in exposure. Differential habitat use by dragonflies helped explain male biases in parasitism in both host species, but was not useful in explaining species biases in parasitism. Species biases in parasitism may be explained by more subtle variation in habitat use not explored in this study, or perhaps by differences in timing of emergence, as we found for the two dragonfly species. Despite species differences in parasitism in nature, we found that mites attached equally successfully to both dragonfly species during experimental infestations. However, mites failed to engorge more often on the dragonfly species less often used as a host in nature. This host species also was more likely to have dead mites in natural infestations as compared to the other host species, which was more often and more heavily parasitized. Our results are consistent with previous research suggesting parasites are less successful on less often used hosts. Such research has implications for understanding determinants of host range for animal parasites.     

Interspecific parasite exchange in a mixed colony of birds

Studies of avian host-parasite interactions rarely include consequences of relationships among hosts for either the host or parasite species. In this study, we examine the ectoparasitic burden of adult and nestling European bee-eaters (Merops apiaster) and rock sparrows (Petronia petronia) in a mixed colony. We found that (1) each bird species had its own species of lice; (2) hematophagous mites parasitized both adults and nestlings of both bird species; (3) Carnus hemapterus, a common parasite of nestling bee-eaters, also infested rock sparrow nestlings, a species not previously described as a host for this dipteran; and (4) whereas C. hemapterus did not show high host specificity within the colony, the emergence of adult flies was synchronized with the start of hatching in bee-eater nests. We suggest that coexistence of these 2 bird species results in parasite exchange, bee-eaters obtaining mites from sparrows and sparrows becoming infested by C. hemapterus. Differences in the detrimental effects of parasite transfer for each host species may result in a process of apparent competition mediated by shared parasites. Interspecific parasite exchange is an important aspect of host-parasite relationships in mixed colonies, which requires further attention.     

Host specificity in spinturnicid mites: do parasites share a long evolutionary history with their host?

Host specificity in parasites can be explained by spatial isolation from other potential hosts or by specialization and speciation of specific parasite species. The first assertion is based on allopatric speciation, the latter on differential lifetime reproductive success on different available hosts. We investigated the host specificity and cophylogenetic histories of four sympatric European bat species of the genus Myotis and their ectoparasitic wing mites of the genus Spinturnix. We sampled >40 parasite specimens from each bat species and reconstructed their phylogenetic COI trees to assess host specificity. To test for cospeciation, we compared host and parasite trees for congruencies in tree topologies. Corresponding divergence events in host and parasite trees were dated using the molecular clock approach. We found two species of wing mites to be host specific and one species to occur on two unrelated hosts. Host specificity cannot be explained by isolation of host species, because we found individual parasites on other species than their native hosts. Furthermore, we found no evidence for cospeciation, but for one host switch and one sorting event. Host‐specific wing mites were several million years younger than their hosts. Speciation of hosts did not cause speciation in their respective parasites, but we found that diversification of recent host lineages coincided with a lineage split in some parasites.     

Differential Water Mite Parasitism,Phenoloxidase Activity,and Resistance to Mites Are Unrelated across Pairs of Related Damselfly Species

Related host species often demonstrate differences in prevalence and/or intensity of infection by particular parasite species, as well as different levels of resistance to those parasites. The mechanisms underlying this interspecific variation in parasitism and resistance expression are not well understood. Surprisingly, few researchers have assessed relations between actual levels of parasitism and resistance to parasites seen in nature across multiple host species. The main goal of this study was to determine whether interspecific variation in resistance against ectoparasitic larval water mites either was predictive of interspecific variation in parasitism for ten closely related species of damselflies (grouped into five “species pairs”), or was predicted by interspecific variation in a commonly used measure of innate immunity (total Phenoloxidase or potential PO activity). Two of five species pairs had interspecific differences in proportions of individuals resisting larval Arrenurus water mites, only one of five species pairs had species differences in prevalence of larval Arrenurus water mites, and another two of five species pairs showed species differences in mean PO activity. Within the two species pairs where species differed in proportion of individuals resisting mites the species with the higher proportion did not have correspondingly higher PO activity levels. Furthermore, the proportion of individuals resisting mites mirrored prevalence of parasitism in only one species pair. There was no interspecific variation in median intensity of mite infestation within any species pair. We conclude that a species’ relative ability to resist particular parasites does not explain interspecific variation in parasitism within species pairs and that neither resistance nor parasitism is reflected by interspecific variation in total PO or potential PO activity.     

Co-evolution between ectoparasites and their insect hosts: a simulation study of a damselfly–water mite interaction

1. A simulation model investigating the co‐evolution of water mites infesting their aquatic insect hosts during emergence is presented. The model is based on field and experimental studies of the ectoparasitic water mite Arrenurus cuspidator and the damselfly Coenagrion puella. 2. Three scenarios were studied: (1) Only the host was allowed to evolve timing of emergence, while the timing of the parasites' infestation opportunity was held constant. (2) Both host and parasite were allowed to evolve. (3) Only the parasite's timing was allowed to evolve, while the host was constrained completely. 3. In the first two scenarios, parasite abundances decreased in the course of evolution and reached values well below those found in the field, whereas in the third scenario, parasite abundances were maintained at a level close to that found in the field. In the second scenario (co‐evolution), the host seemed to be the leader in the evolutionary race. 4. It is concluded that water mite parasitism is capable of shaping emergence patterns in aquatic insects and, despite the same life‐cycle length for host and parasite, the parasite evolves fast enough to shape its hatching pattern to match the emergence pattern of its host.     

Odonates,gregarines and water mites: why are the same host species infected by both parasites?

1. Damselflies and dragonflies are widely parasitised insects and numerous studies have tried to understand this host–parasite relationship. However, most of these studies have concentrated on a single host species, neglecting the larger pattern within the Odonata order. 2. The aim of this paper was to examine different damselfly and dragonfly species for common endo‐ and ectoparasites and whether a general infection pattern can be found. Additionally, the goal was to investigate whether the phylogeny of the host species could explain these possible infection patterns. To this end, a dataset from the existing literature was compiled and the prevalence of endoparasitic gregarines and ectoparasitic water mites was analysed for 46 different odonate species. 3. Three distinct patterns were found: (i) most of the odonate host species had both gregarines and water mites, rather than only either one or neither; (ii) there appears to be a positive association between gregarine and water mite prevalences across host species; (iii) a weak phylogenetic signal was detected in gregarine prevalence and a strong one in water mite prevalence. 4. It is hypothesised that, due to the infection and transmission mechanisms by which water mites and gregarines infect different odonate host species, parasitism is aggregated to common, high‐density species. However, much research is needed in order to fully understand this relationship between odonates and their parasites, especially within the same host populations and host species assemblages.     

Landscape aspects of host-parasite relationships between parasitic arthropods and the narrow-skulled vole Microtus gregalis (Rodentia) in Western Siberia

Comparative zoogeographic analysis of outcomes accumulated in the course of long-term investigation the parasitic and free-living arthropods (Acarina: Parasitiformes; Insecta: Siphonaptera) associated with three subspecies of the narrow-skulled vole (Microtus gregalis gregalis, M. g. major, M. g. eversmanni) in various landscape zones and subzones in a flat part of Western Siberia, foothills of the Altai-Sayan mountain system and mountains of Southwest Altai. The obtained data, on the one hand, recover specific features of certain parasite communities that reflect ecological peculiarity of a host species living in conditions of concrete landscapes, on the other hand, a high degree of similarity between species set of some ectoparasitic and nidicolous arthropod groups from different subspecies of M. gregalis. The systematic list of ectoparasitic and nidicolous arthropods associated with M. gregalis and representing Gamasoidea mites, ticks and fleas is provided.     

Weather dependent effects of nest ectoparasites on their bird hosts

This study reports the relationships between rainfall and ambient temperature with the abundances and prevalences of three species of ectoparasitic arthropods (viz, mites, blowfly larvae, fleas) in pied flycatcher Ficedula hypoleuca nests in three different breeding seasons In addition to its effects on the growth of nestling pied flycatchers, weather conditions were found to determine patterns of abundance and prevalence of ectoparasites Nest ectoparasites had detrimental effects on the fitness (nestling growth and survival until fledgling) of their hosts although the effects and the identity of harmful ectoparasites varied across the years Among the three species of nest ectoparasites, mites had the most consistent harmful effects on nestling growth Fleas were detrimental in the more cold and rainy year, while blowflies caused nestling mortality in the wanner year Different host-parasite interactions were present each year, most likely due to the effects of weather on the activity and timing of development of parasite populations     

Sexual selection and infection by ectoparasites in Wellington tree weta,Hemideina crassidens (Orthoptera: Anostostomatidae)

Abstract Sexual selection can affect the prevalence and intensity of infection of individuals by ectoparasitic mites. According to this theory, males should exhibit greater infection by parasites than females and juveniles should be less infected than adults. In the wild, I investigated whether prevalence and intensity of the chyzeriid mite, Nothotrombicula deinacridae (Dumbleton) differed between the sexes and between developmental stages in Wellington tree weta, Hemideina crassidens. Despite being under strong sexual selection, male tree weta did not exhibit greater parasitism and there was some evidence that adults and juveniles differed in prevalence. The sexual selection hypothesis was not supported in this study.     

中国云南小兽体表革螨的群落相似性

运用系统聚类分析方法对中国云南省境内17种主要小型哺乳动物(小兽)体表革螨群落相似性进行研究,每一种小兽体表的所有外寄生革螨被定义为一个相应的革螨群落。运用SPSS11.5软件完成17种革螨群落的相似性比较。研究结果表明:小兽体表革螨群落结构复杂,物种多样性高;隶属同一个属的小兽体表的革螨群落相似程度高,在系统聚类分析中聚为一类;大多数革螨群落相似性大小与相应小兽宿主在动物分类上的近缘性高低呈现高度一致,但也有一些革螨群落是例外的。这说明小兽体表革螨群落不仅受小兽宿主分类地位的影响,可能还受宿主生境的影响     

Ectoparasite‐induced increase in Drosophila host metabolic rate

Parasites exert numerous effects upon their hosts, including physiological and metabolic changes that can in turn influence various aspects of host life history. Using flow‐through respirometry, we investigated how infection intensity of an ectoparasitic mite (Macrocheles subbadius) affects the respiratory rate (CO₂ production) of its host Drosophila nigrospiracula. Mean fly respiratory rate increased with infection intensity with the strongest effect, a 40% increase relative to uninfected controls, occurring with three mites attached. We also verified the causal relationship between elevated respiration rate and mite attachment by examining changes in host respiration before and after mite exposure. We found that the rate of CO₂ production increased by 11% for individual flies following parasite attachment. Fly locomotor activity was not significantly different between infected and uninfected individuals. Metabolic rate of hosts increased as a result of infection in an intensity dependent manner and was not simply due to changes in host activity. These results demonstrate that parasites can have a significant influence on the energy requirements of their host, which may account for the parasite‐mediated loss in host fitness.     

Physical and physiological costs of ectoparasitic mites on host flight endurance

1. Dispersal is essential for locating mates, new resources, and to escape unfavourable conditions. Parasitism can impact a host's ability to perform energetically demanding activities such as long‐distance flight, with important consequences for gene flow and meta‐population dynamics. 2. Ectoparasites, in particular, can adversely affect host flight performance by diminishing flight aerodynamics and/or by inflicting physiological damage while feeding on host tissue. 3. Experimental flight assays were conducted using two fruit fly‐mite systems: Drosophila nigrospiracula (Patterson and Wheeler) – Macrocheles subbadius (Berlese) and D. hydei (Sturtevan) – M. muscaedomesticae (Scopoli). Flies that are burdened by mites are expected to exhibit lower flight endurance compared to uninfected flies. 4. The results show that the presence of mites (attached) significantly decreased flight endurance by 57% and 78% compared to uninfected D. nigrospiracula and D. hydei, respectively. The physiological damage caused by M. subbadius was revealed through a 53% decline in flight time among previously infected flies (mites removed just prior to flight assay). Surprisingly, the presumably phoretic M. muscaedomesticae also caused a 62% reduction in flight endurance among previously infected D. hydei. 5. These results suggest a strong deleterious effect of ectoparasitic mites on host flight performance, mediated by a reduction in flight aerodynamics and damage to host physiology. Adverse effects on host flight and/or dispersal may have broad implications for gene flow, population genetic structure, and local adaptation in both host and parasite meta‐populations.     

On understanding seasonal increases in damselfly defence and resistance against ectoparasitic mites

Abstract.  1. Defence against parasites and pathogens can be essential, yet not all hosts respond similarly to parasitic challenge. Environmental conditions are thought to explain variation in host responses to parasites.
2.  Lestes forcipatus damselflies emerging later in the season have shown higher resistance to the mite, Arrenurus planus , than hosts emerging earlier. This study was undertaken to determine whether variation in environmental temperatures characteristic of early vs. late emergence times, degree or costs of mite parasitism, and/or size of newly emerged adults could explain seasonal variation in defence and resistance to ectoparasitic mites.
3. In this study damselflies from early vs. late emergence groups differed in size at emergence and mite intensity. In general, early hosts were larger and had more mites than later hosts. However only experimental temperatures experienced by damselflies at emergence influenced defence and resistance against mites and not host size or degree of parasitism.
4. More specifically, hosts from early and late emergence groups did not differ in defence and resistance when held at the same temperatures in incubators. Housing at a high temperature, indicative of later in the season, was associated with higher defence and resistance for damselflies from both early and late emergence groups.
5. These results indicate that daily temperatures in relation to emergence timing can account for seasonal increases in resistance for this temperate insect. Seasonal increases in resistance may be expected for other temperate insect–parasite associations and should have important implications for the phenology of parasites and for seasonal variation in parasite-mediated selection.     

Two new species of Eutrombidium Verdun, 1909 (Acari: Prostigmata: Eutrombidiidae) from Asia and a new host record for this genus

Two new species of larval mites are described Eutrombidium laosanum n. sp. ectoparasitic on undetermined Gryllidae (Orthoptera) from Laos and Indonesia (Lingga Islands) and E. sigirijanum n. sp. ectoparasitic on undetermined Tenebrionidae (Coleoptera) from Sri Lanka.     

Control of the straw itch mite (Acari: Pyemotidae) with sulfur in an insect rearing facility.

The ectoparasitic mite Pyemotes tritici (Lagrèze-Fossat & Montané) (Acari: Pyemotidae) caused paralysis and reduced longevity in eucalyptus longhorned borer, Phoracantha semipunctata F., under laboratory rearing conditions. Application of dusting sulfur to logs that contained pupating borers greatly reduced densities of mites on emerging adult beetles and increased beetle survivorship. Uniform application to all logs in a glasshouse effectively eradicated the mite infestation. A bioassay showed that sulfur may physically impede the dispersal of immature mites by adhering to the cuticle, but sulfur vapor did not act as a toxin.     

The role of host traits, season and group size on parasite burdens in a cooperative mammal

The distribution of parasites among hosts is often characterised by a high degree of heterogeneity with a small number of hosts harbouring the majority of parasites. Such patterns of aggregation have been linked to variation in host exposure and susceptibility as well as parasite traits and environmental factors. Host exposure and susceptibility may differ with sexes, reproductive effort and group size. Furthermore, environmental factors may affect both the host and parasite directly and contribute to temporal heterogeneities in parasite loads. We investigated the contributions of host and parasite traits as well as season on parasite loads in highveld mole-rats (Cryptomys hottentotus pretoriae). This cooperative breeder exhibits a reproductive division of labour and animals live in colonies of varying sizes that procreate seasonally. Mole-rats were parasitised by lice, mites, cestodes and nematodes with mites (Androlaelaps sp.) and cestodes (Mathevotaenia sp.) being the dominant ecto- and endoparasites, respectively. Sex and reproductive status contributed little to the observed parasite prevalence and abundances possibly as a result of the shared burrow system. Clear seasonal patterns of parasite prevalence and abundance emerged with peaks in summer for mites and in winter for cestodes. Group size correlated negatively with mite abundance while it had no effect on cestode burdens and group membership affected infestation with both parasites. We propose that the mode of transmission as well as social factors constrain parasite propagation generating parasite patterns deviating from those commonly predicted.     

Dominant honeybee colony infestation by Varroa destructor (Acari: Varroidae) K haplotype in Japan

Applied Entomology and Zoology - Varroa destructor Anderson and Trueman (Acari: Varroidae) are ectoparasitic mites found in the western honeybee Apis mellifera Linnaeus (Hymenoptera: Apidae)....