A mycosis of the American lobster, Homarus americanus, caused by Fusarium sp.

Successful inoculations of citrus red mites, Panonychus citri, with the nonoccluded virus were made by feeding healthy mites through membranes on contaminated lemon fruit. Manipulation of the membranes showed that healthy mites pick up the virus from contaminated surface substrates rather than from within plant cells. Electron microscopical studies substantiated that feces of infected mites should be highly infectious since the hindgut contains numerous virus rods.     

Monitoring of Dermanyssus gallinae in free-range poultry farms

Various methods for monitoring Dermanyssus gallinae infestations within free-range egg production units were compared. The study was carried out in five egg-producing free-range poultry buildings infested with D. gallinae. Each farm was divided into six zones (each zone including nest boxes, perches and duckboard) for placing two types of traps (corrugated cardboard and thick card traps) or examining dried droppings for presence of mites. Traps were removed 24 h later, placed into bags and mites were counted at the laboratory using binocular magnification. Droppings were also inspected by eye and mite numbers were estimated. All the methods used allowed us to detect mites although their efficacy differed. The number of mites collected was independent of the type of trap used. Examination of the droppings did not differentiate between buildings with differing mite populations. Placing traps in the nest boxes is a less reliable indicator than placing them on the perches. It appears that the most coherent method for evaluating the D. gallinae population within a free-range flock is to place thick card traps throughout the building, on perches favoured by birds.     

On the Front Line: Quantitative Virus Dynamics in Honeybee (Apis mellifera L.) Colonies along a New Expansion Front of the Parasite Varroa destructor

Over the past fifty years, annual honeybee (Apis mellifera) colony losses have been steadily increasing worldwide. These losses have occurred in parallel with the global spread of the honeybee parasite Varroa destructor. Indeed, Varroa mite infestations are considered to be a key explanatory factor for the widespread increase in annual honeybee colony mortality. The host-parasite relationship between honeybees and Varroa is complicated by the mite''s close association with a range of honeybee viral pathogens. The 10-year history of the expanding front of Varroa infestation in New Zealand offered a rare opportunity to assess the dynamic quantitative and qualitative changes in honeybee viral landscapes in response to the arrival, spread and level of Varroa infestation. We studied the impact of de novo infestation of bee colonies by Varroa on the prevalence and titres of seven well-characterised honeybee viruses in both bees and mites, using a large-scale molecular ecology approach. We also examined the effect of the number of years since Varroa arrival on honeybee and mite viral titres. The dynamic shifts in the viral titres of black queen cell virus and Kashmir bee virus mirrored the patterns of change in Varroa infestation rates along the Varroa expansion front. The deformed wing virus (DWV) titres in bees continued to increase with Varroa infestation history, despite dropping infestation rates, which could be linked to increasing DWV titres in the mites. This suggests that the DWV titres in mites, perhaps boosted by virus replication, may be a major factor in maintaining the DWV epidemic after initial establishment. Both positive and negative associations were identified for several pairs of viruses, in response to the arrival of Varroa. These findings provide important new insights into the role of the parasitic mite Varroa destructor in influencing the viral landscape that affects honeybee colonies.     

Ubiquity and Diversity of Human-Associated Demodex Mites

Demodex mites are a group of hair follicle and sebaceous gland-dwelling species. The species of these mites found on humans are arguably the animals with which we have the most intimate interactions. Yet, their prevalence and diversity have been poorly explored. Here we use a new molecular method to assess the occurrence of Demodex mites on humans. In addition, we use the 18S rRNA gene (18S rDNA) to assess the genetic diversity and evolutionary history of Demodex lineages. Within our samples, 100% of people over 18 years of age appear to host at least one Demodex species, suggesting that Demodex mites may be universal associates of adult humans. A phylogenetic analysis of 18S rDNA reveals intraspecific structure within one of the two named human-associated Demodex species, D. brevis. The D. brevis clade is geographically structured, suggesting that new lineages are likely to be discovered as humans from additional geographic regions are sampled.     

Spermatozoa production in male <Emphasis Type="Italic">Varroa destructor</Emphasis> and its impact on reproduction in worker brood of <Emphasis Type="Italic">Apis mellifera</Emphasis>

Reproduction in Varroa destructor exclusively takes place within the sealed honey bee brood cell and is, therefore, limited by the duration of the postcapping period. Oogenesis, ontogenetic development and mating must be optimized to ensure the production of as many mated daughter mites as possible. One adult male mite has to mate with up to five sister mites and transfer 30–40 spermatozoa to each female. We analyzed the production and transfer of male spermatozoa during a reproductive cycle by counting all spermatozoa in the genital tracts of the male and daughter mites in 80 worker brood cells at defined times after cell capping. We could show that spermatozoa production in male mites is an ongoing process throughout their adult lifetime starting after the adult molt. The spermatozoa are transferred to the females in an early non-capacitated stage and require further maturation within the female’s genital tract. Our study points out that a Varroa male has at any time in the brood cell enough spermatozoa to inseminate all daughter mites but does not waste energy in producing a big surplus. In total one male produced, on average, 125 spermatozoa during a reproductive cycle in worker brood which is sufficient for successful matings with at least three daughter mites. Spermiogenesis in Varroa males represents therefore a further adaptation to the limited time available for reproduction.     

Random amplified polymorphic DNA analysis of kinship within host-associated populations of the symbiotic water mite Unionicola foili (Acari: Unionicolidae)

Kinship relations within populations of unionicolid water mites are not well known, owing to their complex life cycles and the fact that interactions between active and resting stages for some species are transitory. A number of species of unionicolid water mites are, however, obligate symbionts of freshwater mussels and spend most of their life cycle in association with these hosts. Among these species of mites, parents and offspring are more likely to co-occur and thus provide opportunities to address questions related to the structure of the mating system. The present study employs random amplified polymorphic DNA (RAPD) analysis to address kinship within populations of Unionicola foili living in symbiotic association with the host mussel Utterbackia imbecillis. DNA was amplified from adult mites and a representative number of eggs or larvae (n = 20-30) that were removed from mussels collected on three separate occasions (July, November, and March) over a 12-month period. Parsimony analyses of the molecular data for adults and progeny collected from mussels during July, November, and March revealed distinct groupings, that for the most part, corresponded to mites collected from each of the sampling periods. Many of the genetic markers obtained for male and female U. foili were not evident among the larvae or eggs, suggesting that adults obtained from a host mussel at the time of collection were not the parents of a majority of the progeny. However, female mites and eggs collected from mussels during March and November shared more markers than did females and progeny examined during July. Furthermore, many offspring in the July sampling period were found to have one or more parents absent from the sampled population. Overall, RAPD profiling appears to have limited usage in determining kinship within populations of U. foili, due to its recruitment patterns, and the relatively large number of adults and progeny per mussel. It may, however, prove to be a useful method for assessing genetic relatedness among unionicolid mussel-mites that have substantially lower population densities.     

Evaluation of Blattisocius dolichus (Acari: Blattisociidae) for biocontrol of root-knot nematode,Meloidogyne incognita (Tylenchida: Heteroderidae)

The root-knot nematode, Meloidogyne incognita Kofoid and White (Tylenchida: Heteroderidae), is one of the most important plant parasitic nematodes attacking many plant roots. In this paper, the predation and biocontrol efficiency of Blattisocius dolichus Ma (Acari: Blattisociidae) on this nematode were studied. The predation rate and the environmental factors affecting predation rate of B. dolichus on second-stage juveniles of M. incognita (Mi-J2) were studied in experimental arenas in plastic dishes. Both female and male mites had greater capability in consuming Mi-J2, and daily predation rate of female and male mites was not less than 35 and 29.6 nematodes within seven days, respectively. Temperature, nematode density and starvation affected B. dolichus predating on Mi-J2, and when offered 300 nematodes per dish, the predation rate of mites starved for 96 h was the highest at 25 °C, with female and male mites consumed 50.5 and 54 nematodes in 24 h, respectively. The biocontrol of B. dolichus against M. incognita was carried out on potted water spinach Ipomoea aquatic in a greenhouse. The water spinach roots were inoculated with 1,000 Mi-J2 ten days after releasing 100, 200, 300, 400 and 500 mites per pot. Compared to the nematodes–alone control, the number of root-knots of all mite treatments and the number of egg masses of the treatments with 300, 400 and 500 mites significantly decreased. Effect of releasing 500 mites on control of the root nematode M. incognita was best among all mite treatments, reduced the root-knots and egg masses 37.1 and 55.1 %, respectively, but no significant difference was observed compared to 400 mites treatment.     

Potential lethal and non-lethal effects of predators on dispersal of spider mites

Predators can affect prey dispersal lethally by direct consumption or non-lethally by making prey hesitate to disperse. These lethal and non-lethal effects are detectable only in systems where prey can disperse between multiple patches. However, most studies have drawn their conclusions concerning the ability of predatory mites to suppress spider mites based on observations of their interactions on a single patch or on heavily infested host plants where spider mites could hardly disperse toward intact patches. In these systems, specialist predatory mites that penetrate protective webs produced by spider mites quickly suppress the spider mites, whereas generalist predators that cannot penetrate the webs were ineffective. By using a connected patch system, we revealed that a generalist ant, Pristomyrmex punctatus Mayr (Hymenoptera: Formicidae), effectively prevented dispersal of spider mites, Tetranychus kanzawai Kishida (Acari: Tetranychidae), by directly consuming dispersing individuals. We also revealed that a generalist predatory mite, Euseius sojaensis Ehara (Acari: Phytoseiidae), prevented between-patch dispersal of T. kanzawai by making them hesitate to disperse. In contrast, a specialist phytoseiid predatory mite, Neoseiulus womersleyi Schicha, allowed spider mites to escape an initial patch, increasing the number of colonized patches within the system. Our results suggest that ants and generalist predatory mites can effectively suppress Tetranychus species under some conditions, and should receive more attention as agents for conservation biological control in agroecosystems.     

The Honey Bee Pathosphere of Mongolia: European Viruses in Central Asia

Parasites and pathogens are apparent key factors for the detrimental health of managed European honey bee subspecies, Apis mellifera. Apicultural trade is arguably the main factor for the almost global distribution of most honey bee diseases, thereby increasing chances for multiple infestations/infections of regions, apiaries, colonies and even individual bees. This imposes difficulties to evaluate the effects of pathogens in isolation, thereby creating demand to survey remote areas. Here, we conducted the first comprehensive survey for 14 honey bee pathogens in Mongolia (N = 3 regions, N = 9 locations, N = 151 colonies), where honey bee colonies depend on humans to overwinter. In Mongolia, honey bees, Apis spp., are not native and colonies of European A. mellifera subspecies have been introduced ~60 years ago. Despite the high detection power and large sample size across Mongolian regions with beekeeping, the mite Acarapis woodi, the bacteria Melissococcus plutonius and Paenibacillus larvae, the microsporidian Nosema apis, Acute bee paralysis virus, Kashmir bee virus, Israeli acute paralysis virus and Lake Sinai virus strain 2 were not detected, suggesting that they are either very rare or absent. The mite Varroa destructor, Nosema ceranae and four viruses (Sacbrood virus, Black queen cell virus, Deformed wing virus (DWV) and Chronic bee paralysis virus) were found with different prevalence. Despite the positive correlation between the prevalence of V. destructor mites and DWV, some areas had only mites, but not DWV, which is most likely due to the exceptional isolation of apiaries (up to 600 km). Phylogenetic analyses of the detected viruses reveal their clustering and European origin, thereby supporting the role of trade for pathogen spread and the isolation of Mongolia from South-Asian countries. In conclusion, this survey reveals the distinctive honey bee pathosphere of Mongolia, which offers opportunities for exciting future research.     

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.     

Microorganisms associated with the spider mite predator Metaseiulus (= Typhlodromus) occidentalis: Electron microscope observations

Two morphologically distinct forms of microorganisms were observed with the electron microscope in the tissues of the phytoseiid mite Metaseiulus (= Typhlodromus) occidentalis. The forms were distinguished on the basis of cell wall structure and cytoplasmic inclusions. One microorganism, designated type A, was observed in all mites examined. The second microorganism, type B, was observed in approximately two-thirds of the mites examined. If present, type B microorganisms occurred in all ovaries and egges, suggesting that transovarial transmission may take place. In some mites large numbers of type B microorganisms were observed within Malpighian tubule lumens and in a rectal plug. Whether this population was primarily or secondarily associated with a pathology is discussed.     

Detection of honeybee tracheal mites (Acarapis woodi) by simple staining techniques

A total of 12 staining techniques, including five anionic and five cationic stains, and two mordant stains, were tested as possible histopathological methods for the detection of the honeybee tracheal mite, Acarapis woodi. The cationic stains stained the parasitic mites intensively and the ensheathing tracheae weakly positive in thin thoracic sections. The improved clarity and contrast of the stained mites within the tracheae in the thin thoracic sections facilitated the detection process. Even at very low levels of infestation, stained mites were detected easily and accurately under a dissecting microscope at a magnification as low as 10 ×. Consequently, examination of dissected trachae under a phase compound microscope, currently used for diagnosis of the mites, is no longer necessary. The stained specimen can also be mounted permanently on microslides.     

Host finding behaviour of the coconut mite Aceria guerreronis

For the coconut mite, Aceria guerreronis Keifer, its host plant, the coconut palm, is not merely a source of food, but more generally a habitat to live in for several generations. For these minute organisms, finding a new plant is difficult and risky, especially because their main mode of dispersal is passive drifting with the wind and because they are highly specialized on their host plant. Consequently, the probability of landing on a suitable host is very low, let alone to land in their specific microhabitat within the host. How coconut mites manage to find their microhabitat within a host plant is still underexplored. We tested the hypothesis that they use volatile chemical information emanating from the plant to find a specific site within their host plants and/or use non-volatile plant chemicals to stay at a profitable site on the plant. This was investigated in a Y-tube olfactometer (i.e. under conditions of a directed wind flow) and on cross-shaped arenas (i.e. under conditions of turbulent air) that either allowed contact with odour sources or not. The mites had to choose between odours from specific parts (leaflet, spikelet or fruit) of a non-infested coconut plant and clean air as the alternative. In the olfactometer experiments, no mites were found to reach the upwind end of the Y-tube: <5 % of the mites were able to pass the bifurcation of the “Y”. On the cross-shaped arenas, however, a large number of coconut mites was found only when the arm of the arena contained discs of fruit epidermis and contact with these discs was allowed. The results suggest that coconut mites on palm trees are not attracted to specific sites on the plant by volatile plant chemicals, but that they arrested once they contact the substrate of specific sites. Possibly, they perceive non-volatile chemicals, but these remain to be identified.     

Mitochondria-rich cells in the astigmatic mites,Diplaegidia columbae (Buchholz) (Analgidae) and Falculifer rostratus (Buchholz) (Falculiferidae) (Acari: Astigmata)

Mitochondria are well-characterized intracellular organelles usually concentrated in locations of high energy consumption. Light microscopic and transmission electron microscopic observations of the internal anatomy of the feather mites Diplaegidia columbae and Falculifer rostratus were conducted. In the anterior half of the bodies of the mites, we found several dozen of distinctive mitochondria-rich (MR) cells filled with abundant, large mitochondria. Mitochondria are placed individually or enclosed in small groups within an elaborated lamellar system forming a mitochondria–lamellae complex (MLC). The role of the MLC as well as the MR cells is not clear at present, but their involvement in heat generation is hypothesized and briefly discussed.     

Unseen fungal biodiversity and complex inter-organismal interactions in Protea flower heads

A unique microbiome occurs within the flower heads of various Protea species endemic to Africa. These include two lineages of ophiostomatoid fungi, Knoxdaviesia (Microascales) and Sporothrix (Ophiostomatales), that have members occurring exclusively in this environment and that rely on mites as their primary mode of spore dissemination. The mites, in turn, attach to the bodies of Protea-pollinating beetles and the beaks and bodies of birds for long-distance movement, establishing a hierarchical dispersal network for the ophiostomatoid fungi. This inter-organismal network is highly successful, achieving fungal dispersal over vast distances. Multiple species of fungi, mites and bacteria have been described from this unique niche over the past four decades. The intricacies of their symbiotic interactions continue to be unravelled. This review covers all current knowledge of the “distinctly African” Protea-ophiostomatoid fungus environment and illustrates the depth of a fascinating unseen fungal biodiversity niche.     

Acaricidal Activity of Eugenol Based Compounds against Scabies Mites

Backgound

Human scabies is a debilitating skin disease caused by the “itch mite” Sarcoptes scabiei. Ordinary scabies is commonly treated with topical creams such as permethrin, while crusted scabies is treated with topical creams in combination with oral ivermectin. Recent reports of acaricide tolerance in scabies endemic communities in Northern Australia have prompted efforts to better understand resistance mechanisms and to identify potential new acaricides. In this study, we screened three essential oils and four pure compounds based on eugenol for acaricidal properties.

Methodology/Principal Findings

Contact bioassays were performed using live permethrin-sensitive S. scabiei var suis mites harvested from pigs and permethrin-resistant S. scabiei var canis mites harvested from rabbits. Results of bioassays showed that clove oil was highly toxic against scabies mites. Nutmeg oil had moderate toxicity and ylang ylang oil was the least toxic. Eugenol, a major component of clove oil and its analogues –acetyleugenol and isoeugenol, demonstrated levels of toxicity comparable to benzyl benzoate, the positive control acaricide, killing mites within an hour of contact.

Conclusions

The acaricidal properties demonstrated by eugenol and its analogues show promise as leads for future development of alternative topical acaricides to treat scabies.     

The ectoparasitic mite Tropilaelaps mercedesae (Acari, Laelapidae) as a vector of honeybee viruses

The ectoparasitic mites Varroa destructor and Tropilaelaps mercedesae share life history traits and both infect honeybee colonies, Apis mellifera. Since V. destructor is a biological vector of several honeybee viruses, we here test whether T. mercedesae can also be infected and enable virus replication. In Kunming (China), workers and T. mercedesae mites were sampled from three A. mellifera colonies, where workers were exhibiting clinical symptoms of deformed wing virus (DWV). We analysed a pooled bee sample (15 workers) and 29 mites for the presence of Deformed wing virus (DWV), Black queen cell virus (BQCV), Sacbrood virus (SBV), Kashmir bee virus (KBV), Acute bee paralysis virus (ABPV), and Chronic bee paralysis virus (CBPV). Virus positive samples were analysed with a qPCR. Only DWV +RNA was found but with a high titre of up to 10⁸ equivalent virus copies per mite and 10⁶ per bee. Moreover, in all DWV positive mites (N= 12) and in the bee sample virus–RNA was also detected using RT-PCR and tagged RT-PCR, strongly suggesting virus replication. Our data show for the first time that T. mercedesae may be a biological vector of DWV, which would open a novel route of virus spread in A. mellifera. Received 6 June 2008; revised 14 August 2008; accepted 10 September 2008.     

Defense suppression benefits herbivores that have a monopoly on their feeding site but can backfire within natural communities

Background

Plants have inducible defenses to combat attacking organisms. Hence, some herbivores have adapted to suppress these defenses. Suppression of plant defenses has been shown to benefit herbivores by boosting their growth and reproductive performance.

Results

We observed in field-grown tomatoes that spider mites (Tetranychus urticae) establish larger colonies on plants already infested with the tomato russet mite (Aculops lycopersici). Using laboratory assays, we observed that spider mites have a much higher reproductive performance on russet mite-infested plants, similar to their performance on the jasmonic acid (JA)-biosynthesis mutant def-1. Hence, we tested if russet mites suppress JA-responses thereby facilitating spider mites. We found that russet mites manipulate defenses: they induce those mediated by salicylic acid (SA) but suppress those mediated by JA which would otherwise hinder growth. This suppression of JA-defenses occurs downstream of JA-accumulation and is independent from its natural antagonist SA. In contrast, spider mites induced both JA- and SA-responses while plants infested with the two mite species together display strongly reduced JA-responses, yet a doubled SA-response. The spider mite-induced JA-response in the presence of russet mites was restored on transgenic tomatoes unable to accumulate SA (nahG), but russet mites alone still did not induce JA-responses on nahG plants. Thus, indirect facilitation of spider mites by russet mites depends on the antagonistic action of SA on JA while suppression of JA-defenses by russet mites does not. Furthermore, russet mite-induced SA-responses inhibited secondary infection by Pseudomonas syringae (Pst) while not affecting the mite itself. Finally, while facilitating spider mites, russet mites experience reduced population growth.

Conclusions

Our results show that the benefits of suppressing plant defenses may diminish within communities with natural competitors. We show that suppression of defenses via the JA-SA antagonism can be a consequence, rather than the cause, of a primary suppression event and that its overall effect is determined by the presence of competing herbivores and the distinct palette of defenses these induce. Thus, whether or not host-defense manipulation improves an herbivore’s fitness depends on interactions with other herbivores via induced-host defenses, implicating bidirectional causation of community structure of herbivores sharing a plant.

     

Detection,Prevalence and Phylogenetic Relationships of Demodex spp and further Skin Prostigmata Mites (Acari,Arachnida) in Wild and Domestic Mammals

This study was conceived to detect skin mites in social mammals through real-time qPCR, and to estimate taxonomic Demodex and further Prostigmata mite relationships in different host species by comparing sequences from two genes: mitochondrial 16S rRNA and nuclear 18S rRNA. We determined the mite prevalence in the hair follicles of marmots (13%) and bats (17%). The high prevalence found in marmots and bats by sampling only one site on the body may indicate that mites are common inhabitants of their skin. Since we found three different mites (Neuchelacheles sp, Myobia sp and Penthaleus sp) in three bat species (Miotis yumanensis, Miotis californicus and Corynorhinus townsendii) and two different mites (both inferred to be members of the Prostigmata order) in one marmot species (Marmota flaviventris), we tentatively concluded that these skin mites 1) cannot be assigned to the same genus based only on a common host, and 2) seem to evolve according to the specific habitat and/or specific hair and sebaceous gland of the mammalian host. Moreover, two M. yumanensis bats harbored identical Neuchelacheles mites, indicating the possibility of interspecific cross-infection within a colony. However, some skin mites species are less restricted by host species than previously thought. Specifically, Demodex canis seems to be more transmissible across species than other skin mites. D. canis have been found mostly in dogs but also in cats and captive bats. In addition, we report the first case of D. canis infestation in a domestic ferret (Mustela putorius). All these mammalian hosts are related to human activities, and D. canis evolution may be a consequence of this relationship. The monophyletic Demodex clade showing closely related dog and human Demodex sequences also supports this likely hypothesis.