Description of adults and nymph, and redescription of the larva, of Ornithodoros marinkellei (Acari:Argasidae), with data on its phylogenetic position

The argasid tick Ornithodoros marinkellei Kohls, Clifford, and Jones, 1969 was described 4 decades ago based on larval specimens collected from bats (Pteronotus spp.) in Colombia and Panama. Thereafter, larval O. marinkellei parasitizing bats were reported from Venezuela, Guyana, and Brazil. Herein, we describe the adults and nymph, and redescribe the larva of O. marinkellei based on specimens recently collected in the western Brazilian Amazon region. In contrast to all other known adult argasids, the idiosoma of both males and females of O. marinkellei is covered with sclerotized plaques. The idiosoma of the nymph of O. marinkellei is entirely micromamillated, and differs from the adults by the absence of plaques. The larva of O. marinkellei is morphologically similar to the larvae of the 2 other species belonging to the subgenus Subparmatus , i.e., Ornithodoros viguerasi Cooley and Kohls, 1941 and Ornithodoros mormoops Kohls, Clifford, and Jones, 1969 . Because of the long and narrow dorsal plate, the larva of O. marinkellei is readily distinguished from O. viguerasi and O. mormoops. Comparison of our larvae from Brazil with O. marinkellei paratype specimens from Colombia confirmed their taxonomic identification. However, a few morphological differences, particularly in the size of the gnathosoma, were observed. Further studies are necessary to clarify whether O. marinkellei is a complex of different species, or a single species represented by morphologically polymorphic, and geographically distinct populations. Partial mitochondrial 16S rDNA gene sequences were generated for O. marinkellei specimens from Brazil, and compared with available homologous sequences in GenBank. Phylogenetic analyses revealed O. marinkellei to be distinct from the remaining argasid species available in GenBank, including other bat-associated tick species that are found in sympatry with O. marinkellei in the Neotropical region.     

Limb regeneration and apolysis in the tick, Ornithodoros tartakovskyi.

Limb regeneration potential and the apolysis process were investigated in the argasid tick, Ornithodoros tartakovskyi. Developmental instars received single or multiple amputations and were subsequently allowed to undergo single or multiple apolyses. Amputated ticks regenerated complete normal limbs but only after four successive apolyses. Following a single apolysis, the majority of regenerated limbs were essentially miniature duplicates of normal legs but commonly lacked normal chaetotaxy and/or tarsal hump(s). The site of amputation distal to the coxa-trochanter joint, number of limbs removed from an individual, and instar amputated did not consistently influence the extent of regeneration. Coagulation and clot formation were observed.The limbs of the tick apolysed within the old leg hulls. Larvae and nymphs amputated relatively early during the period of apolyses regenerated limbs; late amputations precluded regeneration. The process of apolysis was irreversible and not obviously affected by amputations.     

A proteomic approach to the identification of salivary proteins from the argasid ticks Ornithodoros moubata and Ornithodoros erraticus

The saliva of ticks contains anti-haemostatic, anti-inflammatory and immunomodulatory molecules that allow these parasites to obtain a blood meal from the host and help tick-borne pathogens to infect the vertebrate host more efficiently. This makes the salivary molecules attractive targets to control ticks and tick-borne pathogens. Although Ornithodoros moubata and O. erraticus are important argasid ticks that transmit severe diseases, to date only a few of their salivary proteins have been identified. Here we report our initial studies using proteomic approaches to characterize the protein profiles of salivary gland extracts (SGE) from these two argasids. The present work describes the proteome of the SGEs of both tick species, their antigenic spots, and the identification of several of their proteins. The whole number of identifications was low despite the good general quality of the peptide mass maps obtained. In the O. moubata SGE, 18 isoforms of a protein similar to O. savignyi TSGP1 were identified. In the O. erraticus SGE we identified 6 novel proteins similar to unknown secreted protein DS-1 precursor, NADPH dehydrogenase subunit 5, proteasome alpha subunit, ATP synthase F0 subunit 6, lipocalin and alpha tubulin. Finally, the current drawbacks of proteomics when applied to the identification of acarine peptides and proteins are discussed.     

The possibility of sex and nymph discrimination by the male cockroach,Nauphoeta cinerea

The possibility of sex and nymph discrimination by males was investigated in the cockroach,Nauphoeta cinerea (Olivier). A sexually mature male takes a courting position toward a sexually mature female when he comes into contact with her and recognizes her through antennal contact. In contrast, males often behave aggressively toward each other: they bite at each others; wings and/or legs, chase each other and antennate mutually. The male, however, does not show conspicuous behavior (mating behavior or aggressive behavior) toward nearby nymphs. The male produces audible sounds when he courts a sexually mature but non-receptive female who does not respond to his courtship behavior. We found that the male also stridulates after he repeatedly courts immature teneral females, males and (last-instar) nymphs. After the bodies of teneral insects are sclerotized, the male shows courship and stridulation behavior toward sexually mature but non-receptive females but not toward mature males and nymphs. At this stage the male begins to behave aggressively toward other post-teneral mature males. We think that the variability of the sexually mature male's behavior toward other conspecifics (courtship behavior toward female, aggressive behavior toward male and no conspicuous response toward nymph) results from the male's recognition of adult and nymph.     

Osmotic regulation and salinity tolerance of the stonefly nymph, Paragnetina media

Nymphs of Paragnetina media were able to tolerate a range of salinities in the external media up 1.1% NaCl (～ 354 mOsm/l.) Nymphs maintained in distilled water showed excellent osmoregulation by producing hyposmotic urine. In a range of salinities, 0.4–0.95% NaCl, nymphs maintained their baemolymph concentration hyperosmotic to the external media. A breakdown in osmotic regulation occurred at 1.1% NaCl. There was no significant change (P > 0.01) in the oxygen consumption, indicating that metabolic energy demand for the osmoregulation was not affected.     

Saliva of the soft tick, Ornithodoros moubata, contains anti-platelet and apyrase activities.

1. Pilocarpine-induced saliva of the soft tick Ornithodoros moubata inhibits platelet aggregation induced by ADP or collagen, even when diluted 2000 times into platelet rich plasma. 2. Saliva contains apyrase (ATP-diphosphohydrolase) activity, which has an optimal pH of 7.0 for ADP and of 8.0 for ATP hydrolysis, respectively. Both Ca2+ and Mg2+ activate the reactions. 3. The mean specific activities for ATP and ADP hydrolysis at pH 7.5 were 0.97 and 0.74 mumoles orthophosphate/min/mg protein. 4. These results, which demonstrate for the first time such activities in the saliva of soft ticks, support the hypothesis that the saliva of blood sucking arthropods serves an anti-hemostatic role during feeding and that large amounts of salivary apyrase activity have evolved independently in hematophagous arthropods.     

Ornithodoros porcinus ticks, bushpigs, and African swine fever in Madagascar

African swine fever (ASF) has recently made its appearance in Madagascar. Ticks of the Ornithodoros moubata group, considered to be O. porcinus Walton, 1962 were formerly known to occur in western Madagascar, but seem to have disappeared from that region. However, three new sites where they occur were found in the humid and cool central highlands of Anatananarivo province. These ticks are known to be efficient reservoirs and vectors of ASF and constitute a considerable complication to the control of the disease. The authors also discuss another potentially complicating factor, the presence of a species of African bushpig, Potamochoerus larvatus.     

On the evacuation of sperm from the spermatophore of the tick, Ornithodoros savignyi

The paper deals with the different mechanisms involved in the process of spermatophore evagination, its triggering, its intermediate steps, and the cause of the flow of spermiophores from the ectospermatophore to the endospermatophore.The methods employed involved exposure of the spermatophores to the influence of various media and different environmental conditions, as well as mass spectrometric measurements in respect of the gas formed in the spermatophore during evagination.Results showed the possibility of retardation, interruption, and/or total inhibition of the process and produced conclusive proof that the gas generated in the spermatophore and responsible for the flow of spermiophores was CO₂.     

Hyperparasitism in Ornithodoros erraticus

Hyperparasitism is common in laboratory colonies of Egyptian Ornithodoros erraticus whether the ticks are on or off the rodent host. Sex, recent engorgement, and size appear to be major factors in this feeding relationship. Males, and nymphs that produced males (N-male), parasitized females and nymphs that produced females (N-female) more frequently than they parasitized males and N-male. Females and N-female seldom parasitized females and N-female and did not parasitize males or N-male. Engorging and recently engorged, large ticks attracted smaller unfed ones. No preferred attachment site was observed. Hyperparasitizing females and parasitized females weighed less, had a longer preoviposition period, and produced fewer eggs than normally feeding, unparasitized females. About 30% and 80% of the females parasitized by males and females, respectively, died within 3 mo; only 7% of unparasitized females died within the same period. The proximity of replete or engorging ticks may be sufficient stimulus for hyperparasitism. Additional factors may include production of an attracting kairomone by fed ticks or the absence under certain conditions of a deterrent to hyperparasitism normally produced by fed ticks. Borrelia crocidurae spirochetes are transmitted during hyperparasitism.     

Disaggregation of aggregated platelets by apyrase from the tick, Ornithodoros savignyi

Apyrase, secreted by ticks during feeding, is a platelet aggregation inhibitor that functions as a regulator of the host's hemostatic system. This present study concerns the disaggregation effect of salivary gland apyrase from the tick Ornithodoros savignyi. Secondarily aggregated platelets, disaggregated by apyrase, exhibited a reversal of shape from a spherical (aggregated) form to a discoid form, reminiscent of reversible aggregation at low ADP concentrations in citrated platelet-rich plasma. However, they showed a dilatory open canaliculary system and an absence of granules indicating disaggregation after degranulation had taken place. In contrast, disaggregation by the fibrin(ogen)olytic enzyme, plasmin, showed that platelets degranulated, but retained a spherical form with numerous extended pseudopods. While thrombin had no effect on aggregation or clotting of platelets disaggregated with plasmin, it did activate those platelets disaggregated with apyrase and clotted the plasma. This is the first study to describe the disaggregating effects of tick derived apyrase on aggregated platelets. It also shows that apyrase can disaggregate platelets even after secondary aggregation and degranulation of platelets has taken place. Platelet aggregation is one of the main barriers encountered by ticks during feeding and counteraction of this process by ticks is an important factor for successful feeding.     

Some studies on the respiration of stonefly nymph,Paragnetina media (Walker)

The gills of Paragnetina media function as true respiratory organs. The animals with all the thoracic gill removed did not respire more than a few minutes. The respiratory rates showed a correlation to the body weight.