Risk of predation for two reptile tick species

Experiments were conducted in the Mount Mary region of South Australia where the distributions of the two reptile-tick speciesAponomma hydrosauri andAmblyomma limbatum narrowly overlap. Engorged larvae and nymphs were placed in boxes with and without access to predators and left for 1 week. At two out of five sites there was greater loss from open access boxes in replicates during warmer periods of the year. Predation by ants appears to be the most likely explanation for the loss of ticks.     

Reproductive interactions between two Australian reptile tick species

In South Australia the two tick species Amblyomma limbatum and Aponomma hydrosauri share the same common reptile host species, but have allopatric distributions which abut along a narrow parapatric boundary. Reproductive interference is a mechanism that has previously been suggested could contribute to maintaining the boundary. Populations of each species were established in pens within the range of Aponomma hydrosauri. Pens held either each species alone, or the two species together. The performance of females in those pens was monitored over 28 months. There was no indication that the proportion of attached females which mated and engorged was reduced by the presence of heterospecifics. There was no indication that the time taken to mate, engorge and detach was any longer in the presence of heterospecifics. The experiment did not support the hypothesis that reproductive interference contributes to maintaining the parapatric boundary. However, Amblyomma limbatum in the pens had a shorter season of reproductive activity, and achieved much smaller numbers of reproductive females. This may inhibit successful colonization of cooler habitats to the south of its distribution.     

Mating behaviour and parapatry in two species of Australian reptile tick

Summary Few quantitative studies have examined the ecological consequences of similarities and/or differences in mating behaviour of parapatric species. Reproductive interference occurs between several parapatric species of Australian reptile tick, due to similarities in their mating behaviour (Andrews et al. 1982a). Attempts to determine whether reproductive interference serves to maintain parapatry between Amblyomma limbatum and Aponomma hydrosauri have been hindered because of difficulties in providing conditions conducive to conspecific mating in Amb. limbatum. The present study examined whether off-host and/or onhost temperature influenced the subsequent mating behaviour (i.e. the proportion of females that mate and the time when mating occurs) of these two species. Irrespective of the temperature experienced by ticks prior to host attachment, specific on-host temperatures were needed to induce mating in Amb. limbatum (i.e. host cloacal temperatures >32° C prior to the time of peak mating activity). Significantly more Amb. limbatum females were mated and the time taken by females to mate decreased with increasing on-host temperatures. mating in Ap. hydrosauri occurred over a wider range of on-host temperatures and the time when mating occurred did not alter at different on-host temperatures. In addition, significantly more Ap. hydrosauri males moved and each male made more moves on hosts than did Amb. limbatum males. It is suggested that Ap. hydrosauri may in consequence have a competitive mating advantage over Amb. limbatum at a boundary. Similarities in mating behaviour, on the other hand, increase the probability of reproductive interference, hence reduce the reproductive fitness of colonizing females of both species. We propose that similarities and differences in mating behaviour could play a critical role in the maintenance of parapatric boundaries.     

Serotonin-like immunoreactivity in the central nervous system of two ixodid tick species

Immunocytochemistry was used to describe the distribution of serotonin-like immunoreactive (5HT-IR) neurons and neuronal processes in the central nervous system (CNS), the synganglion, of two ixodid tick species; the winter tick, Dermacentor albipictus and the lone star tick, Amblyomma americanum. 5HT-IR neurons were identified in the synganglion of both tick species. D. albipictus had a significantly higher number of 5HT-IR neurons than A. americanum. The labeling pattern and number of 5HT-IR neurons were significantly different between sexes in D. albipictus, but were not significantly different between sexes in A. americanum. 5HT-IR neurons that were located in the cortex of the synganglion projected processes into the neuropils, invading neuromeres in the supraesophageal ganglion including the protocerebrum, postero-dorsal, antero-dorsal and cheliceral neuromeres. In the subesophageal ganglion, dense 5HT-IR neuronal processes were found in the olfactory lobes, pedal, and opisthosomal neuromeres. Double-labeling with neurobiotin backfilled from the first leg damaged at the Haller’s organ revealed serotoninergic neuronal processes surrounding the glomeruli in the olfactory lobes. The high number of the 5HT-IR neurons and the extensive neuronal processes present in various regions of the synganglion suggest that serotonin plays a significant role in tick physiology. This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation by the USDA for its use. The U.S. Government’s right to retain a non-exclusive, royalty free license in and to any copyright is acknowledged.     

Interspecific differences in microhabitat choice by two species of Australian reptile tick

The microhabitat choice of all life cycle stages, both unfed and engorged, of two Australian ixodid ticks, Amblyomma limbatum and Aponomma hydrosauri, were compared in the laboratory. When offered a choice between bare soil (or sand) and soil covered with litter, most ticks moved into the litter, except unfed larvae which often took refuge within crevices on the surface of exposed sand. The two species differed in the position they adopted within the litter. Ap. hydrosauri were predominately found at the interface between the soil and litter. Amb. limbatum were more often found higher up in the litter. There were also interspecific differences in the body orientation of ticks within the litter. All life cycle stages of Ap. hydrosauri adopted a position with their dorsal surface facing upwards, whereas unfed stages of Amb. limbatum were more frequently found with their ventral surface facing upwards. The behaviour of each species probably represents a different compromise between two factors, maximizing host detection, and minimizing their exposure to desiccation or predation.     

A comparison of the reproductive parameters of females of two reptile tick species

In comparisons of females of two reptile tick species Aponomma hydrosauri and Amblyomma limbatum, Ap. hydrosauri was initially larger, and after mating on the host engorged faster and remained attached for a shorter time before completing engorgement and detaching. Amb. limbatum had a longer period of engorgement, and achieved a greater engorged weight. Engorged Amb. limbatum females laid significantly more eggs than equivalent sized Ap. hydrosauri. Although the two species are ecologically similar and were collected from the same site for this study, their reproductive differences probably reflect adaptations to different conditions in their largely allopatric ranges.     

No competition for resources between two tick species at their parapatric boundary

Summary Aponomma hydrosauri and Amblyomma limbatum are tick species with the same major host species, the sleepy lizard Trachydosaurus rugosus, but parapatric distributions in South Australia. Near Mt. Mary one species is abruptly replaced by the other over one kilometre. There is substantial overlap in feeding sites on the hosts. This suggested that interspecific competition, during feeding, may be an important mechanism preventing further overlap of the distributions of the two species. However, in the overlap region there was no resource shortage, and each species infested hosts independently of the other species. Also in laboratory experiments at the highest densities encountered in the field, larvae and nymphs of each species attached and engorged equally well whether alone or mixed with the other species. These data refuted the, hypothesis of interspecific competition between the two species while feeding.     

On the occurrence of two new species of Trichophyton in Indian soils

Summary Two new species ofTrichophyton, T. indicum andT. evolceanui, isolated from soil in India by the hair baiting technique, are described.T. indicum is characterized by its flat colony and delicately roughened microconidia. It is common and widely distributed in soil in India. T. evolceanui can be distinguished fromT. indicum by its heaped and folded colony on tomato juice agar and its echinulate and obovate microconidia which are consistently wider than those ofT. indicum on the various culture media tested.T. evolceanui also differs fromT. indicum in producing perforating organs on hair in vitro soil culture. It has restricted occurrence in Indian soils.     

Host-odour recognition in two tick species is coded in a blend of vertebrate volatiles

The questing behaviour of ixodid ticks serves for identification and localisation of approaching hosts and is evoked by carbon dioxide, vibrations, visual and odour stimuli. In an olfactometer, we examined the specificity of the questing response of larvae of Boophilus microplus, a one-host tick which develops mainly on cattle, and Ixodes ricinus, a three-host tick with a broader host spectrum. While all mammalian odours tested were equally stimulatory for I. ricinus, B. microplus was clearly more activated by bovine odours. A phenolic fraction of bovine odour stimulated B. microplus only. Attractive components of the host odours were identified by exposing the ticks to single chemicals and mixtures. Single chemicals stimulated questing responses only at levels higher than the levels detected in the bovine odour. However, an artificial odour blend of 37 pure chemicals, diluted to concentrations at which the individual components were inactive, proved to be as effective as natural host odour for both tick species. Further fractionation of the blend revealed that the combinatory effect was achieved by only 7 compounds in both species. Although B. microplus responded to the same synergistic mixture of volatiles as I. ricinus, it showed significant higher sensitivity to the cattle-associated compounds 1-octen-3-ol and 2-nitrophenol and this might contribute to its host-specificity. Accepted: 20 March 1999     

On two new species of Mesochaetopterus (Polychaeta) from the Brazilian coast

Es wurden zwei neue Arten von Mesochaetopterus (Chaetopteridae) (Polychaeta) beschrieben und mit den restlichen Arten dieser Gattung verglichen.

Der 60 cm lange Mesochaetopterus xerecus zeigt eine gewisse Ähnlichkeit mit M. tay‐lori, aber unterscheidet sich durch die Länge und Pigmentierung der Tentakel, existenz von einem Paar Augen, Anzahl der Parapodien in der vorderen Körperregion, Form der dunklen starken Borsten des 4. Segments, Anzahl der "accessory feeding organs”;, Anzahl der Zähne der Haken der Neuropodia.

Mesochaetopterus xejubus ist eine kleinere Art von ungefähr 7 cm Länge und ist in Form und Größe M. minuta am ähnlichsten. Es unterscheidet sich jedoch durch die Form und Größe des Peristomium, Farbe der Tentakeln, Anzahl der Parapodia der vorderen Körperregion, Anzahl und Form der dunklen starken Borsten des 4. Para‐podiums der vorderen Region, Anzahl der "accessory feeding organs”;, Anzahl der Segmente der mittleren Körperregion, Anzahl der Zähne der Haken der Neuropodia und schleimdrüsenreiches Epithelium der mittleren Körperregion.     

Two new species and two new combinations in Mesoamerican Ericaceae

Satyria ventricosa andVaccinium monteverdense from Panama and Costa Rica, respectively, are described and illustrated.Gonocalyx megabracteolatus andVaccinium talamancense are new combinations. Relationships of the new species are discussed. Keys are provided for the entire genusGonocalyx, and forSatyria in Mesoamerica.

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Resumen  Se describenSatyria ventricosa yVaccinium monteverdense de Panamá y Costa Rica, respectivamente, con sus ilustraciones. Se hace una nueva combinación deGonocalyx megabracteolatus yVaccinium talamancense. También se discuten las relaciones entre las nuevas especies. Se incluyen claves para el género completoGonocalyx y para el géneroSatyria en Mesoamérica.

     

A new species and two new records of Ulocladium from China

A new species and two new Chinese records in the genus Ulocladium from soil are reported. New species is Ulocladium leve, and the new records are U. alternariae and U. consortiale. Latin diagnosis of the new species is presented. Holotype specimen （dried culture） of the new species and dried cultures of two new records are deposited in the Herbarium of Shandong Agricultural University： Plant Pathology （HSAUP）.     

Lack of resistance against the tick Ixodes ricinus in two related passerine bird species

Although many wild bird species may act as reservoir hosts for tick-transmitted diseases and/or support long-distance dispersal of infected ticks, to date no research has been done on the extent to which songbirds may acquire resistance to ixodid ticks. Here we investigate whether two passerine species belonging to the family Paridae, the blue tit (Cyanistes caeruleus) and the great tit (Parus major), are able to acquire resistance after repeated infestations with Ixodes ricinus nymphs. As blue tits are less frequently exposed to I. ricinus in the wild than great tits, we expected I. ricinus to be less adapted towards the blue tit’s resistance mechanisms. Over the three infestation sessions we observed consistently high tick attachment rates and yields, high engorgement weights, and short engorgement and moulting durations, indicating that neither of the two songbird species is able to mount effective immune responses against I. ricinus nymphs after repeated infestations. As a consequence of the lack of resistance, birds were unable to prevent the direct harm (acute blood depletion) caused by tick feeding. Birds compensated the erythrocyte loss without reduction in general body condition (body mass corrected for tarsus length). The lack of resistance suggests that I. ricinus has a long co-evolutionary history with both avian hosts, which enables the tick to avoid or suppress the host’s resistance responses.