Diversification of Cercopithifilaria species (Nematoda: Filarioidea) in Japanese wild ruminants with description of two new species

Twelve of the 17 Cervus nippon nippon deer from Kyushu Island, Japan, that we examined were infected with one or two Cercopithifilaria species. C. longa n. sp. adults were in the subcutaneous tissues of limbs and the abdomen, and C. crassa n. sp. adults were in the skin, mainly in the anterior part of the back; the distribution of the dermal microfilariae generally matched that of the adult worms. The two new species were assigned to the group of primitive Cercopithifilaria species that parasitize ruminants (bavids and cervids), but the new species could readily be distinguished from others morphologically. C. longa was more primitive and resembled C. bulboidea, one of the five species from the serow Capricornis crispus, a Japanese member of the Caprinae, and species from Bovidae in Africa. C. crassa had a thick body and large spicules like C. rugosicauda from Capreolus capreolus in Europe, the only previously known Cercopithifilaria species from cervids, but it also had one or two hypertrophied pairs of caudal papillae, an unusual character found so far only in Japanese parasites. Among the 12 species known from ruminants, four are African, one is European and more highly evolved, and seven are Japanese, with some being primitive and some more evolved. The great diversity of Cercopithifilaria species in the two wild ruminants that live in Japan seems to have resulted from local speciation, which occurred during the Pleistocene, from a primitive form of the C. longa type derived from Eurasiatic ancestors, which has disappeared or, more probably, not yet been discovered.     

Aspects of the life cycle of Schistosoma margrebowiei infection in laboratory mammals

Schistosoma margrebowiei Le Roux, 1933 has been recorded in a number of mammals in Africa. The parasite was maintained in the laboratory using Bulinus natalensis as intermediate host and hamsters, mice and gerbils as definitive hosts.Worm recovery, growth of paired worms, egg output and egg viability were determined and compared in the three laboratory hosts. The results in the three hosts are discussed and the mouse was observed to be suitable for the long term studies on S. margrebowiei in the laboratory. Hamsters and gerbils were observed to be useful for the study of the acute phase of the disease.     

Laboratory studies on the life cycle of Leydigia acanthocercoides Fisher (1854) (Cladocera: Chydoridae)

The biology of Leydigia acanthocercoides has been studied under laboratory conditions with reference to longevity, instar duration, growth, fecundity and embryonic development at a temperature range of 28–30 °C. It has three preadult and thirteen adult instars. Under the given laboratory conditions this species produces 20 eggs during a life span of 23 days. The number of eggs produced is uniformly constant in all adult instars. The growth rate seems to be exponential in the early phase of the life cycle as in other Cladocera. The general pattern of embryonic development of L. acanthocercoides is similar to those of other tropical cladocerans though differences in the duration of total developmental period have been recorded.Part of Ph.D. thesis.     

Further studies of Dirofilaria roemeri (Nematoda: Filarioidea) in naturally and experimentally infected Macropodidae.

Larval development of D. roemeri occurs in the subcutaneous and intermuscular connective tissue and intramuscularly in the pelvic region and hind limbs of the wallaroo and eastern grey kangaroo. Host response to developing larvae is not evident at 1, 14 and 28 days. The development of D. roemeri in the red kangaroo exhibits features previously observed in both normal and abnormal hosts. Low-level blood microfilaraemia of brief duration occurs in the red kangaroo, which may act as a secondary reservoir of infection for other kangaroo and wallaby species. Among commercially harvested Macropodidae in Queensland there is a greater prevalence of D. roemeri in wallaroos and grey kangaroos than in red kangaroos. Infection is most prevalent in animals from south-central and south-western districts.     

Aspects of the life history of Muspicea borreli (Nematoda: Muspiceidae), parasite of the house mouse (Mus domesticus) in Australia

Prevalence of Muspicea borreli (Nematoda) infection in wild populations of Mus domesticus in forests in southeastern New South Wales and in rural Canberra, Australia was variable, relatively low and the parasite occurred predominantly in male mice. Experimental infection of BALB/c mice occurred only via subcutaneous inoculation but was achieved using i) adults containing embryonating eggs, ii) adults containing active larvae and iii) active larvae dissected from the uterus of female worms. Experimental infection was not established using adults containing unembryonated eggs and was not established via intraperitoneal, percutaneous nor oral routes. Evidence indicates that larvae develop to the infective stage in the uterus of the adult worm, suggests that an obligate developmental phase on the host skin does not occur and that autoinfection is possible. Experimental infection predominated in males; females rarely became infected. When male BALB/c mice were inoculated subcutaneously with M. borrelia, immediately paired with an uninoculated female and permitted to breed for 90 days, infection was found in male and female offspring only of the second and subsequent litters or in the breeding female partner. Transmission to the young occurred within 21 days of birth and fifth-stage M. borrelia were found in offspring of the second and subsequent litters only after 35 or more days. However, when a male was inoculated but mating delayed for 23 days, infection was found in progeny of the first and second litters. The life cycle is direct and the prepatent period in BALB/c mice is estimated at 50-60 days. The precise mode of transmission of the parasite in breeding pairs of mice was not determined but larvae remained active for approximately an hour in balanced saline solutions (pH = 7.2) and in human saliva but died under conditions emulating free-living (tap water pH = 7.1) and stomach (pepsin solution pH = 2) environments. Transmission was not effected by transplacental, transmammary nor transseminal routes. Consequently, it is difficult not to conclude that transmission may occur via penetration of skin or mucous membranes, and allogrooming behaviour may be particularly important in this regard.     

Morphology and life history of Scytosiphon canaliculatus comb. nov. (Scytosiphonales,Phaeophyceae) from Japan*

Morphology of field material and life history in culture were studied in Scytosiphon canaliculatus (Setchell et Gardner) comb. nov. from northern Japan. Erect gametophytes of S. canaliculatus are cylindrical, tubular, up to 7 mm wide and 40 cm long, and without regular constrictions. S. canaliculatus has pronounced anisogamy and ascocysts accompanied with plurilocular gametangia. The life history of S. canaliculatus showed an alternation between erect gametophytes and crustose prostrate sporophytes bearing unilocular sporangia. Since field sporophytes of S. canaliculatus were found to be identical with Hapterophycus canaliculatus Setchell et Gardner (Ralfsiaceae, Phaeophyceae), it is proposed to transfer H. canaliculatus to the genus Scytosiphon. In the field, gametophytes with plurilocular gametangia appeared in spring and disappeared in summer. Sporophytes with unilocular sporangia were collected in late autumn and winter. Unilocular sporangia were produced at 15°C in short-day culture conditions and unispores developed into erect gametophytes at 5–15°C. It is suggested that the seasonal Occurrence of gametophytes in the field is due to the seasonal formation of unilocular sporangia, which is regulated by temperature and photoperiod.     

An experimental investigation of the development of Porocephalus crotali (Pentastomida : Porocephalida) in the western diamondback rattlesnake (Crotalus atrox)

The development of Porocephalus crotali in the rattlesnake definitive host (Crotalus atrox) is described. Infective nymphs excyst, penetrate the body cavity by boring through the stomach mucosa, and, in as little as 12 days, enter the lung where they grow to maturity. Copulation, which was observed at 75 and 86 days post-infection, is followed by prolonged sperm storage in spermathecae. This heralds a long prepatent period. Egg production, commencing 230–250 days after infection, is massive and continuous over a lifetime of several years. Hook data indicates that at least three moults separate the infective nymph and the adult female making a minimum of nine for the complete development from the primary larva. There was little evidence of pathological symptoms.     

The life history and culturing of Xestoleberis hanaii (Crustacea,Ostracoda)

Xestoleberis hanaii Ishizaki, 1968 is one of the most abundant species on the Japanese coast and can be collected in all seasons from intertidal calcareous algae on rocky shores. Several characteristics make this species a suitable `experimental animal' in the laboratory: (1) adaptability to artificial environments (room temperature, petri dish, artificial seawater, single cultured food-type), (2) high fertility (active copulatory behaviour, egg brooding within the carapace, high egg productivity) and (3) rapid growth rate. Females mate after the final moult (when the reach sexual maturity); oviposition of fertilized eggs takes place over a period of four days after the final moult. Eggs (about 40 in total) are laid a few at a time in the postero-dorsal brood space of the carapace; they hatch in about 9 d as A-7 instars which are then discharged from the brood space within a day or two. Seven moults take place within the next approx. 33 (female) or 39 (male) days to reach adulthood. Adult females live for about 18 weeks and may repeat the reproductive cycle three times; adult males live for about 14 weeks.     

Illness, injury, and disability among Shiwiar forager-horticulturalists: implications of health-risk buffering for the evolution of human life history

Human life history is distinguished by long lifespan, delayed reproduction, intergenerational asymmetric benefit transfers from adults to juveniles and between adults, and a large brain able to engage in unprecedented levels of learning, reasoning, and insight. The evolution of these traits depends on relatively low human mortality. Understanding why humans have low mortality is therefore critical for understanding the evolution of key human traits. One explanation is that the evolution of food provisioning during periods of health crisis reduced mortality. This hypothesis turns on health risk having posed a significant adaptive problem that could be effectively buffered by healthcare provisioning. Unfortunately, the frequency, duration, and fitness effects of temporary disability are difficult to estimate based on osteological evidence alone, and systematic ethno-biological research on these issues among extant small-scale societies with little access to Western medical care is lacking. Here I present data on 678 injuries and illnesses suffered by 40 Shiwiar forager-horticulturalists, based on physical evidence and informant reports. A subsample of 17 individuals provided data on incidence and duration of disability for 215 pathological incidents. Results indicate that injury and illness occur frequently across the lifespan. Most living individuals have suffered temporarily disabling health crises likely to have been lethal without provisioning. The fitness effects of surviving these episodes are high, suggesting that the Shiwiar population structure and lifeway are dependent on infrequent extended provisioning to temporarily disabled individuals, and that provisioning of aid during healthcare crises effectively lowers mortality in this small-scale society.     

The life history of Brotia hainanensis (Brot, 1872) (Gastropoda: Prosobranchia: Thiaridae) in a tropical forest stream

An investigation of the prosobranch snail Brotia hainanensis (Brot, 1872) (Gastropoda: Thiaridae) in Tai Po Kau Forest Stream, New Territories, Hong Kong, has been undertaken with population samples collected at approximately 14-day intervals between August, 1977 and March, 1979. This species shows two peaks of recruitment per annum, one in spring and a second in the latter part of summer. Growth to sexual maturity is rapid, taking approximately 8.5 months, and in this respect, as well as its dual peak of recruitment, B. hainanensis displayed some variation from the iteroparous pattern of life cycles considered to be characteristic of freshwater prosobranch snails. Mortality after the young snails reach maturity is high due to severe seasonal spates in the stream and it is suggested that the modification of the life cycle of B. hainanensis from the type more usually encountered in freshwater prosobranchs reflects that this is an r-selected species adapted to a habitat where high density-independent mortality occurs.     

新疆褐家鼠种群生命表及其在干旱区的生存能力分析

从2000年至今,曾于野外捕捉的褐家鼠3 837只,其中雌鼠2 685只,雄鼠1 152只,经鉴定划分为幼年组(Ⅰ)、亚成年组(Ⅱ)、成年Ⅰ组(Ⅲ)、成年Ⅱ组Ⅳ、老年组(Ⅴ)等5个年龄组,其年龄结构探讨种群数量动态,结果表明,种群中Ⅱ龄的平均生命期望值最高1.0357,其次为Ⅲ龄0.9488。该种群中1龄个体占优势地位,种群属于增长性种群,种群内禀增长率rm为0.2789/年,年周限增长率λ为1.3217,世代时间T为2.623年,种群经一世代的净增殖率R0为2.0782。     

The life cycle of Euclinostomum heterostomum (Rudolphi, 1809) (Trematoda: Clinostomatidae)

In small forest streams of West Nigeria the snail species Bulinus globosus was found to be the first intermediate host of a clinostomatid species which proved in successful infection experiments with the cichlid fish Tilapia zillii as second intermediate host to be Euclinostomum heterostomum (Rudolphi, 1809). Final hosts are herons. The morphology of the redia and the morphology and behaviour of the cercaria are described for the first time. The metacercaria which settles dorsal to the swim-bladder or in the kidney of the host fish requires more than two months (at tropical temperatures) for full development. Histological sections of the metacercaria revealed that its pharynx is provided with only few muscle fibres but surrounded by many myoblast-like cells, and the fact that the interior surface of this organ has a dense brush-like lining consisting of long microtriches. The pathology of infected fish is briefly described, and remarks about the geographical distribution of the parasite are given.     

The unusual life history of a southern Iberian Peninsula population of Torleya major (Ephemeroptera: Ephemerellidae)

Abstract The nymphal biology of a population of Torleya major (Klapálek) in southern Iberian Peninsula was studied. An atypical life cycle pattern is described, with eggs hatching in August producing a fast‐developing cohort with adults emerging in autumn and a second slow‐developing cohort with adults emerging in spring of the following year. Nymphal growth occurred primarily in summer–autumn (in the first cohort) and in spring (in the second). The origin of such a life history is discussed. Nymphs were collector‐gatherers, consuming mainly detritus. Although ontogenetic shifts on the use of trophic resources were detected, similar food was utilized during the months when both cohorts cohabited, eliminating the possibility that the rapid growth of the first cohort could be related to the utilization of different food resources.     

Desiccation of Panagrolaimus rigidus (Nematoda): survival,reproduction and the influence on the internal clock

Following the life-table experimental schedule, cohorts of aparthenogenetic strain of the free-living nematode Panagrolaimus rigidus were desiccated for six days at theages of4, 8, 12, and 19 d (age effect) and cohorts aged 8 d weredried for15, 20, 40, and 60 days (time effect) to determine theirability torecover and to reproduce.Nematode age had poor effect on recovery after 6 days ofdesiccation until the mean longevity of the nematode (19 daysinhydrated medium) is approached, while increasing times ofdesiccation (from 6 to 60 d) remarkably decreased capacity forrecovery (from 80 to 8%). Anhydrobiosis experienced atdifferentages or for different durations modified the timing of thenematodelife cycle events, but not the pattern of age-specificfecunditynor survival curves. The age-specific fecundity is largelyretainedfollowing anhydrobiosis, but when matched to that of thenematodeskept hydrated (controls), it declines for increasing durationsofdesiccation. Anhydrobiosis appears to cause a reset of theanimalsinternal clock, that is dependent on the duration ofdesiccation.     

WAX AND WANE OF MICROCYSTIS (CYANOPHYCEAE) AND MICROCYSTINS IN LAKE SEDIMENTS: A CASE STUDY IN QUITZDORF RESERVOIR (GERMANY)1

Benthic stages of the annual life cycle of the meroplanktonic cyanobacterium Microcystis spp. in relation to microcystin (MCYST) dynamics in sediments of a shallow lake (Quitzdorf Reservoir, Germany) were investigated. Based on changes in the absolute abundance of benthic Microcystis, the annual life cycle was subdivided into four phenological stages: reinvasion, pelagic growth, sedimentation, and overwintering. Habitat‐coupling processes, such as reinvasion of the pelagic zone in spring as well as autumnal sedimentation, were particularly triggered by changes in water temperature. During reinvasion substantial losses of Microcystis were detected. Only a minor part of benthic Microcystis (about 3%) formed the inoculum for pelagic growth. Between 65% and 85% of the benthic Microcystis stock disappeared during the reinvasion phase. Because these colonies were neither detected within the sediments nor in the pelagic inoculum, it was concluded that they were subjected to decay. The occurrence of extracellular MCYSTs in the pelagic zone during this period, which cannot solely originate from the pelagic Microcystis population, supports this conclusion. Dynamics of benthic Microcystis and MCYSTs were characterized by almost identical successions with a decrease during reinvasion, an increase during sedimentation, and remarkable invariability throughout pelagic growth and overwintering. It can be deduced that MCYSTs are preserved within benthic resting stages of Microcystis because they could play a role during overwintering or reinvasion.     

Aspects of the life history of Rhodophysema elegans (Rhodophyta,Peyssonneliaceae)

The life history of Rhodophysema elegans is described from laboratory culture and the field in Newfoundland, Canada. Sexual plants are lacking and tetraspores germinate to produce new tetrasporangial plants. Approximately 30–35 chromosomes were counted in vegetative cells of successive generations. There was no evidence of chromosome pairing in the early stages of division of tetrasporangial initials, indicating that the tetrasporangia are apomeiotic.     

The life cycle of Amblyomma neumanni Ribaga, 1902 (Acari: Ixodidae) in the laboratory

A colony of Amblyomma neumanni was started with engorged females collected from cattle in the province of Salta (24° 51S, 65° 33W), Argentina. The larvae and nymphs were fed on rabbits and the adults on calves. The non-parasitic stages were maintained in darkness at 27 ± 1°C and 83–86% RH. The life cycle (pre-feeding period not tested) had a mean duration of 205.7 days. The mean time (days) for the different phases of the cycle were as follows: feeding of females 8.8, pre-oviposition 23.8, oviposition 41.4, minimum egg incubation 76.1, feeding of larvae 8.5, pre-moult to nymphs 16.4, feeding of nymphs 7.9 and pre-moult to adults 22.8. The mean recovery rates of larvae, nymphs and females were 83.8, 85.6 and 89.3%, respectively. The nymphs moulting to females were heavier (8.1 ± 2.34 mg) than those moulting to males (6.0 ± 2.34 mg; p < 0.01), but their range of engorgement weight showed overlap (2.3–16.2 versus 2.2–12.8 mg, respectively). Two gynandromorphs were detected between the nymphs. A comparison of biological parameters of A. neumanni with other American Amblyomma species from mammals is presented. © Rapid Science Ltd. 1998     

Distribution of third-stage Dirofilaria roemeri (Nematoda: Filarioidea) in the tissues of tabanidae (Diptera)

The distribution of third-stage D. roemeri in its tabanid intermediate host was observed in histological sections of naturally infected Dasybasis oculata and Tabanus parvicallosus. Larvae invade the brain, eye, nerve cord, muscles of the mouthparts, horizontal and indirect flight muscles, fat body, hind gut and gonad of flies. Third-stage D. roemeri migrate from the abdomen via the haemocoelic spaces of the thorax to the head of the fly. Evidence suggests that larvae escape from the intermediate host by rupturing the tip of the labrum or the labro-epipharyngeal membranes. Injury was observed in the eye, nerve cord and musculature. There was no evidence that the parasite had a detrimental effect on the host and tabanids showed no response to the presence of filarioids. Species of Dasybasis and Tabanus acting as intermediate host of D. roemeri in nature epitomize the concept of a ‘good’ host.