Surface topography of the tegument of adult Schistosoma nasale Rao, 1933 from Sri Lanka

Scanning electron microscopical studies of adult male and female Schistosoma nasale are reported. The tubercles on the dorsal and dorso-lateral surfaces of unpaired male S. nasale are devoid of spines. In paired male worms the tubercles on the dorsal surface are large and also are devoid of spines, but some tubercles on the dorso-lateral surface possess spines. Pit-like openings are visible on the surface of the smooth tubercles. The oral and ventral suckers on the male worm are well developed and are invested with spines, as are the gynaecophoric canal and flap. Ciliated sensory receptors are distributed over the surface of the male worm. The oral and ventral suckers of the female worm are much smaller than those of the male: spines occur on both suckers. The surface of the female is non-tuberculate and is thrown into transverse folds. Pit-like openings are visible at higher magnifications. The anterior end of the female is heavily invested in ciliated receptors, whereas the posterior end is heavily spined. The surface topography of S. nasale is discussed in relation to other species of Schistosoma.     

Factors affecting sex ratio in rearing ofCoeloides sordidator (Hym.: Braconidae)

Five factors known to affect the sex ratio (% of males) in parasitic Hymenoptera were investigated forCoeloides sordidator, a parasitoid ofPissodes weevils. The host age, the age of ovipositing females, and the host of origin had a significant impact on the sex ratio of offspring. In contrast, the number of ovipositing females had an insignificant effect on sex ratio whereas the effect of host density could not be clearly defined. The sex ratio decreased with host age, probably because, like many other hymenopteran parasitoids, females tend to lay male eggs on small hosts and female eggs on larger hosts in order to maximize the size and fitness of their female offspring. The sex ratio also varied with the age of the mother, younger females laying more male eggs and older females more female eggs. The host of origin also had an influence on sex ratio. The strain fromPissodes castaneus was significantly more male-biased than the strain fromP. validirostris, which corroborates previous observations made on field populations     

Nematode lungworms of two species of anuran amphibians: evidence for co-adaptation

Genetic studies have indicated that some parasite species formerly thought to be generalists are complexes of morphologically similar species, each appearing to specialize on different host species. Studies on such species are needed to obtain ecological and parasitological data to address whether there are fitness costs in parasitizing atypical host species. We examined whether lungworms from two anuran host species, Lithobates sylvaticus and Lithobates pipiens, differed in measures of infection success in L. pipiens recipient hosts. We also determined if the worms from the two host species were sources of genetically resolvable species of morphologically similar nematodes. Sequences of internal transcribed spacer and lsrDNA regions of adult lungworms from each host species indicated that worms from L. sylvaticus matched Rhabdias bakeri, whereas worms from L. pipiens matched Rhabdias ranae. Our work suggested that these morphologically similar species are distant non-sibling taxa. We infected male and female metamorphs experimentally with lungworm larvae of the two species. We observed higher penetration, higher prevalence and higher mean abundance of adult worms in lungs of male and female metamorphs exposed to R. ranae larvae than in lungs of metamorphs exposed to R. bakeri larvae. Furthermore, metamorphs exposed to R. ranae larvae carried larger adult female worms in their lungs. Some variation in infection measures depended on host sex, but only for one parasite species considered. Overall, the differential establishment and reproductive potential of R. ranae and R. bakeri in L. pipiens suggests co-adaptation.     

Seasonal and regional occurrence of <Emphasis Type="Italic">Acanthocephalus</Emphasis> sp. (Acanthocephala: Echinorhynchidae) in fishes and isopods (<Emphasis Type="Italic">Asellus hilgendorfi</Emphasis>) in a lake system in northern Japan

 The echinorhynchid acanthocephalan Acanthocephalus sp. was collected and described from four species of fishes (rainbow trout Oncorhynchus mykiss, Sakhalin huchen Hucho perryi, Japanese pond smelt Hypomesus nipponensis, and threespine stickleback Gasterosteus aculeatus) from a lake system, the Tsugaru-Jūniko Lakes, in Aomori Prefecture, northern Japan. In rainbow trout, the prevalence and intensity of infection markedly differed between lakes, and the fish were most frequently and most heavily infected in the lakes with a dense population of the isopod intermediate host Asellus hilgendorfi. In isopods, the prevalence of acanthocephalan larvae increased in the late winter and reached its highest level in March or April. In rainbow trout, male worms were abundant from winter to spring, and female worms were immature during these seasons. Gravid females were abundant in summer and autumn. These findings indicate that Acanthocephalus sp. is an annual species and its recruitment from the intermediate host to the fish occurs mainly in winter and spring. Received: January 9, 2002 / Accepted: April 18, 2002 Acknowledgments We thank Professor Shōichi Saito, Faculty of Education, Hirosaki University, for his encouragement during this study. Thanks are also due to many students of the Nature Study Laboratory, Faculty of Education, Hirosaki University, for their assistance in the field. We are greatly indebted to the Iwasaki Village Office and Fukaura Forestry Office for giving us permission for the survey. Correspondence to:A. Ohtaka     

Bleaching increases likelihood of disease on Acropora palmata (Lamarck) in Hawksnest Bay, St John, US Virgin Islands

Anomalously high water temperatures may enhance the likelihood of coral disease outbreaks by increasing the abundance or virulence of pathogens, or by increasing host susceptibility. This study tested the compromised-host hypothesis, and documented the relationship between disease and temperature, through monthly monitoring of Acropora palmata colonies from May 2004 to December 2006, in Hawksnest Bay, St John, US Virgin Islands (USVI). Disease prevalence and the rate of change in prevalence showed a positive linear relationship with water temperature and rate of change in water temperature, respectively, but only in 2005 during prolonged periods of elevated temperature. Both bleached and unbleached colonies showed a positive relationship between disease prevalence and temperature in 2005, but the average area of disease-associated mortality increased only for bleached corals, indicating host susceptibility, rather than temperature per se, influenced disease severity on A. palmata.     

Pathogenicity of the gill artery worm Philometra obturans (Nematoda) in northern pike (Esox lucius) in southwest Finland

The pathogenicity of female Philometra obturans (Prenant, 1886) was investigated. Fish samples were taken in May and June 2001 from Lake Littoistenj?rvi, in southwest Finland. The intensity of infection varied between 1 and 4 worms, these being found in the afferent artery of the 2 outermost gill arches. The prevalence was 33.9% (n = 59). Host condition and tissue reactions were investigated through dissection and analysis of histopathology. The parasites obstructed the gill arteries, and the arterial wall was stretched around intact worms. Hypertrophy of the arterial wall was observed, especially when only disintegrating remains of the parasites were present. Infected pike were in a poorer condition after catch, transportation, and holding in aquaria and thus less tolerant to stress than uninfected pike. This was correlated with the number of infected gill arteries (P < 0.05). The results show that infection with this nematode has a detrimental effect on the host when combined with environmental or physiological stress and may result in host mortality.     

Morphological aspects of Schistosoma mansoni adult worms isolated from nourished and undernourished mice: a comparative analysis by confocal laser scanning microscopy.

Malnutrition hampers the course of schistosomiasis mansoni infection just as normal growth of adult worms. A comparative morphometric study on adult specimens (male and female) recovered from undernourished (fed with a low protein diet - regional basic diet) and nourished (rodent commercial laboratory food, NUVILAB) white mice was performed. Tomographic images and morphometric analysis of the oral and ventral suckers, reproductive system and tegument were obtained by means of confocal laser scanning microscopy. Undernourished male specimens presented smaller morphometric values (length and width) of the reproductive system (first, third and last testicular lobes) and thickness of the tegument than controls. Besides that, it was demonstrated that the dorsal surface of the male worms bears large tubercles unevenly distributed, but kept grouped and flat. At the subtegumental region, vacuolated areas were detected. It was concluded that the inadequate nutritional status of the vertebrate host has a negative influence mainly in the reproductive system and topographical somatic development of male adult Schistosoma mansoni, inducing some alterations on the structure of the parasite.     

Morphometric study of Schistosoma mansoni adult worms recovered from Undernourished infected mice

Some unfavourable effects of malnutrition of the host on Schistosoma mansoni worm biology and structure have been reported based upon brigthfield microscopy. This paper aims to study by morphometric techniques, some morphological parameters in male and female adult worms recovered from undernourished albino mice in comparison with parasites recovered from well-fed infected mice. Undernourished animals were fed a multideficient and essentially low protein diet (RBD diet) and compared to well-fed control mice fed with the commercial diet NUVILAB. Seventy-five days post-infection with 80 cercarie (BL strain) animals were sacrificed. All adult worms were fixed in 10% formalin and stained with carmine chloride. One hundred male and 60 female specimens from each group (undernourished and control) were examined using an image system analysis Leica Quantimet 500C and the Sigma Scan Measurement System. The following morphometrical parameters were studied: body length and width, oral and ventral suckers, number and area of testicular lobes, length and width of ovary and uterine egg. For statistical analysis, the Student's t test for unpaired samples was applied. Significant differences (p < 0.05) were detected in body length and width, in parameters of suckers, uterine egg width, ovary length and area of testicular lobes, with lower values for specimens from undernourished mice. The nutritional status of the host has negative influence on S. mansoni adult worms, probably through unavailability of essential nutrients to the parasites.     

Species-specific prevalence of mermithid parasites in populations of six congeneric host caddisflies of Ecnomus McLachlan, 1864 (Trichoptera: Ecnomidae)

Mermithid nematodes are entomophagous parasites and, despite being present in diverse aquatic insects, studies of caddisflies acting as definitive hosts are few and the ecological impacts on host populations are largely unknown. During a four-year study in a stream in southeastern Australia, parasitic mermithid worms were commonly found inside adult caddisflies, but only species of the genus Ecnomus McLachlan, 1864 (Ecnomidae). Ecnomus were the definitive host and parasite prevalence ranged from <1% to nearly 50% across six species. Species-specific prevalence varied little between years and was typically higher in males than in females. Parasite intensity ranged from 1 to 6 (median = 1), but did not vary between species or sexes. Infected hosts could fly, but were castrated and died when worms emerged. High prevalence and virulence (reproductive failure and death of the host) suggests that these parasites could potentially play a role in the population dynamics of some Ecnomus spp.     

Feeding the fairy shrimp Streptocephalus (Anostraca - Crustacea) with the rotifer Anuraeopsis

Laboratory-cultured Streptocephalus torvicornis were offered 8 concentrations (from 6 to 800 ind. ml^–1) of Anuraeopsis fissa for periods of 2 h 30 min. Two size classes, small (male: 14.7 mm± 1.6, female: 15.4 mm± 1.3) and large (male: 20.0 mm±2.0, female: 23.1 mm± 1.5), of S. torvicornis were used. Functional response for large S. torvicornis (both sexes) plateaued at 400 rotifers ml^–1, while in small specimens it did so at 200 prey ml^–1. Females consumed significantly more (30%) prey than males. Large males consumed maximum 4730 rotifers h^–1, females 6560 h^–1.     

Variability of the opisthaptoral hard parts ofGyrodactylus callariatis Malmberg, 1957 (Monogenea: Gyrodactylidae) from Atlantic codGadus morhua L. in the Oslo Fjord,Norway

The present study describes the variability of the opisthaptoral hard parts ofGyrodactylus callariatis Malmberg, 1957 infesting juvenile Atlantic codGadus morhua L. in the Oslo Fjord, Norway. Samples were taken monthly or bimonthly from January 1993 to July 1994. The length of the 14 characters measured varied considerably throughout the period, and showed a significant regression on the water temperature: as the water temperature increased the length of the hard parts decreased andvice versa. There were no significant differences in the size of the hard parts between young worms (without penis) and older worms (with penis). Some of the characters (especially the anchor shaft) from parasites located on the skin and fins were significantly longer than those of parasites located in the oral cavity, pharynx and gills. Generally, the variation in the shape of the hard parts was small; the anchor root, ventral bar membrane and ventral bar processes were the most variable parts. The shape of the hard parts did not vary as a consequence of seasonal changes in the water temperature, age of the worms or site on the host.     

Reproductive performance of Nesolynx thymus (Hymenoptera: Eulophidae), in relation to age of Musca domestica (Diptera: Muscidae)

An investigation was undertaken to record the influence of host age on the reproductive performance of Nesolynx thymus (Hymenoptera:Eulophidae). This is an indigenous, gregarious, ecto-pupal parasitoid of certain dipteran insects, including the tachinid fly, Exorista bombycis (Louis) which is a well-known endo-larval parasitoid of the silkworm, Bombyx mori. Each gravid N. thymus female was allowed to parasitise 1–4-day-old puparia of Musca domestica L. for 2 days at a parasitoid–host ratio of 1:20. The parasitised host puparia were observed for progeny recovery, sex ratio, female longevity and fitness (adult size). In addition, reproductive performance of the parasitoid progeny was assessed by allowing its females to parasitise for 2 days, 3-day-old puparia of E. bombycis at a parasitoid–host ratio of 1:4. There was a significant negative correlation between host age and parasitisation rate, parasitoid developmental duration, sex ratio and female longevity while the correlation was positive between host age and parasitoid recovery per host puparium. Similarly, negative correlation was observed between host age and morphometric parameters (body length, head width and wing span of male and female and length and width of female abdomen) of the progeny adults. Host age did not have any impact on the reproductive performance of progeny adults when allowed to parasitise puparia of E. bombycis.     

Freeze tolerance and accumulation of cryoprotectants in the enchytraeid Enchytraeus albidus (Oligochaeta) from Greenland and Europe

The freeze tolerance and accumulation of cryoprotectants was investigated in three geographically different populations of the enchytraeid Enchytraeus albidus (Oligochaeta). E. albidus is widely distributed from the high Arctic to temperate Western Europe. Our results show that E. albidus is freeze tolerant, with freeze tolerance varying extensively between Greenlandic and European populations. Two populations from sub Arctic (Nuuk) and high Arctic Greenland (Zackenberg) survived freezing at −15 °C, whereas only 30% of a German population survived this temperature. When frozen, E. albidus responded by catabolising glycogen to glucose, which likely acted as a cryoprotectant. The average glucose concentrations were similar in the three populations when worms were frozen at −2 °C, approximately 50 μg glucose mg⁻¹ tissue dry weight (DW). At −14 °C the glucose concentrations increased to between 110 and 170 μg mg⁻¹ DW in worms from Greenland. The average glycogen content of worms from Zackenberg and Nuuk were about 300 μg mg⁻¹ DW, but only 230 μg mg⁻¹ DW in worms from Germany showing that not all glycogen was catabolised during the experiment. Nuclear magnetic resonance spectrometry (NMR) was used to screen for other putative cryoprotectants. Proline, glutamine and alanine were up regulated in frozen worms at −2 °C but only in relatively small concentrations suggesting that they were of little significance for freeze survival. The present study confirms earlier reports that freeze tolerant enchytraeids, like other freeze tolerant oligochaete earthworms, accumulate high concentrations of glucose as a primary cryoprotectant.     

Relationship between overweight, obesity and socioeconomic factors of adolescents in Vojvodina, Serbia

Obesity is a very important issue in developed societies and depends on many factors. The aim of this paper was to determine a possible relationship between overweight, obesity and socioeconomic factors among adolescents in Vojvodina. A cross-sectional anthropometric study was carried out from 2001 to 2004 in towns of Vojvodina, northern Serbia. The research included height and body weight measurements as well as body mass index (BMI) of 1236 schoolboys and 1414 schoolgirls aged 15–18 years. The socioeconomic factors (SES) included parents’ level of education and monthly income per family member. The overweight prevalence of about 10% (85 < P < 95) and the prevalence of obesity of 5% (P > 95) were recorded in both male and female adolescents. A significant correlation (p < 0.01) between all socioeconomic factors was observed in male subjects, although there were no significant differences in the prevalence of overweight and obesity when different categories of subjects set by SES were compared. In females lower rates of the prevalence of overweight and obesity were detected in the subjects whose parents had a university education, but the difference was not significant. Regarding the prevalence of obesity, a significant difference was recorded between females with high and low incomes, those with a high income showing significantly greater prevalence of obesity than females coming from low income families. The results of the research indicate that in Vojvodina the family income is the only factor that significantly correlates with female obesity.     

Effects of social status and stress on patterns of gastrointestinal parasitism in wild white‐handed gibbons (Hylobates lar)

Although gibbons (family Hylobatidae) are typically monogamous, polyandrous groups occur regularly. Stress associated with elevated intragroup competition among males in polyandrous groups may increase susceptibility to infectious disease. To better understand this interplay, as well as to provide the first comprehensive assessment of parasitism in free‐ranging gibbons, we characterized the richness of gastrointestinal parasites and examined their prevalence in males from 14 groups (10 pair‐living, 4 multi‐male) of white‐handed gibbons (Hylobates lar) at Khao Yai National Park, Thailand. From September 2008 to May 2009, 324 fecal samples were collected from 23 individually recognizable male gibbons and screened for gastrointestinal helminths and protozoa after isolation via fecal floatation, sedimentation, and immunofluorescent antibody detection. A total of 10 parasite species recovered, including seven nematodes, two protozoans, and one trematode. Parasite richness and species‐specific prevalence were examined relative to social organization (pair‐living vs. multi‐male), male status (primary vs. secondary), age (subadult, adult, senior), fecal glucocorticoid levels, and time of the year. No relationship was found between parasite richness and sociodemographic or physiological factors. Similarly, prevalence of infection with parasite species was not associated with the majority of sociodemographic factors; however, Ternidens sp. and Balantidium coli varied seasonally and Trichuris sp. decreased with increasing age. Moreover, observational data suggest that competition is low in this gibbon population, and our findings are consistent with those observations in that cooperative defense may offset stress and reduce susceptibility to infection. Am J Phys Anthropol 150:602–608, 2013. © 2013 Wiley Periodicals, Inc.     

Seasonal changes in the population of the mite Unionicola intermedia (Hydrachnellae,Acari) from the freshwater mussel Anodonta anatina (Unionidae)

Although numbers were low in winter, males of Unionicola intermedia were found throughout the year. A mean of 2.5 (±0.26 SE) males per mussel was found with a range of 0 to 20. Females had a mean of 13.07 (±0.87 SE) per mussel and a range from 0 to 57, with the highest mean in August. The incidence of males was much lower than that of females. Nymphs and females were highly aggregated and males showed aggregation at a lower level of significance for nine months of the year. Although the primary sex ratio is unknown, the tertiary sex ratio is 86% female and on a monthly basis ranged from 68.9% to 96.7% female. It is speculated that reproduction is arrhenotokous. The sex ratio and the significant seasonal variations of the active stages may be influenced by the dispersal pattern of this species and by the biology of its host.     

Effects of three different cultivars of cruciferous plants on the age‐stage,two‐sex life table traits of Plutella xylostella (L.) (Lepidoptera: Plutellidae)

Plutella xylostella is an important pest of cruciferous crops worldwide. However, information regarding the age‐stage, two‐sex life parameters of P. xylostella, which is vital for designing more effective control methods, is currently lacking. The present study reports age‐stage, two‐sex life table parameters for P. xylostella on napa cabbage (Brassica oleracea var. napa), white cabbage (B. oleracea var. capitata), and cauliflower (B. oleracea var. botrytis) under laboratory conditions at 25 ± 2°C, 50–60% relative humidity, and a 16‐h light : 8‐h dark photoperiod. The time for development from an egg to a male or female adult P. xylostella on white cabbage (mean [± SE] 41.15 ± 0.54 and 39.50 ± 0.54 days, respectively) was significantly longer than that on cauliflower and napa cabbage. Furthermore, P. xylostella fecundity on cauliflower (261.90 ± 4.53 eggs female) was significantly highest than on napa cabbage and white cabbage. Intrinsic rate of increase (r) and finite rate of increase (λ) were highest on cauliflower 0.182 day^?1 and 1.199 day^?1 respectively as comparison to napa cabbage and white cabbage. The highest gross reproductive rate (GRR) and net reproductive rates (R₀) of P. xylostella 65.87 and 52.58 respectively on cauliflower then those of other hosts. The findings of the present study indicate that cauliflower is the most suitable cultivar (host) for the development of P. xylostella. Based on these findings, crops like cauliflower can be used as trap crops when napa cabbage and white cabbage are the main crops.     

Substrate-borne vibrational signals and stridulatory organs for sexual communication in leafminer,Liriomyza sativae (Diptera: Agromyzidae)

The vegetable leafminer (Liriomyza sativae [Burgess]) is a highly polyphagous pest that threatens vegetables and horticultural plants. Although sexual communication is a key component of the animal behavioral repertoire, the mechanism underlying sexual communication in L. sativae remains to be elucidated. Here, we used laser vibrometry to characterize the vibrational signals emitted by L. sativae during pair formation. By emitting trains of vibrational pulses (male calling) the male initiated communication on the host plant. The female then became immobile and responded to the male calling by emitting replies (female replies), which in turn triggered male replies consisting of a rapid series of chirps and trills. If the female replied, a continuous exchange of male and female replies ensued, representing a duet. In playback trials, a playback signal caused responses from the opposite sex. Moreover, scanning electron microscopy revealed vibration-producing stridulatory organs in both male and female individuals. The files in males were more developed than those in females, and older male specimens had more signs of abrasion. The results provide new insight into the mating biology of L. sativae.