Number of results to display per page
Search Results
662. Scanning and transmission electron microscopy of the histopathological impact of Macrogyrodactylus clarii (Monogenea: Gyrodactylidae) on the gills of catfish, Clarias gariepinus
- Creator:
- El-Naggar, Mohammed Mohammed, Cable, Joanne, Zaky Arafa, Safaa, El-Abbassy, Samir Ahmed, and Kearn, Graham C
- Format:
- print, počítač, and online zdroj
- Type:
- model:article and TEXT
- Subject:
- histopatologie, nemoci ryb, histopathology, fish diseases, ultrastructure, aquatic health, monogeneans, 2, and 59
- Language:
- English
- Description:
- Scanning and transmission electron microscopy (TEM) were used to study the histopathological effects of the monogenean Macrogyrodactylus clarii Gussev, 1961 on the gills of the catfish Clarias gariepinus (Burchell). Suction generated during attachment created 'footprints' on host surfaces in which the host tissues were elevated above the general gill surface. 'Footprints' were bordered by four clefts caused by the muscular flaps on the anterior, lateral and posterior margins of the haptor. The hamuli points penetrate the gill tissue but no evidence was found for the insertion of the marginal hooklets. At the site of attachment, host cells adjacent to the lateral flaps often appeared compressed and widely spaced with large intercellular spaces. Desquamation of these surface epithelia was also apparent and some of the widely spaced epithelial cells had pseudopodium-like processes. Cells within the upper surface epithelial layer of the host were vacuolated and necrotic. Ruptured blood capillaries (blood spaces) in the secondary gill lamellae contained atypical compressed erythrocytes, agranular and granular leucocytes and evidence of haemorrhaging. Cells with fibrotic cytoplasm, putative phagocytes and host mucous cells were evidence of a host response at the site of parasite attachment. The possible role of these cells is discussed in relation to host resistance against infection., Mohammed Mohammed El-Naggar, Joanne Cable, Safaa Zaky Arafa, Samir Ahmed El-Abbassy, Graham C. Kearn., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
663. Scolex morphology of monozoic tapeworms (Caryophyllidea) from the Nearctic Region: taxonomic and evolutionary implications
- Creator:
- Oros, Mikuláš, Uhrovič, Dalibor, Choudhury, Anindo, Mackiewicz, John S, and Tomáš Scholz
- Format:
- print, počítač, and online zdroj
- Type:
- model:article and TEXT
- Subject:
- tasemnice, ryby, srovnávací mytologie, skenovací elektronová mikroskopie, tapeworms, fishes, comparative mythology, scanning electron microscopy, Catostomidae, Cestoda, scolex terminology, identification, 2, and 59
- Language:
- English
- Description:
- A comparative study of the scoleces of monozoic tapeworms (Cestoda: Caryophyllidea), parasites of catostomid and cyprinid fishes (Teleostei: Cypriniformes) in the Nearctic Region, was carried out using light and scanning electron microscopy. Scoleces of 22 genera of North American caryophyllideans were characterised and their importance for taxonomy, classification and phylogenetic studies was critically reviewed. Nearctic genera exhibit a much higher variation in the shape and form of scoleces compared with taxa in other biogeographical regions. The following basic scolex types can be recognised in Nearctic caryophyllideans: monobothriate (Promonobothrium Mackiewicz, 1968), loculotruncate (Promonobothrium, Dieffluvium Williams, 1978), bothrioloculodiscate (Archigetes Leuckart, 1878, Janiszewskella Mackiewicz et Deutsch, 1976, Penarchigetes Mackiewicz, 1969, Pseudoglaridacris Oros, Uhrovič et Scholz, 2018), fixomegabothriate (Capingens Hunter, 1927), bulbate and bulboacuminate (Atractolytocestus Anthony, 1958), cuneiloculate (Hypocaryophyllaeus Hunter, 1927, Rowardleus Mackiewicz et Deutsch, 1976, Spartoides Hunter, 1929), biacetabulate, bulboloculate, bothrioloculodiscate (Biacetabulum Hunter, 1927), tholate (Hunterella Mackiewicz et McCrae, 1962), cuneifimbriate (Khawia Hsü, 1935), cuneiform (Calentinella Mackiewicz, 1974, Caryophyllaeides Nybelin, 1922, Edlintonia Mackiewicz, 1970), hastate (Pseudolytocestus Hunter, 1929), loculotholate (Bialovarium Fischthal, 1953, Pliovitellaria Fischthal, 1951), and cuneiformoloculate (Glaridacris Cooper, 1920, Isoglaridacris Mackiewicz, 1965). The same type of scolex may be shared by species of different genera or families and species of the same genus can have a scolex of conspicuously different morphology, e.g. in Promonobothrium. Scolex morphology may be therefore of limited use in generic designation., Mikuláš Oros, Dalibor Uhrovič, Anindo Choudhury, John S. Mackiewicz and Tomáš Scholz., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
664. Scorpion reproductive strategies, allocation and potential; a partial review
- Creator:
- Warburg, Michael R.
- Type:
- article, články, model:article, and TEXT
- Subject:
- Zoologie, entomologie, Scorpiones, reproductive strategies, reproductive allocation, reproductive potential, litter size, 2, and 59
- Language:
- English
- Description:
- Most scorpion species are iteroparous, breeding more than once during their life. Some of these species are parthenogenetic. The other reproductive strategy (RS) semelparity, when scorpions breed only a single time during their life, is rare and has been documented only once. The mass allocated by the female to produce either a litter or a single offspring is the reproductive allocation (RA). It is difficult to calculate RA since the difference in female mass before and after parturition is difficult to obtain. In addition, the litter size is hardly ever accurate because of maternal cannibalism. An attempt was made to calculate RA in Nebo hierichonticus (E. Simon, 1872). Based on litter size, on breeding frequency and on longevity of the female, it is possible to estimate the reproductive potential (RP). These aspects of scorpion reproduction are reviewed and the difficulties involved in this study are discussed. and Michael R. Warburg.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
665. Screening for anthelmintic resistance in equid strongyles (Nematoda) in Romania
- Creator:
- Cernea, Mihai, Cristina, Romeo T, Ştefănuţ, Laura C, Carvalho, Luís M. Madeira de, Taulescu, Marian A, and Cozma, Vasile
- Format:
- electronic, počítač, and online zdroj
- Type:
- model:article and TEXT
- Subject:
- koně, osli, horses, donkeys, Strongylinae, Cyathostominae, benzimidazoles, Ivermectin, 2, and 59
- Language:
- English
- Description:
- Resistance to anthelmintic medication of equid strongyles is a worldwide phenomenon and for this reason systematic investigations of resistant parasite populations are necessary. The purpose of the present study was to investigate the presence and distribution of equid strongyles resistant to the anthelmintics used in Romania, as well as the pre-treatment and post-treatment prevalence of species of strongylid nematodes. The Faecal Egg Count Reduction Test was performed between 2010 and 2013 on a total number of 588 horses and 23 donkeys from 26 locations (subgroups). Animals of the first group (I) consisting of subgroups no. 1-11 were treated with Albendazole (ABZ), those of the second group (II) consisting of subgroups no. 12-23 with Fenbendazole (FBZ), while Ivermectin (IVM) was used on animals of the third group (III) consisting of subgroups no. 24-26. Resistant strongyles have been found in 82% (average lower limit of the 95% confidence interval, LCL95%, was 65) of the total equids from the group treated with ABZ. In the group of horses treated with FBZ, resistant strongyles were identified in 75% of the subgroups (LCL95% = 44). No resistant strongyles have been identified in IVM-treated horse groups (LCL95% = 98). The pre-treatment prevalence of the species of the Strongylinae Müller, 1780 was 22%, whereas that with nematodes of the subfamily Cyathostominae Molin, 1861 78%. Post-treatment reduction of strongyline nematodes was observed (5%), which demonstrates the sensitivity of large strongyles to common anthelmintics. The post-treatment prevalence of cyathostomes was of 95%, which proves their resistance, especially to ABZ- and FBZ-based anthelmintics., Mihai Cernea, Romeo T. Cristina, Laura C. Ştefănuţ, Luís M. Madeira de Carvalho, Marian A. Taulescu, Vasile Cozma., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
666. Seasonal constraints on the mandible allometry of Lucanus cervus (Coleoptera: Lucanidae)
- Creator:
- Hardersen, Sönke, Macagno, Anna L. M., Sacchi, Roberto, and Toni, Ilaria
- Type:
- article, články, model:article, and TEXT
- Subject:
- Zoologie, entomologie, Allometry, Coleoptera, Lucanidae, Lucanus cervus, mandibles, season, size, time constraints, 2, and 59
- Language:
- English
- Description:
- In insects, allometries of exaggerated traits such as horns or mandibles are often considered species specific and constant during a season. However, given that constraints imposed by the advancing season affect the developmental processes of organisms, these allometries may not be fixed, and the switch point between morphs may vary between populations and within populations during a season. The hypothesis of such a seasonal variation in exaggerated traits was tested using the dimorphic males of the beetle Lucanus cervus. The remains of specimens killed by predators were collected along forest tracks from mid May to late August 2008 in a protected lowland forest in northern Italy. The largest beetles were collected in mid May and average size thereafter decreased. Males collected early in the season mostly had large mandibles (i.e. they belonged to the major morph). In contrast, late in the season the probability of finding males with large mandibles was very low. The threshold body size determining morph expression also shifted during the season. Early in the season, the threshold pronotum width for a 50% chance of developing into the major morph was 1.74 cm, whereas later in the season it was 1.90 cm. This shift in the threshold body size was interpreted as the effect of phenotypic plasticity in a population exposed to constraints imposed by the advancing season. and Sönke Hardersen, Anna L.M. Macagno, Roberto Sacchi, Ilaria Toni.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
667. Seasonal cues mediate host behaviour modification and cocoon polymorphism in Microplitis mediator (Hymenoptera: Braconidae)
- Creator:
- Luo, Shu-Ping, Michaud, J.P., Li, Jian-Cheng, Zhang, Jing, Liu, Xiao-Xia, and Zhang, Qing-Wen
- Type:
- article, články, model:article, and TEXT
- Subject:
- Zoologie, zoologie, entomologie, Hymenoptera, Braconidae, Microplitis mediator, Lepidoptera, Noctuidae, Mythimna separata, photoperiod, host behaviour, pupation site selection, cocoon polymorphism, temperature, 2, and 59
- Language:
- English
- Description:
- Laboratory experiments were conducted to examine the effects of photoperiod and temperature on the pupation behaviour of the parasitoid, Microplitis mediator (Haliday) (Hymenoptera: Braconidae), parasitizing larvae of Mythimna separata Walker (Lepidoptera: Noctuidae). A combination of long photoperiod (14 + h L) and warm temperatures (20–24°C) caused parasitized caterpillars to climb to upper plant parts where the parasitoid produced a green, non-diapausing cocoon on a green leaf, initially retaining the dying caterpillar host as a protective covering. In contrast, short photoperiod (8–10 h L) and low temperature (16–18°C) induced host caterpillars to descend the plant where the parasitoid produced a brown, diapausing cocoon either hanging by silk from a senescing leaf or simply lying on the soil, but without any continued association with the host. These findings illustrate the potential for seasonal environmental cues to simultaneously mediate diapause induction, cocoon polymorphism, and alternate forms of host behaviour modification in a hymenopterous parasitoid., Shu Ping Luo ... [et al.]., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
668. Seasonal occurrence and biological parameters of the common green lacewing predators of the common pistachio psylla, Agonoscena pistaciae (Hemiptera: Psylloidea)
- Creator:
- Fatemeh, Kazemi and Mehrnejad, Mohammad Reza
- Type:
- article, články, model:article, and TEXT
- Subject:
- Zoologie, entomologie, Chrysopidae, lacewings, Chrysoperla lucasina, Psylloidea, Agonoscena pistaciae, pistachio psylla, population density, weeds, intrinsic rate of increase, theoretical threshold, food consumption, biological control, 2, and 59
- Language:
- English
- Description:
- Species in the carnea complex of the common green lacewing are predators of the common pistachio psylla, Agonoscena pistaciae in both cultivated pistachio plantations and on wild pistachio plants in Iran. The seasonal occurrence of common green lacewings was monitored in pistachio orchards from 2007 to 2008. In addition, the effect of different temperature regimes on preimaginal development, survival and prey consumption of the predatory lacewing Chrysoperla lucasina fed on A. pistaciae nymphs were studied under controlled conditions. The adults of common green lacewings first appeared on pistachio trees in mid April and were most abundant in early July, decreased in abundance in summer and increased again in October. The relative density of common green lacewings was higher in pistachio orchards where the ground was covered with herbaceous weeds than in those without weeds. In the laboratory females of C. lucasina laid an average of 1085 eggs over 60 days at 22.5°C. The maximum prey consumption occurred at 35°C when the larvae consumed 1812 fourth instar psyllid nymphs during their larval period. The intrinsic rate of natural increase (rm) was 0.11. The total development (egg-adult) required 385 degree-days above the theoretical lower developmental threshold of 9.6°C. and Fatemeh KAZEMI, Mohammad Reza MEHRNEJAD.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
669. Seasonal occurrence and microhabitat specificity of Paradiplozoon ichthyoxanthon Avenant-Oldewage in Avenant-Oldewage et al., 2014 (Monogenea: Diplozoidae) infecting Labeobarbus aeneus (Burchell) (Teleostei: Cyprinidae) from the Vaal Dam, South Africa: water quality and host size as determining factors?
- Creator:
- Gilbert, Beric M and Avenant-Oldewage, Annemariè
- Format:
- print, počítač, and online zdroj
- Type:
- model:article and TEXT
- Subject:
- ekologie, epidemiologie, ecology, epidemiology, Afrika jižní, Africa, Southern, ectoparasite, seasonality, smallmouth yellowfish, gill arch, 2, and 59
- Language:
- English
- Description:
- This is the first study detailing the microhabitat specificity of the monogenean parasite, Paradiplozoon ichthyoxanthon Avenant-Oldewage in Avenant-Oldewage et al., 2014. Samples of the monogenean were collected from the gills of the smallmouth yellowfish Labeobarbus aeneus (Burchell) from the Vaal Dam, South Africa, over four seasons with the use of gill nets. Host condition factor fluctuated between the different seasons, with the highest values recorded in summer. Adults and diporpas of P. ichthyoxanthon were found in all four seasons. Adult parasites predominantly infect the first gill arch, whereas diporpas were found on the second and fourth arches. In utero eggs were also found throughout the sampling seasons and their number negatively correlated with the condition factor of the host. The occurrence of adults and diporpas of P. ichthyoxanthon correlated with the size of the host but not the condition factor. Water quality of the study site also had little correlational relationship with the occurrence of the parasites and fluctuations were related to season. The main factor that may drive the microhabitat specificity of P. ichthyoxanthon is the flow of water over the surfaces of the gills and chances of the parasites becoming dislodged. Size of the attachment organs has also been shown to play a role in this specificity, because smaller attachment structures favour stronger holdfast to areas where flow might be stronger compared to larger attachment structures., Beric M. Gilbert, Annemariè Avenant-Oldewage., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
670. Seasonal polyphenism in body size and juvenile development of the swallowtail butterfly Papilio xuthus (Lepidoptera: Papilionidae)
- Creator:
- Komata, Shinya and Sota, Teiji
- Format:
- print, počítač, and online zdroj
- Type:
- article, články, journal articles, model:article, and TEXT
- Subject:
- Zoologie, motýli, otakárkovití, butterflies, Papilionidae, Papilio xuthus, seasonal polyphenism, body size variation, adaptive growth decision, protandry, temperature-size rule, time constraint, 2, and 59
- Language:
- English
- Description:
- Seasonal polyphenism in adults may be a season-specific adaptation of the adult stage and/or a by-product of adaptive plasticity of the juvenile stages. The swallowtail butterfly Papilio xuthus L. exhibits seasonal polyphenism controlled by photoperiod. Adults emerging in spring from pupae that spend winter in diapause have smaller bodies than adults emerging in summer from pupae that do not undergo diapause. Pupal diapause is induced by short-day conditions typical of autumn. To explore the interactive effects of temperature and developmental pathways on the variation in adult body size in P. xuthus, we reared larvae at two temperatures (20°C, 25°C) under two photoperiods (12L : 12D and 16L : 8D). Pupal weight and adult forewing length were greater in the generation that did not undergo diapause and were greater at 25°C than at 20°C. Thus, body size differences were greatest between the individuals that were reared at the longer day length and higher temperature and did not undergo diapause and those that were reared at the shorter day length and lower temperature and did undergo diapause. Unlike in other Lepidoptera, larvae of individuals that undergo diapause had shorter developmental times and higher growth rates than those that did not undergo diapause. This developmental plasticity may enable this butterfly to cope with the unpredictable length of the growing season prior to the onset of winter. Our results indicate that there are unexplored variations in the life history strategy of multivoltine Lepidoptera., Shinya Komata, Teiji Sota., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public