In Vitro Parasitism of Rotylenchus robustus by Isolates of Hirsutella rhossiliensis

We tested the hypothesis that isolates of Hirsutella rhossiliensis from host nematodes in the family Hoplolaimidae (Rotylenchus robustus and Hoplolaimus galeatus) would be more virulent to R. robustus than would isolates from host nematodes not in the Hoplolaimidae (Heterodera schachtii and Criconemella xenoplax). Nematodes were touched to 10-20 spores of different isolates and incubated at 20 C in 4.5 mM KC1; the percentage of nematodes colonized (filled with hyphae) was determined after 2, 5, 10, 20, and 30 days. The hypothesis was rejected because isolates from H. schachtii and C. xenoplax were equivalent or better at parasitizing R. robustus than were isolates from R. robustus and H. galeatus. In addition, the R. robustus and H. galeatus isolates were as pathogenic to C. curvata as they were to R. robustus, but produced fewer spores per colonized nematode (H. schachtii) than did the other isolates.     

Genetic evidence for a complex of species within Rugopharynx australis (Mönnig, 1926) (Nematoda: Stronglyloidea) from macropodid marsupials

An electrophoretic analysis using 17 enzyme loci was carried out on specimens of the gastric nematode of macropodid marsupials, Rugopharynx australis (Mönnig, 1926), collected from Macropus eugenii (Desmarest), M. fuliginosus (Desmarest), M. giganteus Shaw, M. robustus Gould, M. rufogriseus (Desmarest), M. rufus (Desmarest), Thylogale billardierii (Desmarest) and Wallabia bicolor (Desmarest) from south-eastern Australia. The extent of fixed genetic differences between nematodes from different host species ranged from 0–53%. The two distinct morphological forms of the parasite found in M. rufogriseus differed at 50% of loci. Specimens present in M. fuliginosus and M. giganteus were indistinguishable genetically, as were nematodes from M. rufus and M. robustus. Of the two morphologically distinct congeners included in the analysis as controls, Rugopharynx epsilon (Johnston & Mawson, 1939) was genetically distinct (46–69% fixed genetic differences) from all specimens of the R. australis complex while R. rufogrisea Magzoub, 1964 was closely related to one of the two species occuring in M. rufogriseus. It was concluded that R. australis is a species complex, with a genetically distinct species present in M. eugenii, M. fuliginosus/M. giganteus, M. robustus/M. rufus, W. bicolor and T. billardierii, and two species in M. rufogriseus.     

Plant parasitic nematodes associated with the roots of wind toppled trees at the Royal Botanic Gardens, Kew

Root and soil samples from 21 trees blown down in Kew Gardens during the gales of October 1987 yielded 29 species of plant parasitic nematodes. Pratylenchus crenatus, P. thornei and P. penetrans were the only endoparasitic nematodes found. The common occurrence of P. crenatus and the root ectoparasitic nematodes, such as Merlinius microdorus, Paratrichodorus pachydermus and Rotylenchus robustus reflected the predominantly sandy nature of most of the soil samples. Species rarely recorded in Britain included Hemicriconemoides pseudobrachyurum, Paralongidorus maximus and Xiphinema pseudocoxi, all of which may be introductions.     

Distribution of trichodorid nematodes in Great Britain

This survey describes the distribution of trichodorid nematodes in Great Britain. Twelve species were recorded, including the newly described species Trichodorus hooperi Loof, 1973 and the first British record of T. sparsus Szczygiel, 1968. In the survey 3614 samples and records were analysed using the Statistical Package for Social Sciences computer programme. Seven hundred and ninety-two positive sites, containing 971 trichodorid populations, were located. Outline maps show the geographical distribution of each species. T. primitivus de Man, 1880 was the most commonly found species and had a cosmopolitan distribution. Paratrichodorus pachy-dermus Seinhorst, 1954 was the next most prevalent and occurred mostly in eastern England and Scotland. Populations of the other ten species were more restricted in both number and distribution. The distribution of trichodorid spp. with respect to altitude, soil type, pH and primary vegetation was tested using chi-squared contingency tests. A significant relationship between nematodes and environmental factors was found in all cases examined. However, interactions were found between several environmental factors and further tests were applied to study the independence of the species distributions with respect to these interactions.     

Effect of selective planktivory by fry of Rhamdia sapo (Pimelodidae: Pisces) on zooplankton community structure

SUMMARY.

• 1 The direct and indirect effects of predation by larval fish (Rhamdia sapo) on zooplankton in rearing tanks are analysed. Rhamdia sapo larvae showed an unusual species-selectivity for Acanthocyclops robustus, the main invertebrate predator present.
• 2 Acanthocyclops robustus populations were markedly reduced, presumably as a direct consequence of species-selective removal. Other zooplanktonic prey were not significantly affected by R. sapo predation.
• 3 Rotifers increased in tanks with fish, but this was not related to herbivorous crustacean variables (biomass, mean weight, abundance and species composition). On the contrary, rotifer biomass was negatively correlated with some A. robustus variables (biomass and mean weight of adults + copepodites and nauplii biomass). Thus, the rotifer increase appears to be an indirect effect of predation on A. robustus by R. sapo larvae.

     

Rhizoctonia spp. Associated with Container-Grown Ericaceous Plants in Scotland

Fungi with Rhizoctonia-like mycelia were isolated from the foliage, stem-base and roots of ericaceous plants collected from nurseries in Scotland. Isolated fungi were identified as either binucleate Rhizoctonia spp. or Rhizoctonia solani on the basis of hyphal characteristics and nuclear number. The optimum temperature range for growth of binucleate Rhizoctonia spp. and R. solani was 20 and 25 C, resepctively. All isolates tested for pathogenicity caused foliar browning, and webs of mycelial growth were observed on dead and dying foliage. Binucleate Rhizoctonia spp. and R. solani are recorded for the first time on container-grown ericaceous plants in Scotland.     

Nematodes associated with forest and woodland trees in Scotland

A survey of the nematode genera associated with trees in Scotland showed that Tylenchus sensu lato, Aphelenchoides, Tylencholaimus, Trichodorus, Helicotylenchus, Rotylenchus, Criconemoides s.l., Hemicriconemoides, Tylencho-rhynchus, Pratylenchus and Paratylenchus s.l. were commonly found in soil samples collected from around the roots of coniferous and deciduous trees. Only Criconemoides s.l. appeared to have a significant preference for deciduous woods. The presence of undergrowth in woods and forests was associated with significantly greater numbers of plant-parasitic nematodes. Measurements of abiotic factors indicated that, in mineral soils, pH affected the incidence of most genera, but soil type, moisture content and altitude had little effect.     

Use of a nematode, Heterorhabditis heliothidis, to control black vine weevil, Otiorhynchus sulcatus, in potted plants

Application of aqueous suspensions of infective juvenile Heterorhabditis heliothidis, isolate T327, to the soil resulted in up to 100% parasitisation of larvae of the black vine weevil, Otiorhynchus sulcatus, in potted yew, raspberries and grapes in nurseries, and over 87% parasitisation on potted cyclamens and strawberries. Pupae and newly emerged adults on grapevines were also parasitised. Another isolate, T310, produced 92.5 to 98.5% parasitism of O. sulcatus larvae on potted cyclamens in glasshouse, but was less effective on strawberries. Neoaplectana bibionis was found to be less effective than H. heliothidis T327 strain. The use of these nematodes provides an economical and effective method for controlling O. sulcatus on potted plants in glasshouses and nurseries.     

Soil-borne viruses occurring in nursery soils and infecting some ornamental species of Rosaceae

Soil from twelve of twenty-six sites on ten nurseries growing ornamental trees and shrubs contained viruliferous nematodes, transmitting arabis mosaic virus (AMV) at eight sites, tomato black ring virus at three and tobacco rattle virus at one site. Tobacco necrosis virus was detected at two sites. Xiphinema spp. were found at nine sites, Longidorus spp. at sixteen and Trichodorus spp. at thirteen sites. Thirty-one ornamental species of Rosaceae were tested for virus infections and AMV was found in Spiraea bumalda, Spiraea japonica alba and Kerria japonica.     

The role of weed hosts and the distribution and activity of vector nematodes in the ecology of tobacco rattle virus

At a site in eastern Scotland, nine common species of arable weeds were infected with tobacco rattle virus (TRV), and some of these, notably Viola arvensis and Stellaria media, comprised an overwintering reservoir of the virus. TRV was seed-borne both in naturally and in experimentally infected V. arvensis (2–10%), and occasionally in other weed species. In the glasshouse at 20 ^oC a naturally infective population of vector nematodes (Tricho-dorus spp.) kept in soil free of plants retained its infectivity for 20 wk, although few Trichodorus survived for this period. In the field, the incidence of TRV infection in potato (spraing disease) in plots kept free of weeds for 1–5 years was 3–4 times that in weed-infested plots but Trichodorus numbers did not differ appreciably between the two treatments. Presumably the virus is retained for long periods in its vectors and these feed on potato more frequently when other hosts are not available. Weeds are probably important in the long term as hosts of both TRV and its vectors, but in the short term weed control seems unlikely to prevent potato spraing because of the long persistence of TRV in vector populations. In the field, Trichodorus accumulated near the interface between topsoil and subsoil, and the incidence of spraing was greatest where the topsoil was shallowest. When cucumber seedlings were exposed to virus-carrying Trichodorus, TRV reached a greater concentration in roots at 20 ^oC than at 24 ^oC, and the virus was not detected in roots at 29 ^oC. In a sandy soil, TRV was transmitted only when the water content exceeded 15%, and at least 30 % water was needed for maximum transmission. Annual records of rainfall and spraing disease suggest that spraing is most prevalent when the summer is wettest. TRV is not confined to cultivated land. Stabilized sand dunes supporting a pure stand of Ammophila armaria were colonized by Trichodorus pachyder-mus, but TRV was detected only where the plant community had enlarged to include V. arvensis and other dicotyledons. In such situations, TRV may be introduced in the seed of V. arvensis, and the movement of soil by wind probably contributes to the dispersal of Trichodorus.     

Morphological development of the structures related to annualism in the ovarian follicle of the killifish Millerichthys robustus (Costa,1995) (Teleostei: Cyprinodontiformes)

Ovaries of five females of the annual fish teleost species Millerichthys robustus were processed, and the development of the cortical alveoli, zona pellucida and secondary envelope during oogenesis were described. We also documented the origin of the cortical alveoli in time and space similar to the Balbiani body; the synthesis of three generations of cortical alveoli and an active zona pellucida prior to vitellogenesis, which is implicated in the entry of oils to the interior of the oocyte. We found that in this species, the diameter of the alveoli is greater than in the other teleost fish species reported in the literature, except for Fundulus heteroclitus, in which the diameter is similar. The thickness of the zona pellucida recorded in M. robustus is the greatest reported to date. Likewise, two periods of secondary envelope deposition were documented: filaments during pre‐vitellogenesis and, subsequently, trapeze‐shaped projections during the maturation of the oocytes. We report about development of structures that are considered key for the survival of embryos in annual fish during the long periods of diapause in their extreme habitats. The development of peripheral structures described here probably reflects the changes in the physiology of the oocytes in M. robustus. J. Morphol. 277:1219–1230, 2016. © 2016 Wiley Periodicals, Inc.     

Effect of temperature on growth and nitrogen mineralization of fungi and fungal-feeding nematodes

Dish and column microcosms containing alfalfa-sand medium were established to determine effect of temperature on growth and N mineralization ability of two fungi (Rhizoctonia solaniand Botrytis cinerea) and two nematodes (Aphelenchus avenaeand Aphelenchoides composticola). The microcosms were incubated at 15, 20, 25 and 29 °C for 21 days. In the dish microcosms, hyphal growth rates of both fungal species increased with temperature in the range of 15–25 °C. Above that temperature range, the growth rate of R. solani remained almost constant while that of B. cinereadecrease considerably. The population growth rate of A. avenae increased with temperature between 15 and 29 °C on colonies of R. solani and B. cinerea in dish microcosms. The growth rate of A. composticola also increased in the range of 15–25 °C but decreased greatly beyond that temperature range independent of the fungal species as food source. Inorganic N (NH₄ ⁺ + NO₃ ^–) was collected from each column microcosm by leaching every 3 days. In the columns containing R. solani, there was a significant effect of temperature on the amount of N detected in the fungus+A avenaeor A. composticolabut not in the fungus alone columns. The total amount of N was greatest at 29 °C for A. avenaeand at 20 °C for A. composticola columns, concurrent with the population growth rates of the nematodes. In the columns containing B. cinerea, the effect of temperature on the amount of inorganic N was not significant in either the fungus alone or fungus+nematode columns, although the population growth rates of the both nematode species were highest at 20 °C. For B. cinerea, the N amount across temperatures was the same or larger for the fungus alone as for the fungus+nematode columns. In general, the contribution of fungal-feeding nematodes to N mineralization was small in any combinations of fungus and nematode species at any temperature. Similarity in C/N ratio of the fungal and nematode biomass, organic substrate C/N ratios too low for measurable increase in net mineralization by the nematodes and small reproduction of the nematodes in the column microcosms were probable contributory factors.     

Prolonged diapause and seed predation by the acorn weevil,Curculio robustus,in relation to masting of the deciduous oak Quercus acutissima

Many researchers have studied the relationship between masting by trees and seed predation by insects. Most of these studies have been plant centered, with little focus on the insect perspective. To estimate the effect of mast seeding on insect seed predators, the life‐history traits of these insects must also be considered because some seed insects can survive lean years by prolonged diapause. In this study, I examined larval infestation of acorns and life‐history traits of the acorn weevil, Curculio robustus (Roelofs) (Coleoptera: Curculionidae), in relation to acorn production of the deciduous oak Quercus acutissima Carruthers (Fagaceae) in a coppice stand in central Japan in 2004–2009. Curculio robustus females oviposit into Q. acutissima acorns, inside which the larvae develop. Mature larvae leave acorns and burrow into the soil, where they overwinter. Although germination did occur in acorns infested by weevil larvae, the percentage of germination was lower in acorns damaged by many larvae. Acorn production in Q. acutissima varied considerably among years. Both the number of C. robustus larvae infesting acorns and the percentage of acorns infested were affected by the amount of acorns produced by Q. acutissima, and two successive lean years appeared to have a considerable impact on C. robustus population size. Consequently, only a small fraction of the acorns produced were lost to predation in a mast year after two successive lean years. However, C. robustus could survive the two successive lean years because of prolonged larval diapause, probably leading to a marked decrease in population size. These findings suggest that masting in Q. acutissima succeeds as a predator satiation strategy in response to acorn damage by C. robustus, and that C. robustus has developed prolonged diapause as a counter‐adaptation.     

Mandibular development in Australopithecus robustus

Australopithecus robustus has a distinct mandibular anatomy, with a broad and deep corpus and a tall, relatively upright ramus. How this anatomy arose through development is unknown, as gross mandibular size and shape change have not been thoroughly examined quantitatively in this species. Herein, I investigate A. robustus mandibular growth by comparing its ontogenetic series with a sample of recent humans, examining age‐related size variation in 28 linear measurements. Resampling is used to compare the amount of proportional size change occurring between tooth eruption stages in the small and fragmentary A. robustus sample, with that of a more complete human skeletal population. Ontogenetic allometry of corpus robusticity is also assessed with least squares regression. Results show that nearly all measurements experience greater average increase in A. robustus than in humans. Most notably, A. robustus corpus breadth undergoes a spurt of growth before eruption of M₁, likely due in part to delayed resorption of the ramus root on the lateral corpus. Between the occlusion of M₁ and M₂, nearly all dimensions experience greater proportional size change in A. robustus. Nested resampling analysis affirms that this pattern of growth differences between species is biologically significant, and not a mere byproduct of the fossil sample size. Some species differences are likely a function of postcanine megadontia in A. robustus, although the causes of other differences are less clear. This study demonstrates an important role of the postnatal period for mandibular shape development in this species. Am J Phys Anthropol 154:436–446, 2014. © 2014 Wiley Periodicals, Inc.     

Coexistence of the predatory cyclopoids Acanthocyclops robustus (Sars) and Mesocyclops leuckarti (Claus) in a small eutrophic lake

The coexistence of two common species of predatory cyclopoid copepods, Acanthocyclops robustus and Mesocyclops leuckarti, in a small, eutrophic lake was studied. Both species are of similar size, inhabit the same water layers and have similar seasonal occurrence. A. robustus shows faster embryonic and postembryonic development and produces bigger clutches. Ingestion rates of A. robustus are higher than in M. leuckarti, especially with large prey types and low temperatures. Females of A. robustus are heavily preyed upon by fish. This predation pressure leads to extremely skewed sex ratios, which are unfavourable to population growth. A. robustus is therefore, on balance, favoured in productive lakes. Dominance over M. leuckarti is, however, less clear in warmer years.     

A Trichodorus (Triplonchida: Trichodoridae) Nematode from Thrips (Thysanoptera: Panchaetothripinae)

A thrips insect Caliothrips sp. (Thysanoptera: Panchaetothripinae) from persimmon fruit (Ebenaceae: Diospyros sp.) from an unknown origin, possibly Asia, was intercepted in a passenger bag in November 2012 at the Peace Arch Border Crossing from Canada to Blaine, WA, by a USDA-APHIS-PPQ port inspector. Nematodes were attached to the abdomen of the female insect and sent to us in saline. Seven nematodes (five females, two males) were measured and these and others were processed for permanent slides. An adult female and a female juvenile were prepared for PCR. Morphologically these nematodes belonged to the Trichodorus sparsus group, and the 28S rDNA D2-D3 sequence showed greatest similarity to Trichodorus paragiennensis (94%) and T. giennensis (93%), with greatest morphological similarity to the latter species. Among other morphological differences, the innermost uterus width is wider than in related species. Trichodorus spp. are normally found in soil, so this is the first population seen in the atypical habitat of an insect. Morphological and molecular characteristics of Trichodorus sp. are presented, but a putative new species name is not currently advisable because of relatively poor condition of specimens. Ecological associations are also discussed.     

Possible utilization of weeds for the management of plant parasitic nematodes infesting some vegetable crops

Leaf extracts of noxious weeds such as Solanum xanthocarpum and Argemone maxicana were used as bare-root dip treatment for the management of three important plant-parasitic nematodes, Meloidogyne incognita, Rotylenchulus reniformis and Tylenchorhynchus brassicae infesting tomato (Lycopersicon esculantum ) and chilli (Capsicum annuum) plants. Significant reduction was observed in the root-knot development caused by M. incognita, multiplication of nematode populations of R. reniformis and T. brassicae on both the test plants. Larval penetration of second stage juveniles of M. incognita was also inhibited at various concentrations of leaf extracts and dip durations. Leaf extract of S. xanthocarpum caused relatively more inhibition in root-knot development in case of root-knot nematode, nematode multiplication of reniform and stunt nematodes than that of A. maxicana. Because of dip treatment in leaf extracts of Argemone maxicana and Solanum xanthocarpum, the plants show better growth and at the same time the populations of nematodes such as M. incognita, R. reniformis and T. brassicae significantly decreased, which naturally improved plant growth. The efficacy of root-dip treatment with respect to improvement in plant weight and reduction in root-knot development and nematode populations, increased with increasing the concentration of leaf extracts and dip durations.     

A thermostable lipase produced by a newly isolated <Emphasis Type="Italic">Geotrichum</Emphasis>-like strain,R59

Growth and production of lipase by a new Geotrichum-like strain, R59, were studied. Production of extracellular lipase was substantially enhanced when the initial pH of the culture medium, types of carbon and nitrogen sources, substances probably stimulating the lipase biosynthesis, the temperature, and time of growth were optimized. Sucrose and triolein were the most effective carbon sources for lipase production. Maximum lipase activity (146 U/ml^–1) was obtained with urea as the nitrogen source. Growth at 30°C, an initial pH of 6.0 and incubation time of 48 h were found as optimum conditions for cell growth and production of lipase by Geotrichum-like strain R59. The enzyme was thermostable and exhibited very high activity after 1 h incubation at 60°C.     

A nursery Area for Sharks and Rays in Northeastern Brazil

Synopsis Elasmobranch nurseries are habitats where females give birth to their young and juveniles spend their early life history. Hypotheses concerning nurseries suggest that these provide the young a better source of food and protection against predation, however the degree of exposure to predatory risk in nursery areas vary. According to Branstetter hypothesis, slow growing species are either born at relatively large sizes or use protected nursery grounds, whereas faster growing species tend to rely more on growth rates than others factors. Primary nurseries are habitats where parturition occurs and in which the young live for a short time and secondary nurseries are habitats in which juveniles are found after leaving the primary nursery and before reaching maturity. Rhizoprionodon porosus and Carcharhinus acronotus use coastal waters off Cai?ara do Norte as both primary and secondary nurseries, while Carcharhinus limbatus makes use of the area as a seasonal primary nursery in late spring and early summer. C. falciformis apparently makes use of the end of inner continental shelf and the outer continental shelf as a primary nursery. Gymnura micrura, Rhinobatos percellens and Narcine brasiliensis makes use of coastal and turbid waters of region as both primary and secondary nurseries throughout the year, while Dasyatis guttata utilizes the area as a primary nursery. Aetobatus narinari and Rhinoptera bonasus, although caught in lesser number, appear to use the region as both primary and secondary nurseries and only primary nursery respectively. Dasyatis marianae (endemic from Northeastern Brazil) may use coastal sandbanks as a primary nursery, while Dasyatis Americana apparently exploits waters about 10 – 20 m in depth with rocky reef substrate only as secondary nursery. There was a measurable degree of temporal and spatial separation among sharks’ species, which may effectively create separate ecological niches, whereas among rays, with the exception of the stingray D. marianae, a spatial and temporal overlaps were observed. The Branstetter’s hypothesis was supported.     

Do plant parasitic nematodes have differential effects on the productivity of a fast- and a slow-growing grass species?

We have examined the interaction between plant parasitic nematodes and plant species from different stages of grassland succession. In these grasslands, fertiliser application was stopped in order to restore the former nutrient-poor ecosystems. This management resulted in a reversed succession of high- to low-productivity. Nematodes isolated from a high-productive early-successional field and a low-productive late-successional field were inoculated to sterilised soil planted with seedlings of either Lolium perenne (a fast-growing early-successional species) or Festuca rubra (a slow-growing late-successional species). The experiment was performed at low and high supply rates of nutrients. We hypothesised that at a low nutrient supply rate the growth of L. perenne will be more reduced by nematode herbivory than the growth of F. rubra. Furthermore, we hypothesised that higher numbers of plant parasitic nematodes will develop under L. perenne. We found no support for our first hypothesis, because nematodes did not affect plant growth. Our results suggest that changes in the nutrient availability rather than plant parasitic nematodes affect plant succession in impoverished grasslands. On the other hand, plant species and nutrient supply rate significantly affected the density and composition of the plant parasitic nematode community. In line with our second hypothesis, plant parasitic nematodes reproduced better on the fast-growing L. perenne than on the slow-growing F. rubra. Our results, therefore, suggest that the succession of the plant parasitic nematode community is probably more affected by changes in the plant community than the other way round.