Association Between Early-Stage Juveniles of Sailfin Catfish (Pterygoplichthys, Loricariidae) and Floating Hydrophytes: Behaviour Supports Species Dispersal?

The vertical distribution of early-stage juvenile sailfin catfish (Pterygoplichthys, Loricariidae), an invasive species, were investigated in littoral habitats and the center of channel with floating hydrophytes from the Red River system in Vietnam. Sailfin catfish were sampled from the upper water column with associated floating hydrophytes of the invasive water hyacinth (Eichhornia crassipes) and native water spinach (Ipomoea aquatic) and the bottom using hand nets (2-mm mesh sizes). Significantly higher numbers of early-stage juveniles were associated with floating hydrophytes compared to bottom sampling. The association between early stages of sailfin catfishes and floating hydrophytes, especially the free-floating invasive water hyacinth, supports the potential mechanism in the dispersal of an invasive fish.

Just metamorphosed amphibians: imagos or metamorphs?

The term metamorph for just metamorphosed amphibians appeared surreptitiously in the batrachological literature. It is shown here that this term is linguistically unjustified and conceptually confusing, as it has never been associated with a clear, formal definition stating in particular when does this developmental stage start and end. The use of the term imago for an individual resulting from the last metamorphosis following a larval stage, which exists for insects since 1767 and for amphibians since 1808, is much preferable. For amphibians, the formal definition of this term was given in 1978 as an animal having completed its metamorphosis, before having substantially grown and until the first major ecological event in its life cycle (such as migration, hibernation or aestivation). In amphibians, this stage is followed by a stage juvenile and a stage subadult until the stage adult is reached, which is defined by sexual maturity and ability to reproduce. Given the diversity of developmental modes in the animal kingdom, it would be vain to try to homogenise the terminology of all detailed developmental stages across all groups. However, the possibility to homogenise the use of the term imago throughout zoology for specimens resulting from the ‘last metamorphosis’ (i.e., drastic change not only of form but also in some anatomical structures), whether followed by growth and minor transformations or not, and whether associated with sexual maturity or not, would certainly be worth considering. This would allow to have a few general descriptive terms to designate the main similar, but not homologous, ‘landmarks’ observed in the development of many animals (egg, larva, imago and adult), just like we have a general term (metamorphosis) for ‘similar’ phenomena which are not homologous. This would not prevent specialists of the various zoological groups to have specific terms for more precisely defined ‘stages’ which are proper to these groups.

Issi saaneq gen. et sp. nov.—A New Sauropodomorph Dinosaur from the Late Triassic (Norian) of Jameson Land, Central East Greenland

The Late Triassic (Norian) outcrops of the Malmros Klint Formation, Jameson Land (Greenland) have yielded numerous specimens of non-sauropod sauropodomorphs. Relevant fossils were briefly reported in 1994 and were assigned to Plateosaurus trossingensis. However, continuous new findings of early non-sauropod sauropodomorphs around the globe facilitate comparisons and allow us to now revise this material. Here, the non-sauropod sauropodomorph Issi saaneq gen. et sp. nov. is described based on two almost complete and articulated skulls. The two skulls represent a middle-stage juvenile and a late-stage juvenile or subadult. Issi saaneq differs from all other sauropodomorphs by several unique traits: (1) a small foramen at the medial surface of the premaxilla; (2) an anteroposteriorly elongated dorsoposterior process of the squamosal; (3) a relatively high quadrate relative to rostrum height; (4) a well-developed posterodorsal process of the articular. These features cannot be explained by taphonomy, ontogeny, or intraspecific variation. Issi saaneq shows affinities to Brazilian plateosaurids and the European Plateosaurus, being recovered as the sister clade of the latter in our phylogenetic analysis. It is the northernmost record of a Late Triassic sauropodomorph, and a new dinosaur species erected for Greenland. Issi saaneq broadens our knowledge about the evolution of plateosaurid sauropodomorphs.

Can vermicompost and biochar control Meloidogyne javanica on eggplant?

Summary The root-knot nematode, Meloidogyne javanica, is the most damaging species of plant-parasitic nematodes in eggplant cultivation in Iran. We studied the effect of pistachio and date palm biochars, vermicompost and a mixture of each of these biochars with vermicompost on M. javanica. To investigate the effect of these organic materials on survival, hatching and attraction of the second-stage juvenile (J2) towards the root, bioassays were performed in the laboratory using extracts of organic material. Vermicompost extract increased J2 mortality and decreased hatching and the number of J2 attracted to the eggplant roots. However, either type of biochar alone or mixed with vermicompost did not cause J2 mortality, nor did they inhibit hatching and attraction of J2 towards the root. To determine the effect of organic matter on J2 invasion and reproduction, pot experiments were performed in a completely randomised design with four replications in the glasshouse. Vermicompost reduced the number of J2 that penetrated the roots, number of egg masses and the final population of M. javanica eggs and J2. The suppressing effect of vermicompost might be attributed to the release of toxic compounds such as ammonium and improved soil nutrient and plant growth, leading to plants more tolerant to nematode damage. Pistachio and date biochars alone or combined with vermicompost had no adverse effect on the nematode reproduction compared to non-treated soil. Both types of biochar reduced the suppressing effect of vermicompost, most probably due to the absorbance of suppressive compounds in vermicompost by the high surface area of the biochar.

Sensitive, Accurate and Rapid Detection of the Northern Root-Knot Nematode, Meloidogyne hapla, Using Recombinase Polymerase Amplification Assays

Rapid and reliable diagnostics of root-knot nematodes are critical for selections of effective control against these agricultural pests. In this study, recombinase polymerase amplification (RPA) assays were developed targeting the IGS rRNA gene of the northern root-knot nematode, Meloidogyne hapla. The RPA assays using TwistAmp® Basic, TwistAmp® exo and TwistAmp® nfo kits (TwistDx, Cambridge, UK) allowed for the detection of M. hapla from crude extracts of females, eggs and juveniles without a DNA extraction step. The results of the RPA assays using real-time fluorescence detection (real-time RPA) in series of crude nematode extracts showed reliable detection after 13 min with a sensitivity of 1/100 of a second-stage juvenile and up to 1/1000 of a female in reaction tubes. The results of the RPA assays using lateral flow dipsticks (LF-RPA) showed reliable detection within 30 min with a sensitivity of 1/10 of a second-stage juvenile and 1/1000 of a female in reaction tubes. The RPA assay developed here is a successful tool for quick, accurate and sensitive diagnostics of M. hapla. The application of the LF-RPA assay has great potential for diagnosing infestation of this species in the lab, field or in areas with a minimal laboratory infrastructure.

Root-knot nematode (Meloidogyne incognita) and its management: a review

Root-knot nematode (RKN) Meloidogyne incognita stands out among the most harmful polyphagous endoparasite causing serious harm to plants, and distributed all over the globe. RKN causes reduced growth, quality and yield along with reduced resistance of the host against biotic and abiotic stresses. Infective second stage juvenile enters host roots with the help of the stylet and becomes sedentary getting into the vascular cylinder. Dramatic changes occur in host cells, making a specialized feeding site, induced by the secretion of effector protein by RKN. M. incognita can be controlled by nematicides, biocontrol agents, botanicals essential oils and growing resistant cultivars. Nematicides are no longer allowed to use in many parts of the world because of environmental hazards and toxicity to humans and other organisms. Researchers are concentrating on searching suitable alternatives to nematicides for effective management of M. incognita. This review mainly tries to explain the biology of M. incognita and different management options recommended in recent years. However, an effective and economical management of M. incognita remains an immense challenge.

Medium-term outcomes of total hip arthroplasty in juvenile patients

Background Juvenile hip osteoarthritis is often the end result of congenital conditions or acquired hip ailments occurred during the paediatric age. This study evaluated the middle term results of total hip arthroplasty for end-stage juvenile hip osteoarthritis. Materials and methods This is a retrospective analysis of prospectively collected data on a cohort of 10 consecutive patients (12 hips), aged between 14 and 20 at operation, who underwent cementless total hip arthroplasty for end-stage juvenile secondary hip osteoarthritis in two orthopaedic tertiary referral centres between 2009 and 2018. Results Juvenile hip osteoarthritis occurred as a consequence of developmental dysplasia of the hip, Legg-Calvé-Perthes disease, femoral head necrosis or slipped capital femoral epiphysis. All patients showed a significant improvement in Harris Hip Score (p < 0.01) at 3.3 years average follow-up (range 0.7–10.1 years). Conclusion The management of juvenile hip osteoarthritis following developmental dysplasia of the hip, Legg-Calvé-Perthes disease, femoral head necrosis or slipped capital femoral epiphysis is still challenging. Careful preoperative planning is essential to achieve good outcomes and improve the Harris Hip Score in these young patients. Total hip arthroplasty is a suitable option for end-stage secondary juvenile hip osteoarthritis, when proximal femoral osteotomies and conservative treatments fail to improve patients’ symptoms and quality of life. Level of evidence IV

The Screening of Resistance against Meloidogyne graminicola in Oats

Including pest resistance elements against the major local concern is naturally important in the breeding process. Oat (Avena sativa L.) has been recently reintroduced into Taiwan as a winter alternative forage crop, and its agronomic performance has been evaluated at different locations in the country. This study examined the resistance to root-knot nematode, Meloidogyne graminicola, in four oat (Avena sativa L.) breeding lines of mass planting potential for winter in Taiwan. The host attraction level to the nematode, and the penetration and reproduction ability of nematode towards host roots were evaluated by chemotaxis assay, root staining assay, root galling, and nematode extraction. Based on the gall index (GI) and multiplication factor (R), the resistance of each oat line was evaluated. At 24 h postinoculation, second-stage juvenile (J2) nematodes appeared most attracted by oat breeding lines UFRGS136104-3 and UFRGS136119-2. The number of J2s successfully penetrated into the two breeding lines were also high. However, at 40 days postinoculation, observation of the oats in the newly developed culture bag nematode-inoculation system revealed that the amount of root galls and 2nd generation nematodes were significantly higher in line LA08085BS-T2 than in other lines. In sum, oat breeding line UFRGS136104-3 was highly resistant to M. graminicola by inhibiting the gall formation and nematode reproduction, while UFRGS136106-3 and UFRGS136119-2 showed relatively weak resistance and oat line LA08085BS-T2 would be a moderately susceptible host to M. graminicola, with high numbers of root gall formation. The outcome of this study provides ground information for nematode-resistant oat cultivar breeding.