Ecological specialization and niche overlap of subterranean rodents inferred from DNA metabarcoding diet analysis

Knowledge of how animal species use food resources available in the environment can increase our understanding of many ecological processes. However, obtaining this information using traditional methods is difficult for species feeding on a large variety of food items in highly diverse environments. We amplified the DNA of plants for 306 scat and 40 soil samples, and applied an environmental DNA metabarcoding approach to investigate food preferences, degree of diet specialization and diet overlap of seven herbivore rodent species of the genus Ctenomys distributed in southern and midwestern Brazil. The metabarcoding approach revealed that these species consume more than 60% of the plant families recovered in soil samples, indicating generalist feeding habits of ctenomyids. The family Poaceae was the most common food resource retrieved in scats of all species as well in soil samples. Niche overlap analysis indicated high overlap in the plant families and molecular operational taxonomic units consumed, mainly among the southern species. Interspecific differences in diet composition were influenced, among other factors, by the availability of resources in the environment. In addition, our results provide support for the hypothesis that the allopatric distributions of ctenomyids allow them to exploit the same range of resources when available, possibly because of the absence of interspecific competition.     

Purification of rabies virus glycoprotein produced in Drosophila melanogaster S2 cells: An efficient immunoaffinity method

Most rabies vaccines are based on inactivated virus, which production process demands a high level of biosafety structures. In the past decades, recombinant rabies virus glycoprotein (RVGP) produced in several expression systems has been extensively studied to be used as an alternative vaccine. The immunogenic characteristics of this protein depend on its correct conformation, which is present only after the correct post-translational modifications, typically performed by animal cells. The main challenge of using this protein as a vaccine candidate is to keep its trimeric conformation after the purification process. We describe here a new immunoaffinity chromatography method using a monoclonal antibody for RVGP Site II for purification of recombinant rabies virus glycoprotein expressed on the membrane of Drosophila melanogaster S2 cells. RVGP recovery achieved at least 93%, and characterization analysis showed that the main antigenic proprieties were preserved after purification.     

Lethal and sublethal effects of insecticides on the survival and reproduction of Brevipalpus yothersi (Acari: Tenuipalpidae)

The overuse of insecticides to control vector insects such as Diaphorina citri Kuwayama in citrus groves has altered the population dynamics of pest mites. Among phytophagous mites, population outbreaks of citrus leprosis mite, Brevipalpus yothersi Baker, have been increasingly intense and frequent in Brazilian citrus groves. Despite the great importance of the B. yothersi mite for citrus production, the lethal and sublethal effects of insecticides on this mite have not yet been studied. Therefore, in this study, the effects of insecticides commonly used for D. citri control on B. yothersi mortality, reproduction, and instantaneous growth rate were assessed. For this, two experiments were carried out, one under controlled conditions and another in a greenhouse. The insecticides tested were beta-cyfluthrin, bifenthrin, buprofezin, chlorpyrifos, dimethoate, pyriproxyfen, and thiamethoxam at 0 (control), 0.0625, 0.125, 0.25, 0.5, 1, and twofold the recommended insecticide concentration for D. citri control. The pyriproxyfen insecticide provided high mortality of B. yothersi even at low concentrations. Furthermore, this insecticide negatively interfered with the reproduction of this mite. Beta-cyfluthrin, bifenthrin, buprofezin, chlorpyrifos, dimethoate, and thiamethoxam, in the tested concentrations, showed low impact on citrus leprosis mite. Regarding the reproduction of the mite, no significant increase in fecundity was observed on B. yothersi females exposed to insecticide residues, regardless of the concentration tested. Therefore, the application of these insecticides in the management of pest insects is unlikely to promote an increase in the citrus leprosis mite population.

     

Performance of Sclerodermus brevicornis,a parasitoid of invasive longhorn beetles,when reared on rice moth larvae

Biological control efficiency can be improved by developing effective mass‐rearing systems to produce large numbers of high‐quality parasitoids. This study explored an alternative host for rearing Sclerodermus brevicornis (Kieffer) (Hymenoptera: Bethylidae), a potential biocontrol agent for the suppression of exotic and invasive wood‐boring longhorn beetle (Coleoptera: Cerambycidae) populations in the European agroforestry ecosystems. We tested larvae of the rice moth, Corcyra cephalonica Stainton (Lepidoptera: Pyralidae), as host for the parasitoid. We quantified the probability and timing of host attack and parasitism as well as reproductive success, offspring production, and the characteristics of adult offspring. As S. brevicornis is a quasi‐social species (multiple females, communally produced offspring broods), we also explored the effects of varying the number of females to which individual hosts were presented, with the aim of determining the optimal female‐to‐host ratio. As time to host attack can be a limiting factor in S. brevicornis rearing protocols, we tested the use of adult females of another bethylid species, Goniozus legneri Gordh, to paralyse C. cephalonica larvae prior to presentation. We identified the conditions within our experiment that maximized offspring production per host and offspring production per adult female parasitoid. We found that C. cephalonica is suitable as a factitious host and, as it is considerably more straightforward for laboratory rearing than cerambycid species, it is a good candidate for adoption by future S. brevicornis mass‐rearing and release programmes.     

Fishers’ ecological knowledge on the reproduction of fish and shrimp in a subtropical coastal ecosystem

Hydrobiologia - Fishers’ ecological knowledge (FEK) has contributed to a better understanding about the reproduction of fishery resources, especially where biological data are scarce or...     

A safe haven for potential reproductive aggregations of the critically endangered Brazilian guitarfish (Pseudobatos horkelii)

Brazilian endemic batoid elasmobranch populations have declined dramatically in the past 40 years due to anthropic activities (e.g., overfishing). The Brazilian guitarfish, Pseudobatos horkelii, included in the IUCN red list of endangered species [Critically Endangered (CR)], has been captured as by-catch by trawling fishing boats to the edge of extinction. Despite governmental conservation initiatives, the species is still caught and commercialized along the Brazilian coast. In this study, the authors report three rare aggregation events for the Brazilian coast of P. horkelii, inside the only nearshore no-entry Brazilian marine protected area. Strategies for its protection are also discussed.     

Body movements during the off-ice execution of back spins in figure skating

Using an optoelectronic motion capture system, we quantitatively assessed the arrangement of body segments and the displacement of the horizontal projection of the center of mass (CM) in seven skaters performing off-ice back spins on a rotating device (spinner). The position of the CM at the beginning of the spins was not a determining factor, but its rapid stabilization towards the center of the spinner, together with the achievement of a stable arrangement of trunk and limbs, was crucial to get the dynamic equilibrium, necessary for a lasting performance. At full spinning, however, there was an indicative variety of individual body postures. A final deceleration, associable with the loss of body equilibrium, was detected in the last spin of most of skaters.In conclusion, the current investigation demonstrated that the off-ice execution of back spin, a critical movement of ice skating, can be measured in laboratory, thus providing quantitative information to both the skaters and the coaches. The analysis is not invasive, and it may be proposed also for longitudinal evaluations of skating and postural training.     

Correlation between macrophyte vegetation and some water properties in the irrigation system of the Lower river Po Plane

Abstract

The distribution of macrophytic plant communities, defined by phytosociological numerical methods, in the irrigation system of the Lower river Po Plane was correlated with water characteristich. Water samples were collected periodically within phytocoena well-characterized from the phytosociological viewpoint. Nymphaeid-dominated communities (all. Nymphaeion) usually occur in deeper waters than elodeid- myriophyllid-, and ceratophyllid-dominated vegetation types (all. Potamogetonion). Hydrochemically, all of the studied waterbodies can be classified as rich in electrolytes and in bicarbonates. The distribution of phytocoena reflects a gradient in nutrient content: the Nymphoidetum peltatae characterizes waters moderately rich; the Myriophyllum spicatum community and the Trapetum natantis fairly rich; the Potamogetonetum pectinati and the Ceratophyllum demersum community very rich in nutrients.