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[en] There are serious concerns over the adverse impacts of microplastics (MPs) on living organisms. The main objective of this study was to test the effects of MPs on the total length, weight, condition factor (CF), transcriptional level of antioxidant, anti and pro-apoptotic, and neurotransmitter genes, and the histopathology of the gill, liver, brain, kidney, and intestine in the larvae of zebrafish (Danio rerio). Fish were exposed to one of three levels of pristine low-density polyethylene (LDPE) fragments (5, 50, or 500 μg/L) for 10 or 20 days. No significant changes were observed in any of the selected biomarkers across MP concentrations at days 10 or 20. The expression of casp9 (caspase 9, apoptosis-related cysteine protease), casp3a (caspase 3, apoptosis-related cysteine protease a) and cat (catalase), however, were significantly lower in the larvae sampled at day 20 than day 10. We provide evidence that virgin short-term exposure to LDPE fragments has minimal impact on biomarker responses in D. rerio larvae. - Highlights: • Zebrafish larvae were exposed to graded concentrations of LDPE for 10 or 20 days. • Changes in the gene expressions and the histopathology of organs were investigated. • None of the treatments significantly affected the biomarker responses. • The expression of cat, casp 3a, and casp 9 were lower at the day 20 than day 10. - Exposure to LDPE fragments had limited effect on biomarker responses in D. rerio larvae.
[en] Highlights: • Spz5 is a novel ligand for the Toll-1 receptor in Drosophila. • Proteolytic processing of Spz5 seems to be dispensable for Toll-1 ligand activity. • Spz5 acts as a Toll-1 ligand in larval extract. The Drosophila Toll-1 receptor is involved in embryonic development, innate immunity, and tissue homeostasis. Currently, as a ligand for the Toll-1 receptor, only Spätzle (Spz) has been identified and characterized. We previously reported that Drosophila larva-derived tissue extract contains ligand activity for the Toll-1 receptor, which differs from Spz based on the observation that larval extract prepared from spz mutants possessed full ligand activity. Here, we demonstrate that Spz5, a member of the Spz family of proteins, functions as a ligand for the Toll-1 receptor. Processing of Spz5 by Furin protease, which is known to be important for ligand activity of Spz5 to Toll-6, is not required for its function to the Toll-1 receptor. By generating a spz5 null mutant, we further showed that the Toll-1 ligand activity of larva-derived extract is mainly derived from Spz5. Finally, we found a genetic interaction between spz and spz5 in terms of developmental processes. This study identified a novel ligand for the Drosophila Toll-1 receptor, providing evidence that Toll-1 is a multi-ligand receptor, similar to the mammalian Toll-like receptor.
[en] A morphological, molecular, and behavioural characterization of Rhionaeschna galapagoensis is presented, based on a series of specimens and observations from San Cristóbal Island, Galápagos, including both adults and larvae. Several of the characters proposed earlier to distinguish between the adults of this species and its closest relative, R. elsia, are found to be variable, but the presence of a black band over the fronto–clypeal suture is confirmed as a good diagnostic character. The ultimate instar larvae of R. galapagoensis is described for the first time, and diagnosed from its closest relatives by a combination of characters, including the acute angle between the prothoracic apophyses, absence of lateral spines on abdominal segment 6, and length of cerci relative to paraprocts. Molecular analysis confirmed that R. galapagoensis and R. elsia are sister species, and showed that their genetic distance is the closest among the analyzed species, which is to be expected given the young age of the Galápagos Islands. The larvae of R. galapagoensis were very common and widespread in the mountain streams and a pond in the southwest of San Cristóbal. Swarms of tens of individuals formed at sunrise in the coastal vegetation, together with adults of Tramea cf. cophysa, feeding on small flying insects. Males showed patrolling behaviour on small sections of the streams and at a pond. Only one copulation was observed, lasting 10 minutes. Females oviposited alone on floating vegetation in running and standing waters. Our observations corroborate that R. galapagoensis and R. elsia are two parapatric species, morphologically and genetically close. In San Cristóbal, R. galapagoensis had large populations, apparently not threatened. (Author)
[en] Radio-immuno assays for ecdysteroids and juvenile hormones during the postembryonic development in Leptinotarsa decemlineata show constant presence, with high titers of ecdysteroids except during the feeding period of the 4th larval stage. The three natural juvenile hormones are present but their ratios fluctuate according to developmental phases. The JH I is the most abundant during the burrowing period (stage IV). The JH II is the predominant form at the beginning of the pupal stage. The JH III is only form in the young adults. The JH level is very low during the 4th larval instar
[fr]Les dosages radioimmunologiques des ecdysteroides et des hormones juveniles au cours du developpement post-embryonnaire de Leptinotarsa decemlineata mettent en evidence: - la presence continue et en quantite importante des ecdysteroides sauf au cours de la periode alimentaire des larves du stade IV. - les 3 JH sont presentes mais en proportions variables selon les phases du developpement. La JH I est la plus abondante pendant la periode d'enfouissement (stade IV). La JH II predomine au debut du stade nymphal. La JH III existe seule chez les jeunes imagos. Les 3 JH sont tres peu abondantes au cours du 4e stade larvaire
[en] Radiosensitivity of larvae and puape of carob moth to gamma radiation have been studied. One day old adult males were collected as last instar larvae from laboratory colony and used to study the effect of radiation female fecundity and fertility. Thirty to sixty virgin males were used per each dose, and the crosses were made by confining three mating pairs in plastic jars. There was no significant difference between the mean number of eggs per cage of three pair matings for doses of 10-25 krad, compared with the control
[en] In field O3-enrichment experiments increased herbivore densities have been reported, which could be due to negatively affected host location behavior of natural enemies. We addressed the impact of doubling background O3 on the host location of the parasitoid Cotesia plutellae by conducting 24-h trials in an open-air O3-fumigation system during two consecutive years. Two circles (radii 1.40 and 4.00 m) of Plutella xylostella-infested potted cabbage plants were placed in the O3 and ambient plots. Female wasps were released into each plot from the center, and observed 5 times over a 24-h period to assess their host location capability. Thereafter, plants were kept in laboratory conditions until larvae pupation to determine parasitism rates. No significant differences were detected between ambient and O3-enriched environments either in the number of wasps found in the field, or in the percentages of parasitized larvae. This suggests that moderately elevated O3 will not affect the behavior of this parasitoid. - Atmospheric ozone increases do not directly affect the biological control of the cabbage pest, Plutella xylostella
[en] Short communication. A summary of a DEA report submitted under the title ''Etude au moyen du Zinc Radioactif 65Zn du comportement des chenilles d'Heliothis armigera hubner (Lepidoptera, Noctuidae) sur Tomate.'' Univ. de Droit d'Economie et des Sciences d'Aix-Marseille-III. Faculte des Sciences et Techniques de Saint-Jerome. INRA-MONTEAVET, Station de Zoologie
[en] The effectiveness of biological products and insecticides in controlling the infestation of Tirathaba rufivena in oil palm estates in Sarawak, Malaysia was evaluated. The study was conducted in two sites from November 2014 to May 2015 on oil palm aged 4 and 5 years. The treatments tested in both sites were commercially available and MPOB-produced Bacillus thuringiensis product, Metarhizium anisopliae, chlorantraniliprole and cypermethrin. The study showed that the first and second instar larvae of bunch moth were found mostly on male inflorescences, and the third and fourth instar larvae were found on female inflorescences and developing bunches. All treatments were effective in reducing the larval population of bunch moth as early as seven days after the first treatment (DAFT). However, the larval population at plots treated with B. thuringiensis recorded inconsistent results. In Site 1, it was observed that only the commercial B. thuringiensis was able to control the larval population of bunch moth up to 34 DAFT. Whereas in Site 2, both B. thuringiensis and Metarhizium anisopliae products gave control as good as chemicals up to 49 DAFT. Chlorantraniliprole application gave rapid reduction and was able to reduce and maintain low population of bunch moth up to 59 days after the last spraying. A more comprehensive study is needed to be carried out by incorporating other control measures such as mass trapping of adults and spraying of larvae using biological and chemical products in the coastal peat areas. (author)