The efficiency of tobacco Bel-W3 and native species for ozone biomonitoring in subtropical climate, as revealed by histo-cytochemical techniques

We aimed to verify whether hydrogen peroxide (H₂O₂) accumulation and cell death are detected early in three bioindicators of ozone (O₃), Nicotiana tabacum ‘Bel-W3’, Ipomoea nil ‘Scarlet O’Hara’ and Psidium guajava ‘Paluma’, and whether environmental factors also affect those microscopic markers. The three species were exposed to chronic levels of O₃ in a subtropical area and a histo-cytochemical technique that combines 3,3′-diaminobenzidine (DAB) with Evans blue staining was used in the assessments. The three species accumulated H₂O₂, but a positive correlation with O₃ concentration was only observed in N. tabacum. A positive correlation between O₃ and cellular death was also observed in N. tabacum. In I. nil and P. guajava, environmental factors were responsible for symptoms at the microscopic level, especially in P. guajava. We conclude that the most appropriate and least appropriate bioindicator plant for O₃ monitoring in the subtropics are N. tabacum ‘Bel-W3’ and P. guajava ‘Paluma’, respectively.     

Bioaccumulation of 10 trace elements in juvenile fishes of the Lower Paraná River,Argentina: implications associated with essential fish growing habitat

This study assessed the concentration, bioconcentration, and bioaccumulation of As, Cd, Co, Cr, Cu, Mg, Mn, Ni, Pb, and Zn in juvenile fishes (Acestrorynchus pantaneiro, Brycon orbygnianus, Cyphocharax voga, Megaleporinus obtusidens, Odontesthes bonariensis, Pimelodus maculatus, Prochilodus lineatus, Salminus brasiliensis, and Schizodon borelli) in the Lower Paraná River (Argentina), the most extensive floodplain from the Plata Basin. The floodplain is crucial for the reproduction and growth of various species such as P. lineatus, M. obtusidens, and S. brasiliensis, which complete their life cycle in this environment. In total, 90 individuals were sampled for nitrogen stable isotope, and trace element analysis in muscle tissue, water, and sediment was analyzed. The results show that all the studied species bioaccumulate Cr, Mg, Ni, and Zn. In particular, B. orbygnianus and P. maculatus presented the highest bioaccumulation factor for Cr. A biodilution of Co through the food chain was observed. No positive correlation was found between element concentration and trophic level, but we observed significant differences between trophic guilds (herbivorous, omnivorous, and carnivorous). Our findings suggest that feeding habits determine trace element concentrations. To establish differential behavior between different species within the aquatic web further studies are necessary, particularly in the floodplain of the Paraná, which is a crucial nursery area for most commercially important fishes from the Plata Basin.

Graphical abstract

     

Ecotoxicity of imidacloprid to soil invertebrates in two tropical soils with contrasting texture

Environmental Science and Pollution Research - Imidacloprid is one of the most commercialized insecticides in agriculture in the world, with a broad spectrum of action. However, little is known...     

Nocturnal herbivore-induced plant volatiles attract the generalist predatory earwig <Emphasis Type="Italic">Doru luteipes</Emphasis> Scudder

Numerous studies have demonstrated that entomophagous arthropods use herbivore-induced plant volatile (HIPV) blends to search for their prey or host. However, no study has yet focused on the response of nocturnal predators to volatile blends emitted by prey damaged plants. We investigated the olfactory behavioral responses of the night-active generalist predatory earwig Doru luteipes Scudder (Dermaptera: Forficulidae) to diurnal and nocturnal volatile blends emitted by maize plants (Zea mays) attacked by either a stem borer (Diatraea saccharalis) or a leaf-chewing caterpillar (Spodoptera frugiperda), both suitable lepidopteran prey. Additionally, we examined whether the earwig preferred odors emitted from short- or long-term damaged maize. We first determined the earwig diel foraging rhythm and confirmed that D. luteipes is a nocturnal predator. Olfactometer assays showed that during the day, although the earwigs were walking actively, they did not discriminate the volatiles of undamaged maize plants from those of herbivore damaged maize plants. In contrast, at night, earwigs preferred volatiles emitted by maize plants attacked by D. saccharalis or S. frugiperda over undamaged plants and short- over long-term damaged maize. Our GC-MS analysis revealed that short-term damaged nocturnal plant volatile blends were comprised mainly of fatty acid derivatives (i.e., green leaf volatiles), while the long-term damaged plant volatile blend contained mostly terpenoids. We also observed distinct volatile blend composition emitted by maize damaged by the different caterpillars. Our results showed that D. luteipes innately uses nocturnal herbivore-induced plant volatiles to search for prey. Moreover, the attraction of the earwig to short-term damaged plants is likely mediated by fatty acid derivatives.     

What can the Allium cepa test say about pesticide safety? A review

Environmental Science and Pollution Research - The increasing use of pesticides has caused global concerns about the toxic effects and adverse consequences of pesticides on humans and the...     

Attraction of entomopathogenic nematodes to sugarcane root volatiles under herbivory by a sap-sucking insect

Few systems have been described in which herbivore-induced root volatiles mediate attraction of entomopathogenic nematodes (EPNs), and they only concern root damage inflicted by chewing insects. EPNs, especially Heterorhabditis indica and Steinernema carpocapsae, are potential biological control agents of sugarcane spittlebug (Mahanarva fimbriolata) populations. Here, we investigated the response of these two species of EPNs to sugarcane root volatiles damaged by M. fimbriolata nymphs in a belowground six-arm olfactometer. We also examined changes on root volatile profile in response to herbivory of sugarcane spittlebug nymphs. Results showed that both EPN species did not discriminate between odors of undamaged sugarcane and moistened sand (blank). However, when EPNs were exposed to odors of spittlebug-damaged and undamaged sugarcane roots, both species significantly preferred odors of spittlebug-damaged roots. Headspace collection followed by GC–MS analyses showed no qualitative difference (total of 11 compounds) between volatile profiles of spittlebug-damaged and undamaged sugarcane roots. In contrast to the previous studies involving feeding by root chewing insects, our root volatile analysis did not reveal any up-regulation resulting from sugarcane spittlebug damage, but the down-regulation of the terpenes dihydromyrcenol and β-isomethyl ionone when compared with the profile of undamaged sugarcane roots. Here, we propose alternative explanations for the EPN attraction to spittlebug-damaged roots as it is unlikely that reduced concentrations of the volatiles play a role in this interaction. Further studies are necessary to determine the key compounds of the root volatile emission to enhance biological control efficacy with EPNs against M. fimbriolata in sugarcane.     

Monitoring an outdoor smoking area by means of PM<Subscript>2.5</Subscript> measurement and vegetal biomonitoring

The extension of pollutant accumulation in plant leaves associated with its genotoxicity is a common approach to predict the quality of outdoor environments. However, this approach has not been used to evaluate the environmental quality of outdoor smoking areas. This study aims to evaluate the effects of environmental tobacco smoke (ETS) by assessing particulate matter 2.5 μm (PM_2.5) levels, the pollen abortion assay, and trace elements accumulated in plant leaves in an outdoor smoking area of a hospital. For this, PM_2.5 was measured by active monitoring with a real time aerosol monitor for 10 days. Eugenia uniflora trees were used for pollen abortion and accumulated element assays. Accumulated elements were also assessed in Tradescantia pallida leaves. The median concentration of PM_2.5 in the smoking area in all days of monitoring was 66 versus 34 μg/m³ in the control area (P?<?0.001). In addition, the elements Al, Cd, Cu, Ni, Pb, Rb, Sb, Se, and V in Tradescantia pallida and Al, Ba, Cr, Cu, Fe, Mg, Pb, and Zn in Eugenia uniflora were in higher concentration in the smoking area when compared to control area. Smoking area also showed higher rate of aborted grains (26.1?±?10.7 %) compared with control (17.6?±?4.5 %) (P?=?0.003). Under the study conditions, vegetal biomonitoring proved to be an effective tool for assessing ETS exposure in outdoor areas. Therefore, vegetal biomonitoring of ETS could be a complement to conventional analyses and also proved to be a cheap and easy-handling tool to assess the risk of ETS exposure in outdoor areas.