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Background: Beauveria are entomopathogenic fungi of a broad range of arthropod pests. Many strains of Beauveria have been developed and marketed as biopesticides. Beauveria species are well-suited as the active ingredient within biopesticides because of their ease of mass production, ability to kill a wide range of pest species, consistency in different conditions, and safety with respect to human health. However, the efficacy of these biopesticides can be variable under field conditions. Two under-researched areas, which may limit the deployment of Beauveria-based biopesticides, are the type and amount of insecticidal compounds produced by these fungi and the influence of diet on the susceptibility of specific insect pests to these entomopathogens. Methods: To understand and remedy this weakness, we investigated the effect of insect diet and Beauveria-derived toxins on the susceptibility of diamondback moth larvae to Beauveria infection. Two New Zealand-derived fungal isolates, B. pseudobassiana I12 Damo and B. bassiana CTL20, previously identified with high virulence towards diamondback moth larvae, were selected for this study. Larvae of diamondback moth were fed on four different plant diets, based on different types of Brassicaceae, namely broccoli, cabbage, cauliflower, and radish, before their susceptibility to the two isolates of Beauveria was assessed. A second experiment assessed secondary metabolites produced from three genetically diverse isolates of Beauveria for their virulence towards diamondback moth larvae. Results: Diamondback moth larvae fed on broccoli were more susceptible to infection by B. pseudobassiana while larvae fed on radish were more susceptible to infection by B. bassiana. Furthermore, the supernatant from an isolate of B. pseudobassiana resulted in 55% and 65% mortality for half and full-strength culture filtrates, respectively, while the filtrates from two other Beauveria isolates, including a B. bassiana isolate, killed less than 50% of larvae. This study demonstrated different levels of susceptibility of the insects raised on different plant diets and the potential use of metabolites produced by Beauveria isolates in addition to their conidia.

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Emerging contaminants such as sunscreens, hair dyes and flame retardants have been found at important concentrations in surface water (river, lake, ocean), but their negative impact on different aquatic species is not fully known. This study evaluated the effect of benzophenone (BZ), 2,5-diaminotoluene sulfate (PTD), p-phenylenediamine (PPD) and tetrabromobisphenol A (TBPA) on survival (LC50) and the impact of sublethal concentrations (LC25) on the activity of enzymes linked to stress oxidative process in brine shrimp under two temperature conditions (22 °C and 28 °C) for 24 h and 48 h of exposure time. LC50 values obtained for each chemical substance and the activity of GST, AChE and LDH were significantly affected by the temperature conditions and exposure time. In contrast, GPx was only altered by the tested compound. TBBPA (LC50 from 17.05 up to 28.55 µg/L) and BZ (LC50 from 14.86 up to 24.49 mg/L) resulted in the most toxic substances for A. salina. The impact of dyes, such as PTD and PPD, on aquatic organisms is limited. These are the first results that show that not only dyes, but their respective by-products induce harmful effects in brine shrimp (LC50 for PTD and PPD were 23.6-396.3 and 52.0-164.9 mg/L respectively). Although this study model was very useful to evaluate the ecotoxicity of the different ECs, additional research is needed to increase available information related to the effects of dyes and other non-studied micropollutants on aquatic systems in general.

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Ecological communities across the globe are exposed to diverse natural and anthropogenic stressors and disturbances that can lead to community-wide impacts. Contaminants are a group of anthropogenic disturbances that are ubiquitous in the environment and can trigger trophic cascades, increased susceptibility to pathogens, reduced biodiversity, and altered ecosystems. In these ecosystems, substantial attention has been given to evolved resistance in targeted pest species, but little attention has been given to the evolution of resistance in nontarget species in nature. For the present study, the authors used laboratory toxicity tests to determine if 2 common, co-occurring species of freshwater zooplankton (Simocephalus vetulus and Daphnia pulex) showed population-level variation in sensitivity to a common insecticide (chlorpyrifos). For both species, it was found that populations living near agricultural fields--a proxy for pesticide use--were more resistant to chlorpyrifos than populations collected from ponds far from agriculture. This finding is consistent with the evolution of resistance to pesticides. To the authors' knowledge, only 1 previous study (using Daphnia magna) has demonstrated this relationship. Collectively, these results suggest that evolved resistance may be common in zooplankton populations located near agriculture. Moreover, because zooplankton play a key role in aquatic food webs, it is expected that population variation in resistance would dramatically alter aquatic food webs, particularly with exposure to low concentrations of insecticides.

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The present study examined photo-induced toxicity and toxicokinetics for acute exposure to selected polycyclic aromatic hydrocarbons (PAHs) in zebrafish. Photo-enhanced toxicity from co-exposure to ultraviolet (UV) radiation and PAHs enhanced the toxicity and exhibited toxic effects at PAH concentrations orders of magnitude below effects observed in the absence of UV. Because environmental exposure to PAHs is usually in the form of complex mixtures, the present study examined the photo-induced toxicity of both single compounds and mixtures of PAHs. In a sensitive larval life stage of zebrafish, acute photo-induced median lethal concentrations (LC50s) were derived for 4 PAHs (anthracene, pyrene, carbazole, and phenanthrene) to examine the hypothesis that phototoxic (anthracene and pyrene) and nonphototoxic (carbazole and phenanthrene) pathways of mixtures could be predicted from single exposures. Anthracene and pyrene were phototoxic as predicted; however, carbazole exhibited moderate photo-induced toxicity and phenanthrene exhibited weak photo-induced toxicity. The toxicity of each chemical alone was used to compare the toxicity of mixtures in binary, tertiary, and quaternary combinations of these PAHs, and a predictive model for environmental mixtures was generated. The results indicated that the acute toxicity of PAH mixtures was additive in phototoxic scenarios, regardless of the magnitude of photo-enhancement. Based on PAH concentrations found in water and circumstances of high UV dose to aquatic systems, there exists potential risk of photo-induced toxicity to aquatic organisms.

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The acute and chronic toxicity of chemicals to fish is routinely assessed using fish acute and early life stage (ELS) test results, usually with freshwater species. Under some regulations with certain substances, however, data on saltwater species may also be required. Evidence from earlier studies suggests that saltwater fish species are generally no more sensitive than freshwater species and that when they are more sensitive to a substance the difference in sensitivity is usually less than a factor of 10. However, most of these studies concentrated on acute lethal toxicity results for a wide range of substances and across a range of taxonomic groups. In the present study, the authors compare freshwater and saltwater acute median lethal concentration (LC50) and chronic ELS no-observed-effect concentration (NOEC) results from standardized regulatory studies specifically for fish species exposed to the same plant protection or biocidal product active substances to determine the value of testing in both freshwater and saltwater fish. The results suggest that, in most cases, use of a freshwater fish 96-h LC50 or longer-term ELS NOEC should be sufficient to protect saltwater species. In a small number of cases (12%), saltwater ELS NOECs were more sensitive by a factor >10, although differences in sensitivity were not consistent for this small number of substances when 96-h LC50 and longer-term ELS NOECs were compared. It is debatable whether such a low probability merits the additional animal use required to run saltwater fish tests, especially when onshore contaminants released to estuaries and coastal environments are likely to be diluted many-fold when compared with concentrations found in freshwaters.

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It has been suggested that Xenopus laevis is less sensitive than other amphibians to some chemicals, and therefore, that the Frog Embryo Teratogenesis Assay-Xenopus (FETAX) may have limited use in risk assessments for other amphibians. However, comparisons are based mostly on results of FETAX, which emphasizes embryos. Larval X. laevis may be more sensitive to chemicals than embryos and may serve as a better life stage in risk assessments. The present study was conducted to determine the lethal and sublethal effects of 3 insecticides (malathion, endosulfan, and α-cypermethrin) on X. laevis embryos and larvae and to compare toxicity of X. laevis with that of other amphibians. All 3 insecticides have different modes of action, and they caused mortality, malformations, and growth inhibition in both developmental stages. Compared with embryos, larvae were more sensitive to endosulfan and α-cypermethrin but not to malathion. Xenopus laevis larvae had low sensitivity to endosulfan, median sensitivity to malathion, and high sensitivity to α-cypermethrin/cypermethrin relative to other larval amphibians. Our results suggest that X. laevis larvae may generate more protective toxicity estimates in risk assessments than embryos. Xenopus laevis may have limited use in evaluating risk of organochlorine insecticides to other amphibians but may provide useful toxicity thresholds for pyrethroid and perhaps organophosphorus insecticides.

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The toxicity of drilling fluid XP-07 on gills of three life stages (fry, fingerling and post fingerling) of Tilapia guineensis was evaluated in a 96h static bioassay. The mortality rates of the organisms were determined using the same concentrations of XP-07 in all the life stages. At the end of 96h, the gills were examined for histopathological changes. The 96h median lethal concentrations for fry (Fr), fingerlings (F) and post fingerlings (PF) were 5.03, 7.77 and 6.93 percent XP-07 respectively. The median lethal time values decreased as concentration and time of exposure increased. The histopathological studies carried out on gills of T. guineensis showed injuries, which increased progressively with the concentration of the fluid. The fry stage was the most susceptible to the drilling fluid. This states the need for care to be taken in handling drilling fluids in Niger delta, since this area serves as breeding and nursery ground for several fish species.

A toxicidade do líquido de perfuração XP-07, nas brânquias de Tilapia guineensis, foi avaliada por meio de um bioensaio estático de 96h em três estágios da vida do peixe (larva, alevino e juvenil). As taxas de mortalidade do organismo foram avaliadas nas mesmas concentrações de XP-07 para todos os estágios de vida do peixe. As brânquias foram avaliadas ao final de 96 horas, com o objetivo de observarem-se mudanças histopatológicas. A concentração média letal para 96h foi de 5,03; 7,77 e 6,93 por cento para larvas, alevinos e juvenis, respectivamente. O tempo médio letal diminuiu à medida que a concentração e o tempo de exposição aumentaram. Os estudos histopatológicos realizados nas brânquias de T. guineensis indicaram lesões que aumentaram progressivamente com a concentração do fluido. A fase larval é a mais suscetível ao fluido de perfuração. Concluiu-se que é necessário cuidado no manuseio de fluidos de perfuração no Delta do Niger, uma vez que esta é uma área de reprodução e berçário para várias espécies de peixes.