Melipona scutellaris Latreille, 1811 (Hymenoptera, Apidae) is a pollinator of various native and cultivated plants. Because of the expansion of agriculture and the need to ensure pest control, the use of insecticides such as fipronil (FP) has increased. This study aimed to evaluate the effects of sublethal doses of FP insecticide on M. scutellaris at different time intervals (6, 12, and 24 h) after exposure, via individually analyzed behavioral biomarkers (locomotor activity, behavioral change) as well as the effect of FP on different brain structures of bees (mushroom bodies, antennal cells, and optic cells), using sub-individual cell biomarkers (heterochromatin dispersion, total nuclear and heterochromatic volume). Forager bees were collected when they were returning to the nest and were exposed to three different concentrations of FP (0.40, 0.040, and 0.0040 ng a.i/bee) by topical application. The results revealed a reduction in the mean velocity, lethargy, motor difficulty, paralysis, and hyperexcitation in all groups of bees treated with FP. A modification of the heterochromatic dispersion pattern and changes in the total volume of the nucleus and heterochromatin were also observed in the mushroom bodies (6, 12, and 24 h of exposure) and antennal lobes (6 and 12 h) of bees exposed to 0.0040 ng a.i/bee (LD). FP is toxic to M. scutellaris and impairs the essential functions required for the foraging activity.
Birds have often played an important role as environmental bioindicators, and different species can be useful due to their bioaccumulating capacity. The micronuclei test is a cytologic technique used for accessing DNA and is a biomarker for damage to DNA. This study analysed the Cerrado avian community, especially the efficiency of the blue-black grassquit (Volatinia jacarina) in responding to pesticide contamination in situ on different-sized coffee farms in southeast Brazil. The micronuclei test was used in erythrocytes of birds. Eighty-two individuals of 21 bird species belonging to 11 families that were found in all study areas were used to evaluate micronuclei (MN) frequency. Two hundred fifty-two MN were counted in every area of study. The MN average count was 3/10,000 erythrocytes, and 17.1% of all bird species exhibited no MN. The average MN was 1.29 ± 0.69 in small farms, 2.59 ± 1.65 in medium farms, and 5.41 ± 1.34 in large farms. Small farms accounted for 14.3% of MN frequency, medium farms 27.8%, and large farms 57.9%. V. jacarina was the most abundant species found and displayed a sensitive response to environmental contamination. Pesticides appear to induce MN formation in a dose-dependent way when farms are analysed according to their area. Therefore, biomonitoring birds remain an efficient means to detect environmental pollutants, especially pesticides. V. jacarina responds as a sensitive biomonitor, showing a dose-dependent response to pesticides used in coffee farms.
The micronucleus (MN) test and analysis of heavy metal biological accumulation in Tradescantia pallida (T. pallida) were bioassays used to assess the genotoxic potential of emissions from a complex of ceramic industries into the atmosphere in a city in Brazil that is considered a national reference source for roof tile production. The ceramic industry emission-exposed T. pallida plants were biomonitored during the dry season, in June, July, and August 2013. In addition to the contaminated monitoring site, a reference site in a peri-urban area was utilized, for comparative purposes. Genotoxicity assessments were determined monthly, while heavy metal bioaccumulation was measured at the end of the total exposure period. The MN frequency was significantly greater in T. pallida plants exposed in the ceramic industry emission monitored area compared to the reference site, and highest MN rates were observed in July and August. With respect to heavy metal bioaccumulation in T. pallida leaves, cadmium (Cd) and chromium (Cr) concentrations were significantly higher in plants at the ceramic industry emission monitoring site. Thus, in relation to the parameters assessed, T. pallida was found to be sensitive to atmospheric contamination by heavy metals attributed to ceramic products emissions generated by the ceramic industry, confirming that this plant species may be employed as a reference organism in biomonitoring studies.
In International guidelines for standard ecotoxicological bioassays, Daphnia magna is the most applied microcrustacea for assessing toxicity of different pollutants. However, in research realized in tropical and subtropical areas, autochthonous species must be prioritized because they are adapted to the specificities of ecosystems. In this sense, the present study aimed to assess and compare (with D. magna) the sensitivity of the tropical species Dendrocephalus brasiliensis as alternative test species for monitoring of contaminants in tropical and subtropical freshwaters, by carrying out acute toxicity tests with different pollutants. According results, D. brasiliensis presented EC50-48 h values lower than D. magna for all substances tested, indicating higher sensitivity of the tropical organism in relation to the temperate organism. Furthermore, comparing the results obtained with data from other studies, D. brasiliensis is more sensitive to the chemicals tested than D. magna and has similar sensitivity to Pseudosida ramosa and Ceriodaphnia dubia, common species in tropical areas. In view of this, we suggest that D. brasiliensis can be used as alternative test species for monitoring of contaminants in tropical and subtropical freshwaters.
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