Banca de QUALIFICAÇÃO: SERGIO CLEMENTINO DA COSTA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : SERGIO CLEMENTINO DA COSTA
DATE: 18/06/2024
TIME: 10:00
LOCAL: Online via Google Meet
TITLE: Toxic effects of mixtures of the pesticides acetamiprid, emamectin benzoate, and fipronil on zebrafish (Danio rerio) embryos and larvae.
KEY WORDS: Pesticides, fish, toxicological effects, acetamiprid, emamectin benzoate, fipronil.
PAGES: 73
BIG AREA: Ciências Biológicas
AREA: Fisiologia
SUMMARY: Acetamiprid, emamectin benzoate, and fipronil are pesticides widely used to protect monocultures of sugarcane, corn, soybeans, and cotton against pests. However, the effectiveness of these pesticides comes with significant environmental concerns, as they are classified as extremely toxic and pose serious risks to aquatic ecosystems. The common practice of applying these substances in mixtures on agricultural crops further intensifies the potential for damage, especially when these compounds contaminate water, amplifying their adverse effects on non-target aquatic organisms. Surface water contamination by pesticides is often associated with a combination of substances, rather than a single compound, as several active ingredients are commonly applied simultaneously to crops and/or various crops use the same water sources. However, the current assessment of the effects of these pesticides is predominantly based on isolated substances, which may underestimate their ecological relevance. In view of this, the present study aimed to investigate the effects of the combined use of three pesticides: acetamiprid, emamectin benzoate, and fipronil. For this, acute toxicity tests were carried out in the laboratory, evaluating lethality, sub-lethality, and epiboly, from exposures of the isolated compounds and in mixtures, using zebrafish embryos and larvae as test organisms. The embryos were exposed for periods of 24 to 120 hours post-fertilization (hpf) for the evaluation of epiboly, mortality, teratogenic effects, and heart rate. The study groups were divided into: control, acetamiprid (ACT), emamectin benzoate (BE), fipronil (FP), their binary mixtures (50% + 50%) and ternary (33% + 33% + 33%) at concentrations ranging from 50 μg/L to 16 mg/L. The results obtained indicated that the three isolated pesticides caused toxic effects in the embryos and larvae, with fipronil being the most toxic, showing significant differences in the three concentrations used in the toxicological tests, affecting up to 100% of the tested animals and resulting in a high mortality rate. On the other hand, acetamiprid proved to be less toxic. In the tests with the mixtures, it was observed that the combination of emamectin benzoate and fipronil (BE + FP) promoted a synergistic toxic effect in the embryos, with a high mortality rate and a large proportion of affected animals. Similarly, in the heart rates of the embryos, significant variations (p < 0.05) were found in the groups exposed to fipronil (FP) and emamectin benzoate (BE) when compared to the control group. In the epiboly test, the isolated pesticides fipronil and emamectin benzoate reduced the percentage of epiboly more than acetamiprid, when compared to the control. Our partial results indicated that both the isolated pesticides and their mixtures affect the exposed animals, altering their heart rates and the rate of epiboly. In addition, the data show that the toxicity of the mixtures differs depending on the endpoints analyzed. Therefore, works that seek to understand the effects of pesticide mixtures are fundamental, as they help to understand their effects in a more realistic way. The additive effects of these mixtures are still poorly understood, highlighting the importance of additional studies in this area.
COMMITTEE MEMBERS:
Presidente - PABYTON GONCALVES CADENA
Interno - PAULO ROBERTO ELEUTERIO DE SOUZA
Externa à Instituição - MARIANE CAJUBÁ DE BRITTO LIRA NOGUEIRA - UFPE