Banca de DEFESA: SERGIO CLEMENTINO DA COSTA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : SERGIO CLEMENTINO DA COSTA
DATE: 20/12/2024
TIME: 08:00
LOCAL: VIDEOCONFERÊNCIA
TITLE:

Toxic Effects of the Pesticides Acetamiprid, Emamectin Benzoate, and Fipronil Isolated and in Mixtures on Zebrafish (Danio rerio) Embryos and Larvae

KEY WORDS:

Pesticides, fish, toxicological effects, acetamiprid, emamectin benzoate, fipronil

PAGES: 96
BIG AREA: Ciências Biológicas
AREA: Fisiologia
SUMMARY:

Acetamiprid, emamectin benzoate, and fipronil are widely used pesticides to protect
monocultures of sugarcane, corn, soybeans, and cotton from pests. However, the
effectiveness of these pesticides is accompanied by significant environmental
concerns, as they are classified as highly toxic and pose serious risks to aquatic
ecosystems. The common practice of applying these substances in mixtures in
agricultural crops further intensifies their potential for harm, 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 multiple active
ingredients are commonly applied simultaneously to crops and/or different crops use
the same water sources. However, the current assessment of these pesticides' effects
predominantly focuses on isolated substances, which may underestimate their
ecological relevance. In this context, the present study aimed to investigate the
effects of the combined use of three pesticides: acetamiprid, emamectin benzoate,
and fipronil. To this end, acute toxicity tests were conducted in the laboratory,
evaluating lethality, sub-lethality, and epiboly, through exposures to the isolated and
mixed compounds, using zebrafish embryos and larvae as test organisms. The
embryos were exposed for periods ranging from 24 to 144 hours post-fertilization
(hpf) to assess epiboly, mortality, teratogenic effects, and heart rate. The study
groups were divided into: control, acetamiprid (ACT), emamectin benzoate (EB),
fipronil (FP), their binary mixtures (50% + 50%), and ternary mixtures (33% + 33% +
33%) at concentrations ranging from 50 μg/L to 16 mg/L. The results indicated that all
three isolated pesticides caused toxic effects in the embryos and larvae, with fipronil
being the most toxic, showing significant differences across the three concentrations
tested, affecting up to 100% of the tested animals and resulting in a high mortality
rate. On the other hand, acetamiprid was less toxic. In tests with mixtures, the
combination of emamectin benzoate and fipronil (EB + FP) showed a synergistic toxic
effect on the embryos, with a high mortality rate and a large proportion of affected
animals. Similarly, in heart rate measurements, significant variations (p < 0.05) were
observed in the groups exposed to fipronil (FP) and emamectin benzoate (EB)
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 results indicated that both isolated pesticides and their
mixtures affect the exposed animals, altering their heart rates and epiboly rate.
Furthermore, the data show that the toxicity of the mixtures differs depending on the
endpoints analyzed. Therefore, studies aimed at understanding the effects of
pesticide mixtures are crucial, as they help to provide a more realistic understanding
of their impacts. The additive effects of these mixtures are still poorly understood,
emphasizing the need for further studies in this area.

COMMITTEE MEMBERS:
Externo ao Programa - 2140782 - ALEX SOUZA MORAES - nullExterno à Instituição - FRANCISCO DE ASSIS LEITE
Externa à Instituição - MARIA DO CARMO DE BARROS PIMENTEL - UFPE
Presidente - PABYTON GONCALVES CADENA
Externa à Instituição - SÂMARA DA SILVA GOMES