Banca de QUALIFICAÇÃO: VINÍCIUS MONTEIRO FERREIRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : VINÍCIUS MONTEIRO FERREIRA
DATE: 28/10/2025
TIME: 09:00
LOCAL: Sala Prof. Laerte Grisi - LQEPV (Bloco G do Anexo I do IV)
TITLE:

Standardization of Bioassays for Evaluating Insecticide Efficacy on Cochliomyia hominivorax Larvae (Diptera, Calliphoridae)

KEY WORDS:

Control; Cochliomyia hominivorax; in vitro test; larvicide.

PAGES: 93
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUMMARY:

Cochliomyia hominivorax is the main causative agent of myiasis in Latin America. Although a wide range of drugs are currently available to control its infective stages, there are reports of reduced efficacy for some of these compounds. The method of application can influence drug efficacy, highlighting the need for standardized in vitro testing protocols that simulate field application conditions as realistically as possible. This study aimed to evaluate the efficacy of different in vitro bioassay methodologies against third-instar larvae of C. hominivorax. Two active ingredients, chlorpyrifos and fipronil, were tested using four methodologies: activity by contact with filter paper impregnated with different concentrations of the ectoparasiticides and by immersing larvae for 1, 3, and 5 minutes in solutions containing different concentrations of the same ectoparasiticides. In the impregnation tests, nine concentrations of each active ingredient (1000–1 µg/mL for chlorpyrifos and 5000–1 µg/mL for fipronil) were applied to filter paper discs, along with a control containing distilled water and a placebo composed only of the diluents. After drying, the discs were placed in Petri dishes, and ten third-instar (L3) C. hominivorax larvae were added to each. In the immersion tests, groups of ten larvae were submerged in solutions containing nine different concentrations, in addition to control and placebo groups with the same concentrations used in the impregnation tests. All tests were performed in sextuplicate. After treatments, the tests were incubated at 28°C and 70% relative humidity. Larvicidal effects were evaluated 24, 48, and 72 hours after exposure, and emergence inhibition was assessed ten days after incubation. Estimated lethal concentrations (LC₅₀) were calculated using the RStudio software, and mortality data were statistically compared using the Kruskall-Wallis test and Dunn's multiple comparison test. The 72-hour LC₅₀ for chlorpyrifos were 280, 1863, 663.6, and 830.9µg/mL for the impregnation, immersion tests for 1, 3, and 5 minutes, respectively. For fipronil, the corresponding values were 18, 4.5, 1.6, and 3.0µg/mL, in the same period. Regarding emergence inhibition, the LC₅₀ for chlorpyrifos were 57.8, 637, 135.6, and 142.5µg/mL; and for fipronil, 7.1, 4.5, 1.6, and 3.0µg/mL. 1.0, 1.2, and 1.2µg/mL, respectively, using the same methodologies. The results demonstrate that the efficacy of insecticidal compounds varies significantly depending on the in vitro methodology used.

COMMITTEE MEMBERS:
Presidente - 2929889 - THAIS RIBEIRO CORREIA AZEVEDO
Interna - ***.630.647-** - BARBARA RAUTA DE AVELAR - UFRRJ
Interna - 3103528 - CLAUDIA BEZERRA DA SILVA
Interna - 3161989 - GABRIELA FERREIRA DE OLIVEIRA