A New Technique Using Low Volumes: A New Technique to Assess the Molluscicidal Activity Using Low Volumes

Abstract

Schistosomiasis is a disease endemic in several states of Brazil. The population control of the transmitter mollusks is done with Bayluscide WP 70®, in the control programs. OMS preconize molluscicidal assays using Becker with 500 mL of final volume, restringing the number of natural products and synthetic drugs to be tested in function of high quantity of material necessary. A new technique to assess the toxic effects for Biomphalaria sp. is the purpose of this work, for developing adaptation for this aquatic organism, using a low volume of test solution in 24-well plates. We used Biomphalaria glabrata (10–12 mm size) in a static system, consisting of the following components: Becker containing 10 snails or 24-well plates where snails were individualized for a volume of 2 mL per well for 24 and 48 hours. For the assays, we added aqueous solutions of Bayluscide WP 70, at a concentration of 1–5 mg/L, distilled water, and 1% dimethyl sulfoxide. Data were evaluated using Kappa's coefficient, Z factor validation, and comparison study. This technique to assess the toxic effect has proven to be a useful tool to detect lethal and sublethal effects, which could be used as a new evaluation protocol.

Bioatividade Comparada entre os Extratos Fracionados em Hexano e em Acetona das Folhas de Plectranthus grandis sobre Biomphalaria glabrata / Compared Bioactivity between Hexane and Acetone Fractional Extracts from Plectranthus grandis leaves on Biomphalaria glabrata

“…CL 50 = 98,57mg/L CL 90 = 177,00 mg/L Nosso trabalho com a fração em acetona de P. grandis, corrobora com os observados por Santos et al (2003) que testaram a atividade moluscicida dos extratos e frações de Physalis angulata sobre B. tenagophila e acharam a CL90 = 201,2 mg/L para o pool de fisalinas das folhas. SANTOS et al (2003SANTOS et al ( , 2017, utilizaram moluscos com diâmetro de concha entre de 6 -10 mm, para verificar a atividade moluscicida de P. angulata e 10 -12 mm no trabalho de uma nova técnica para avaliar atividade moluscicida usando baixos volumes. Utilizamos esta técnica para os ensaios biológicos e similar diâmetro de concha dos moluscos.…”

Nanoemulsion containing essential oil from Xylopia ochrantha Mart. produces molluscicidal effects against different species of Biomphalaria (Schistosoma hosts)

“…Molluscicidal assays - Nanoemulsion of essential oil from X. ochrantha (100 ppm) was diluted to three different concentrations (80 ppm, 60 ppm, and 40 ppm) in distilled water. For the assay, 10 adult snails of B. glabrata species (measuring 10-12 mm diameter, from Sumidouro, RJ, Brazil) were exposed to 2 mL of the nanoemulsion, in a 24-well plate for 48 h at room temperature, according to the bioassay adapted from WHO, 1983 17 ( Fig. 1 ).…”

Ocotea pulchellaas an alternative against schistosomiasis: chemical analysis, development of nanoemulsion and biological control activity

“…The action of the selected NE was evaluated for biological control of B. glabrata using the methodology of Santos et al (2017). Clams of size 10-12 mm were individually placed in 24-well plates and exposed to concentrations of 20, 40, 60, 80, 100 and 120 ppm in the final 2 mL NE volume.…”