Preliminary phytochemical screening and molluscicidal activity of the aqueous extract of Bidens pilosa Linné (Asteraceae) in Subulina octona (Mollusca, Subulinidade)

Lethal Doses of Saponins from Quillaja saponaria for Invasive Slug Arion vulgaris and Non-Target Organism Enchytraeus albidus (Olygochaeta: Enchytraeidae)

Simple Summary

The Spanish slug, known by its scientific name Arion vulgaris, causes significant damage to agriculture and private gardens around the world. To control this pest, the use of saponin-rich plant extracts is gaining importance as they exhibit strong molluscicidal activity against gastropods and are safe (as saponin residues) in agriculture products. However, despite their proven safety in food, they still do not have a widespread application due to their liquid form and the absence of more accurate knowledge of their effects on other organisms. In this study we evaluated an extract from the bark of the soap tree Quillaja saponaria on slugs and on the white worms Enchytraeus albidus. It was found that slugs were significantly more sensitive to saponin extract at 2 and −1 °C compared to 15 °C. The lethal effect of saponins was stronger on adult slugs than on juveniles. However, lethal effect on worms was much stronger than on slugs. Overall, our results show that Q. saponaria saponins may be a successful slug control tool, especially during colder periods, but its concentration should be selected according to the age of slugs. However, high toxicity to white worms limits its use as an environmentally benign alternative means of slug control.

Abstract

The slug, Arion vulgaris Moquin-Tandon, 1855, is a serious pest in agriculture and private gardens. White worm, Enchytraeus albidus Henle, 1837, is an important model of decomposer organism in the terrestrial ecosystem. Saponins, which are secondary metabolites of plants, have previously been shown to have some molluscicidal effect. We investigated which doses of saponins are lethal to the slug, A. vulgaris, and to the non-target organism, E. albidus. An aqueous solution with different concentrations of saponin extract from the bark of the soap tree, Quillaja saponaria Mol., was used in repeat treatments. Slugs were tested in filter paper contact tests as they are naturally exposed to soil contact while crawling. Worms were tested in soil contact tests as they live below ground. It was found that lethality of saponins depends on the slug age group and the environmental temperature. The median lethal concentration (LC₅₀, at 15 °C) on adults was 68.5 g/L, and on juveniles, 96.9 g/L. The slugs were significantly more sensitive at 2 and −1 °C compared to 15 °C. The LC₅₀ (at 6 ℃) on E. albidus was 2.7 g/L (or 0.5 g/kg dry weight of soil), far below those in A. vulgaris (at 15 ℃ and lower). The LC₅₀ for worms at -1℃ was also significantly lower than at 6 ℃. Therefore, we can conclude: (1) that Q. saponaria saponins may be a successful slug control tool used during colder times of the year, but its concentration should be selected according to the age group of A. vulgaris; (2) this measure is more toxic than expected to white worms, which limits its use.

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

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.

Ethnobotanical study of medicinal plants used by Ribeirinhos in the North Araguaia microregion, Mato Grosso, Brazil

ETHNOPHARMACOLOGICAL IMPORTANCE

Currently, in many traditional communities, such as the riverine community in the North Araguaia microregion (Mato Grosso, Brazil), plant knowledge and use represent the main, if not the only, therapeutic resource for the maintenance of health and/or treatment of diseases. This study aimed to identify and document species of medicinal plants used by local experts from riverine communities in the North Araguaia microregion in Mato Grosso State, and to further chemical and pharmacological studies on species selected based on searches in the relevant literature.

MATERIALS AND METHODS

This is a cross-sectional ethnobotanical study, with non-probabilistic sampling (n =60), that applied the snowball method to select local riverine experts who understand medicinal plant use. Socio-demographic, ethnobotanical and ethnopharmacological data (vernacular name, uses, geographical origin, habit, method of preparation and part used) on medicinal plants were collected during semi-structured interviews. The results were analyzed by descriptive and quantitative means: indices of use-report (UR) were used to select plant species with therapeutic potential.

RESULTS

In total, 309 plant species belonging to 86 botanical families were cited; 73% were native to Brazil, and Fabaceae was the most representative family (11.3%). Arboreal was the predominant life form (37.2%). The leaf was the most used part (28.9%). Infusion was the most commonly reported method of preparation (31.3%). The plants reported in the survey were indicated for 18 of the 22 ICD-10 disease categories. The disease categories most commonly cited were the infectious and parasitic diseases (IPD, 718 UR), digestive system diseases (DSD, 565 UR) and respiratory system diseases (RSD, 504 UR), representing 16.6%, 13.1% and 11.7%, respectively of the total UR. Dysphania ambrosioides L. was the most sighted in the IPD category 50 UR. Copaifera langsdorffii Desf. (133), Lafoensia pacari A. St.-Hil. (131), and Cecropia pachystachya Trécul (126) were the species with the highest UR. Bidens pilosa L., Vernonia ferruginea Less, and L. pacari, respectively, were the most cited native plants used to treat such diseases. Of the 8 investigated native plants, C. langsdorffii, and Brosimum gaudichaudii are the most prominent: in addition to having been widely studied, in terms of phytochemical and pharmacological, these species have been marketed as pharmaceutical products, with associated patent deposits.

CONCLUSIONS

Local riverine experts from the North Araguaia microregion use a wide variety of medicinal plants in self-care health, especially those species used to treat IPD. The therapeutic potential of some of these plants has been scientifically validated; however, there are other species whose pharmacological effects and safety remain to be properly investigated. Thus, the present study, aside from being a basis for future chemical, pharmacological and agronomic bioprospecting studies, may contribute to the development of the management, conservation and sustainable use of medicinal flora in the microregion studied.

Active saponins from root of Pueraria peduncularis (Grah. ex Benth.) Benth. and their molluscicidal effects on Pomacea canaliculata

BACKGROUND

Pueraria peduncularis (Grah. ex Benth.) Benth., which belongs to the Leguminosae family, exhibits resistance to many crop pests in agricultural production. Pomacea canaliculata is an important invasive snail in rice fields and causes severe yield losses. To evaluate the toxicity of P. peduncularis to P. canaliculata, in this study the molluscicidal activity of root extracts of P. peduncularis was tested against P. canaliculata; the active compounds were isolated, and the structures of these compounds were analysed using nuclear magnetic resonance (NMR) analysis and mass spectral analysis.

RESULTS

Our results showed that the molluscicidal activity of the root crude extract differed between P. canaliculata with different shell diameters after treatment for 72 h. The median lethal concentration (LC₅₀ ) was 5.511 mg L^-1 against snails of 1.5 ± 0.2 cm diameter and 12.383 mg L^-1 against snails of 2.5 ± 0.2 cm diameter. Furthermore, two active ingredients isolated from root methanol extracts were identified as pedunsaponin A and pedunsaponin C. Both pedunsaponin A and pedunsaponin C showed strong molluscicidal activities, with LC₅₀ values of 3.893 and 4.252 mg L^-1 , respectively, against snails with shell diameters of 1.5 ± 0.2 cm after treatment for 72 h.

CONCLUSION

Pueraria peduncularis extracts exhibit high molluscicidal activity and have great potential value for exploring a molluscicide to control Pomacea canaliculata. © 2016 Society of Chemical Industry.