Ram P. Yadav

Molluscicides from some common medicinal plants of eastern Uttar Pradesh, India.

Many aquatic snails act as intermediate hosts for the larvae of trematodes, Fasciola hepatica and Fasciola gigantica, which cause the diseases fascioliasis and schistosomiasis. The WHO has tested several thousands of synthetic compounds for the control of the snail host. Although effective, these molluscicides have so far not proved themselves to be entirely satisfactory. With a growing awareness of environmental pollution, efforts are being made to discover molluscicidal products of plant origin. Being products of biosynthesis, these are potentially biodegradable in nature. Several groups of compounds present in various plants have been found to be toxic to target organisms at acceptable doses ranging from <1 to 100 ppm. Common medicinal plants, i.e. Thevetia peruviana, Alstonia scholaris (Family; Apocynaceae), Euphorbia pulcherima and Euphorbia hirta (Family; Euphorbiaceae), have potent molluscicidal activity against freshwater snails. The toxicological actions of Thevetia peruviana may be due to the presence of apigenin‐5‐methyl ether (flavonoid) and triterpenoid glycosides, while a number of alkaloids (pseudo‐akuammigine in addition to betulin, ursolic acid and β‐sitosterol), steroids and triterpenoids are present in Alstonia scholaris and the diterpenoids, pulcherrol, β‐sitosterol, hentriacontane, ellagic acid and β‐amyrin are present in Euphorbia hirta and in Euphorbia pulcherima. Although, at present very little literature is available on the control of vector snails through plant origin pesticides, an attempt has been made in this review to assemble all the known information on molluscicidal properties of common medicinal plants of eastern Uttar Pradesh, India, which might be useful for the control of harmful snails. Copyright

Efficacy of euphorbia hirta latex as plant derived molluscicides against freshwater snails

Os efeitos toxicos das combinacoes binarias e terciarias do po de latex da Euphorbia hirta Linn assim como outros compostos vegetais moluscicidas foram avaliados em sua acao sobre caramujos de agua doce Lymnaea (Radix) acuminata e Indoplanorbis exustus em represas. Estas combinacoes mostraram significante efeito dose e tempo dependente contra ambos os caramujos. Estes compostos em doses altas foram tambem letais para peixes de agua doce Channa punctatus (Bloch) (Channidae {Ophicephalidae}), que compartilham o ambiente com estes caramujos mas a dose LC90 (24h) para caramujos aparentemente nao tem propriedade de matar as populacoes de peixes quando uma populacao mista de peixes e caramujos sao tratadas.The toxic effect of binary and tertiary combinations of Euphorbia hirta Linn latex powder with other plant molluscicidal compounds, were evaluated against the freshwater snails Lymnaea (Radix) acuminata and Indoplanorbis exustus in pond. These combinations showed significant time and dose dependent effect against both the snails. These compounds at higher doses were also lethal to freshwater fish Channa punctatus (Bloch) (Channidae {Ophicephalidae}), which shares the habitat with these snails, but the LC90 (24h) doses of snails have no apparent killing properties in fish populations when treated in mixed population of snails and fish.

Toxic Effects of Euphorbiales on Freshwater Snail Lymnaea acuminata in Ponds

ABSTRACT Latex extract of the medicinal euphorbious plants, Jatropha gossypifolia, Euphorbia pulcherima, and Croton tiglium were tested as molluscicides in natural ponds against the freshwater snail Lymnaea acuminata. The molluscicidal activity of latex extracts of all the three plants was time and dose dependent at all the exposure periods. A significant negative correlation between LC values of latex extracts and exposure periods existed, thus LC50 values decreased from 17.32 mg/L (24 h) to 5.66 mg/L (96 h) in case of Jatropha gossypifolia, 3.79 mg/L (24 h) to 1.56 mg/L (96 h) in case of Euphorbia pulcherima and 12.32 mg/L (24 h) to 4.85 mg/L (96 h) in case of Croton tiglium against Lymnaea acuminata. The latex of all the three euphorbiales may probably be used as potent eco-friendly molluscicides in natural ponds for managing the harmful snail population.

Toxic effects of crotocaudin extracted from the medicinal plant Croton tiglium.

The compound crotocaudin extracted from the stem bark of the medicinal plant Croton tiglium Linn. was administered for 24 h or 96 h to the freshwater vector snail Lymnaea (Radix) acuminata Lamarck in order to test its toxicity. L. acuminata is the intermediate host of Fasciola hepatica and Fasciola gigantica which cause immense harm to man and his domestic animals. It was observed that the molluscicidal activity of crotocaudin against L. acuminata is time- as well as dose-dependent. There was a significant negative correlation among LC50 values and exposure periods, i.e. increasing the exposure time, the LC50 value of crotocaudin decreased from 5.37 μM (24 h) > 2.08 μM (48 h) > 1.36 μM (72 h) to 1.01 μM (96 h), respectively, against L. acuminata. The toxicological experiments to proof for environmental toxicity, if any, have also been carried out on the non-target freshwater fish Channa punctatus (Bloch) [Channidae (Ophicephalidae)], which shares the habitat with L. acuminata. The sublethal doses of crotocaudin (40% and 80% of LC50) administered over 24 h caused significant changes in the carbohydrate and nitrogenous metabolisms in nervous, hepatopancreas, and ovotestis tissues of Lymnaea acuminata. Channa punctatus was also exposed to sublethal doses of crotocaudin (40% and 80% of 24-h LC50 of L. acuminata) for 96 h which showed significant alterations in the metabolism in muscle, liver, and gonad tissues. After withdrawal of crotocaudin the snail tissues recovered in part after 7 days and the fish tissues completely.

EFFECTS OF SINGLE, BINARY AND TERTIARY COMBINATIONS WITH Jatropha gossypifolia AND OTHER PLANT-DERIVED MOLLUSCICIDES ON REPRODUCTION AND SURVIVAL OF THE SNAIL Lymnaea acuminata

The effect of sub-lethal doses (40% and 80% of LC50/24h) of plant derived molluscicides of singly, binary (1:1) and tertiary (1:1:1) combinations of the Rutin, Ellagic acid, Betulin and taraxerol with J. gossypifolia latex, leaf and stem bark powder extracts and their active component on the reproduction of freshwater snail Lymnaea acuminata have been studied. It was observed that the J. gossypifolia latex, stem bark, individual leaf and their combinations with other plant derived active molluscicidal components caused a significant reduction in fecundity, hatchability and survival of young snails. It is believed that sub-lethal exposure of these molluscicides on snail reproduction is a complex process involving more than one factor in reducing the reproductive capacity.