S2 L4 Molluscicides, rodenticicides, fungicides

1. S2 L4 Molluscicides, rodenticicides, fungicides Anna Drew http://curriculum.toxicology.wikispaces.net/2.1.16+Pharmacognosy

2. Mollusc control • relatively minor pests in agriculture • disease in developing countries bring other challenges • schistosomiasis (bilharzia) • South America, Africa, Far East • intestinal and bladder damage • parasitic blood fluke • Schistosoma haemotobium, S.mansoni, S.japonicum • part of its life-cycle in the fresh water snails • eg Biomphalaria glabrata • Bulinus, Biomphalaria, Oncolmelania

3. http://www.wellcome.ac.uk/en/labnotes5/animation_popups/schisto.htmlhttp://www.wellcome.ac.uk/en/labnotes5/animation_popups/schisto.html

5. Over 1000 plant species tested for molluscicidal activity 1980-1995 • Wide range showed promise • Leguminosae • Araliaceae • Compositae • Liliaceae • Features • available in sufficient quantity • capable of easy propogation in region required • water soluble active constitiuents • easily extracted • high toxicity for molluscs; low for humans

6. Phytolacca dodecandra • endod berry of this Ethiopian plant • triterpinoid saponins eg lemmatoxin • composed of oleanolic acid • with branched sugar side chains at C-3 • cultivation outside natural habitat disappointing • does not kill snail egg masses • Swartzia madagascariensis • Leguminosae tree found throughout Africa • pods contains similar saponins • Swartzia simplex • South American species • leaves contain glycosides of oleanolic acid • gypsogenin, gypsogenic acid • Tetrapleura tetraptera • Leguminosae, Nigeria • Saponins • Euphorbia conspicua latex

7. Spirostanol saponins • Balanites aegyptica (Zygophyllaceae) • Potent • Balanitin 1-, 2-, 3- • Tannins • Leguminosae • eg Acacia sp • Napthoquinones • Diospyros usambarensis, Malawi • juglone and plumbagin type • in bark (problem) • Isobutylamines • Asteraceae, Rutaceae, Piperaceae • Steroidal glycoalkaloids • Solanum mammosum

8. Anthraquinones • Morinda lucida (Rubiaceae) • Unsaturated anacardic acids • of cashew shells (Anacardium occidentale) • very active but treated water -> dermatitis • Sesquiterpenes • Ambrosia maritima, Senegal • Isoflavonoids • Milletia thoningii, W.African legume • Saponins • Chenopodium quinoa

9. Niclosamide used for flatworms in vet. medicine has been tested in waterways toxic to fish expensive Trifenmorph also used for fascioliasis lifecycle includes snail toxic to fish

10. Metaldehyde cyclic oligomer of acetaldehyde slugs, snails Metal salts iron III phosphate aluminium sulphate (alum) Acetylcholinesterase inhibitors contact Diatomaceous earth

11. Rodenticides • Red squill • Urginea maritima (Liliaceae) • Constituents: • cardioactive glycosides • glucosides – scilliroside, scillirubroside • Action: convulsions, respiratory failure • Strychnine • Strychnosnux vomica (Loganiaceae) • Constituent: = alkaloid • Action: muscle contractions, death by asphyxia • Use: extermination of moles • toxic to others – not poison of choice

12. Coumarins • Naturally found in many plants • eg woodruff Galium odoratum (Rubacieae) • -> synthetic derivatives • Warfarin • Difenacoum • Bromadiolone • Chlorophacinone • Diphacinone • Flocoumafen • Pindone • Valone • Coumatetralyl • eg Brodifacoum ‘superwarfarin’ • long action; elimination half-life 20-130 days • Action: “thin the blood” • inhibit vitamin K epoxide reductase • enzyme that recycles oxidated vitamin K to its reduced form after it has participated in the carboxylation of several blood coagulation proteins, mainly prothrombin and factor VII • ↓ blood coagulation • animal dies from internal bleeding • dehydration early on so animal seeks water • Use: rat baits, also for rabbits and possums

14. Fungicides • Use: eg mildews • Neem • Garlic (onion, chive) • Peppermint oil • Cinnamon powder • Apple cider vinegar • Tea • Couch grass • Elder leaf • Cyperus rotundus • Sodium bicarbonate • Potassium bicarbonate • Diatomaceous earth • Bleaches / peroxide

15. Inorganic salts • Copper • Bordeaux mixture CuSO4/lime • Chestnut mixture CuSO4/NaCO3 – alkali varies • Use: fruit and vines • Action: • Cu2+ absorbed by spore drawing water in so it bursts • alkali helps CuSO4 to stick to leaf surface • (adhesion can also be improved with cotton seed oil) • Sulphur • as a dust or wettable powder, with lime • for copper-shy plants • Mercury • Seed dressing for monocots, certain turf diseases

16. Organic mercurials • wheat bunt Tillia caries • Dithiocarbamates • Thiram • wettable powder as insoluble • seed dressings, Botrytis sp (soft fruit) • low mammalian toxicity • Trichloromethylthiocompounds • Captan • apple scab Venturia inequalis • Quinones • Diclone, Chloranil • light sensitive • seed dressings for Brassica legumes • Nitro compounds • Dinocap, Dinitroorthocresol • apple, pear • highly phytotoxic • Chloronitrobenzenes • Quintozene, Technazine • dry rot – Fusidarium on potato – pretreat before winter storage • Quintozene – good soil fungicide for Rhizoctonia solani

17. Systemics: • Organophosphorous compounds • Triamphos • powdery mildew on roses • Kitzin • Japan paddy rice pest Pyricularia oryzae • Salicylanilide analogs • had been used in greenhouses for many years against tomato disease Clodosporium fulvan • had to modify structure to make it systemic for rusts and smuts • -> Carboxin, Oxycarboxin, Benomyl • Phosphorylated pyrimidines • Diazenon • Phenols • Chlorineb • good root protectors