Transcript S2 L4 Molluscicides rodenticides fungicides

S2 L4 Molluscicides,
rodenticicides, fungicides
Anna Drew
http://curriculum.toxicology.wikispaces.net/2.1.16+Phar
macognosy
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
http://www.wellcome.ac.uk/en/labnotes5/animation_popups/schisto.html
• Over 1000 plant species tested for molluscicidal
activity 1980-1995
• Wide range showed promise
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Leguminosae
Araliaceae
Compositae
Liliaceae
• Features
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available in sufficient quantity
capable of easy propogation in region required
water soluble active constitiuents
easily extracted
high toxicity for molluscs; low for humans
• 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
• 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
• 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
• 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
• Metaldehyde
• Metal salts
– iron III phosphate
– aluminium sulphate
(alum)
– cyclic oligomer of
acetaldehyde
– slugs, snails
• Acetylcholinesterase
inhibitors
– contact
• Diatomaceous earth
Rodenticides
• Red squill
• Urginea maritima (Liliaceae)
• Constituents:
– cardioactive glycosides
– glucosides – scilliroside, scillirubroside
• Action: convulsions, respiratory failure
• Strychnine
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Strychnos nux vomica (Loganiaceae)
Constituent: = alkaloid
Action: muscle contractions, death by asphyxia
Use: extermination of moles
– toxic to others – not poison of choice
• Coumarins
• Naturally found in many plants
– eg woodruff Galium odoratum (Rubacieae)
• -> synthetic derivatives
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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
Fungicides
• Use: eg mildews
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Neem
Garlic (onion, chive)
Peppermint oil
Cinnamon powder
Apple cider vinegar
Tea
Couch grass
Elder leaf
Cyperus rotundus
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Sodium bicarbonate
Potassium bicarbonate
Diatomaceous earth
Bleaches / peroxide
• 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
• 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
• 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