Fw: [News-Australia] Super rats high on poison invade Sydney

See the news item below. They are as big as cats, so I heard. And of 
course there are the two-legged rats there, being prolific in a place 
like Sydney.



The usual cumulative poison in modern (from 1948) rat baits, combined 
with an attractant and dyed blue-green to make them less attractive to 
birds, used to be warfarin ((RS)-4-hydroxy- 3-(3- oxo- 1-phenylbutyl)- 2H- chromen- 2-one),
 an anti-coagulant (still used medically in small amounts to prevent 
blood clots in thrombosis and phlebitis cases) derived from coumarin, 
until rats resistant to it began to appear; see http://en.wikipedia.org/wiki/Warfarin . Its molecular structure is at http://upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Warfarin.svg/220px-Warfarin.svg.png . 



It is still used for this purpose, although more potent poisons such as brodifacoum , which is now the most common poison used, have since been developed, see http://en.wikipedia.org/wiki/Brodifacoum .
 The chemical structure of brodifacoum is similar to that of warfarin, 
except that it has a much larger aromatic side-chain on the 
4-hydroxy-coumarin base structure, and this side-chain also has a 
bromine atom, see http://upload.wikimedia.org/wikipedia/commons/thumb/d/d7/Brodifacoum.svg/200px-Brodifacoum.svg..png
 , which makes it extremely toxic and much less biodegradable, although 
less volatile and water-soluble; but at the same time much costlier to 
synthesize than warfarin. As the result of the added bromine atom, 
brodifacoum has an especially long half-life in the body, up to several 
months, requiring prolonged treatment with antidotal vitamin K
 for both human and pet poisonings. Secondary poisonings of predators 
that eat several poisoned rat carcases can occur due to 
the extreme persistence of brodifacoum in both target and 
non-target species. It may also be dispersed by insects that feed on 
poisoned bait without harm and retain the poison within their bodies.



But if rats resistant to brodifacoum as well as warfarin also begin 
appearing, as the article below says, what alternative poisons could be 
used?



An obvious choice of another fairly easily-produced synthetic pesticide 
would be "1080", sodium monofluoroacetate, which is used in New Zealand 
against the introduced Australian brushtail opossum, mostly in aerial 
drops in bush areas too remote or rugged for trapping or shooting or use
 of instant-kill cyanide paste for recovery of the pelts; see http://en.wikipedia.org/wiki/Sodium_fluoroacetate
 . It is easily produced by reacting sodium monochloroacetate with 
potassium fluoride. Fluoroacetate is toxic to all aerobic species and 
highly toxic to mammals and insects, and unlike brodifacoum, very 
water-soluble and much more readily biodegradable. However, 
weight-for-weight, it is about 50 times less toxic than brodifacoum, for
 a lethal dose, and some marsupial species from the southwest of West 
Australia are resistant to it. It can also be used against rabbits, 
wildcats, feral dogs, stoats, wild pigs and similar. The effectiveness 
of sodium fluoroacetate as a rodenticide was first reported in 1942; and
 the Wikipedia article mentions its use as a rodenticide in Mexico, 
Japan, and Israel, so it could substitute for brodifacoum. It is also 
toxic to insects, but a very low risk to fish and reptiles. Secondary 
poisoning of wildcats and stoats that scavenge poisoned opossum or 
rabbit carcases following 1080 operations is common. New Zealand is the largest 
user of sodium fluoroacetate, mostly by DOC.



Arsenic (see http://en.wikipedia.org/wiki/Arsenic
 ) used to be used as a cumulative pesticide for all pest species, 
including insects and bacteria, mostly as lead arsenate and the oxide; 
but its limited supply in ores, and now its important uses in 
semiconductors, alloys, and Tanalin wood preservative (copper 
chromate-arsenate), have made it much too valuable for that. It is also 
too slow in its action, and leaves insoluble residues that can never be 
biodegraded.



Strychnine and brucine, alkaloids derived from the seeds of Strychnos 
species (mostly native to Indonesia and Philippines), have long been 
used as rodenticides, being instantly-acting and much more poisonous to 
rats than brodifacoum; see http://en.wikipedia.org/wiki/Strychnine . However, only limited supplies of Strychnos seeds are available, and strychnine/brucine cannot be economically synthesized.



Potassium or sodium cyanide are used in jams or pastes for killing 
opossums in New Zealand, where instant kill is desired for recovery of 
the pelts, and have been used in baits for other pests such as rats and 
insects, being instantly lethal to many species, although they are about
 10 times less toxic than brodifacoum. They are fairly readily 
synthesized. However, these cyanides are water-soluble, and liable to be
 hydrolyzed in acid conditions to either cyanogen or hydrogen cyanide 
(prussic acid), which being very volatile can kill by inhalation in a 
similar manner to carbon monoxide. Because of this, a licence is 
required to store, handle and use cyanide in New Zealand.



White phosphorus, usually dispersed in a jam or paste, has also been 
used as a pestidide, mainly for opossums, due to to its liver toxicity, 
with about the same lethality as that of brodifacoum. However, it has 
largely gone out of use because it is spontaneously inflammable on 
exposure to air in the absence of liquid; see http://en.wikipedia.org/wiki/White_phosphorus 





John W.



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http://nz.news.yahoo.com/a/-/mp/13816809/super-rats-high-on-poison-invade-sydney/




		
		
		
Super rats high on poison invade Sydney

		
		
		Yahoo! New Zealand

	
		May 30, 2012, 2:37 pm

	
	


		
		  


    
		
		
		
	

	
		
		
		

	
	

	
	
			
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A new breed of rodents dubbed 'super rats' has overrun one of Australia's biggest cities.
The
 Daily Telegraph reports the creatures are too clever to be caught with 
conventional traps and are immune to most commercially-available poison. They
 are reportedly also intelligent enough to steal the food out of traps 
without setting them off, making them a big problem across Sydney.
Australian Museum naturalist Martin Robinson told The Daily Telegraph the rats aren't just immune to bait, they thrive on it. "A
 lot of suburban rats have been baited for as long as Sydney has been 
settled, so many populations have become immune to those baits.".
According to Robinson, there's only one way to get rid of the creatures which are dirtier than cockroaches.. Bacon
 rind or anchovies are attached to the trap and tied down with 
fuse-wire. This ensures the rodents can't escape without springing the 
catch.
Colonies of rats are known to be well-established in Hyde 
Park, but an increases in rat infestations have been reported in 
Cronulla, Brighton Le Sands, Rose Bay, Bellevue Hill, Surry Hills and 
Paddington...
Like most other unwanted visitors, cold weather conditions push rats indoors.



[Non-text portions of this message have been removed]



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