Note: In most of this outline, one should consider "insecticide" to include "acaracide".
Acquired resistance to insecticides can and does develop -- Resistance to certain chlorinated hydrocarbons already a problem in certain areas.
ENVIRONMENTAL PROBLEMS --
Have been caused by widespread and indiscriminant use of insecticides. Rachel Carson - "Silent Spring". Federal Environment Pesticide Control Act (PEPCA) of 1972 administered by EPA controls distribuion, sale and use of insecticides throughout the entire U.S. and specifies the penalties that may be imposed the the misuse of pesticides. State governments may set stricter standards. Since all users are legally responsible, it behooves them to be fully informed by contacting the following for authoritative and detailed information on insecticides. State or extension veterinarian or similar authority must be especially aware of potential for adulteration of meat, eggs and milk intended for human consumption.\B\n
As a result of the tighted regulations and bans on chlorinated hydrocarbons - BALD EAGLES ARE BACK IN INDIANA IN 1994-95!!!!!
Insecticides are used --
Formulations have major influence on degree of toxicity, duration of action and convenience of application.
Organophosphorus compounds
Carbamates
Chlorinated hydrocarbons
Natural Products, e.g., Nicotinoids, pyrethroids, rotenoids.
Miscellaneous compounds, e.g., thiocyanates, nitrophenols, organofluorine compounds, sulfonates, sulfides, sulfones, fumigants, arsenicals, fluorides, mercurials.
Piperonyl butoxide (commonly used with pyrethrins)
Natural organic, e.g., petroleum products
Natural inorganic, e.g., dusts
Food attractants
Sex attractants (Pheromones)
The withdrawal of many chlorinated hydrocarbons from the market has increased the importance of this class of pesticides.
The residue (environmental and in animals) problems are nil, but these compounds are more acutely toxic than the chlorinated hydrocarbons being replaced. Moreover, there are long term (months) effects on some enzyme systems in animals not showing overt toxicity that may still cause deleterious reactions to other drugs, e.g. succinylcholine.
These drugs act by forming irreversible phosphoryl- acetyl-cholinesterase intermediates, thereby inactivating the enzyme that terminates neurotransmission at cholinergic junctions. This allows ACh released by nerve action potentials to accumulate at neuromuscular junctions, parasympathomimetic neuroeffectors, all autonomic ganglia and at cholinergic synapses in the CNS. The signs produced are predictable and are related to the degree of poisoning. Insect cholinesterases are more sensitive to the action of these drugs than mammals and toxicity to mammals is also controlled somewhat by decreasing bioavailability through manipulation of dose forms.
vary depending on the agent, dose, and individual sensitivity. SLUDD.
Salivation, muscle fasiculatious and tumors; vomiting and diarrhea; miosis followed by mydriasis; ataxia and convulsions.
massive i.v. and s.c. doses of atropine sulfate to effect, e.g. start with 0.5-1.0 mg i.v. and a smaller dose s.c. immediately
if early (2-24 hr) after exposure, try AChE regenerator - pralidoxime chloride
supportive therapy
Compounds used by essentially all of the methods listed earlier including pastes and gels applicable to the tongue as well in "flea collars"
More than 5 * 103 synthesized
Use a 3% dairy and livestock dust and in 1% concentration (plus 0.25% vapona; dichlorvos) in oil base for stock spray.
May be used on cattle (lactating and beef) for control of a variety of flies, some ticks, lice and chorioptic mage mites.
Should not be used for Brahman cattle nor regular application to calves less than 6 months of age. Brahman cattle are less sensitive to the other organophosphates listed here.
CO-RAL wettable powder (25%) is available for preparation of appropriate dilutions to be used for dipping or spraying to control cattle grubs, screwworms, flies, lice, keds, fleeceworms, etc.
CO-RAL is contraindicted for use in dairy goats during lactation and 14 days before parturition, on sick, convalescent, or stressed livestock, or on animals less than 3 months old. It must not be applied in conjunction with certain medications such as phenothiazine or other organophosphates, nor with pyrethrins.
Emulsifiable concentrate for control of fleas and ticks on dogs.
Wide variety of uses. May be applied to beef and lactating dairy cows or used as "scatterbait". Pest strips contains 18.6% dichlorvos. Flea collars for dogs - 9.3%; for cats - 4.65%. A flea medallion for dogs contains 18.6%. Flea collars are claimed to have 3 months duration of effectiveness. Other cholinesterase inhibitors should not be sued on animals with the collars. Dog fea collars should not be used on cats, whippets, or greyhounds. Contact dermatitis frequently occurs under the flea collars. Some animals are sufficiently sensitive that the collars can cause systemic effects, e.g., miosis. Simultaneous use of flea collars on several cats and a Shell pest strip in a small room caused organophosphate toxicity in one cattery.
Ronnel is among the least toxic organophosphates
Various formulations include ronnel.
for use in ruminants as spray or backrubbers, and as "scatter granules" and spot treatment of screwworm infestion and other cutaneous myiases.
in feed for grub control
as topical or systemic agent for control of ectoparasites in dogs and cats. Combined oral and topical treatment is claimed superior to either alone for some conditions.
combination of ronnel and dichlorvos for fleas, ticks, and lice on dogs.
See list on page 901, JBM5th
Act by acetylcholinesterase inhibition
Signs of intoxication similar to those of organophosphates; differentiate mainly on the basis of history of exposure to one or the other. The carbamates typically have a lower dermal toxicity than the organophosphates, but there are exceptions.
These are not "broad-spectrum" insecticides, e.g., houseflies and common cockroaches are less sensitive than rats.
Essentially the same as for organophosphates except NO AChE regenerator.Carbamates are reversible and pralidoxime may increase their toxicity.
Status in flux
Accumulate in environment
Accumulate in adipose tissues of animals and tissues of animals through food chain
Toxic to fish, crustaceans and causes thin egg shells in birds
Resistance developing to some
Symptomatic, pentobarbital or other anticonvulsant, e.g. calcium gluconate. Must remove unabsorbed toxin from skin and gut.
Fats in ration promote absorption and enhance toxicity.
Oral administration of activated charcoal is frequently recommended to absorb insecticide, but this is of doubtful efficacy. However, recent use of cholestyramine (an agent approved by FDA to lower cholesterol absorption) in treatment of KEPONE toxicity in man raises the possibility that it may be useful if economically feasable. Science 199(4331):893-5, 1978.
Try phenobarbital to induce hepatic microsomal oxidase system - enhance biotransformation and removal of insecticide
Epinephrine - BAD! May get fibrillation.
vary with compound.
\BChlorinated ethane derivatives\n
\B\fs<10.000>DDT\b - (use currently restricted) first synthesized in 1874, but not used as an insecticide till 1939. Probably one of the most effective synthetic insecticides. Low acute toxicity to animals, but accumulates in fatty tissues and may contribute to chronic disease although no definite casual link has been established. Does, however, accumulate in natural food chain where its estrogen-like activity interferes with such things as reproduction in birds. Also has acute toxicity in some low aquatic animals. Signs of acute toxicity primarily related to CNS excitation.
\B\fs<14.000>LINDANE (gamma isomer of cyclohexane; benzene hexachloride) The major member of group called the Hexachlorocyclohexanes that is used on animals.
Signs of toxicity resemble those produced by DDT. Primarily neurotoxicity manifested by tremors, ataxia, convulsions, prostration and increased respiration. Violent tonic and clonic convulsion may be seen in severe acute poisoning. Some isomers (beta and delta) that may occur in technical grades are CNS depressants. These compounds accumulate in fatty tissues and in cases of accidental poisoning, e.g. of dairy cattle food, disappearance from tissues and milk is very slow. Calves (less than 3 months old) are especially sensitive to lindane and one must not treat them with preparations intended for adult animals. Application of 5.1 mg lindane/kg BW to calves in a screwworm ointment has produced toxicity. Suckling pigs and lambs appear to be more resistant.
common / naive misconception
It is a common misconception that natural products are less toxic to mammals than those just covered. This is not true since the oral LD50 to rats of some commonly used agents place them in the highly or moderately toxic range: nicotine 10-60 mg/kg; Pyrethrum and rotenone 100-300 mg/kg. Therefore, you'd better wash that stuff from the garden and be careful applying it.
Toxicity related to effects on nicotinic cholinergic receptors. No application to animal pests.
(NOT TO BE CONFUSED WITH RONNEL
Derived from the tuber root of Derris elliptica, a legume.
Used by some tribes to paralyze fish.
Has fast knock-down action on all surface parasites, e.g. lice, scabies, fleas, but no persistence.
Local toxicity includes conjunctivitis, dermatitis, pharyngitis, and rhinitis. May produce gastrointestinal irritation, nausea and vomition after oral exposure.
Inhalation of dust more dangerous than above routes. May cause respiratory stimulation followed by depression with fits and convulsions.
May act by inhibiting oxidation of NADH2 to NAD. This reduces the availability of NAD to serve as a cofactor in many steps of the Krebs cycle, etc.
Major area of research in 1980's was to synthesize new compounds in this class. Very effective as insecticides.
Used since ancient times.
Derived from flowers of chrysanthemums.
Used in many commonly used preparations because of rapid "knockdown".
Since frequently not fatal in insect, usually combined with more toxic, slower-acting poisons.
15g of a concentrate p.o. has killed adult human. Death is due to respiratory failure. Contact dermatitis is a common occurrence that may rarely extend to anaphylactic-type reaction. Massive oral doses may cause signs of CNS excitation, convulsion and paralysis.
Some heavily used derivatives -- especially in anti-flea preparations.
Allethrin - a synthetic pyrethroid may produce less dermatitis.
Resmethrin
Allethrin
Fenvalerate
Permethrin
These drugs act by slowing closure of the excitable membrane ion channels opened during action potentials so that there are multiple action potentials.
Elemental sulfur (sublimed sulfur) and its preparations, the most common of which is "Lime-Sulfur" are frequently used to control ectoparasites. The mixture contains CaS2, CaS5 and CaS2O3.
Lime sulfur dip has been used to control psoroptic and chorioptic mange in sheep, cattle and horses as well as sarcoptic mange in the above plus swine and dogs. Animals must be dipped in 2% solution at about 100oF at weekly intervals till condition is controlled.
Various ointment preparations of sulfur have been prepared for small animal use.
should be to remove breeding grounds and food supplies. Also, increased use of natural enemies and such things as release of sterilized screwworm males are important in control programs.
Not act on juvenile hormone receptors.
Believed to disrupt CHITIN SYNTHESIS and DEPOSITION
Given po to dogs and cats q30days
Very lipophilic so accumulates in adipose tissues from which is released slowly to the blood
Adults ingest drug with blood and pass drug to egg via ovary.
Most eggs fail to hatch. Those few that do fail to develop, i.e., die in first molt.
binds to juvenile hormone receptor, but is not broken down by juvenile hormone esterases in insect larvae
Very stable in environment
Not affected by UV light
Not readily evaporate from site of application
Fleas - Ovicidal & larvacidal -- BASUS; ECTOGARD; IMPASS
Cockroaches -- TORUS
Fireants -- LOGIC
Pump sprays & inverted aerosol premise sprays
Available alone for flea preventative or in combination to kill adults
Good for flease -- ovicidal and larvacidal
OVITROL for dogs and cats (plus natural pyrethrin)
OVITROL FLEA -EGG COLLAR -- for extended activity in dogs and cats
SIPHOTROL -- with pyrethroid and chlorpyrifos for indoor dog and cat fleas
Growth regulator
Blocks formation of new cuticle
Only for "FILTH" flies (e.g., housefulies
Not survive molt from first to second instar
for dairy & beef cattle -- horn flies, face flies, stable flies, houseflies
Interferes with chitin deposition & prevents shedding of old skin leading to death of larvae or pupae
Prevents egg hatching
bolus releases drug over 5 mo period
80% eliminated in feces unchanges
MAY control fleas in dogs and cats for long period of time
Kill by inhibiting monoamine oxidase
Acaricidal
Good for cattle ticks, mange mites of swin and dogs
Good against pests that have developed resistance to organophosphates and carbamates
May act directly on vltage sensitive gates in nerve membrane (Campbell & Rew 1985)
MITABAN
approved for cattle, swine, dogs, US
NOT horses -- may cause fatal colon impaction
For generalized demodecosis
Collar for dogs -- Ticks for 4 months Collar enought amitraz to make dog ill if eaten
Oral LD50 rats -- 800 mg/kg
Dermal LD50 rabits -- >200 mg/kg
Appliy to skin of dog in 0.025% solution produces transient sedation, depression of rectal temperature & increases blood blucose
Well tolerated when fed at 0.25 mg/kg/d x 90 days
At 1-4 mg/kg hyperglycemia consistently observed
Sedation most fequent untoward effect