Post on 11-Jan-2016
InsecticidesInsecticides
A Brief Overview of a Complex Subject
Modes of Entrance into Modes of Entrance into InsectInsect
Contact - dermal – through the skin
Stomach - oral – through the mouth
Respiration - inhalation through the nose or gills
Systemic - combination of above
Toxicity to humans or Toxicity to humans or nontarget organismsnontarget organisms
Most insecticides have the capacity to affect non-target organisms
Same as previously discussed Highly toxic – LD50 0 – 50 mg/kg
Moderately toxic - LD50 50 – 500 mg/kg
Low toxicity - LD50 500 – 5,000 mg/kg
Nontoxic - LD50 <5,000 mg/kg
Toxicity to insects Toxicity to insects natural enemiesnatural enemies
Most insecticides have the potential to affect populations of beneficial insects.
Toxicity to insects Toxicity to insects natural enemiesnatural enemies
Highly toxic - Pest populations recover much faster than enemy populations in nature
Toxicity to insects Toxicity to insects natural enemiesnatural enemies
Moderately toxic – Pest populations recover somewhat faster than enemy populations in treated environment
Toxicity to insects Toxicity to insects natural enemiesnatural enemies
Low toxicity – Natural enemies are maintained to a degree & quickly attack recovering pest populations
Toxicity to insects Toxicity to insects natural enemiesnatural enemies
Nontoxic – Normal enemy population levels are maintained which quickly attack recovering pest populations
Environmental hazardEnvironmental hazard
Environmental hazard of insecticides is generally evaluated as a function of persistence often compared to effectiveness
Environmental hazardEnvironmental hazard
High – Environmental persistence far greater than period of effectiveness (> 5 months and often > a year)
Environmental hazardEnvironmental hazard
Intermediate – Persists beyond effectiveness (3-5 month half-life)
Environmental hazardEnvironmental hazard
Low – Persists about the period of effectiveness (up to about 3 months) and then degrades completely over several months
Environmental hazardEnvironmental hazard
Very low – Persists for short periods (>45 days) and degrades completely
Resistance/Resurgence Resistance/Resurgence HazardHazard
The hazard of populations developing resistance and resurging is evaluated for most insecticides
Resistance/Resurgence Resistance/Resurgence HazardHazard
High – Strong potential to develop resistance and resurge
Resistance/Resurgence Resistance/Resurgence HazardHazard
Intermediate – Moderate potential to develop resistance in treated environments
Resistance/Resurgence Resistance/Resurgence HazardHazard
Low – Minimal potential to develop resistance
Resistance/Resurgence Resistance/Resurgence HazardHazard
None – No resistance developed, no resurgence after many treatments
InsecticidesInsecticides
OrganochlorinesOrganochlorines
•Also called the chlorinated hydrocarbon insecticides•Characterized by containing chlorine and carbon atoms•Powerful nerve poisons•Most affect a broad spectrum of non-target organisms along with the target pests•Long persistence and residual activity
OrganochlorinesOrganochlorines
Several were used in forestry DDT Lindane Dicofol (Kelthane) Endosulfan (Thiodan)
OrganophosphatesOrganophosphates
•Also known as the Ops• Characterized by containing carbon and phosphorus atoms• Generally only short term persistence and limited residual activity• Unfortunately, often have broad spectrum activity against beneficial insects
OrganophosphatesOrganophosphates
Several used in forestry or applied to forests for public health purposes
Malthion (Malathion and Cythion) Acephate (Orthene) Methyl parathion (Methyl parathion) Diazinon (Diazinon and Spectracide) Chlorpyrifos (Dursban and Lorsban) Azinphos methyl (Guthion)
OrganosulfursOrganosulfurs
•Small group of sulfur containing insecticides•Low insect toxicity, but with good miticidal characteristics
CarbamatesCarbamates
•Insecticides which are derivatives of carbamic acid•Non-target toxicity is chemical specific, ranging from low to very high• Generally only short term persistence and limited residual activity• Often with broad spectrum activity against beneficial insects
CarbamatesCarbamates
Very few used in forestry Carbaryl (Sevin) Aldicarb (Temik) Methomyl (Lannate)
BotanicalsBotanicals
•Chemicals extracted or derived from plants •May be present and subsequently extracted from the plant material (a constitutive chemical), or• May be activated in the plant as a response to insect activity (inducible chemicals)
BotanicalsBotanicals
•Some are chemically modified after extraction to enhance their insecticidal properties
BotanicalsBotanicals
Pyrethrins Retenone Ryaia
BotanicalsBotanicals
Pyrethrins
1. Very toxic to cooled blooded animals, some peoples and cats.
2. Very effective on most insects.3. it rapidly breaks down in
sunlight, air and water.
BotanicalsBotanicals
Retenone1. Derived from the roots of over 68
plant species and is very toxic to fish, pigs, and cool blooded animals
2. Used to control leaf eating caterpillars and beetles
3. Direct contact may cause skin and mucus membranes irritation.
BotanicalsBotanicals
Ryaia1. Botanical insecticides made from
the ground stem of Ryana speciosa
2. Is highly toxic to the fruit moths, and citrus thrips
Nicotine Nicotine
• Nicotine a plant defense alkaloid • Nicotine is a fast acting contact killer
for soft bodies but does not kill most chewing insects.
• Concentrate is very poisons if inhaled.• Highly toxic to warm blooded animals.• Pale yellow to dark brown liquid.
NicotineNicotine
• The effectiveness is similar that of organophosphorous compounds
• Nicotine inhibits the function of acetylcholine receptors located at the neuromuscular junctions.
• Nicotine is highly lipophilic and can pass through dermal tissues as well as the blood brain barrier.
Essential oilsEssential oils
Some plants also produce essential oils in specialized gland cells:-
1. Peppermint oil( (زيت روح النعناعcontrol of household pests such as cockroaches and ants.
2. Clove oil((كبش قرنفلinhibit soil born fungal disease.
3. Citrus oil control of flea, aphid and mites4. Lavender oil insect repellent.5. Thyme oil6. Rosemary oil 7. Cedar oil--
Microbial PathogensMicrobial Pathogens
•Fungi, bacteria, viruses, etc. which can be used to cause disease in an insect population•Relatively narrow spectrum of activity, not broad spectrum insecticides•Several have been genetically engineered to kill target insects more rapidly
Microbial PathogensMicrobial Pathogens
Bacillus thuringiensisBacillus SphaericusBaculovirus
RepellantsRepellants
•Large group of unrelated chemicals•Many experimental chemicals – but to the present no truly effective forest protectant chemical•Mostly have found use for people or livestock protection
RepellantsRepellants
Repellent for foliage feeders (مواد طاردة للحشرات التي تتغذى على االوراق النباتية)Such as:-• bordeaux mixture (copper sulfate, hydrate lime, water)Repelles of beetles and grasshoppersCopper ions affect enzymes in the fungal spores
in such a way as to prevent germination.
RepellantsRepellants
Repellents for crawling insectالمواد الطاردة للحشرات الزاحفة Such as:- • Cresol ( organic compound, used as
disinfectants)• Trichlorobenzene (effect for along time, repelled
white ants)
Repellents to fabric eating insectsالمواد الطاردة للحشرات التي تتغذى على المواد
المصنعة
RepellantsRepellants
repellents to blood sucking insectsSuch as:-• Dimethyl phthalate ( anopheles, aedes,
culex)• 2-Ethyl-1.3- hexonediol ( house fly,
mosquito, flea)• DEET( applied to skin and cloths and is used
to repel mosquitoes)• Citronella oil ( personal insect repellents
such as mosquito)• Oil of lemon Eucalyptus ( active against
mosquito)
الشروط الواجب توافرها في المواد الطاردةالشروط الواجب توافرها في المواد الطاردة
ان التسبب حساسية لجلد االنسان و الحيوان -1اال ينتج عن استعمالها رائحة غير مقبولة و ان ال يكون لها -2
تاثير على المالبسان تعطي حماية لمدة طويلة بتركيزات منخفضة -3
ان تكون رخيصة الثمن و يمكن الحصول عليها بسهولة -4اال يكون لها تأثير سام على االنسان و الحيوان -5
ان يبقى مفعولها لمدة طويلة -6يجب ان يكون لها تاثير طارد النواع عديدة من الحشرات -7 يجب ان ال يفقد مفعولها بسرعة بواسطة عرق االنسان-8
FumigantsFumigants
•Fumigants generally contain a halogen (chlorine, bromine, fluorine, etc.) in their molecules•Small molecules which vaporize at relatively low temperatures
FumigantsFumigants
Methyl bromide Dichloropropene Chloropicrin Metam-sodium
Transgenic Crops with Transgenic Crops with Insecticidal PropertiesInsecticidal Properties
Plants genetically engineered to enhance insecticidal properties
Pheromones
Pheromones(chemical used for communication within species)
Chemical signal that triggers a natural response in another member of the same speciesBehavioral chemicals = semiochemicals
• Sex PheromonesAre released by either one( mainly the female) or both genders
for the purpose of mate attraction• Aggregation pheromonesFunction in defense against predator, mate selection
and overcoming host resistance by mass attack• Alarm phrmones Some species release a volatile substance when
attacked by predator that can trigger flight ( in aphid)
Pheromones
• Trail pheromonesAre common in social, for example ants make their
paths with these pheromones which are non volatile hydrocarbones
• Releaser pheromones Are powerfull attraction molecules that some
insects may use to attract males from a distance of two miles or more
Pheromones
بدا المختصون في استخدام الفرمونات و خاصة الجنسية منها للحد من اضرار الحشرات حيث
تم انتاج مركبات شبيهة بالفرمونات و قد نجحت بعض التطبيقات الحقلية باستخدام
الفرمونات المصنعة للتقليل من اضرار بعض الحشرات كدودة جوز القطن القرنفلية و يمكن
استخدام الفرمونات المصنعة او الطبية في مقاومة الحشرات بتوجيه افراد االفات الى
.مصائد تحتوي على مواد سامة