Effects Of Pesticides On Ecosystems Guided by – Dr Shweta Patwardhan

Pesticides:The Food and Agriculture Organization (FAO) has

defined pesticide as:any substance or mixture of substances intended for

preventing, destroying, or controlling any pest, including vectors of human or animal disease,

unwanted species of plants or animals, causing harm during or otherwise interfering with the production, processing, storage, transport, or marketing of food,

agricultural commodities, wood and wood products or animal feedstuffs, or substances that may be

administered to animals for the control of insects, arachnids, or other pests in or on their bodies. The

term includes substances intended for use as a plant growth regulator, defoliant, desiccant, or agent for

thinning fruit or preventing the premature fall of fruit. Also used as substances applied to crops either before

or after harvest to protect the commodity from deterioration during storage and transport.

Different Pesticide Products

Classification Of Pesticides:

Target Pest Group: e.g., herbicides, insecticides, fungicides, rodenticides, and pediculicides.

Chemical structure: e.g., organic, inorganic, synthetic, or biological (biopesticide)and physical state e.g. gaseous (fumigant).

Plant derived or Botanicals:   pyrethroids, rotenoids,nicotinoids.

Herbicides Rodenticide

Botanical

Effects On Ecosystems:  Over 98% of sprayed insecticides and 95% of herbicides reach a

destination other than their target species, including non-target species, air, water and soil.

 Pesticide drift occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them. Pesticides are one of the causes of water pollution, and some pesticides are persistent organic pollutants and contribute to soil contamination.

 Pesticide use reduces biodiversity, reduces nitrogen fixation, contributes to pollinator decline, destroys habitat (especially for birds) and threatens endangered species.

 Chlorinated hydrocarbon pesticides dissolve in fats and are not excreted, organisms tend to retain them almost indefinitely. Biological magnification is the process whereby these chlorinated hydrocarbons are more concentrated at each level of the food chain. Among marine animals, pesticide concentrations are higher in carnivorous fishes, and even more so in the fish-eating birds and mammals at the top of the ecological pyramid.

Water pollution

Effects On Ecosystems:  Global distillation is the process whereby pesticides are

transported from warmer to colder regions of the Earth, in particular the Poles and mountain tops. Pesticides that evaporate into the atmosphere at relatively high temperature can be carried considerable distances by the wind to an area of lower temperature, where they condense and are carried back to the ground in rain or snow.

Pesticides also affect animal health in the following ways:

Cattle readily eat arsenic compounds. They will eat grass sprayed with monosodium methanearsonic acid (MSMA). Arsenic damages small blood vessels, which affects the blood supply, to major organs. Membranes of  the digestive tract are inflamed causing diarrhoea, abdominal pain, thirst, weakness and collapse.

Organochlorine insecticides include DDT, lindane, toxaphene, and heptachlor. Residues can build up in the fat of livestock. Toxicity to livestock resulted from effects on the nervous system. Muscle tremors and twitches, seizures, and unusual behaviour were signs of poisoning. Death is caused by respiratory failure during sustained seizures and/or high body temperature.

Ingestion of concentrate or forages recently sprayed at rate of 12 pounds per acre with sodium chlorate herbicide is likely to cause fatal poisoning. The toxic action is oxidization of  haemoglobin in red blood cell producing a brown pigment called methemoglobin. Red blood cells are destroyed, the blood, muscles, and urine are brown and inflammation of the intestines causes diarrhoea.

Arsenic poisoning in cattle

Methaemoglobinemia lesions

Pesticides also affect animal health in the following ways:Pesticides may impact wildlife through secondary poisoning

when an animal consumes prey species that contain pesticide residues. Examples of secondary poisoning are birds of prey becoming sick after feeding on an animal that is dead or dying from acute exposure to a pesticide, and the accumulation and movement of persistent chemicals in wildlife food chains.

Toxic levels of carbamate insecticides like methomyl and carbofuran can cause seizures and respiratory arrest in dogs. Organophosphate toxicity, meanwhile, may lead to chronic anorexia, muscle weakness and muscle twitching which may last for days or even weeks.

Poisoning in wildlife

Poisoning in pets

Elimination Of Pesticides:

Manual removal of weeds.Covering weeds with plastic.Placing traps and lures for pests like rodents.Removing pest breeding sites.Maintaining healthy soils that breed healthy, more resistant

plants.Cropping native species that are naturally more resistant to

native pests.Supporting biocontrol agents such as birds and other pest

predators.Biotechnology can also be an innovative way to control

pests.

Manual Weeding

Pest Traps

Eliminating Pest Breeding Sites

Biocontrol Agents

THANK YOU!!!