Tuesday, May 21, 2019

Pesticides, its merits, demerits, causes and alternatives



                    WHAT ARE PESTICIDES, ITS DEFINITION?







Pesticides are chemical substances that are meant to kill pests. In general, a pesticide is a chemical or a biological agent such as a virus, bacterium, antimicrobial, or disinfectant that deters, incapacitates, kills, pests.




The most common of these are herbicides which account for approximately 80% of all pesticide use. Most pesticides are intended to serve as plant protection products (also known as crop protection products), which in general, protect plants from weeds, fungi, or insects.




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 and 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, arachnids, or archer pests in or on their bodies.



ORIGIN OF THE WORD PESTICIDES:

Since before 2000BC, humans have utilized Pesticides to protect their crops. The first known pesticides was elemental Sulphur dusting used in ancient Sumer about 4500years ago in ancient Mesopotamia.
Ancient Sumerians used elemental Sulphur to protect their crops from insects, whereas Medival farmers experimented with Chemical using arsenic, lead on common crops.
In 1939DICHLORO-DIPHENYLE-TRICHLORO-ETHANE(DDT) WAS DISCOVERED, WHICH HAS become extremely effective and rapidly used as the insecticide in the World. However 23 years later due to biological effects and human safety, DDT has been banned in almost 86 countries.


TYPES OF PESTICIDES:

There are many different types of pesticides, each is meant to be effective against specific pests. The term "-cide" comes from the Latin word "to kill."



The most commonly applied pesticides are:
1.   Insecticides to kill insects,
2.   Herbicides to kill weeds,
3.   Rodenticides to kill rodents and
4.   Fungicides to control fungi, mold, mildew etc.



THESE ARE GROUPED ACCORDING TO THE TYPES OF PESTS THEY KILL, WHICH ARE AS FOLLLOWS:
1.   INSECTICIDES—INSECTS
2.   HERBICIDES—PLANTS
3.   RODENTICIDES----RODENTS(RATS & MICE)
4.   BACTERICIDES---BACTERIA
5.   FUNGICIDES---FUNGI
6.   LARVICIDES---LARVAE
7.   BIODEGRADABLE---THIS KIND IS THOSE WHICH CAN BE BROKEN DOWN BY MICROBES AND OTHER LIVING BEINGS INTO HARMLESS COMPOUNDS
8.   PERSISTENT—THESE ARE ONE THOSE WHICH MAY TAKE MONTHS OR YEARS TO BREAK-DOWN
9.   CHEMICALLY-RELATED PESTICIDES----E.G.—ORGANOPHOSPHATE---THEY EFFECT THE NERVOUS SYSTEM BY DISRUPTING THE ENZYME THAT REGULATES A NEUROTRANSMITTER.






EFFECTS, MERITS AND DEMERITS OR EFFECTS, ADVANTAGES AND DISADVANTAGES:



EFFECTS:
1.   Pesticides are poisonous and unfortunately they can harm more than just “pest” at which they are targeted.
2.   They are toxic and exposure to pesticides cannot only cause a number of health effects, but is linked to a range of serious illness and diseases in humans, from respiratory problems to cancer.

3.   Acute health problems may occur in workers that handle pesticides such as abdominal pain, dizziness, headache, nausea, vomiting, as well as skin and eye problems.

4.  Also has harmful effect to environment and soil.

5.   It has long term impact on environment and pollution.






                                              








                                    ADVANTAGES:


1.   With the use of pesticides more crops grow on our land so that we can gain more from exporting our produce to other countries.

2.   New types of pesticides makes the use of herbicides or fertilizers possible and there is no damage to the crops.


3.   To improve crop quality and supply and greatly improved Human Health around the World.

4.   Pesticides improve crop production and harvest productivity.

5.   Pesticides also prevent diseases found in fresh fruits and vegetables as well.

6.   Chemical pesticides now go through thorough and expensive test before Government Registration and release.

7.   Pesticides have been linked with human health hazards, from short-term impacts such as headaches and nausea to chronic impacts like cancer, reproductive harm.

8.   The use of these also decreases the general bio-diversity in the soil. If there are no chemicals in the soil there is a higher soil quality and this allows for higher water retention, which is necessary for plants to grow.

9.   Controlling pests and plant disease vectors.

10.               Controlling human/livestock disease vectors and nuisance organisms.

11.               Controlling organisms that harm other human activities and structures.

                                 DISADVANTAGES:

1.   They are able to restrain pests, but it can also kill other organisms as well.

2.   Not only they can affect animals but they can effect humans.
3.   A pesticide is a biological, physical or chemical agent used to kill plants or animals that are harmful to people.
4.    The main disadvantage of pesticides is that they are very hazardous to our health if used incorrectly.



5.   Health being threatened by the continuous use of pesticides that are known health hazards.
6.   Another disadvantage is that pesticides can be cause for cancer for anyone who are often exposed to pesticides.
7.   Chemical could also cause birth defects.
8.   Accidental inhalation, on the job.
9.   Cause a number of pollution problems through spray drift on to surrounding areas direct contamination of users or the public and as residues on food.
10.               The WHO estimated in 1999 that 20,000 people die annually world-wide from pesticides poisoning incident.
11.               Effects of pesticides residues in foods, especially for infants, whose system have weaker resistance levels to poisons.
 levels to poisons.





CAUSES:

PEOPLE CAN EXPERIENCE UNINTENTIONAL PESTICIDES EXPOSURES IN A NUMBER OF WAYS INCLUDING:-

1.   Not following label safety instructions when using pesticides. Wearing rubber gloves and protective eyewear can prevent over-exposure.

2.   Applying too much pesticides product.

3.   Applying pesticide products in breezy conditions.

4.   Improperly using a pesticide e.g. staying in rooms where foggers are used or using outdoor use products inside your house.

5.   Storing pesticides in an unsecured place that children and pets can access.

6.   Accidental exposure such as spills.

7.   Not wearing recommended personal protective equipments (e.g. rubber gloves, protective eyewear, long pants, long sleeved shirts).

8.   Equipment malfunction.

9.   Post-application exposure from a treated area.

10.               Accidental exposure from aerial treatment or spray drift.

11.               Pets, domestic animals and wildlife (such as mammals, birds, fish, insects and plants) can experience unintentional exposure to pesticides.

12.               The environment (air, soil and water) can be contaminated by pesticides overuse.



                                ALTERNATIVES TO PESTICIDES:

1.   BY C PLANTING: maggots prefer radishes over corn and tomato, worms prefer dill over tomatoes. Therefore certain plants can be strategically placed so that they lure harmful insects away from plants you wish to protect. These are commonly referred to as “trap plants”.
2.   BIOLOGICAL CONTROLS: use of larger natural predators include the use of birds and other insects. E.g. in a small town in Michigan, cockroaches became so plentiful that they were coming home in student’s lunch boxes. Michigan state passed laws requiring schools to seek alternatives to chemical pest. According to De Fazio, Allegari’s school system became the 1st in the Country to eliminate pesticides in favour of biological controls. Now the cockroaches in Allegar School district are dined on by tiny wasp parasitoids and attacked by nematodes placed in strategic locations throughout the school. These wasp are the size of a pinhead and when we consistently apply and manage the biological controls, they work. The little predators were so hungry soon the cockroaches all disappeared.
3.   BACTERIAL PREDATORS: ONE OF THE MOST COMMONLY USED BACTERIAL SPECIES IS bt/Bacillies thurigensis. At sporulation, the bacterium produces a spore and a protein crystal which releases powerful toxins when degraded by the gut fluids in larvae consuming it; death can occur in 30 minutes to 3 days. Timing has to be right—larvae must be feeding on leaves treated with spores. Doesn’t work with adults not feeding on leaves.
4.   VIRUSES: 1600 virus isolates which can cause disease in 1100 species of insects. i.e. a peptide hormone was isolated and incorporated into a baculovirus. The peptide was active in preventing larvae feeding and causing mortality among corn earworm larvae.
5.   FUNGI: fungi control involves the use of another non-pathogenic fungus. Unchecked, wilt fungi waste little time invading a plant through its roots and xylem, or vascular water supply system. The pathogens use the xylem as a conduit to spread and grow in the plant, causing blockages and stealing vital nutrients. Such assaults can exact a heavy toll on yield. The protect out microbes colonize the root system better than their pathogenic brethren. They live on and in the vicinity of the roots, as well as just inside the roots’ epidermis, or outer cell layer. There they crowd out the competing pathogens for sugars, amino acids and other nutrients both need in order to flourish but the good fungi don’t cause disease and they are not fungal freeloaders. Helping plants to help themselves. Scientist named the phenomenon induced systemic resistance. In greenhouse studies, Fravel and Larkin observed the response in tomatoes, muskmelons and watermelons. ‘induced systemic resistance’ might be likened to the immune response of a child vaccinated against a germ-caused disease. As part of treatment, a doctor administers a weakened form/strain of the germ to the young patient.
6.   NEMATODES: they are simple worms consisting of an elongated stomach and reproduction system inside a resistant outer cuticle. Mostly nematodes are so small between 400 micrometers to 5mm long. Their small size, resistant cuticle and ability to adapt to severe and changing environments have made nematodes one of the most abundant types of animals on earth; most of the nematodes feed on bacteria, fungi and other soil organisms. Other are parasitic, obtaining their food from animals (such as the dog heartworm), humans (such as the pinworm) and plants. Agricultural cultivation encourages an increase in parasitic nematodes that feed on the crops being grown.
7.   PHEROMONES: THESE SYNTHESIZED CHEMICALS act to attract the opposite sex into bags/traps. Insects of the same species can communicate with one another by releasing small quantities of chemical substances from their bodies into the air. These distinct ‘scents’ which are called pheromones, will attract others to the source of that attraction. As a result it is now possible to communicate with certain insects by using these synthesized pheromones enabling us to attract them, or disrupt them from their normal behaviour.
8.   JUVENILE HORMONES: Anti juvenile and juvenile hormones mess up the moulting cycles of insects.
9.   BOLL WEEVIL: common name for a destructive beetle that infests cotton plants. The adult insect has a long snout, is grayish in colour, and is usually less then 6mm(less than 0.24 in) long. Feeding only on the cotton plant, it begins in early spring to puncture the buds and bolls and lay its eggs in them. The eggs hatch into larvae in 3 to 5 days. The life cycle of the boll weevil from egg to egg laying adults is about 3 weeks. 4 or 5 generations may breed in one season.
10.               SUSTAINABLE FARMING WORK/AGRICULTURE:

                     CULTURAL METHODS:

1.   Rotating crops to decrease weeds and insects while also increasing soil nitrogen and decreasing soil loss.

2.   Burning infested crop residues to kill off eggs instead of tilling back into earth.

3.   Planting crops at times that conflict with pest emergence.

4.   Mixed crops—plant crops with horizontal v/s vertical leaves so pests can move readily or mixed crops which appeal to limited insect tastes so not one species can grow quickly.

THESE TECHNIQUES REQUIRE MORE KNOWLEDGE, MORE LABOUR.





NATURAL AND ARTIFICIAL PESTICIDES:


Natural techniques involving compounds made with the roots of tropical vegetables and chrysanthemums.

Types of Natural Pesticides:
a. Fungicides
b. Herbicides
c. Insecticides











    Artificial Pesticides-Arsenic and mercury compounds to control body lice and other pesticides. Oil, ash, sulphur and other materials to protect their livestock and their crops from various pesticides.

Artificial or Specific Synthetic Chemical pesticides are:
a. Glyphosate
b. Acephate
c. Deet
d. Propoxur
e. Metaldehyde
f. Boric acid
g. Diazinon
h. Dursban
I. DDT
j. Malathion



















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