Biology, asked by laisammavc19, 7 months ago

I need 5 points about the
decrease in useful pests how its affect plant health​

Answers

Answered by Anonymous
11

An excellent example of the effect of genetic change is the sterile pollen trait bred into most major corn varieties to aid in the production of hybrid seed. Plants containing Texas (T) cytoplasm transfer this male sterile trait via the cytoplasm; it is associated with a particular type of mitochondrion. Unknown to breeders, these mitochondria also carried vulnerability to a toxin produced by the pathogenic fungus Helminthosporium maydis. The result was the corn leaf blight epidemic in North America in the summer of 1970.

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Answered by Anonymous
2

Answer:

Although most insects grow and multiply in the crop they damage, certain grasshoppers are well-known exceptions. They can exist in a relatively harmless solitary phase for a number of years, during which time their numbers may increase. They then enter a gregarious phase, forming gigantic migratory swarms, which are transported by winds or flight for hundreds or thousands of miles. These swarms may completely destroy crops in an invaded region. The desert locust (Schistocerca gregaria) and migratory locust (Locusta migratoria) are two examples of this type of life cycle.

Medical significance

Insect damage to humans and livestock also may be direct or indirect. Direct human injury by insect stings and bites is of relatively minor importance, although swarms of biting flies and mosquitoes often make life almost intolerable, as do biting midges (sand flies) and salt-marsh mosquitoes. Persistent irritation by biting flies can cause deterioration in the health of cattle. Some blowflies, in addition to depositing their eggs in carcasses, also invade the tissue of living animals including humans, a condition known as myiasis. An example of an insect that causes this condition is the screwworm fly (Cochliomyia) of the southern United States and Central America. In many parts of the world, various blowflies infest the fleece and skin of sheep. This infestation, called sheep-strike, causes severe economic damage.

insects that affect human health

The human botfly (Dermatobia hominis), housefly (Musca domestica), tsetse fly (genus Glossina), assassin bug (family Reduviidae), yellow fever mosquito, and Anopheles mosquito are examples of insects that are of medical significance to humans.

Encyclopædia Britannica, Inc.

insect pests of cattle

The screwworm and horn fly (Haematobia irritans) are insect pests of cattle.

Encyclopædia Britannica, Inc.

Many major human diseases are produced by microorganisms conveyed by insects, which serve as vectors of pathogens. Malaria is caused by the protozoan Plasmodium, which spends part of its developmental cycle in Anopheles mosquitoes. Epidemic relapsing fever, caused by spirochetes, is transmitted by the louse Pediculus. Leishmaniasis, caused by the protozoan Leishmania, is carried by the sand fly Phlebotomus. Sleeping sickness in humans and a group of cattle diseases that are widespread in Africa and known as nagana are caused by protozoan trypanosomes transmitted by the bites of tsetse flies (Glossina). Under nonsanitary conditions the common housefly Musca can play an incidental role in the spread of human intestinal infections (e.g., typhoid, bacillary and amebic dysentery) by contamination of food. The tularemia bacillus can be spread by deerfly bites, the bubonic plague bacillus by fleas, and the epidemic typhus rickettsia by the louse Pediculus. Various mosquitoes spread viral diseases (e.g., several encephalitis diseases; dengue and yellow fever in humans and other animals).

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