Insect-Insect Relationships, Biology tutorial

History of Insect-Insect Relationships:

Success in controlling the pests through marshalling advantageous insects to 'battle' them was first recorded in the year 1775. In that year, a report through the Swedish naturalist Peter Forskal told how the date growers of Yemen had been noticed to use one type of ant to kill the other which was destructive to the trees. 

The utilization of advantageous ants to protect orchards from insect pests has long been practiced in the Asiatic countries. A report of the year 1936 states citrus growers of south China put bamboo runways among the trees to help the ants in their movements from tree to tree. About a century passed after the publication of Forskal's report prior to pest-killing insects tested through bona fide scientists were transported from one country to the other. In the year 1873, a mite (or Tyroglyphus phylloxerae Riley) was shipped from the United States to France for the control of the grape phylloxerae. In the subsequent year the lady bird (or Coccinella undecimpuctata L) was proposed into New Zealand from England. A third insect Apanteles glomeratus L. a parasite of the cabbage worm was sent to the United States from England in the year 1883 and similarly proved successful. 

Nonetheless such efforts were scattered over 10 years and the true starting of the sustained biological control movement didn't come till l888 and 1889 when Albert Koebele traveled to Australia for the U.S. Department of Agriculture to protect natural enemies of the cottony cushion scale. At this moment of time this pest was killing so many big branches of citrus trees in California that the industry was threatened by extinction. Banks rejected to accept infested groves as collateral for the loans. 

Albert shipped back a few ladybirds (or genus Rodalia) that readily killed cottony cushion scale and thrived over the winter in the groves. Propagating, they rapidly reached sufficient numbers to check the pest and to this day their descendants - altogether by such propagated in the insectaries and released - have kept the scale beneath control. All told, the introduction of this insect probably didn't cost the government more than $5000 comprising the salaries of the scientists. 

For around 25 years, Koebele, the first of the entomological explorers, was engaged in importing the parasites. He worked for U. S. Department of Agriculture, then for the California State Board of Horticulture, and at last for the Hawaii Board of Agriculture and Forestry. Contemporary with him was George Compere of the California Board of Horticulture, who from year 1899 to 1901 traveled to the Far East and Australia in look for scale insect parasites and predators. Subsequent to this, from 1901 to 1904 he served the Government of West Australia in determining and importing parasites of fruit flies. So precious were his services that from the year 1904 to 1910, California and Australia employed him jointly. His quests for insects advantageous to crops took him all around the world. 

By the year l930, the imported parasites had put this pest out of the picture as an economic factor. They have most likely saved citrus growers more than $1,000,000 a year. Yet the net cost to the University of California for the search, importation and establishment of the advantageous parasites didn't surpass $10,000. On September 30, 1942, agricultural officials who were making a regular inspection of a peach orchard in the Southern California's Orange County found an insect larva which distinct from any they had heretofore collected. Whenever they recognized it as the oriental fruit moth, the State's financial entomologists and agricultural administrators were alarmed. They knew well that since 1915, if this moth was first discovered in the United States near Washington, D. C., it had built up a record of raising destructiveness to peaches. As a sign of the extent of its damage, in South Carolina it has rendered 12 % of the peaches unmarketable. In certain eastern orchards the losses to individual growers have reached 50 to 100%. 

As early as 1917 a native ichneumon 'flies', Macrocentrus ancy1ivorus, in realism a wasp, was noticed to be playing a significant part in the natural control of the moth in a limited region on the Atlantic coast. By the year 1929, this insect had clearly illustrated its worth from southern Connecticut to southern Virginia by destroying as high as 90 % of the larvae infesting the twigs.

A process for generating the advantageous parasites was successfully worked out, and in the year 1946, roughly 29 million of them were generated. Around 23 million were shipped to orchardists in 14 counties.

The other recent contribution of the Citrus Experiment Station had to do with the California red scale. For more than half a century, this scale, Aonidiella aurantii, had yearly wrought big damage on the trunks, branches and foliage of citrus trees. In some test orchards it was illustrated that it may be possible to decrease the infestation by means of two species of tiny wasps. These were the so named golden chalcid 'fly' and its relative from the China, Aphytis 'A'.

In describing this achievement, scientists freely let that many other projects have not been so successful and that the expenditure of them should be added to the cost of the successful ones. Nonetheless, they point out that the successes eclipse the failures lots of times over. Moreover, they desire to make it clear that their encouragement of the use of beneficial insects to destroy injurious ones doesn't imply that this process will supplant altogether the employment of insecticides. They warn instead in our enthusiasm for sprays and fumigants, we should not overlook the possibilities of utilizing potential pest-destroying insects.

Insect Predators:

Insect predators include around 10 percent of all insects. Predatory insects have striking adaptations for tracking, detecting, capturing and killing their prey. A few predatory insects utilize sit-and-wait tactics, others actively forage for their prey, and others employ lures to attract the unwary prey. Predatory insects are significant in biological control (example: lady bugs).

Predators catch and eat their prey. A few common predatory arthropods comprise ladybird beetles, carabid (ground) beetles, syrphid (hover) flies, staphylinid (rove) beetles, lacewings, minute pirate bugs, nabid bugs, big-eyed bugs and spiders.

Insect Parasitoids:

A parasitoid is the organism which spends an important part of its history of life joined to or in a single host organism in a relationship which is in essence parasitic; dissimilar a true parasite, though; it finally sterilizes or kills and at times consumes the host. Therefore parasitoids are identical to typical parasites apart from in the direr prognosis for the host.

Parasitoids (at times termed as parasites) don't generally eat their hosts directly. Adult parasitoids lay their eggs in, on, or close to their host insect. If the eggs hatch, the immature parasitoids employ the host as food. Most of the parasitoids are much small wasps and are not simply observed. Tachinid flies are the other group of parasitoids. They look similar to large houseflies and deposit their white, oval eggs on the backs of caterpillars and other pests. The eggs hatch, enter the host and kill it. Parasitoids frequently need a source of food in addition to their host insect, like pollen or nectar.

Parasitoids are the parasitic insects whose larvae build up by feeding in, or on, the bodies of the other host insects (termed as arthropods). The general suppositions about the interaction of the host and parasitoid species are as follows: 

1) Hosts which escape parasitism give mount to the subsequent generation of hosts. 

2) The fraction of hosts which are parasited is a function (to be specified) of the rate of encounter of the two species.

3) The next generation of parasitoids comes from the parasited hosts.  

Insects as Predators and Parasitoids:

I) Host/prey location and acceptance:

1) Random searchers roam in the suitable microhabitat and capture prey on the contact. Illustrations of microhabitats comprise veins, leaf edges, stems, flowers and so on.

  • After the initial contact or meal, further searching comprises more common turn resultant in the predator remaining in similar general location.
  • Random searchers are the most general kind of insect predator. 
  • Illustrations comprise most coleopteran coccinellids, predators, syrphid larvae and lacewings.

2) Hunting or directional foraging distinct from random searching by employing sight or other stimuli to orient to prey from the distance.

3) Ambush or 'lie-n-wait' predators remain in one place and hit at acceptable prey whenever they come in range.

4) Trappers are predators which build up traps in which to capture prey.

II)  Host/prey acceptance and manipulation:

1) Prey acceptance and manipulation through predators.

2) Host acceptance and manipulation by means of parasitoids.

3) Host immune responses.

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