Entomology: The Study of Insects and their Relatives
Insects and their terrestrial relatives belong to the phylum called Arthropoda and have inhabited the earth for an extensive time. Paleontologists show that the earliest fossils, most primitive forms of arthropods date back to the Devonian Period over 350 million years ago (Henning 1981). By the Age of Dinosaurs, 300 million years ago, insects were abundant in number and diversity. Like the dinosaurs, some pre-historic forms of insects were enormous: the dragonfly Meganeuropsis had a wing span of 35 inches, and the giant Mesozoic relatives of the scorpions, the eurypterids, measured over 6 feet in length (Borror and others 1992).
The origins and evolution of insects and related groups is complex. Insects themselves may have descended from the many-legged animals that were similar to present-day centipedes. The functional effectiveness of six-legs was decided early, for it is a constant feature among orders of insects. Wings must have also given considerable advantage to even the earliest insects, which dominated the air millions of years before flying reptiles, birds, and bats. Insects took advantage of multiple developmental stages, metamorphosis, to further diversify occupying many niches and thus increase their chances for survival. All these characteristics contributed to the overriding success of insects as a group: today insect species outnumber those in all other living groups combined (Borror and others 1992).
How Do Insects Interact with Humans
People benefit from insects in many ways, without them, human society could not exist in its present form. In contrast, many insects are destructive, and truly quite obnoxious. Most people are aware of the injurious insects and their effects than they are of the beneficial insects. The destructiveness of these creatures normally hides their beneficial aspects. The many roles that insects play, friend or foe, have an importance in our lives.
The sexual reproduction in flowering plants is made possible by pollination, a process that requires intricate relationship of plant and its pollinator. This process involves the transfer of pollen grains, the male germ cells, from the stamens to the stigma, and pollination takes place in every plant before the flower will bear seeds. A small number of plants are self pollinating, but most plants are cross-pollinating. Insect-pollinated plants are able to produce smaller amounts of pollen, which usually is sticky and adheres to the bodies of insects. Many flowers have peculiar floral structures that help ensure pollen will attach to the insect’s leg and help pollination. Some plants depend on single species for pollination. Some orchids are pollinated by certain long-tongued hawk moths, and the Smyrna fig is pollinated by the fig wasp, Blastophaga psenes (Fenster and others 2004). The most important insect pollinator is the honey bee, Apis mellifera. Without this insect it would be almost impossible to produce orchard fruits; apples, pears, plums, cherries, nuts; and berries; strawberries, blackberries, cranberries and blueberries; such vegetables as melons, cucumbers, pumpkins and squash. Other insects are capable of pollinating these crops, but with urbanization in agricultural areas and the trend toward growing large fields of single crops, the habitats and abundance of other insect pollinators are being reduced. The economic value of the pollinating insects is enormous and the annual yield of insect pollinated plants in the United States is valued at more than $30 billion (Borror and others 1992).
Numerous insects have commercial uses, with the production of their products benefiting humans. For instance, honey and beeswax products produced by honey bees are important as a food source and several commercial products used by man. Production of honey is an old industry “dating back to the time of the pharaohs” (Borror and others 1992). In fact, there are four...
Cited: Fenster C. B., Ambruster W. S, Wilson P, Dudash M. R. 2004. Pollination syndromes and floral specialization. Annual Review of Ecology, Evolution, and Systematics, 35:
Borror D. J., Triplehorn CA, & Johnson N. F. 1992. An Introduction for the Study of Insects. Forth Worth, TX: Harcourt Brace College Publishers.
Gorham J. R. 1976. Insects as food. Bulletin of Society of Vector Ecology, 3: 11-16.
Gould F, Schliekelman P. 2004. Population genetics of autocidal control and strain replacement. Annual Review of Entomology, 49: 193-218.
Henning W. 1981. Insect Phylogeny. New York: Wiley and Sons.
Hogue C. L. 1993. Insects of the Los Angeles Basin. Los Angeles: Natural History Museum of Los Angeles County.
Kettle D. S. 1993. Medical and Veterinary Entomology. Wallingford, UK: CAB International,
Yokoyama T. 1963. Sericulture. Annual Review of Entomology 8: 287-306.
Please join StudyMode to read the full document