Those+pesky+plant+lice+called+Aphids

GJA

Aphids, the plant-sucking louse of the herbaceous world. Vector for disease and agricultural destruction. Aphids can cause crop loss and millions of dollars are spent on insecticides each year to control them.

Kingdom: Animalia Phylum: arthropoda Class: Insecta Order: Hemiptera Suborder: Sternorrhyncha Superfamily: Aphidoidea
 * Taxonomy **


 * Description **

Aphids are small sap-sucking insects that decimate large numbers of cultivated plants in temperate regions. about 4,400 species are known while around 250 species are pests in agriculture and forestry.

Aphids have green, black, brown, pink, or even colorless soft bodies. Their antennae can have as many as 6 segments and their mothparts called stylets are enclosed in a sheath called a rostrum, which is a modified mandible and maxilla into a tube-like sucking structure. Most aphids have a structure that exude defensive fluid called cornicles. A number of different defensive compounds can be produced by some aphids.

More common in temperate zones, Aphids are found worldwide and can migrate great distances mainly through wind dispersal as well as unintentional human dispersal on shipped plant materials containing aphids.


 * Life Cycle **

Aphids have a number of reproductive adaptations enabling in their success as a species. Adaptations like having both asexual and sexual reproduction, egg laying and also live birth of nymphs. Aphids also switch plant food sources during different times of the year from woody plants to more herbaceous ones. Usually, females are the first to hatch from overwintering eggs while some species show a slight mixture. Females develop embryos within their ovarioles enabling live birth of the first instar of female nymph. the offspring resemble their parents in every way except size. One female hatched in spring can produce thousands of decedents typically able to live 20-40 days. As winter approaches female aphids prepare by producing sexual females and males which are identical to their mother except the mothers have one fewer sex chromosome. These sexual aphids may lack wings or even mouthparts. The result is that these sexual aphids mate and the produced eggs to overwinter and hatch the following spring.

Sometimes winged aphids are produced. This is usually a result of low food quantity or even quality. these winged aphid females are able to disperse in hope of founding new colonies.


 * Predators and Prey **

Many aphids only feed on one plant species. Others feed on hundreds of plant species. Consuming sap of phloem vessels in passively plants as many in the order Hemiptera do. Xylem is also consumed in an active sucking manner and is thought to be used for other reasons besides consumption because of it's lack in nutrients and is thus believed to help in regulating the high sucrose osmotic pressure in the aphids stomach. Another way sucrose is regulated is by the excretion of the material which some ant species provide protection for its use as a food source.

Plants with aphid damage can exhibit symptoms like stunted growth, decreased growth rate, yellowing, curled leaves, wilting, and even plant death. The aphids removal of sap literally sucks the life out of plants. Additionally, aphids saliva is toxic to plants and cause damage.

Aphids are often vectors for plant disease. Transmition of these plant viruses affect a number of agriculture products like potatoes, cereals, sugerbeets, or citrus plants which sometimes die as result. Aphids even contributed to the Irish potato famine of the 1840s by transmitting late blight among potatoes.

Aphids destructive abilities have made them enemies of farmers, foresters, and gardeners alike. Luckily, aphids have a variety of insect predators as well as being susceptible to bacterial, fungal, or viral infection. Their soft bodies are also affected by the elements like precipitation, temperature, and wind.

The predators of Aphids include Coccinellidae (ladybugs and their larvae), hoverfly larvae, parasitic wasps, green lacewing larvae (aphid lions), lacewings, and crab spiders. Fungi infect aphids when they brush up against the spores, which then germinates and grows in the aphid.

After about three days a fungus like // Lecanicillium lecanii // will kill the aphid and it's spores will be released.


 * Ecological Importance and Human Impact **

Aphids provide a valuable food source for a number of predators. Additionally they limit the amount of plant growth in a certain area. The problem arises when a particular plant species is being grown for human use. Each year a large amount of resources are expended in attempts to control the destructive effects aphids have on grown crops. Various insecticides have been developed to kill off aphids and protect crop yields. Biological and eco-friendly options like fungal and bacterial pesticides are used in integrated pest management. While backyard infestations can be remedied by attracting predator insect species or simply spraying down the plants with water.

The destruction of crops in the past as result of aphid infestation has caused food shortages and even famine. In modern agriculture insecticides can control aphids but also there are consequences for insecticide use especially if explicitly used.


 * Sources**