Aphids, also known as plant lice, are diminutive, soft bodied, pear shaped insects which feed on plants, typically during the spring and summer seasons. Aphids are amongst the most common type of garden pests and are commonly green in color, though they can also found in pink, brown, yellow and black. There are over 200 species of aphid s, some of which will only feed on specific types of plants, while the majorities are content to eat a myriad of different plants. Aphids are capable of asexual reproduction and can spawn throughout most of the year, sometimes producing nearly 100 young per aphid in the course of just one week. Because reproduction occurs so rapidly, what starts out as a small aphid problem in a garden, farm or greenhouse can quickly become an infestation without adequate intervention.
Aphids are mostly less than 1/4 in. (6 mm) long. Some are wingless; others have two pairs of transparent or colored wings, the front pair longer than the hind pair. In typical aphids (family Aphididae), two tubes called cornicles project from the rear of the abdomen and exude protective substances. Aphids feed by inserting their beaks and sucking sap from stems, leaves, or roots.
Many kinds of aphids secrete a sweet substance called honeydew, prized as food by ants, flies, and bees. This substance consists of partially digested, highly concentrated plant sap and other wastes, and is excreted often in copious amounts. Certain aphid species have a symbiotic relationship with various species of ants that resembles the relationship of domestic cattle to humans; hence the name “ant cows” for aphids. The ants tend the aphids, transporting them to their food plants at the appropriate stages of the aphids’ life cycle and sheltering the aphid eggs in their nests during the winter. The aphids, in turn, provide honeydew for the ants.
Damaging aphid populations may develop over a span of several years. Generally medium to low annual rainfall zones are at a greater risk than high annual rainfall zones. Although aphids usually arrive earlier in high rainfall zones, their populations are often kept at relatively low numbers. This is believed to be due to mortalities caused by a combination of strong winds and rain, high natural enemy numbers such as parasites, and fungi, which thrive in high humidity. Direct feeding damage, occurs when colonies of 30 or more aphids develop on individual growing tips.
The degree of damage depends on the varietal susceptibility, the growth stage of the crop, the percentage of plants infested, the number of aphids per growing tip, and the duration of the infestation. Feeding damage often has no obvious signs or symptoms, although heavily infested plants may be covered in black sooty moulds, which live on the sugary honeydew excreted by aphids, and flowers may be aborted. Other signs of damage include down curled leaves and wilting. The damage causes yield and quality losses, by reducing seed size and weight and numbers of pods per plant.
The damage done by aphids is due to a number of causes, including loss of sap, clogging of leaf surfaces with honeydew, and growth of molds and fungi on the honeydew. Leaf curl, a common symptom of aphid infestation, occurs when a colony attacks the underside of a leaf, causing its desiccation. The downward curl provides protection for the colony, but the leaf becomes useless to the plant. Some species also transmit viral diseases of plants. Among the aphids causing serious damage to food crops are the grain, cabbage, corn root, apple, woolly apple, and hickory aphids and the alder and beech tree blights. Direct damage caused by aphids feeding can cause yield losses of more than 50% in susceptible Lupin varieties. Yellow lupins are the most prone to aphid colonization and occasionally feeding damage may be so bad that crops fail to yield.
Let us take a look at the below article:
Aphids damage early crops
06 Aug, 2013 05:00 AM
There has been significant aphid damage to early sown crops, particular in central NSW.
Pest Facts reported there were many accounts of damage in the Central Tablelands region around Mudgee, NSW.
The damage began in July once the resistance imparted by seed treatment wore off.
Oats have been one of the worst impacted crops.
Oat aphid, corn aphid and rose grain aphid favor barley, but are found in all cereal crops. Heavy infestations of these sap sucking insects cause the crop to turn yellow, be stunted and generally appear unthrifty.
All three aphids can damage crops by feeding on them and in some instances by spreading barley yellow dwarf virus.
The above article shows the extent of damage these creatures can cause. There have been various other articles published which illustrate the extent of damage caused by aphids. According to a recent study by researchers at Iowa State University aphids has become a threat to soybean in the recent years because they possess a unique ability to block the genetic defense response of soybeans and may open the door for other pests to do even more damage to the crops. Their research further made significant contribution as the scientist stated that Aphids emerged as a serious threat to Iowa soybeans around 2000. The insects are native to Asia and most likely came to the United States via international travelers or plants brought into the country. In the years since, aphids have caused soybean farmers major headaches, reducing yields in affected fields by up to 40 percent, a scientist said.
These creatures thus cause a lot of damage in the agricultural sector. Also they invite more pests like the ants to the plants further endangering them. Conventional methods used to combat them include the use of toxic pesticides which are extremely hazardous to the environment. New methods need to be developed to do away with aphids for good. The method used should be 100% effective and should not endanger the environment in any way whatsoever.
Termirepel™ is a non-toxic, non-hazardous insect and pest repellant. It can be best described as a termite aversive. It is effective against a multitude of other insects and pests like weevils, beetles, thirps, bugs, aphids etc. It works on the mechanism of repellence and therefore does not kill the target as well as non-target species. Being non-toxic, it does not harm the soil and environment. Termirepel™ can be added to a thin agricultural film to protect plants and crops from insects like aphids. It can also be incorporated in irrigation pipes to ward of pests.