Aphis fabae is a true bug in the order Hemiptera

Hemiptera

Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...

. Common names include blackfly, black bean aphid, bean aphid and beet leaf aphid. It is a widely distributed pest of agricultural crops.

Distribution

The insect is found throughout Western Europe, Asia, Africa, North and South America.

Description

The black bean aphid is a true bug in the order Hemiptera. It has specialised piercing and sucking mouthparts, which are used to suck plant juices. It is a tiny insect about two millimetres long with a small head and bulbous abdomen. The body is blackish or dark green in colour and the membranous wings, when present, are held angled over the body. The legs and antenna are light yellow. The siphunculi are twice as long as the finger-like tail and both are brownish-black. There are two tube-like protrusions at the rear of the abdomen known as cornicles

Cornicle

The cornicle is one of a pair of small upright backward-pointing tubes found on the dorsal side of the last segment of the bodies of aphids. They are sometimes mistaken for cerci...

 which are the openings of wax glands.

Biology

The eggs of the black bean aphid overwinter on certain host plants which include the spindle tree Euonymus europaeus, Viburnum

Viburnum

Viburnum is a genus of about 150–175 species of shrubs or small trees in the moschatel family, Adoxaceae. Its current classification is based on molecular phylogeny...

and Philadelphus. The aphids that hatch from these eggs in the spring are wingless females known as stem mothers. These are able to reproduce asexually

Asexual reproduction

Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...

 giving birth to live offspring through a process known as parthenogenesis

Parthenogenesis

Parthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occur without fertilization by a male...

. The life span of the parthenogenetic female is about fifty days and during this period, each can produce as many as 30 young. The offspring are also females and able to reproduce without mating but the next generation to be produced are typically winged forms. These migrate to new host plants such as beans, sugar beet, docks and spinach. Further parthenogenesis on these hosts allows large populations of aphids to build up quickly. Winged and wingless forms are produced throughout the summer, the winged forms dispersing to new host plants. As autumn approaches, the winged forms migrate back to the primary hosts. Both males and sexual females are produced here, mating takes place and the females lay eggs which overwinter ready to repeat the life cycle the following year.

Host plants

The black bean aphid is found on sugar beet

Sugar beet

Sugar beet, a cultivated plant of Beta vulgaris, is a plant whose tuber contains a high concentration of sucrose. It is grown commercially for sugar production. Sugar beets and other B...

, beans

Vicia faba

This article refers to the Broad Bean plant. For Broadbean the company, see Broadbean, Inc.Vicia faba, the Broad Bean, Fava Bean, Field Bean, Bell Bean or Tic Bean, is a species of bean native to north Africa and southwest Asia, and extensively cultivated elsewhere. A variety is provisionally...

, potato

Potato

The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...

es, sunflower

Sunflower

Sunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads...

 and tomato

Tomato

The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...

. It colonises more than two hundred species of cultivated and wild plants. Among the latter it prefers Papaver somniferum, Arctium tomentonum, Chenopodium album

Chenopodium album

Chenopodium album is a fast-growing weedy annual plant in the genus Chenopodium.Though cultivated in some regions, the plant is elsewhere considered a weed...

, Atriplex rosea

Atriplex rosea

Atriplex rosea is a species of saltbush known by the common names tumbling saltbush, red orach, and tumbling orach. It is native to Eurasia but it is widespread elsewhere as an introduced species....

, Matricaria recutita and Cirsium arvense

Cirsium arvense

Cirsium arvense is a species of Cirsium, native throughout Europe and northern Asia, and widely introduced elsewhere. The standard English name in its native area is Creeping Thistle.-Alternate names:...

.

Damage

As a result of infestation by the black bean aphid, leaves of sugar beet become swollen, roll and cease developing. The roots develop poorly and the sugar content is lower. Damage to flowers hinders seed formation. Honeydew is produced and sooty moulds develop on the residue. In some other plants the leaves do not become distorted but growth is affected and flowers abort due to the action of toxic saliva. This aphid is also the vector for certain plant virus diseases.