''Paracletus cimiciformis'' is a species of

aphid Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...

with a complex life cycle. Its primary host plant is ''

Pistacia ''Pistacia'' is a genus of flowering plants in the cashew family, Anacardiaceae. It contains 10 to 20 species that are native to Africa and Eurasia from the Canary Islands, all of Africa, and southern Europe, warm and semidesert areas across Asia ...

'' and its secondary host is a grass, where it is present on the roots. Here it is associated with an ant and part of its life cycle is spent in the ant's nest.

Hosts

The primary host for this species is the terebinth or turpentine tree (''

Pistacia terebinthus ''Pistacia terebinthus'' also called the terebinth and the turpentine tree, is a deciduous shrub species of the genus ''Pistacia'', native to the Mediterranean region from the western regions of Morocco and Portugal to Greece and western and s ...

''). Its secondary hosts include the grasses and cereals bent, wild oat,

cock's-foot ''Dactylis'' is a genus of Eurasian and North African plants in the Pooideae, bluegrass subfamily within the Poaceae, grass family. ''Dactylis'' is native to North Africa, they are found throughout the world, and are an invasive species. They ar ...

fescue ''Festuca'' (fescue) is a genus of flowering plants belonging to the grass family Poaceae (subfamily Pooideae). They are evergreen or herbaceous perennial tufted grasses with a height range of and a cosmopolitan distribution, occurring on every ...

, wall barley,

barley Barley (), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains; it was domesticated in the Fertile Crescent around 9000 BC, giving it nonshattering spikele ...

rice Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)—or, much l ...

, meadow-grass, '' Polypogon viridis'', tall fescue, '' Stipellula capensis'', and

wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...

Distribution

''Paracletus cimiciformis'' is native to much of Europe and has been recorded in North Africa and Asia.

Life cycle

The life cycle of ''P. cimiciformis'' is complex. For most of the year, wingless females are produced parthenogenetically, but in the late summer on their secondary hosts (grass), winged males and females are produced which fly to their primary host, the terebinth tree. Here they mate and

overwintering Overwintering is the process by which some organisms pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero temperatures, ice, snow, limited food supplies) make normal activ ...

eggs are laid. In the spring these hatch and the wingless females that develop create swollen galls on the leaves; they live in these galls and reproduce asexually. In late summer some winged females develop which fly off and colonise the roots of grasses. Some of these aphids are carried into their nests by ants, where they overwinter, emerging in the spring to recolonise the roots of their secondary hosts, the whole cycle taking two years.

Ecology

Although ''Pistacia'' is the primary host plant, this aphid is present in parts of Europe where this tree does not grow, and in these localities, the insect stays on the roots of the secondary host all year round. On grasses, it is always found living in association with ants in the genus ''

Tetramorium ''Tetramorium'' is a genus of ants in the subfamily Myrmicinae that includes more than 520 species. These ants are also known as pavement ants. Taxonomy and phylogeny ''Tetramorium'' was first described by Gustav Mayr in 1855 in the same publi ...

'' such as the pavement ant, ''

Tetramorium caespitum ''Tetramorium caespitum'', also known as the red pavement ant, is a species of Myrmicine ant native to Europe, Morocco, and western Asia, but now found on many other continents as a tramp species. Etymology The species is commonly known as the ...

'' and '' Tetramorium semilaeve''. On its secondary host, the aphids have two genetically identical forms. One of these has a rounded green body and sucks the sap of the host plant; it produces honeydew which is consumed by the ants, and in fact the ants herd the aphids and stimulate them to produce honeydew. The other form has a flattened brown body and produces

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

s which mimic those produced by ant larvae. When approached by an ant these flattened aphids remain stationary and get carried into the ant nest and deposited among the ant brood. Here they proceed to prey on the ant larvae, piercing them with their stylets and sucking out the

hemolymph Hemolymph, or haemolymph, is a fluid, similar to the blood in invertebrates, that circulates in the inside of the arthropod's body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which hemolymph c ...

. They stay in the ant nest during the winter, and in the spring are carried to near the surface of the ground with the ant's own young. Here they produce round-bodied aphids which proceed to feed on grass roots and reproduce asexually. Both round-bodied and flattened morphs can reproduce parthenogenetically, producing either form of offspring, and it is unclear what factors trigger the production of one morph in preference to another.

References

{{Taxonbar, from=Q10617188 Aphididae Insects described in 1837 Hemiptera of Europe Insect pests of millets