''Protopulvinaria pyriformis'', commonly known as the pyriform scale, is a species of soft

scale insect Scale insects are small insects of the Order (biology), order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient g ...

in the family

Coccidae Coccidae, from Ancient Greek (''kókkos''), meaning "kernel" or "Kermes (insect), Kermes", are a family of scale insects belonging to the superfamily Scale insect, Coccoidea. They are commonly known as soft scales, wax scales or tortoise scales ...

. It is a pest of

avocado The avocado, alligator pear or avocado pear (''Persea americana'') is an evergreen tree in the laurel family (Lauraceae). It is native to Americas, the Americas and was first domesticated in Mesoamerica more than 5,000 years ago. It was priz ...

and is found in many countries around the world where avocados grow.

Description

The adult female pyriform scale is pear-shaped or heart-shaped, about in length, and is protected by a reddish-brown scale with radial stripes. In mature individuals, the scale hardens and the fluffy white ovisac projects slightly from underneath the scale. Male individuals are not known in South Africa, but have been observed in Florida. The

nymphs A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...

are pale green, flat and oval, and the eggs are pale yellow.

Distribution

The pyriform scale is known from Australia, South Africa, Israel, Italy, France, Spain, Cuba, Florida, and Peru. It is normally found on avocado, and in Peru it is said to be the worst insect pest of avocado, but in Spain it has also been found on

citrus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is nativ ...

. Certain cultivars of avocado seem more susceptible to attack than others.

Life cycle

The mature adult female produces a batch of two to three hundred eggs, by

parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

in most populations, and stores them in her ovisac until they hatch. The first

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

nymph is known as a crawler and moves away from the mother scale. After about 10 days it becomes a second instar, and after a further 17 days, a third instar. After another 25 days, this becomes an immature adult, a stage that lasts for about 28 days, after which the mature adult starts to produce eggs and lives for about 45 days. Unlike most soft scale insects, the female of this species is able to move around. There are two generations per year in South Africa and in Israel.

Damage

Both adults and nymphs feed by sucking sap from the

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

plant. The main damage done by this pest is as a result of the copious amounts of honeydew it secretes.

Sooty mould Sooty mold (also spelled sooty mould) is a collective term for different Ascomycete fungi, which includes many genera, commonly ''Cladosporium'' and ''Alternaria''. It grows on plants and their fruit, but also environmental objects, like fences, ...

grows on this and photosynthesis is reduced, the plant is weakened, leaves may fall, shoots dry up and fruits may be reduced in size and number.

References

{{Taxonbar, from=Q10641012 Coccidae Agricultural pest insects Hemiptera of Africa Hemiptera of Asia Hemiptera of Australia Hemiptera of South America Hemiptera of Central America Hemiptera of North America Insects described in 1894 Taxa named by Theodore Dru Alison Cockerell