''Aleurocanthus woglumi'' is a species of whitefly in the family Aleyrodidae. It is a pest of

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 ...

crops, and is commonly known as the citrus blackfly because of its slate-blue colour. It originated in Asia, but has spread to other parts of the world. The

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

wasps, '' Encarsia perplexa'' and '' Amitus hesperidum'' can help control the pest.

Distribution

This species is native to India, but also occurs in other parts of Asia, Africa, Central and South America, Mexico, the West Indies, Jamaica, and the United States (Florida, Texas, and Hawaii).Governance document

Host species

The citrus blackfly is found on over 300 host plant species, but citrus trees such as

lemon The lemon (''Citrus'' × ''limon'') is a species of small evergreen tree in the ''Citrus'' genus of the flowering plant family Rutaceae. A true lemon is a hybrid of the citron and the bitter orange. Its origins are uncertain, but some ...

, orange and

pomelo The pomelo ( ; or pummelo, ''Citrus maxima''), also known as a shaddock, is the largest citrus fruit. It is an ancestor of several cultivated citrus species, including the bitter orange and the grapefruit. It is a natural, non-hybrid citrus fr ...

are most heavily infested. Noncitrus trees and shrubs, when they grow by themselves, are not normally attacked by this insect, but they may be when they grow close to heavy infestations on citrus. In Hawaii, such trees as mango, avocado, pink tecoma, and surinam cherry have hosted colonies.

Lifecycle

The female blackfly lays batches of eggs in a spiral pattern on the undersides of leaves. The eggs are golden-brown, but darken before hatching, which happens in seven to 10 days.Dowell RV, Cherry RH, Fitzpatrick GE, Reinert JA, Knapp JL. 1981. Biology, plant-insect relations, and control of the citrus blackfly. Florida Agricultural Experiment Station Bulletin 818: 1-48. The

nymph 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 ...

moults three times. 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 ...

is a brown, elongated oval shape, about long with two transparent filaments curling back over the body. The second instar is a darker brown and has short spines on its body. It measures about long. The third instar is glossy black with many stout spines and measures about long by wide. The larval stages last three to 9 weeks. The

pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...

is ovate and black, with short bristles and a marginal fringe of waxy secretion. The adult, when it first emerges, has a pale-yellow head, whitish legs and reddish-brown eyes. Soon afterwards, it darkens, developing a fine covering of waxy powder which gives it a slate-blue appearance. The wings are angled and held in a tented fashion. The whole lifecycle takes from 45 to 130 days, depending largely on the temperature.

Damage

The principal harm done by the citrus blackfly is the sucking of the tree's sap, which deprives it of both water and nutrients. The excretion of honeydew coats the leaf surfaces and encourages the growth of

sooty mold 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, ...

. This can severely impair both leaf respiration and

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

. The combination of all these factors causes a decline in the health and vigour of the tree and a reduction in fruit yield.

Management

The citrus blackfly has a number of natural enemies. The most effective agents for controlling it in Florida are the parasitic wasps, '' Encarsia perplexa'' and '' Amitus hesperidum''. The former has a lower rate of reproduction than does ''A. hesperidum'', but is better able to search out suitable hosts. The latter is well synchronized with its host, as adult female wasps are ready to lay their eggs at about the same time as suitable larval stages of the blackfly are present. These species have been used in

biological control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or o ...

of the pest. For example, both species were introduced into Hawaii in 1999 after discovery of the presence of the citrus blackfly the previous year. Both wasps have succeeded in establishing themselves and are helping to reduce the damage done by the pest. The use of

insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...

s may help to control infestations temporarily, but this is not advised because of the adverse effects on the environment and any existing predators. The application of an oil emulsion may be effective and less toxic. A sufficiency of water and appropriate applications of

fertiliser A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrition, plant nutrients. Fertilizers may be distinct from Liming (soil), liming materials or other non- ...

will encourage growth and minimise damage.

References

External links

Featured Creatures
{{Taxonbar, from=Q1645537 Insects of India Whiteflies Agricultural pest insects Citrus pests Insects described in 1915