Greenhouse whitefly
Encyclopedia
Trialeurodes vaporariorum, commonly known as the glasshouse
or greenhouse whitefly inhabits the world's temperate
regions. It is a primary insect
pest
of many fruit, vegetable and ornamental crops, frequently being found in glasshouses and other protected horticultural environments. Adults are 1-2 mm in length, with yellowish bodies and four wax-coated wings held near parallel to the leaf surface.
s on the undersides of leaves. Eggs are pale yellow in colour, before turning grey prior to hatching. Newly hatched larva
e, often known as crawlers, are the only mobile immature life-stage. During the first and second larval instars, the appearance is that of a pale yellow/translucent, flat scale which can be difficult to distinguish with the naked eye. During the fourth and final immature life-stage referred to as the "pupa
", compound eyes and other body tissues become visible as the larvae thicken and rise from the leaf-surface. However, this stage cannot be defined as a true pupa stage as hemipterans do not exude this stage of development.
sap. As a by-product of feeding, honeydew
is excreted and that alone can be a second, major source of damage. The third and potentially most harmful characteristic is the ability of adults to transmit several plant virus
es. The crop hosts principally affected are vegetables such as cucurbit
s, potato
es and tomato
es, although a range of other crop and non-crop plants including weed
species are susceptible, and can therefore harbour the infection.
(Gahan
). If required, integrated pest management strategies can incorporate applications of selective chemical insecticides that complement these natural enemies. For the majority of outdoor crops chemicals are still the most widely used method of control.
Greenhouse
A greenhouse is a building in which plants are grown. These structures range in size from small sheds to very large buildings...
or greenhouse whitefly inhabits the world's temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
regions. It is a primary insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
pest
Pest (animal)
A pest is an animal which is detrimental to humans or human concerns. It is a loosely defined term, often overlapping with the related terms vermin, weeds, parasites and pathogens...
of many fruit, vegetable and ornamental crops, frequently being found in glasshouses and other protected horticultural environments. Adults are 1-2 mm in length, with yellowish bodies and four wax-coated wings held near parallel to the leaf surface.
Life cycle
Females are capable of mating less than 24 hours after emergence and most frequently lay their eggEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s on the undersides of leaves. Eggs are pale yellow in colour, before turning grey prior to hatching. Newly hatched larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, often known as crawlers, are the only mobile immature life-stage. During the first and second larval instars, the appearance is that of a pale yellow/translucent, flat scale which can be difficult to distinguish with the naked eye. During the fourth and final immature life-stage referred to as the "pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
", compound eyes and other body tissues become visible as the larvae thicken and rise from the leaf-surface. However, this stage cannot be defined as a true pupa stage as hemipterans do not exude this stage of development.
Plant damage
All life-stages apart from eggs and "pupae" cause crop damage through direct feeding, inserting their stylet into leaf veins and extracting nourishment from the phloemPhloem
In vascular plants, phloem is the living tissue that carries organic nutrients , in particular, glucose, a sugar, to all parts of the plant where needed. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Greek word "bark"...
sap. As a by-product of feeding, honeydew
Honeydew (secretion)
Honeydew is a sugar-rich sticky liquid, secreted by aphids and some scale insects as they feed on plant sap. When their mouthpart penetrates the phloem, the sugary, high-pressure liquid is forced out of the gut's terminal opening. Honeydew is particularly common as a secretion in the Hemipteran...
is excreted and that alone can be a second, major source of damage. The third and potentially most harmful characteristic is the ability of adults to transmit several plant virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es. The crop hosts principally affected are vegetables such as cucurbit
Cucurbitaceae
The plant family Cucurbitaceae consists of various squashes, melons, and gourds, including crops such as cucumber, pumpkins, luffas, and watermelons...
s, 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 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...
es, although a range of other crop and non-crop plants including weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
species are susceptible, and can therefore harbour the infection.
Control
Effective control has been provided for many years through the release of beneficial insects, such as the aphelinid parasitoid, Encarsia formosaEncarsia formosa
Encarsia formosa is a species of wasp and a well known parasitoid of greenhouse whitefly. The tiny females are black with a yellow abdomen and opalescent wings. There are many fewer males than females...
(Gahan
Charles Joseph Gahan
Charles Joseph Gahan was born on 20 January 1862 at Roscrea County Tipperary, Ireland. His father, Michael Gahan was the Master of Erasmus Smith's School in Tipperary. He was educated first at Queens College Galway, where he achieved distinction, and then at the Royal School of Mines in Kensington...
). If required, integrated pest management strategies can incorporate applications of selective chemical insecticides that complement these natural enemies. For the majority of outdoor crops chemicals are still the most widely used method of control.