Greenhouse whitefly
| Greenhouse whitefly | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Greenhouse whiteflies |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Trialeurodes vaporariorum | ||||||||||||
| ( Westwood , 1856) |
The greenhouse whitefly ( Trialeurodes vaporariorum ) is a whitefly from the Aleyrodidae family . Together with other species of whitefly , it is also known as the whitefly .
features
The lice reach a body length of approx. 1.5 millimeters. They have a light yellowish body, which, like the wings, which cover the abdomen like a roof when at rest, is coated with a white wax. The wax is excreted in a gland on the abdomen. The white front wings are very large with a wingspan of 5 millimeters and dominate the appearance of the animals, so that they would be more likely to be assigned to flies or small butterflies. The wing veins are severely regressed. Your hind legs have strong jumping muscles.
The larvae are colored yellow-green.
Occurrence
The original range of this species was probably Central America . But around 1848 it was introduced to Europe . Although they can withstand temperatures below 0 ° C for a short time, they can only survive in Central Europe under very favorable conditions outside of greenhouses and apartments.
development
In Central Europe it develops mostly in greenhouses or buildings on useful and ornamental plants . During the warm season, the females lay about four to seven, 0.1 millimeter long, yellow-green, stalked eggs on the underside of the leaves of their forage plants. The rest of the year there are only two. After hatching, the nymphs, sitting on the underside of the leaves, suck plant sap. They are not fussy and can feed polyphagously on plants from 84 different families. In the fourth larval stage, they pupate in an oval puparium that has five pairs of humped wax glands on the upper side, from which long wax threads extend, and wax sticks. The adults hatch through a T-shaped gap on the top of the cover. The development is strongly dependent on the temperature. At 16 ° C the animals need about two months, at 24 ° C the new generation is formed in less than half the time.
Harmful effect and control
The animals are pests on vegetable and ornamental plants and can cause great damage in greenhouses . The damage is primarily not caused by sucking the sap, but by the secretion of honeydew , which begins to mold, especially at high temperatures and humidity.
In addition to pesticides in greenhouses are parasitic wasps and especially the wasp Encarsia formosa as biological control used. These parasitize the larvae (nymphs) of the whitefly and lay their eggs in them. Then these will turn black (see picture of the tomato leaf). New parasitic wasps later hatch from the black puparia, creating a parasitic wasp population. After both species hatch, the transparent egg shell remains; The exit opening shows which animal has hatched: When the ichneumon wasp hatches, the hole is round, the whitefly leaves a T-shaped opening.
For the control of potted plants, attractant stickers are also suitable, which are attached near the infested plants and to which the attracted animals stick.
Web links
- Information at ages.at
- Trialeurodes vaporariorum Westwood - whitefly ( August 8, 2008 memento in the Internet Archive )