Bemisia tabaci and Trialeurodes vaporium
Scientific Name:
Scientific Name:
Crops:
Crops:
- Tomato
Biology
Control Method
Biology
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Definition
Whiteflies are small insects about 1 mm long, characterized by a pair of membranous wings covered with a fine white waxy dust. Whiteflies belong to the order Hemiptera and the subgroup Homoptera, as do aphids and mealybugs.Whiteflies are biting-sucking insects that feed on the sap of the plant, thus weakening the plant and can even lead to its death. Whiteflies can be vectors of several viral or mycoplasma diseases.
Development Lifecycle
Flies undergo an incomplete metamorphosis: after the eggs hatch, the larvae go through four stages before becoming adults. The end of the fourth larval stage corresponds to the formation of a false pupa.Eggs: tiny (about 0.25 mm long), they are oval or conical in shape, light in colour at the time of laying but usually become dark before hatching.
Larvae: oval and flattened, they look like mealybugs. They are usually yellowish or greenish and almost transparent. In the greenhouse whiteflies, the false pupa is adorned with waxy growths. This characteristic is used to differentiate species.
Adults: These small insects, about 1 mm long, have a yellowish body, and have two pairs of membranous wings covered with a whitish powdery wax. The mouthparts are of the stinging-sucking type.
Whiteflies reproduce sexually and by parthenogenesis (without fertilization by the male). During her lifetime (about 1 to 2 months), a female can lay up to 400 eggs that she attaches to the underside of the leaves. Incubation lasts between 5 and 10 days, depending on the species. The 1st instar larva is creeping. It moves for a short time before coming to rest to feed. The following larval stages are immobile. At the end of the 4th instar, the larva stops feeding and forms a false pupa. The adult emerges about 1 week later.
The length of the life cycle of whiteflies is influenced by temperature. The warmer the climate, the shorter the cycle. Under normal conditions, the insect completes its cycle in approximately 1 month. There are several generations per year. Hard return (shift + enter) and then paste content.
Symptoms
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Appearance of numerous small chlorotic spots on the underside of the leaf;
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Whiteflies are usually found on the underside of leaves and their presence can be detected with a magnifying glass. The flight of the adults, when the plants are shaken, reveals the presence of this pest.
Contributing factors
- The high temperatures.
- Greenhouse cultivation is a factor that promotes the spread of the pest due to the conditions present in the greenhouse.
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Control Method
Recommended Prophylactic and Cultural Method
- Weed the greenhouse well.
- Dispose of contaminated plants.
- Carry out regular observations on sticky yellow colour plates and on plants.
- Install insect-proof nets at the openings of the greenhouses.
- Set up an entrance airlock for greenhouses to delay the intrusion of insects.
- As a biological solution: use parasites Macrolophus caliginosus , a predator of Bemisia tabaci ; Encarsia formosa and Eretmocerus eremicus, predators of Trialeurodes vaporium.
Chemical method
- Favor preventive treatment.
- Refer to the yellow traps to position the treatment correctly.
- To prevent addiction or resistance, use applications based on products belonging to different chemical families and modes of action.
