Whitefly

Small sap-sucking insects in the family Aleyrodidae

Whitefly on a leaf

Whiteflies are small, sap-sucking insects that belong to the family Aleyrodidae. They are considered pests in agricultural and horticultural settings due to their ability to transmit plant diseases and cause damage to crops. Whiteflies are closely related to aphids and mealybugs, and they are known for their rapid reproduction and ability to develop resistance to pesticides.

Description

Whiteflies are typically 1–2 mm in length and have a powdery white appearance due to a waxy coating on their wings and bodies. They have two pairs of wings and are often found on the undersides of leaves. The adult whiteflies are capable of flight, which aids in their dispersal and infestation of new plants.

Life Cycle

The life cycle of a whitefly consists of several stages: egg, four nymphal stages (instars), and adult. The eggs are laid on the undersides of leaves and hatch into nymphs, which are initially mobile but soon settle down to feed. The nymphs go through several molts before becoming adults. The entire life cycle can be completed in as little as three weeks under optimal conditions, allowing for rapid population growth.

Feeding and Damage

Whiteflies feed by inserting their mouthparts into the phloem of plants and extracting sap. This feeding can cause yellowing of leaves, wilting, and stunted growth. In addition to direct damage, whiteflies excrete a sticky substance known as honeydew, which can lead to the growth of sooty mold on the plant surfaces, further reducing photosynthesis and plant vigor.

Disease Transmission

Whiteflies are vectors for several plant viruses, including the tomato yellow leaf curl virus and the cassava mosaic virus. These viruses can cause significant yield losses in affected crops, making whitefly management crucial in agricultural settings.

Neomaskellia bergii, a species of whitefly

Control Methods

Controlling whitefly populations involves a combination of cultural, biological, and chemical methods. Cultural controls include removing infested plant material and using reflective mulches to deter whiteflies. Biological control involves the use of natural predators such as lady beetles, lacewings, and parasitic wasps. Chemical control can be achieved with insecticides, although resistance development is a concern.

Biological Control

Orius insidiosus, a predator of whiteflies

Biological control is an important aspect of integrated pest management for whiteflies. Predators such as the Orius insidiosus and parasitoids like Encarsia formosa are used to naturally reduce whitefly populations. These beneficial insects can be introduced into greenhouses and fields to help manage whitefly infestations.

Taxonomy and Diversity

The family Aleyrodidae contains over 1,500 species of whiteflies, with many species exhibiting host plant specificity. Some of the most economically important species include the silverleaf whitefly (Bemisia tabaci) and the greenhouse whitefly (Trialeurodes vaporariorum).

Aleyrodidae wing venation

Related Pages

• Aphid
• Mealybug
• Integrated pest management
• Plant virus