Identifiable traits

It affects all citrus trees in all growth stages. The aphids have long piercing mouthparts which they use to suck the sap on shoot tips and young leaves, which leads to distortions of twigs and inflorescences and the curling, rolling or folding of leaves. They feed on sweet plant phloem, they excrete excess sugar in the form of honeydew. When this honeydew falls onto the leaves, it readily colonized by sooty mold fungi which make the leaves turn black. In result, this limits photosynthesis and has consequences on the vigor of the tree and the quality of the fruits. Tristeza virus is other causing factor which causes damage to citrus trees, which aphids carry.

Inducing factors

Symptoms are caused by the adults and nymphs of the black citrus aphid Toxoptera aurantii. They often co-infect citrus trees and other cultures together with another related species of aphid T. citicida, commonly known as brown citrus aphid. Adult aphids exist in two forms, either with or without wings. Winged aphids can fly a distance of up to 30 km and are found when they become too numerous or when food supply reduces or becomes limited. They have a dull brownish to black body with a length of about 1.5 mm. These black citrus aphids have a simple life cycle and a high reproduction rate that can lead to rapid and severe infestations. Favourable temperature range for development, survival and reproduction varies from 9.4 to 30.4 ˚C. The honeydew attracts ants, which in turn protect the aphids from natural predators. They are considered a vector of the Tristeza disease of citrus and the zucchini yellow mosaic virus.