Toxoptera aurantii (Boyer de Fonscolombe)

Bustillo, Alex, 2015, Part II. Pests, Compendium of Coffee Diseases and Pests, United States of America: The American Phytopathological Society, pp. 45-60 : 49

Toxoptera aurantii (Boyer de Fonscolombe) ( Hemiptera : Aphididae )

is found wherever coffee is grown throughout the tropics and subtropics, including South America, Africa, India, eastern Asia, and Australia, as well as the Mediterranean re ­ gion, Central America, and the southern United States. Only females are found, measuring 2.0-3.0 mm long. They are oval; shiny black, brownish black, or reddish brown, with black siphunculi and caudae; and either winged or wingless, and they have short black-and-white-banded antennae ( Fig. 87 ). Winged individuals tend to have darker abdomens and are slightly thinner. The incidence of winged individuals is dependent on the population density and leaf age.

Reproduction is parthenogenic, and females start reproduc ­ ing soon after becoming adults. They produce five to seven nymphs per day, up to a total of about 50 per female. Newly born nymphs are found grouped together because adult females do not move about while giving birth. Colonies develop preferentially on the lower side of foliage. They may also be found on shoots and flower buds. The development of the black citrus aphid is temperature dependent. In the tropics, males and eggs are not found, and a generation may live as long as 15 days. Generations are continuous throughout the year. Females give birth to living nymphs. There are four nymphal stages. Firststage nymphs are approximately 0.7 mm long, the fourth-stage nymph is about 1.5 mm long, and both are brownish.

This is the only aphid with an audible stridulation or high piercing sound caused by rubbing together two parts of its body, much like crickets. Large colonies produce this scraping sound when they are disturbed.

Damage

T. aurantii feeds by sucking sap from its hosts, causing the plants to become deformed and the leaves to curl and shrivel. In most cases, the black citrus aphid is a minor pest of coffee wherever it is found. It congregates on tender young shoots, flower buds, and the lower side of young leaves. They are not known to feed on the older and tougher plant tissues. On coffee plants, feeding causes some leaf distortion and growth malformation of the leaves and shoot tips. The black citrus aphid is more often a serious pest in coffee nurseries, and they produce honeydew. This sweet and watery secretion is fed on by bees, wasps, ants, and other insects. The honeydew serves as a medium on which sooty mold fungi grow. Sooty mold blackens the leaf, decreases photosynthesis, decreases vigor, and causes malformations of the host.

The black citrus aphid is a vector of viral diseases of Coffea liberica W. Bull ex Hiern , C. arabica L. var. bullata Cramer (blister spot), and C. excelsa A. Chev. (ring spot). On citrus, it is a vector of Citrus tristeza virus, Citrus infectious mottling virus, and Little leaf and lemon-ribbing virus of lemon.

Population Management

Several natural enemies of the black citrus aphid keep this pest under control; sometimes to the extent that insecticides are unnecessary. Predators include Allograpta obliqua (Say) , Chrysopa basalis Walker , Chrysopa microphya McLachlan. Coccinella inaequalis Fabricius , Coelophora inaequalis (Fabricius) , Platyomus lividigaster Mulsant , and Scymnodes lividigaster (Mulsant) . The parasitoids include Aphelinus semiflavus Howard and Lysiphlebus testaceipes (Cresson) ( Fig. 88 ). There are many other predators and parasitoids to this pest throughout the world. T. aurantii is also controlled by the fungus Lecanicillium lecanii (Zimmerman) Zare & W. Gams.

Figures

Fig. 87. Toxoptera aurantii adult female. (Courtesy A. Bustillo, Cenicafé)

Fig. 88. Lysiphlebus testaceipes parasitizing Toxoptera aurantii. (Courtesy A. Bustillo, Cenicafé)