Yellow pecan aphid (Hemiptera: Aphididae

Yellow pecan aphid

(Hemiptera: Aphididae)

The yellow pecan aphid is an indigenous pest of pecans in the United States of America but has been introduced into Egypt, Sicily and South Africa. It has been considered an important pest of pecans in South Africa since 1977, after its introduction in 1976. Host plants of this pest include pecan, hickory and other members of the Juglandaceae (walnut) family.

Nozibusiso Maphumulo

IPM-PROGRAM, NORTH-WEST UNIVERSITY

Yellow pecan aphid classification: Class: Insecta (insects) Order: Hemiptera (bugs) Family: Aphididae Genus: Monelliopsis Species: Pecanis

Yellow pecan aphids are small, soft bodied insects with piercing sucking mouthparts. Adults are yellow with black markings and have reddish eyes. Yellow pecan aphids have both winged and wingless adult forms, and the body length of the winged adults is 1,2 – 1,7 mm.

Yellow pecan aphids reproduce both asexually and sexually and overwinters as eggs. Overwintering eggs are deposited inside the bark crevices of pecan trees. Yellow pecan aphid has multiple generations, it can have up to 30 generations per year. During early summer, female nymphs hatch and move to the new pecan leaves where they begin to feed. Nymphs take about a week to mature after which they asexually produce nymphs. The first offspring are all females and, therefore, give birth to subsequent generations of aphids without mating. As they mature, both winged and wingless forms appear. Males and females mate in autumn, and the females lay black eggs that will overwinter.

The yellow pecan aphid lives and feeds on the leaves of pecan trees. Infestation by yellow pecan aphid reduces both the vitality and yield of pecan trees. The most noticeable damage caused by this pest is secretion of honeydew on the foliage which leads to the development of sooty mold that blocks sunlight and limits photosynthesis. Yellow pecan aphid can impair the growth of shoots and roots. Heavy late-summer infestations result in defoliation of trees. If defoliation occurs too early in the season, the size and fill of nuts can be adversely affected. Yellow pecan aphids can be controlled biologically using predators such as coccinellids, chrysopids and syrphids. These predators can reduce aphid numbers, however, they are unable to keep pest populations at levels that are economically acceptable. Two species of hymenopterous parasitoids, Trioxys pallidus and Aphelinus perpallidus, were introduced from the USA for the biological control of this pest. Enquiries: mashimanenozi03@gmail.com

Figure 1: Wingless yellow pecan aphid adult.

https://extension.okstate.edu/programs/digital-diagnostics/insects-and-arthropods/images/yellow-pecan-aphid/yellowaphid.jpg

Figure 2: Winged yellow pecan aphid giving birth to living young. https://influentialpoints.com/Gallery/Monelliopsis_pecanis_yellow_ pecan_aphid.htm

Figure 3: The adult wasp, Trioxys pallidus attacking walnut aphids. https://calag.ucanr.edu/Archive/?article=ca.v045n05p29

Figure 4: Colonies of yellow pecan aphid on leaves of pecan tree. https://influentialpoints.com/Images/Monelliopsis_pecanis_colonies_on_ Carya_2666007-LGPTew.jpg