Occurrence and Control Methods of Oleander Aphid Infestation

Morphological characteristics: The aphid belongs to the order Homoptera, family Aphididae. Wingless parthenogenetic female: body length 2.3 mm, width 1.2 mm, oval in shape, yellow in color, with distinct markings on the eighth abdominal segment. The body surface has obvious reticulate patterns. The median frontal tubercle is raised, with a flat top; the antennae have imbricate sculpturing and are 2/3 of the body length. The cornicles are long and tubular; the cauda is tongue-shaped, constricted in the middle, bearing 11-14 long curved hairs. Winged parthenogenetic female: body length 2.1 mm, width 1.0 mm, elongate-oval; head and thorax black; antennae 3/4 of the body length. Abdominal segments 2-4 have small marginal tubercles; cornicles are long and cylindrical.

Damage: It infests oleander (Nerium oleander) and yellow oleander (Thevetia peruviana). Adults and nymphs gather in groups on tender leaves and young shoots to suck sap, often covering 10-15 cm of young shoots, causing leaves to curl and seedlings to grow poorly. In severe cases, it affects new shoot growth, causing leaves to become stiff and stems and leaves to die, flowers to become smaller, or flowering to be abnormal. The honeydew secreted often sticks to and covers the leaf surface, with young leaves suffering the most. At the same time, it induces sooty mold, seriously hindering the normal development of the plant.

Occurrence pattern: More than 20 generations occur per year, often overwintering as adults and nymphs in the gaps of terminal shoots, tender leaves, and bud axils. In early to mid-April of the following year, they begin slow activity and reproduce and expand in place to cause damage. Damage by this pest can be seen throughout the year, but the aphid population is largest from May to June, which is the peak breeding period. On the same plant, wingless parthenogenetic adults, nymphs, and winged parthenogenetic aphids can be seen at the same time. Each female aphid can produce about 25-30 nymphs on average. When temperatures are high, aphids tend to congregate in shaded areas. In mid-to-late November, overwintering wingless adults and nymphs can be seen. This aphid has two damage peaks within a year, namely May-June and September-October. In July-August, due to excessively high temperatures and the constraints of various natural enemies, the population density is low and the damage is also reduced. At a temperature of 20°C, completing one generation takes 7-8 days. Adult aphids live 15-21 days.

Control measures:

a. During the peak emergence of adults, capture with nets to reduce the source of infestation.

b. During the egg-laying period, remove leaves bearing eggs.

c. During the peak damage period, spray 50% pirimicarb wettable powder at 5000 times dilution, 2.5% nicotine•matrine emulsifiable concentrate at 800 times dilution, 30% Taoxiaoling emulsifiable concentrate at 2500 times dilution, 50% menazon emulsifiable concentrate at 1000-1500 times dilution, and 2.5% kung fu emulsifiable concentrate at 3000 times dilution.