Peach potato aphid
he peach potato aphid (Myzus persicae) is widely spread in Europe, Asia, North and South America, and Africa. Within the confines of former Soviet Union is a cosmopolite (mainly in an incomplete metamorphosis form). It causes the largest damage to apricot and peach trees (primary hosts) and vegetable crops (peppers, tomatoes, eggplants, cucumbers and others). It has more than 200 secondary (postprimary) hosts. The pest is an agent of viruses.
Biology. Life cycle
he stem mothers or the progenitresses and the wingles virgin females are oblong-oval, their length is 2.5 mm. They are light-green, sometimes pinkish. The antenna hillocks are high. They form a false groove. The cornicles (tubules) are cylindrical, slightly dilated at the base. The caudicle (tail) is finger-shaped. The amphigenous female is 2 mm in length, from a light-brown to cherry color. The tibiae (shanks) of hind legs are thickened with numerous light pseudosensoria. The male is about 1.9 mm in length. Its head, thorax and antennae are black. The abdomen is light-green with black transversal strips which join in a solid spot on the 3rd and the 4th segments of its body. There are dark spots at the sides. The egg is black and has an oblong-oval form.
Mode of life
The pest is known in the form of a complete metamorphosis and in the form of an incomplete metamorphosis. The complete form overwinters in the stage of an egg on primary host-plants (peach, apricot, apple, plum and cherry). The incomplete metamorphosis form overwinters as wingless and winged parthenogenetic females on weeds. Under the complete cycle of development the aphid overwinters in the stage of an egg at the base of fruit tree buds. The pogenitresses hatch in the spring. They reproduce 2–3 generations of apterouses (wingless virgin females). The proginetress lives 24 days and reproduces 60–80 larvae. The life span of the wingless parthenogenetic female amounts to 20–25 days, its fertility is about 100 larvae. In the second generation some quantity of winged migrants emerges. They overfly on the secondary host-plants and reproduce there 2–12 generations. The average duration of larva development is 6.5 days at a temperature of 24°C. In September the winged sexuparae and males emerge on the secondary host-plants. They overfly on fruit trees. In 15 days the larvae of amphigenous females arise. These females lay eggs on shoots for overwintering.
The complete metamorphosis form is not cold-resistant. At a temperature of frost — 6°C the females perish. The individuals of the incomplete form are more cold-resistant. The larvae of progenitresses are born at a temperature of 13–14°C. But the optimal conditions for development are a temperature of 25–28°C and a humidity of 80–85%.
Symptoms of injuries
The primary host-plants are fruit trees (especially peach and apricot), the postprimary are various herbaceous and wood plants in glass-covered ground and outdoor planting. Usually, the pest inhabits the undersides of apical leaves, young shoots and flowers but doesn't deform them. The leaves become yellow, the flowers fall, the flower buds don't open. During life activity the pest leaves on the leaf apparatus of host-plants sugary excretions. After which the sooty fungus develops there. This aphid is a dangerous agent of mosaic virus, which causes the chlorotic disease and the inhibition of plant growth. There is light mottling and curl on affected leaves. The flowers become deformed and motley.
