Plum Black Fruit Sawfly (Holocampa Minuta)

Pest Type: Fruit Pests

Row: Hymenoptera – Hymenoptera

Family: true sawflies – Tenthredinidae

It is found everywhere. It damages plum, cherry plum, thorns, less often apricot and cherry.

The image is 4-5 mm long, the body is black, shiny; antennae short, with 9 segments, filiform, yellow-brown; legs are yellow-brown; wings are transparent, with brownish veins. Egg 0.3? 0.6 mm in size, translucent, whitish with a greenish tint. Larva – 6-8 mm, yellow-white with a brown head; slightly bent, has 10 pairs of legs; starting from the second age it secretes a pungent secret. Pupa 5-6 mm long, yellow-white, loose, cocoon brown, oval.

Eonimph larvae hibernate in the soil at a depth of 3-10 cm (up to 15 in dry land). In spring, when the topsoil is warmed up to 8 ° С, eonymphs turn into pronymphs, which pupate. The emergence of imago from the soil begins 5-7 days before the beginning of plum blossom – in the third decade of April. Additionally, they feed on nectar and pollen from the flowers of stone fruit crops. After mating, the female, using the ovipositor, makes an incision under the epidermis of the calyx of buds or half-open flowers and lays one, less often two eggs. Fertility – from 20 to 60 eggs.

Embryonic development lasts from 4 to 12 days. Larvae are sensitive to spring frosts and die massively at a temperature of -4 ° С. They penetrate into the ovary and feed on pulp and not hardened bone. Brown gum mixed with stool flows from the damaged fetus. Excrement has a terrible smell. During the development of the larva, 3-6 times pass from fetus to fetus. Food lasts 21-28 days. Larvae, completed development, often find themselves on the ground, being inside the damaged fetus. After falling off, they leave the fetus and burrow into the soil for pupation. One generation develops per year. Mass shedding of damaged plum fruits occurs in the third decade of May-early June. In the centers of mass reproduction, the sawfly can damage up to 90% of the plum fruit.

Close to the developmental features and harmfulness, the species up to the plum black sawfly is a stone yellow fruit sawfly. A significant role in reducing the number of sawmills is played by riders: ichneumonids; Braconids, etc.

Protective measures. Autumn plowing of the soil between the rows and cultivation in the trunk circles. Soil cultivation at the end of the mass shedding of damaged plums. Economic damage threshold: during flowering – 5% of damaged flowers; during the period of formation of young fruits – 3-4% of populated ovaries. The most effective is spraying insecticides into the phenophase of a pink bud.

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