Beware of pear stem bees for pear tree growth

Pear stem bees are commonly known as folded bees, truncated bud worms, belonging to the order Hymenoptera, stem bees, widely distributed in china's pear areas, is one of the main pests of pear trees, often in the extensive management of orchards occur more heavily. How to prevent and control the harm of pear stem bees, Professor Bud of the College of Plant Protection of Northwest A & F University provides guidance to the majority of farmers.

<b>Harmful symptoms</b>

When the adult pear stem bee lays eggs, it hurts the young shoots and petioles on the tips with a saw-shaped egg layer, and the affected stems and leaves wilt and droop after being injured, drying and falling off within a few days, forming short branches. The larvae feed on the lower part of the branches, and the moth-eating part turns black and withers. The damage of large trees affects the tree posture and yield, and the damage of young trees seriously affects the growth of branches and the enlargement and shaping of the canopy.

<b>Morphological characteristics</b>

The eggs of the pear stem bee are oblong oval, about 1 mm long, milky white, translucent. Pupae are 7 to 10 mm long and initially milky white and fade to black. The mature larvae are 8 to 11 mm long, slightly flattened, white gradient yellowish at the beginning of hatching, yellowish brown head, bent head and thorax, and upturned tail, showing a "~" shape. The chest foot is extremely small and there is no abdominal foot. Adults are 7 to 10 mm long, black, and shiny. The antennae are filamentous, black. The mouthparts, the sides of the posterior margin of the anterior thoracic dorsal plate, the mid-thoracic lateral plate, the sides of the posterior thorax, and the posterior end of the posterior thorax dorsal plate are all yellow. Females have a saw-shaped ovipositor in their abdomen.

<b>Habits of life</b>

Pear stem bees occur in one generation per year and overwinter in thin white cocoons with old mature larvae in the infested shoots or biennial branches. Pupates in March of the following year, and adults feather from late March to early to mid-April. Adults feather after 3 to 6 days before biting a round feathered hole and flying out. Adults prefer to move, copulate, and lay eggs around noon, and perch on the back of the lower leaves of the canopy in the morning and evening. Before spawning, the adult worm first uses a saw-shaped egg layer to saw the young shoots from 4 to 5 leaves, and then lays eggs in the tender tissue 2 to 3 mm below the wound, and after laying the eggs, the petioles in the lower part of the fracture are sawn one by one, and a female worm can serrate 20 to 30 young shoots, and the egg stage is 7 to 10 days. After hatching, the larvae feed on the underside of the branches, and the affected young branches gradually become black and dry, filling them with insect droppings. In order to enter the marrow of the two-year-old branch from June to July or continue to stay in the annual branch, turn the body around and stop eating. From September to October, the larvae mature and overwinter in cocoons.

<b>Prevention and control methods</b>

In mid-April, after the adult pear stem bee spawns, carefully check tree by tree, remove the new shoots in time, and cut at 1 cm to destroy the eggs laid.

When the pear tree falls, the adults like to gather and are easy to find, taking advantage of the characteristics of the adults roosting in the lower part of the canopy in the morning and evening when they are low temperatures, vibrating the adults and killing them intensively.

Taking advantage of the yellowing characteristics of pear stem bees, the yellow insect trap board is hung in the pear garden during the stinging period of the pear stem bee, which can trap a large number of adult insects.

In years and orchards where the new shoots of pear trees grow to 5 cm to 6 cm, spray 80% dichlorvos 1000 times liquid to kill adult insects.

Zhao Yun

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