Pear stem bees are also called pear stem bees or pear stem saw bees, commonly known as folding bees, prunes, shears and so on. It belongs to the order Hymenoptera, stem bees. It is distributed in various pear-producing areas in China. It is one of the main pests of pear trees. Mainly harmful pears, but also harmful tang pears and so on.
1. Field diagnosis
It is mainly harmful to the new shoots of pear trees. When the new shoots are 6 to 7 cm long, the adults use a saw-shaped ovipositor to serrate 4 to 5 leaves of the young shoots when laying eggs, and then cut off 3 to 4 leaves under the wound, leaving only the petiole. The new shoots shrank and drooped after being sawn, drying and falling off. The larvae feed on the remaining stem marrow, and the worm's feces fill the worm's path after filling the body, and the affected young stem becomes black-brown and half-cut over time, brittle and easy to fold.
Fig. 1 Pear stem bee hazards
Second, morphological characteristics
Adult: Body length 9 to 10 mm, slender, black. Both sides of the posterior margin of the anterior thorax, the base of the wings, the posterior part of the posterior thorax, and the feet are yellow. The wings are yellowish and translucent. Females have a saw-shaped ovipositor in their abdomen.
Eggs: about 1 mm long, oval, slightly curved, milky white, translucent.
Larvae: about l0 mm long, white gradient yellowish at first hatching. The head is yellowish brown. The tail is upturned.
Pupae: all white, pupae, black before feathering, compound eyes red.
Third, the law of occurrence
Generations occur once a year in pear areas across the country, with old mature larvae overwintering in the infested branches. In central Hebei, late March is the peak pupal, in March and April when the pear trees draw new shoots, adults feather, and in May when the new shoots are extracted in large quantities, it is the peak period of spawning. The larvae in western Liaoning pupate intermittently in April and the adult occurrence period occurs in early to mid-May. Adults are active between 10 and 13 o'clock in fine weather, flying, mating and laying eggs. On rainy days and in the morning and evening when the temperature is low, it lies still on the back of the leaves.
Fourth, prevention and control technology
Figure 2 Pear stem bee control technology model diagram
1. Eliminate the source of overwintering insects Combined with winter pruning, prune the dead branches of the victims.
2. Adult insect activity period to kill adult insects Pear tree flowering period, adult insects like to gather, easy to find, should be in the early morning when the adult insects are not active when the vibrating fall to kill.
3. Chemical control During the adult occurrence period (when the new shoots of pear trees grow to 5 to 6 cm), spray insecticides in time. Commonly used agents are 5% fipronil suspension 1500 ~ 2000 times liquid, 80% dichlorvos emulsion 800 ~ 1000 times liquid, 40% oxidized Lego emulsion 800 ~ 1000 times liquid and so on.