Jujube gall midge

Distribution and host this insect belongs to the order Pteroptera, Culicidae. Distributed in Hebei, Shaanxi, Shandong, Shanxi, Henan and other jujube producing areas. The hosts are jujube tree and wild jujube tree.

The harm and symptoms are that the larvae suck the juice of jujube or sour jujube buds and leaves and stimulate the mesophyll tissue to make the injured leaves roll longitudinally to the leaf surface. The injured site changed from green to purplish red, hard and brittle, soon blackened and withered, and there were often several heads and even larvae in a roll of leaves.

Morphological characteristics

1. The adult female is 1.4 to 2.0mm long; the compound eye is black and reniform; the antennae are 14 nodes, black and slender, with whorled setae near both ends of each node; the head is small, the head and chest are gray and black; the abdomen is raised dark brown; there are 3 dark brown spots on the chest and abdomen; the whole body is densely covered with grayish yellow fine hairs; the wings are oval, and the anterior bristles are fine and dark. There are 3 pairs of slender feet, yellow and white, the hair on the outside of the leg is grayish black, the forefoot is as long as the middle foot, and the hindfoot is longer; the ventral surface is yellow-white, orange-yellow or orange-red, with a reddish-brown band on the back of section 15, and section 9 extends into a slender oviposition tube. 8 and 9 can be telescopic. The male is smaller than the female, the body length is 1.0~1.3mm, and the ventral segment is narrow and long.

two。 Yellowish egg white, long oval opening, long diameter about 0.3mm, short diameter about 0.1mm, one end sharpened, covered with a layer of colloid, shiny.

3. The mature larvae are 1.5~2.9mm long, bright, milky to yellowish, with obvious segments, a small brown head and an amber chest fork.

4. The pupa is 1.0~1.9mm long and slightly spindle-shaped. The pupae are milky white at first and then turn yellowish brown. There are a pair of obvious thorns on the top of the head. The antennae, feet and wing buds are clear. 8 segments of abdomen. The female pupa's foot is short and extends to the sixth section, while the male pupa's foot is long and reaches the end of the abdomen. The cocoon is 1.5~2.0mm, oval, gray-white or grayish-yellow silk, with soil particles.

The life history and habits of this insect occurred for 5 or 6 generations a year in Hebei, Henan and Shandong provinces. The larvae overwintered as cocoons in the soil under the canopy, and the next year jujube vegetables began to rise in the topsoil near the ground to pupate. The Yantai area of Shandong Province feathered into adults in mid-late May, then mating and spawning. The peak periods of the 1st to 4th generation larvae were in early June, late June, mid-late July and early-mid-August, respectively, and the fifth generation larvae appeared in the middle of August. When the new shoots of jujube trees stopped growing in early September, the larvae began to enter the soil as cocoons to survive the winter. The egg stage is 3-6 days, the larva duration is 8-13 days, the pupa stage is 6-12 days, and the adult life span is 1-3 days.

The depth of larval overwintering cocoon entry varies with different soil types. The yellow land is mostly at the 2~3cm off the ground, the sand land is at the 1~2cm off the ground, and the sand land is at the 2~4cm. When Rain Water was in summer, the depth of cocoon pupation of larvae was shallower than that in spring and autumn drought.

Adult Eclosion occurs more than 6: 9 am, a few can be postponed to 11:00, and very few Eclosion in the afternoon. Adults fly soon after Eclosion, more than within 20cm of the ground. Adults like to be dark, afraid of light, lay more eggs than at night, and lay eggs on the young leaves at the end of the branch. The number of eggs laid by a single female varies from 40 to 100 eggs. When the larvae are old and mature, they will lose their leaves or fall to the ground with the injured leaves to make cocoons and pupation. There are more than 5 obvious harm peaks in the whole year. Jujube gall midge likes to do harm to jujube branches with low crown, dense branches and leaves or sour jujube, while jujube trees with high crown, sporadic planting or good ventilation and light transmission suffer less.

Prevention and cure method

1. Before pupation and Eclosion, the overwintering larvae are sprinkled with poisonous soil or 1.5% parathion powder, about 200g per plant, then gently rake the ground and bury the chemicals into the soil to poison the larvae, pupae and unearthed adults on the surface of the soil.

two。 Spraying 50% parathion EC or dichlorvos EC 1000 times or 40% omethoate EC 1000 times on the tree during the larval damage period has a good control effect.