Control of jujube gall midge, a pest of jujube trees

Jujube gall midge (Contariniasp.)

(1) Alias and taxonomic status: jujube bud maggot, curly leaf maggot, jujube maggot, belonging to Diptera, Culicidae.

(2) the insect is distributed in all jujube areas in China, and the damage is the most serious in Shandong, Shanxi, Henan, Hebei and Shaanxi, and it is one of the main pests in jujube leaves.

(3) the damage characteristic is that the larvae suck the juice of jujube leaves. The female adult of jujube gall midge lays eggs in the gap of undeveloped tender leaves. After hatching, the larvae feed on the sap of the tender leaves. After being stimulated, the leaves are rolled longitudinally, and the larvae are hidden in them. After the leaves are damaged, the young leaves will become purplish red, hard and brittle, and soon become black and withered. Generally, the seedlings and young trees in the nursery suffer more seriously.

(4) morphological characteristics.

Adults are mosquito-like, orange-red or grayish brown, compound eyes black, kidney-shaped, head and chest grayish brown, antennae grayish black, beaded, belly back raised black. There are 3 in abdomen, chest and back

Black brown spot, front wing translucent, oval, hind wing degenerated into a balance rod, foot 3 pairs. The female has a large abdomen, the ventral surface is yellow-white or orange-yellow, a total of 8 segments, there are reddish-brown bands on the back of segments 1-5, the male is small, grayish yellow, and the ventral segment is long and narrow, with a total of 9 nodes. The antennae are well developed, longer than half the body, and the external genitals are gray. It is synthesized by the basal ganglia and terminal ganglia of the reproductive process, which is nearly circular and the end of the penis is in the shape of "mountain".

The egg is nearly long and conical, translucent, shiny, slightly narrow at one end, white at the beginning of the egg, and then red.

The larvae are milky white, maggot-shaped, legless and have obvious body segments.

The pupa is naked, spindle-shaped, milky white at the initial stage, and then yellowish brown. The female pupa's foot is shorter than the ventral segment. The male pupa reaches the end of the abdomen.

Cocoon long oval, gray-white, with soil particles.

(5) the occurrence habit is in the jujube area of North China. The insect has 5-7 generations a year, overwintering with mature larvae in shallow soil, Eclosion of adults in April of the following year, and laying eggs on newly germinated jujube buds. The first ten days of May is the peak period of damage. The peak periods of the first and fourth generation larvae are: early June, late June, mid-July, early and mid-August, and the fifth generation larvae begin to produce in the middle of August, except overwintering larvae. The average larval stage and pupa stage are 10 days. The depth of overwintering cocoons of larvae varies with soil types. Most of them are 2-3 cm from the ground in yellow soil and 3-5 cm in sandy soil. The most suitable development temperature is 23-27 ℃. In addition, some drought and little rain occurred later in May.

(6) the unearthed prediction method of overwintering larvae can be used for prediction. A certain number of cocoons of jujube gall mosquitoes were buried in the soil layer 2-3 cm deep under the canopy and shrouded in them. From the first ten days of April, the number of unearthed larvae was checked day by day. When the unearthed larvae reached 50%, it was the pest control period, and the peak period of the first generation larvae was calculated from this period.

(7) Prevention and control methods

① agricultural control measures combined with jujube winter management to dig tree plates to eliminate overwintering cocoons.

② chemical control of overwintering adults or mature larvae before Eclosion, ground closure, spraying 50% phoxim under the tree crown, shallow rake after spraying, can kill unearthed larvae or mature larvae. Better control effect can be achieved by spraying 1500 times of 50% omethoate and 2000-3000 times of pyrethroid pesticides during the peak period of larval damage.