Harmful characteristics and control time of wheat midge, a worldwide agricultural pest

Wheat midge is a worldwide agricultural pest, which is widely distributed in major wheat-growing countries in Asia, Europe and America. There are mainly two kinds of wheat midges in China, namely, red trematodes and yellow trematodes. Wheat red midge mainly occurs on both sides of the river in the plain area, while wheat yellow midge mainly occurs in plateau areas and alpine areas. Now let's take a look at the harmful characteristics and control time of wheat trematodes.

I. morphological characteristics and hazard characteristics

The female adult of wheat red midge has a body length of 2~2.5mm, a wingspan of about 5mm, and a tangerine body. The front wing is transparent, there are 4 developed wing veins, and the rear wing is degenerated into a balance stick. The antennae are slender and 14 nodes, and the male shrinks in the middle of each node so that each node is in the shape of a gourd knot, and most of the swelling produces a ring of long ring-like hairs. The antennae of the female are beaded with a ring of short circular hairs. The body length of the male is about 2mm. The egg is long 0.09mm, oblong, light red. The larvae are about 3-3.5 mm long, oval, orange-yellow, small head, no feet, maggot-shaped, with a Y-shaped sword bone on the ventral side of the forechest, forked at the front and deep in the depression. The pupa is long 2mm, naked pupa, orange-brown, with 2 white short hairs in front of the head and 1 pair of long breathing tubes.

Wheat yellow midge, the female length is about 2mm, the body is bright yellow. The egg is 0.29mm, banana-shaped. The body length of the larva is 2~2.5mm, yellowish green or ginger, the body surface is smooth, there is a sword bone piece on the ventral side of the chest, the front end of the sword bone piece is curved and lobed, and there are 2 protuberances at the ventral end. The pupa is bright yellow and has a pair of long hairs at the head end.

Both species of trematodes have one generation a year, and the larvae in adverse environments have dormant habits for many years, so there are also generations for many years. The mature larvae form round cocoons in the soil to survive the winter and summer. The overwintering larvae in the Huang-Huai River Basin broke their cocoons and rose to the soil surface in the first and middle of March, and pupated in large quantities in the middle and last ten days of April, and the peak period of pupation was from late April to early May. After the emergence of adults, it is at the heading and flowering stage of wheat, followed by a large number of eggs (yellow fluke is slightly earlier than wheat red midge). The yellow trematodes lay eggs in the inner and outer glumes of the first heading wheat plant and on their lateral slices, producing 5-6 eggs in one place, and the egg period was 7-9 days. Most of the red midges lay eggs between spikelets and spikelets which have not yet flowered, with 3-5 grains at a place, and the egg period is 3-5 days. After hatching, the larvae are immediately transferred to the glume and attached to the ovary or freshly grouted wheat grains to absorb juice. After the damage caused by the mature larvae, they climb to the glume and wheat awn, fall on the soil surface with rain, dew or automatic bounce, and drill into the soil 10-20 cm to make round cocoons over the summer and winter.

Time and technology of prevention and control

The occurrence of serious land should be controlled in the pupa stage. The control time is April 23-28 of wheat booting stage, 1.5% methyl 1605 powder 2-3 kg per mu or 1.5% wheat trematode 1 2-3 kg, evenly mixed fine soil 30 kg scattered on the surface, watering after sprinkling has a good control effect.

If there are no serious plots, adult stage control must be carried out. The time of control is at the heading stage of wheat-before flowering. That is, from May 1 to 10, 50% phoxim 50 grams plus imidacloprid 20-30 grams plus 50 kilograms of water spray can control adults of trematodes as well as early aphids.

For wheat fields with serious trematodes, it is best to rotate with cotton, rape and other crops to avoid insect sources. The method of "one sprinkle plus one spray" can be adopted: before wheat jointing to booting, 50% phoxim 0.5 kg / mu mixed with fine sand 15 kg / mu is evenly sprinkled (watering after spraying) to kill adults, larvae and pupae. During the period from wheat heading to pre-flowering, 4.5% cypermethrin and other pyrethroid pesticides were added with 40.7% Lesbon 800x mixture (20 ml per sprayer), or "Hanke 140ml" 1500 times solution (10ml "singly hit one" per sprayer). It can effectively kill the adults and eggs of trematodes, and can control wheat aphids and red spiders at the same time.