Scientific name Bradysia odoriphaga Fayang et Zhang Diptera, Ornididae. Alias ​​yellow foot mosquitoes, cockroaches. Distributed in the northeast, north, northwest and northeast China.
Host leeks, onions, garlic, Chinese wolfberry, cabbage, radish, melons, celery, medicinal plants and flowers.
The damage characteristics of larvae are concentrated in the bulbs and soft stems of the leeks. The newly hatched larvae first damage the base of the leek leaf sheath and the upper end of the bulb. In the spring and autumn, the young stems of the leeks cause rot and the yellow leaves die. In summer, the larvae move down into the bulbs, and the bulbs rot in the heavy, and the whole leeks die.
Morphological characteristics Adults are small mosquitoes, body length 2.0-5.5mm, dark brown, small head, compound eye contact, antennae filamentous, 16 knots, with micro hairs. Forefoot leading veins and subfrontal veins are thick and slender. The abdomen is slender, section 8-9. The male mosquito has a pair of vesicular spores on the abdomen end. Egg oval, milky white, 0.240.17mm. Larvae slender body, 6-7mm, head paint black shiny, body white, no foot. The nudibranch is naked and yellowish-white at the beginning, and turns brownish-brown afterwards. It is gray-black before emergence; the head is copper-yellow and shiny.
Living habits 4 generations in Tianjin, 4 to 5 generations in North China, larvae in the leek bulbs or root around the 3-4 cm around the root layer dormant overwintering (in the greenhouse there is no winter, can continue to breed damage). In late March, the phlegm began in late spring and continued until mid-May. From early April to mid-May, it became adult. The generation time of each generation of larvae is: the first generation from late April to late May, the second generation from early to late June, the third generation from early July to late 10th, the fourth generation (overwintering) from early October to next year 4 The end of May is early in May. Overwintering larvae will gradually move to the surface when they want to phlegm, most of them phlegm in 1-2cm topsoil, and a few in the rhizomes. Adults like to move in the wet and low light environment. They are most active from 9 to 11 o'clock. When they are copulated, they inhabit in the earth seams of Putian from 4 pm to noon. They are inactive. The adult fly is good and the intermittent spread can reach about 100 meters. Adults have many habits of copulation, 1 to 2 days after copulation, the eggs are produced in the earth seams around the alfalfa strains or under the clods, and most of them are produced in piles. The eggs of each female are 100 to 300 grains. The larvae disperse after hatching. They first damage the leaf sheaths, young stems, and buds of the pods, and then bite the stems into the larvae and turn to the lower part of the rhizome. Soil moisture is an important factor in the hatching and adult emergence. The moisture content of 3 to 4 cm soil layer is most suitable for 15 to 24%. The soil is too wet or too dry to be conducive to its hatching and emergence. Adults have no tropism towards unfaded manure, and therefore the degree of maturity with which organic manure is applied has nothing to do with the occurrence of this worm. In general, the amount of clay produced is smaller than that of sandy loam, and the emergence rate of soil compacted plots significantly decreases.
Control methods (1) Agricultural control, winter irrigation or spring irrigation can eliminate some of the larvae, such as the right amount of pesticides such as roxen, phoxim, etc., with better results. (2) Chemical control: In adult eclosion period (mid-to-late April, mid-June, late July and mid-October), spray 75% phoxim EC 1000 times to kill adult worms. The best results were achieved at 9 to 10 am. At the beginning of the larvae damage (early May, late July, late October and mid-late October), it was found that when the tips of the larvae begin to yellow and become soft and gradually lodging on the ground, they should be prevented and treated immediately. It is recommended to use 48% of chlorpyrifos (chlorpyrifos) EC, 150-200mL per 667m2, 1000kg of water, and a manual sprayer for workers and peasants-16 to remove the spray and spray the solution forward to the root of the victim crop. Can also increase the amount of medication with the water flow to save labor, effective and safe. In addition, it is also possible to use 75% phoxim EC 500 to 600 times solution or spray.
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