After the corn borer larvae hatched, part of the leaves were hidden in the leaves of the females with the leaves above the planting nodes. The accumulated pollen and leafhopper tissues were fed to the 4th instars, and most of the newly hatched larvae were concentrated on the top of the ear. At the base of the filaments, feeding takes place. In the year of large eggs, there are often several or even dozens of larvae on the top of a spike. The larvae that live on the top of the ear feed on filaments and immature tender granules, making the grain incomplete and causing mildew and reducing the quality of the corn kernels. By the age of 4 to 5, some of these larvae have fallen from the top of the female ear into the rachis, some have fallen from the base of the female ear into the female pedestal, and some have fallen above and below the stalk. At this time, corn has entered the middle and late stages of grouting, and the size of the ear has been determined. Therefore, this generation of larvae mainly affects the grain weight and grain quality.
ã€Morphological characteristics】
The adult body is tan, male body length 10-14mm, wingspan 20-26mm; tentacles filamentous, gray-brown, compound eye black; dark brown wavy lines inside the forewings, brown inside, brown at the base; Dark brown jagged lines, tan outside, between the outer horizontal line and the outer edge line, with 1 brown band. There are 2 brown spots between the inner horizontal line and the outer horizontal line; the inside of the hair margin is brown, the outside is white, the hind wings are grayish yellow, and there is 1 brown band at the center and near the outer edge; the female moth is larger than the male. The body is light in color, the front wings are light yellow, and the lines and stripes are light brown. The broad band between the outer horizontal line and the outer edge line is very light and unnoticeable; the hind wings are grey or grayish brown; the bases of the hind wings have wings. One male moth, more stout; female moth 2, slightly finer. Short oval, flat, slightly shiny; milky white at the time of first birth, followed by yellowish-white, translucent; just before hatching, the center of the egg appears dark spots, which is the larvae's head shell, and the edge is still milky white.
Occurrence rule
The overwintering larvae enter the peak period of phlegm in mid-late and late May, and the overwintering adults thrive from late May to early June and lay eggs on corn. The 1st generation larvae were damaged during the middle and late June. At this time, corn was in the heart and leaf stage, and the damage was heavy. The second generation larvae infested corn (heart stage) and corn (ear stage) in mid-late July. The 3rd generation larvae enter into Shengfa in mid-late August and harm the ears and stems of the corn. Adults often emerge at night, and males have eclosion habits 1-2 days earlier than females. During the day, they often hide in weedy or wheat fields, rice fields, and lush crops. They fly out at night and have a strong flight. Adults have phototaxis and strong sex-induced reactions. Larvae hatch egg shells after hatching. The newly hatched larvae are quick-acting, can crawl quickly, encounter wind or touch, that is, drooping silk, transfer to other sites or spread to neighboring plants. Larvae have a number of characteristics that are sugar-carrying and humectant. Sows with early sowing, lush growth, and dark green leaves often have more eggs than normal corn. For corn of different growth stages, varieties, and sowing dates, the severity of the damage will be different due to the difference in the survival rate of larvae. In the flowering stage, it is most likely to attract codling moths to lay eggs. On the floret and tender grains, the survival rate of the larvae is significantly higher than that of the leaf stage. At the same egg mass or population density, the susceptible species (strain) was heavy and the survival rate of corn borer larvae was high.
[control methods]
Before the overwintering larvae emerge, treatment of stalks of overwintering hosts such as corn, sorghum, and cotton is an effective measure to eliminate overwintering larvae and suppress the base number of overwintering insects: 3 generations of areas, maximize the area of ​​summer corn, compress corn, sorghum, millet, etc. The spring planting area of ​​the host crops will reduce the source of food and breeding sites for the first generation corn borer to control the occurrence of the second and third generations and reduce the damage to the summer corn. Using the female moths to prefer the habit of laying eggs on tall, dense, and vigorously growing host plants, select a small area of ​​trapping zone or temptation plot near the wintering plot site about one month before the normal sowing of spring maize, or A few early-seeding spring corn plots will strengthen fertilizer and water management, promote its early onset, and induce integrated egg production. Planting aphid-resistant varieties is an economic, effective and safe measure for pestilence control. In combination with field management measures for some crops, in particular, seedlings, saplings, and cotton pruning, snoring, and de-hearting can be used to remove eggs directly, which is more closely related to the control of corn borer. Such as the first generation of corn borer damage in the corn seedling stage, can be combined with the seedlings, Dingmiao remove insect strains; second generation corn borer young larvae first in the corn head, petiole damage, and then stolons, can be combined with pruning, topping removed There are insect petioles, tender tips and branches, and brought out of the field to concentrate treatment, can significantly reduce the damage of corn borer.
The optimum period for the control of corn borer is the end of the heart leaf stage, which is the big bell-mouth period, which is the key period for preventing corn borer.
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