Occurrence regularity and control of sweet potato diamondback moth

Sweet potato diamondback moth Herseconvolvuli (Linnaeus) belongs to Lepidoptera, Noctuidae. It is distributed in Japan, as well as in Liaoning, Hebei, Henan, Shandong, Shanxi, Zhejiang, Taiwan, Guangdong and other provinces in China. It mainly harms the plants of Convolvulaceae, Solanaceae and Leguminosae.

I. morphological recognition

1. The adult is 43-53 mm long, with a wingspan of 100m / 120mm, a dark gray head, a grayish brown chest and back, and two clumps of scaly hairs to form a "eight" shape. There are gray-white markings on the middle chest. There is a gray longitudinal band on the abdomen and back. There are white, red and black horizontal lines on both sides of each section. The forewings are grayish brown, densely covered with jagged markings and cloud markings. There are 4 dark brown horizontal bands on the rear wing, and the bristles are white, glue and dark brown.

2. Ovoid, about 2 mm in diameter, yellowish green.

3. The mature larvae are 60-90 mm long and covered with small particles. There are 7 dorsal folds in each of the 7 segments of the abdomen. There are two kinds of body colors: green head green, light yellow twill on both sides, light green chest, topline, subtopline, lower valve line yellow, and yellow-white twill on both sides of abdominal 1-7 segments. The valve is orange, the peri-valve piece is brown, the tail horn is yellow-brown, the tip is black, and the chest foot is yellow-brown; the brown head has 2 black longitudinal stripes, the chest subtopline shows a wide light color strip, and the hip plate shows a yellow band. There are yellowish diagonal stripes on both sides of abdominal section 1 and 7, valves and feet are black.

4. The pupa is brown, the body length is 56 mm, the beak is long and free, scarlet to dark red, the wing reaches the fourth abdominal segment, and the buttocks are triangular.

Second, occurrence regularity

Life history and habits: there are 2 generations in Beijing and 3 generations in South China every year. Overwintering with mature larvae pupating at a depth of 5-10 cm in the soil. The Beijing area appeared in May or early October with phototaxis and scattered eggs on the back of the leaves. The larva damage was seen in South China at the end of May, and there were more larvae from September to October. The larvae ate the tender stem of Yongcai, and the older larvae ate a large amount of food. When the damage was serious, the leaves were eaten up, leaving only the old stem. In South China, the egg stage is 5ml 6 days, the larval stage is 7mi 11 days, and the pupa stage is 14 days. Adults lie dormant during the day, feed on nectar at night, mate and lay eggs. There are a lot of eggs in the luxuriant stems and leaves, and the damage to the larvae is also serious.

III. Prevention and control methods

It generally occurs sporadically and can be eliminated manually with field management, and this pest can be controlled at the same time when controlling other pests.