Introduction to Control Methods for the Bamboo Shoot Pest, the Noctuid Moth

Bamboo shoots have been regarded in China since ancient times as a "rare delicacy among vegetables." Bamboo shoots are a traditional Chinese delicacy, fragrant in taste and crisp in texture, with a very long history of consumption and cultivation. In the Classic of Poetry there are verses such as "the fruits added to the beans, pickled bamboo shoots and minced fish," and "what is that sound? It is the bamboo shoots and cattails," indicating that the people have a history of eating bamboo shoots of 2500 years, even 3000 years.

Growth Habits of Bamboo Shoots

The underground stems of scattered-type bamboo species such as moso bamboo and early bamboo enter the soil relatively deeply, and the rhizomes and shoot buds are protected by the soil layer, so they are not easily damaged by freezing in winter, and the shooting period is mainly in spring. The underground stems of clumping-type bamboo species such as ma bamboo and green bamboo enter the soil shallowly, and the shoot buds often protrude above the soil surface, so they are easily damaged by freezing in winter, and the shooting period is mainly in summer and autumn.

Bamboo originated in the tropics and subtropics, prefers warmth and fears cold, and is mainly distributed in areas with annual rainfall of 1000-2000mm. The optimum temperature for moso bamboo growth is an annual average of 16-17°C, with a summer average below 30°C and a winter average of around 4°C. Ma bamboo and green bamboo require an annual average temperature of 18-20°C, with a January average temperature above 10°C. Therefore, bamboo forests are lush in southern China, while bamboo forests are sparse north of the Qinling Mountains-Huaihe River line. Bamboo requires deep soil with a loose, fertile, moist texture and good drainage and aeration, and the soil pH value should preferably be 4.5-7.

Bamboo shoots are the young buds of bamboo, also called shoots. Bamboo is a perennial evergreen herbaceous plant, and the edible part is the newly born, tender, plump, short and sturdy bud or rhizome. Bamboo originated in China, has many types, strong adaptability, and an extremely wide distribution. Bamboo shoots are sweet and slightly cold in nature and flavor, and have effects such as clearing heat and resolving phlegm, soothing the diaphragm and refreshing the stomach, and relieving thirst and boosting qi. Bamboo shoots also contain a large amount of cellulose, which not only promotes intestinal peristalsis, removes accumulated food, and prevents constipation, but is also a good food for obese people to lose weight.

Introduction and Control of the Bamboo Shoot Pest, the Noctuid Moth

Aliases of the bamboo shoot noctuid moth: bamboo shoot grass noctuid, shoot borer

Order and family of the bamboo shoot noctuid moth: Lepidoptera, Noctuidae.

Scientific name of the bamboo shoot noctuid moth: Oligiavulgaris

Distribution of the bamboo shoot noctuid moth: Henan, Shaanxi, Jiangsu, Zhejiang, Anhui, Jiangxi, Hubei, Hunan, Fujian, Taiwan, China, Guangdong, Guangxi, Guizhou, Sichuan, Yunnan, Chongqing and other regions.

Hosts of the bamboo shoot noctuid moth: moso bamboo, dan bamboo, firm bamboo, red bamboo, Gui bamboo, Buji bamboo, Dianthus bamboo, Ci bamboo, bitter bamboo, purple bamboo, oil bamboo and other bamboo species, as well as grasses of the Poaceae and Cyperaceae families.

Damage symptoms of the bamboo shoot noctuid moth: the larvae bore into and feed on bamboo shoots, and the affected shoots become insect-caused degraded shoots and cannot develop into bamboo. The few that do develop into bamboo also have broken tops and snapped tips, with numerous insect holes, rotten hearts and brittle texture, affecting their ornamental value and the quality of the bamboo timber.

Morphological characteristics of the bamboo shoot noctuid moth:

(1) Adult: body length 14-25 mm, wingspan 32-50 mm, body and wings brown, with a dark brown inverted triangular large spot at the base of the forewing and at the apex respectively, the inner transverse line, outer transverse line and subterminal line faintly visible, and the hindwing yellowish brown.

(2) Egg: nearly spherical, about 0.8 mm long, pale yellowish white.

(3) Larva: body length 30-45 mm, head orange-red. Body purplish brown, dorsal line thin and white, subspiracular line relatively wide and white, but lacking in the first half of the second abdominal segment.

(4) Pupa: 15-26 mm long, reddish brown, with 4 anal spines.

Occurrence pattern of the bamboo shoot noctuid moth: 1 generation occurs per year, overwintering as eggs in the curled and wrinkled edges of dead leaves of grasses of the Poaceae family; hatching begins at the end of February the following year, and at this time, before the bamboo shoots emerge from the soil, the larvae bore into the heart leaves of grasses of the Poaceae and Cyperaceae families to cause damage, resulting in symptoms of dead heart and white heads. The larvae molt 2-3 times in the grass hearts, no longer grow, and when the bamboo shoots emerge from the soil in early to mid-April, the larvae then transfer from the weeds to bore into the shoots to cause damage, first boring in from the small leaves at the shoot tip, feeding and then molting once more, crawling out of the small leaves, then transferring to bite through the shoot sheath and bore into the shoot to cause damage; if the small bamboo shoot sheath is relatively thin, they can bore directly into the shoot. The larvae feed inside the shoot for 18-25 days to mature; when the shoot is small, they can transfer to other shoots to cause damage; by early to mid-May the mature larvae crawl out of the shoot, bore into the loose soil layer to form a thin cocoon and pupate, with a pupal period of 20-30 days; adults emerge in early to mid-June, are active at night, have phototaxis, mate and lay eggs on the same day or the next day, with each female laying more than 380 eggs; the eggs are laid on the edges of dead leaves on the lower part of grasses of the Poaceae family and inside leaf rolls, and overwinter as eggs. Therefore, the presence or absence and abundance of weeds in bamboo forests directly affects the occurrence of this pest.

Control methods for the bamboo shoot noctuid moth:

(1) Manual control: affected shoots have no dew drops at the tip in the early morning and no luster, commonly known as "degraded shoots," and can be dug out early to eliminate the larvae inside the shoots.

(2) Horticultural control: plowing and weeding to eliminate the overwintering eggs on the grass is the key to controlling this pest.

(3) Physical control: black light traps to kill adults.

(4) Chemical control: in mid to late March before the shoots emerge, spray the weeds under and around the bamboo forest with 20% fenvalerate emulsifiable concentrate at 1000-2000 times dilution and other pesticides, spraying once every 7-10 days, for a total of 2-3 sprays, to eliminate the larvae on the grass.