Tea bark beetle

The adults and larvae of tea bark beetle drill into the branches of litchi and longan, and the branches with a diameter of 1 cm to 2 cm suffer the most, and a large number of near-round small wormholes can be seen in the appearance. If the damaged branches are cut open, a number of horizontal tunnels that have been drilled into a near ring will be found in the xylem, and there are often dark brown beetles thinner than rice grains or milky white legless larvae and pupae. The damaged branches are weakened due to the obstruction of water and nutrient transport, and often cause withered branches, broken branches, and even found that the whole young tree was killed. Tea bark beetle has been found in the main producing areas of litchi and longan in China in recent years, while the occurrence and damage of Zhongshan, Dongguan, Shenzhen and Maoming in Guangdong are more serious. It has also been found in many Southeast Asian countries, such as India, the Philippines and Sri Lanka. In addition to litchi and longan, it can also harm tea trees, cocoa, coffee, rubber, camphor trees, willows and other economic trees.

Morphological characteristics of tea bark beetles belong to Coleoptera and Cerambycidae. The adult is small, only 1.3-2.4 mm long, dark brown, cylindrical. The head extends into a short beak, the antennae are knee-shaped, and the ends are swollen into a ball, which is an important feature of the insect. The chest dorsal plate and sheath wings are densely carved and hairy. The male adult is smaller and lighter in color. Ovoid, oval, ca. 0.6 mm. The larvae are milky white and have no feet, and the mature larvae are about 2.4 mm long. The pupa is milky white to yellowish brown, 1.2 to 2.4 mm long. The life history and main habits of tea bark beetles occur for 6 generations a year in the vicinity of Guangzhou, and the generations overlap because of the long life span of adults. The adults overwintered mainly in the cavernous tunnels and began to warm in the next spring to build new tunnels. The insect camp lives in concealment, lays eggs in the tunnel, and only goes out for short activities in sunny afternoons during the spread of adults, so pesticide control is difficult to be effective. The degree of host damage is closely related to variety, tree age, tree potential and management level: March red and Huai branches are rarely injured, and those with old tree age, poor management and weak tree potential are seriously injured. The degree of damage was negatively correlated with the water potential of the tree. The prevention and control methods should be based on strengthening the cultivation and management of the orchard, reasonably applying nitrogen fertilizer, strengthening the tree potential and improving the water potential of the tree body, cut off the pest branches thoroughly after fruit harvest and clearing the garden in winter, and collect the dead branches and broken branches in the garden and burn them together. When necessary, field investigation and observation can be strengthened to spray 90% Batan wettable powder, 80% dichlorvos emulsion, 50% fenitrothion emulsion or 1000 times isocarbophos during the spread of adult activities.