What are the control methods for the tea white scale (Pseudaulacaspis pentagona)?

The tea white scale belongs to the order Homoptera, family Diaspididae. It is distributed in most tea-producing provinces across the country and is an important tea tree pest in East China and Southwest China. Besides damaging tea, it also harms various plants such as citrus, pear, and apple. It damages tea trees by nymphs and female adults parasitizing on branches and trunks and sucking sap. Affected tea trees sprout sparsely, decline in vigor, age prematurely, and in severe cases shed a large number of leaves or even die. Morphological characteristics: the female's scale cover is grayish-white, about 1.5 mm long, narrow and slightly curved like a bent eggplant, slightly wider at the rear end and with a brown scale point at the front end. Beneath the female's scale cover there is also a layered dark brown shield shell; in the later stage of growth, the dark brown shield shell is what is commonly seen in the field.

The female adult of the tea white scale is pear-shaped and pale yellow. The male adult is slender and weak, with one pair of wings, pale purple body, and a copulatory organ at the end of the abdomen. Eggs are oval, pale purple, laid beneath the scale cover. Newly hatched nymphs are oval, pale purple, with legs and antennae, and 2 tail hairs at the end of the abdomen, and can crawl. After settling, they secrete wax on their back to form a scale cover. Female nymphs settle on branches and trunks, while male nymphs tend to settle on the serrations at the edges of tea leaves; their scale covers are slender and grayish-white. Male pupae are long oval and pale purple.

Occurrence pattern: In tea areas of the Yangtze River basin, 3 generations occur per year, overwintering as mature nymphs on tea branches and trunks. They emerge in late March of the following year and begin laying eggs in mid-to-late April. The peak hatching periods of the 1st to 3rd generation nymphs are respectively in mid-to-late May, late July to early August, and mid-September to early October. The 1st and 2nd generation nymphs hatch relatively uniformly.

Control methods: (1) Nursery stock quarantine. Disinfect nursery stock parasitized by scale insects; (2) Strengthen tea garden management, clear the base and open up the lower part. Promote ventilation and light penetration in the tea garden, and promptly prune tea branches with severe infestation; (3) Protect natural enemies. Pruned branches with pests should be piled up in a centralized place for a period of time to let parasitic wasps emerge and fly back to the tea garden. In tea gardens with a high density of ladybugs, manual transplantation can be used to help, and pesticide use should be avoided as much as possible during the active period of ladybugs; (4) Chemical control. Apply pesticides during the peak hatching period of nymphs. You can use 25% phosmet, 25% quinalphos, 50% malathion, 25% buprofezin at 800-1000 times dilution. You can also choose 0.5 degree Baumé lime sulfur mixture, 10-15 times rosin mixture, 25 times anthracene oil or machine oil emulsion.