Green Production Technology Innovation Team, Tea Research Institute, Yunnan Academy of Agricultural Sciences / Xishuangbanna Comprehensive Test Station, National Tea Industry Technology System
Mycterothrips gongshanensis, a new Pest on tea plants, belongs to the order Insecta, family Thysanoptera, genus Thripidae, and species Mycterothrips. It is a cryptic Bud and leaf pest that has been widely occurring in tea gardens in Yunnan province in recent years, with increasingly severe damage.
I. Distribution and Damage
Mycterothrips gongshanensis is prevalent in tea-growing areas of Yunnan, causing outbreaks in some tea gardens. The adult and nymph stages hide in the crevices between buds and leaves or at the tips and edges of the first leaf below the bud, feeding on the sap of young shoots and tender buds. Initially, the tips and edges of the affected leaves show yellow spots, which then gradually develop into brown patches. The buds and leaves become deformed and curled, the internodes shorten, and their growth slows down. Severe cases result in the easy detachment of leaves upon slight touch, leading to leaf fall and bare shoots, significantly affecting tea yield and quality, and potentially causing substantial economic losses in summer and autumn tea production.
Damage caused by Mycterothrips gongshanensis
II. Morphological Identification
Egg: Milky white, translucent, kidney-shaped, 0.2-0.3 mm long, about 0.1 mm wide.
Nymph: There are four instars. First-instar nymphs are initially milky white, turning pale yellow-green later, approximately 0.3-0.6 mm long, with antennae extending forward, without wing buds; second-instar nymphs are yellow-green, 0.7-1.0 mm long, with antennae extending forward, no wing buds; third-instar nymphs (pseudo-pupae) have a yellow-white head-thorax, yellow abdomen, white and transparent legs and antennae, 0.7-0.9 mm long, wing buds start to appear, cylindrical, hairless, hindwings longer than forewings, antennae erect or adhering to the dorsal surface of the head; fourth-instar nymphs (pupae) initially have a yellow-white body, white legs, antennae, and wings, 0.8-1.1 mm long, wing buds gradually elongate and display trichomes, forewings and hindwings nearly equal in length, antennae adhere to the dorsal surface of the head behind them, as they grow and develop, the color of the wings and antennae darken, gradually turning brownish-brown overall.
Female adult: 1.1-1.3 mm long, brown to dark brown in color. The forewings are dark brown, with lighter bases and ends. There is a transverse stripe behind the eyes on the head. The antennae have eight segments, with forked sensory cones on segments III and IV. The pronotum is wider than it is long; the mesonotum has a transverse stripe, with sensory pores present along the anterior edge; the metanotum has a transverse stripe in the middle front and longitudinal stripes on the sides. The forewing has an interrupted row of bristles on the pre-marginal vein and two apical bristles. The abdominal tergites II-VIII have transverse stripes with numerous microtrichia on them.
Male adult: Slightly smaller than the female, 0.9-1.1 mm long, with a lighter color than the female. Antennal segment VI is almost as long as in the female. The egg is kidney-shaped, 0.2-0.3 mm long, milky white and translucent, with two red ocelli visible near hatching.
III. Occurrence, Damage Patterns, and Characteristics
Mycterothrips gongshanensis occurs every month in Yunnan and does not overwinter. Nymph numbers typically exceed those of adults, with population numbers gradually increasing from late February. The population growth shows a bimodal pattern, with peaks from mid-April to mid-May, and from early September to early October. After mid-October, population numbers continuously decline. This pest has a high survival rate, strong reproductive capacity, short generation cycle, and rapidly expanding population. Under constant temperature conditions of 25°C, the egg period averages 3.9 days, and the duration of the first-instar nymph, second-instar nymph, third-instar nymph (pre-pupa), and fourth-instar nymph (pupa) are 1.7, 3.1, 2.2, and 3.3 days respectively. The average lifespan of the female adult is 15.5 days, and the male adult is 14.1 days. The completion of one generation takes an average of just 21.3 days, with the average number of eggs laid per female being 36.1. This pest can cause outbreak damage, and in many tea gardens in Yunnan, the occurrence of M. gongshanensis exceeds that of other Thrips species.
The small size and strong concealment of M. gongshanensis make it prone to hiding within bud crevices and leaf gaps, where adults lay eggs inside the bud tissues. As the buds grow, the hatched nymphs begin to feed inside the buds, often resulting in the phenomenon of “visible damage but no visible pests” in the field. This delays recognition of the infestation until significant damage occurs, missing the optimal control period and leading to unsatisfactory results. This pest is strongly attracted to tender parts, primarily damaging young buds, with the most severe damage occurring in growing buds. Initially, the outer layer of the young buds slightly turns brown, and the petioles at the junction of the bud and leaf gradually turn brown. Later, as the buds expand, the bud heads peel off layer by layer, the young leaves turn brown, curl, deform, and fall off, leaving only “bare stalks.”
Adults and nymphs of M. gongshanensis avoid strong light, quickly escaping when exposed to light. During the day, when the light is strong, they hide in the gaps within buds, between leaves, and under the curled margins of young leaves for feeding and resting. On cloudy days, adults can be seen active on the leaves. Nymphs feed in clusters. When the population is large or the buds and leaves become scorched and withered, adults and nymphs have the ability to move to new locations. Eggs are laid inside the tender buds, and after hatching, the nymphs immediately start feeding inside the buds.
Damage caused by Mycterothrips gongshanensis in Wulang Mountain Town, Nanjian County on April 28, 2024
Damage caused by Mycterothrips gongshanensis in Wulang Mountain Town, Nanjian County on April 28, 2024
Symptoms of damage caused by Mycterothrips gongshanensis in Simao District, Pu'er City on April 25, 2024
Symptoms of damage caused by Mycterothrips gongshanensis in Simao District, Pu'er City on April 25, 20