Identification and Control Methods for the White-Winged Leafhopper in Rice

Scientific name Thaia rebiginosa Kuoh, formerly mistaken for Erythroneura subrufa (Motschulsky), belongs to the order Homoptera, family Cicadellidae. It is distributed south of the Yellow River and east of Xichang, Sichuan. Damage is severe in parts of the mountainous areas of Yunnan, Guizhou and Sichuan and in Hanzhong, Shaanxi.

Hosts include rice, @#@245@#@, barley, sugarcane, wild rice stem, corn, rapeseed and others.

Damage characteristics: adults and nymphs pierce and suck leaf sap; damaged leaves first show scattered small white spots, which later join into dotted streak marks, or white streak marks that eventually turn brown, affecting growth and development and the 1000-grain weight.

Morphological characteristics: female body length 3.5-3.7 mm, male slightly smaller. Head, thorax and abdomen orange-yellow. The front margin of the head has one half-moon-shaped white spot on each side. The center of the pronotum has one light grayish-yellow diamond-shaped spot, with one small white dot on each side of the spot. Forewings grayish-white, semi-transparent, with iridescent sheen; hindwings light orange, more transparent than the forewings. Egg length 0.65 mm, nearly bottle-shaped, slightly curved, pointed at one end and bluntly rounded at the other, milky white. Nymphs have 5 instars in total. The final-instar nymph body length is 2.4-3.2 mm, light yellow-green, with obvious bristles on the body.

Life habits: In Zhejiang, Anhui and Hunan it has 3 generations per year, and further south 3-6 generations per year. It overwinters as adults on weeds in wheat fields, green manure fields and wind-sheltered, sunny spots. The following spring, overwintering adults first damage wheat fields; after early rice emerges, they move in to damage and reproduce, then spread to early rice main fields or late rice fields. When late rice enters the harvest season, the insect again migrates to overwintering hosts. Adults are active and good at flying; when disturbed they dodge sideways or fly elsewhere. Nymphs have poor jumping ability and when disturbed walk diagonally or sideways. When the temperature is below 1°C, adults mostly hide in soil cracks or at the base of plants, and begin activity above 2°C. At an average temperature of 21-23°C, the egg period is 15-16 days; the nymph period is 17-21 days for the first and second generations and 33-40 days for the third generation. Adult lifespan is 20-30 days, and 194 days for the overwintering generation. They prefer to emerge in the morning and feed on the upper leaves of plants, with a strong tendency toward tender green growth and toward light. They mostly lay eggs during the day in the cavities of the main veins of rice leaves; during the tillering stage they lay on the first and second leaves at the base of rice plants, and during the heading stage mainly on the third leaf, with 1-3 eggs per site, occasionally 5. The overwintering generation lays 45-60 eggs per female, the first generation 55-60 eggs, and the second generation 30 eggs. When the temperature is below 20°C and the relative humidity is 85%-90%, many nymphs die, lifespan is short, and egg production declines. In production, if there is much rain in May and June, and the temperature is relatively high in August and September with a certain amount of rainfall, a major outbreak may occur. In rice-wheat double-cropping and mixed double-season rice planting areas, second-season late rice suffers severe damage, followed by late-maturing mid-season rice. Early-sown and early-transplanted rice is generally susceptible in the early stage; with excessive nitrogen fertilizer and vigorous rice seedling growth, the insect population is large and damage is severe. Natural enemies mainly include @#@255@#@, Strepsiptera insects, Harmonia axyridis, various spiders and others.

Control methods: (1) For early rice and late rice seedling fields, spray 5 days before pulling seedlings, which has an obvious effect on reducing later insect populations. (2) Control in the main field should be carried out in a timely manner according to insect conditions; for the types and amounts of pesticides, see the black-tailed leafhopper.