What to Do About the Green Leafhopper on Rice? A Detailed Guide to Effective Control Methods
Scientific name: Homoptera, Delphacidae. Distributed in the wild rice stem (Zizania latifolia) and rice-growing areas of both southern and northern China.
Hosts include rice, wild rice stem, and wild Zizania latifolia.
Damage characteristics: adults and nymphs pierce and suck the sap of rice; affected leaves develop yellowish-white to light brown or reddish-brown spots, after which the leaves gradually turn yellow and dry up from the tip toward the base; excrement covers the leaf surface, forming a sooty mold-like coating; the female's egg-laying scars are initially water-soaked, then secrete white downy waxy powder; once wounds appear, the plant loses water, wilting in clumps and dying off in patches.
Morphological characteristics: male adult body length 5-6.1 mm, female 5.7-7 mm, slender, body pale green, compound eyes and simple eyes black or reddish-brown; the vertex protrudes in front of the compound eyes, slender, conical; the tip of the rostrum and the teeth of the hind tibial spur are dark brown. The pronotum and the mesoscutellum each bear 3 longitudinal ridges; the length of the entire mesothorax equals the sum of the vertex and pronotum; the female's external genitalia often secrete a white downy waxy substance. The male's genitalia are slender and sword-shaped. Eggs are 0.7-1 mm long, banana-shaped, initially semi-transparent, milky white to grayish-yellow. Nymphs pass through 5 instars; newly hatched nymphs are milky white and slightly transparent; after the 1st instar they develop waxy powder; the 5 waxy filaments trailing from the tip of the abdomen resemble white downy material; 1st and 2nd instars have no wing pads; from the 3rd instar the body turns green; in the 4th instar the forewing pads are shorter than or close to the hindwing pads; in the 5th instar the forewing pads completely cover the hindwing pads.
Life habits: 3 generations per year in Jilin; in Jiangsu, Jiangxi, Zhejiang, Hubei, Shang-
-hai 4-5 generations per year; after the 2nd and 3rd generations the generations overlap; it overwinters as diapause eggs in the leaf veins, leaf sheaths, or dead leaves of hosts such as autumn Zizania latifolia and wild Zizania latifolia. In Hubei, overwintering eggs begin to hatch in early to mid-April, reaching their peak from late April to early May; adults first appear in early June; the first generation occurs from early June to late July, the second generation from early July to early September, and the third generation from mid-August to mid-October. The overwintering generation's egg stage lasts 6-8 months; at 22-26°C the first generation's egg stage lasts 10-12 days; the nymph stage lasts 26-38 days at 15-22°C; the egg-laying period lasts 9-25 days, with the peak of egg-laying beginning 2-3 days after laying starts; adult lifespan is 3-7 days. Natural enemies include parasitic wasps, spiders, lacewings, ladybugs, and frogs.
Control methods: (1) Begin surveying the number of overwintering eggs in March. (2) Before the eggs hatch in February, burn the dead rice leaves or cut them away completely, and thoroughly clear weeds from field edges, ponds, and ditches. (3) When the 2nd-3rd instar nymphs of the overwintering generation on summer rice are at their peak, spray a 2500-fold dilution of 10% imidacloprid wettable powder, or a 1000-fold dilution of 30% acephate emulsifiable concentrate, 50% fenitrothion emulsifiable concentrate, or 2000-fold dilution of 20% buprofezin emulsifiable concentrate; apply 5% fipronil suspension concentrate at 20 ml per 667 sq m, or 90% monosultap technical powder at 50-60 g per 667 sq m diluted with water for spraying; or a 2000-fold dilution of 20% fenvalerate or 2.5% deltamethrin emulsifiable concentrate; adding 0.2% neutral laundry powder to the spray solution can improve control efficacy. A 75% mixture of buprofezin and other agents wettable powder at 650 g per 667 sq m can also be used to control rice planthoppers while also controlling the striped stem borer, the yellow stem borer, and the rice leaf roller. In addition, spraying 2% BPMC (fenobucarb) dust at 2 kg per 667 sq m is also effective.