The scientific name of this pest is *Nilaparvata lugens* (Stål), which belongs to the order Hemiptera, family Delphacidae. Its geographical distribution spans from Jilin in the north down to Liaoning, Hebei, Shanxi, Shaanxi, and Ningxia, extending as far west as Gansu, and then southward through Sichuan, Yunnan, and Tibet. This insect primarily infests rice plants.
The injury characteristics of *N. lugens* involve nymphs clustering at the lower parts of rice tillers, where they feed on sap. Female adults use their ovipositor to pierce leaf sheaths and leaves, causing dehydration or infection by sclerotia. Their excreta often lead to mold growth, which hinders photosynthesis and respiration in rice plants, eventually leading to plant drying. Commonly referred to as "erupting," "top-through," or "collapse," severe infestations can result in complete crop failure.
In terms of life habits, *N. lugens* exhibits multiple generations depending on the region. In Hainan, there are 12–13 generations per year, with overlapping generations and no overwintering. In Guangdong, Guangxi, and southern Fujian, the number of generations ranges from 8–9, occurring between March and May. In southern Guizhou, it's about 6–7 generations from April to June, while in the middle and lower reaches of the Min River, Guizhou, northern Fujian, and southern Zhejiang, there are 5–6 generations, migrating from May to June. In northern Jiangxi, Hubei, Hunan, Zhejiang, and southeastern Sichuan, there are 4–5 generations, migrating from mid-July to mid-August. In northern Jiangsu, northern Anhui, and southern Shandong, only 2–3 generations occur, moving from July to August. In other northern rice-growing areas, there are typically 1–2 generations, also moving between July and August.
The main sources of infestation spread from south to north, following warm, moist air currents. There are approximately five large-scale movements annually, with populations returning south in the fall. The egg development period varies: 17 days at 17°C, 9 days at 23–24°C, and 7–8 days at 27–30°C. Nymphs develop in 15–16 days at 24–26°C. Short-winged adults remain in one place, while long-winged individuals migrate. They can fly strongly shortly after emergence, using high-altitude air currents for movement. During spring and summer, they fly at altitudes of 1,500–2,000 meters, preferring high humidity for migration. The initial flight temperature is around 18.2°C.
Adults show a strong attraction to green rice and males can mate multiple times. At 24–27°C, mating begins 2–3 days after emergence, with each female laying an average of 200–700 eggs. The average lifespan of one generation is 10–18 days, with field multiplication rates ranging from 10 to 40 times per generation. Nymphs prefer damp, humid environments, typically inhabiting rice plants within 10 cm of the water surface. When insect density exceeds 0 or 4 per cluster, uneven distribution occurs, potentially leading to field collapse.
At the late stage of rice growth, many long-winged adults emerge and migrate out. The 1–3 age stages are critical for wing-type differentiation. Due to changes in farming systems and complex rice varieties with longer maturation periods, the population has increased, leading to more serious damage. The optimal temperature for its growth is 20–30°C, with 26°C being ideal. The Yangtze River valley’s summer temperatures are not excessively hot, but higher temperatures in late autumn favor its occurrence. Brown planthoppers tend to migrate during rainy seasons, and high rainfall facilitates their landing. Large-scale occurrences are common in cloudy, wet fields, especially when nitrogen fertilizer is overused, resulting in dark green seedlings, high density, and prolonged deep water irrigation—conditions that promote reproduction and heavy infestation.
Natural enemies include the rice blast wasp, brownback Trichogramma, rice red beetle, rice silk nematode, black-shouldered lucid plague, and others.
For prevention and control, effective measures include accurate forecasting and analysis of migration trends, uniform planting planning, and rational arrangement to reduce insect sources. Field management should focus on proper fertilizer and water control to prevent excessive growth, maintain appropriate field drainage, and reduce humidity. Breeding and promoting insect-resistant rice varieties is essential to prevent new biotype outbreaks. For example, the hybrid rice variety Xiaoyou 6 shows mild damage in areas affected by biotype I of the brown planthopper. Other resistant varieties such as Xiang Zao No. 1, No. 3, Guang You Qing, Qi Gui Zao 25, Wei You 35, II You 46, D You 64, Wei You 64, Nanjing 14, Yang Dao No. 3, Water Source 290, Xiushui 620, and others may be selected based on local conditions.
Protecting and utilizing natural enemies is also crucial. During the peak nymph hatching period and the 2nd–3rd instar stage, spraying 2.5% fluquinconazole WP or 25% fluquinconazole wettable powder is recommended. For early and late rice fields, apply 20–30g/667m² for early rice and 50g for late rice. Alternatively, 10% suspension agent can be used at 50–100ml/667m², or 10% imidacloprid WP diluted 2000 times, applying 10–20L of solution per 667m². This method achieves over 90% control effectiveness for up to 30 days.
Other options include 80% insecticidal powder at 35–40g/667m², which provides better early control than leafhopper treatments and controls multiple pests. Promote the use of 20% Confodol Concentrate Solvent at 6–8ml/667m², 40% inactivated bellflower oil at 30–40g/667m², or 10% Dagongchen WP at 2g active ingredient per 667m². These treatments also control leafhoppers, Scutellariae, and rice leaf rollers. Additionally, 75% citric acid WP (containing buprofezin) at 650g/hm² can control planthoppers and treat other pests like Scutellariae and rice leaf rollers.
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