Alert! A major outbreak of rice planthoppers in late-season rice fields.

At present, mid-season rice in South China and the Jiangnan region, as well as single-season rice in Southwest and Northeast China, are in the grain-filling to harvest stage; double-season late rice in South China and Jiangnan is at the tillering to panicle‑initiation stage; and single-season late rice in the middle and lower reaches of the Yangtze River is in the panicle‑formation to booting stage. Owing to a high initial pest population and frequent recent typhoon activity, populations of rice planthoppers—both at light traps and in the fields—are elevated across much of southern China, with a clear trend toward severe outbreaks in eastern South China, central Jiangnan, the middle and lower Yangtze River basin, and the Jianghuai rice-growing area.
I. Recent Developments
Currently, the nationwide area affected by rice planthoppers in mid- and late-season rice stands at 105 million mu‑times, up 17% from the same period last year and 10% above the five-year average for this time of year. Overall, the infestation is at a moderate level (Level 3), with heavier to severe outbreaks (Levels 4–5) reported in eastern South China, central Jiangnan, and the middle and lower reaches of the Yangtze River.
First, since mid-August, pest populations attracted to light traps in most rice-growing areas of southern China have been higher than the long-term average for this period. According to monitoring data from 217 regional stations nationwide, from August 11 to September 2, the cumulative number of brown planthoppers caught at light traps across southern rice regions reached 430,000, with the brown planthopper accounting for 61% of the total. During this time, the average daily catch per trap exceeded five times the level recorded during the same period last year in eastern South China, the middle and lower reaches of the Yangtze River, and the Jianghuai rice region, and was 1.2 to 4 times the five-year average; in most rice-growing areas of central and southern China, catches increased by 13% to 170% compared with the same period last year.
Second, in recent weeks, rice-growing areas along the southeastern coast have experienced peak moth‑attracting activity dominated by the brown planthopper. Affected by Typhoon Maysak, from late August to early September, multiple monitoring sites in southeastern coastal provinces such as Fujian, Guangdong, and Zhejiang recorded daily trap catches exceeding 10,000 individuals, with a high proportion of brown planthoppers. For example, at 19 monitoring sites in Fujian, the average daily catch per light from August 27 to September 2 reached 1,497 individuals, with brown planthoppers accounting for 60% of the total; in Jianning, a single light on August 25 attracted 10,080 individuals, 95% of which were brown planthoppers, while in the field on August 28, a single light captured 12,800 individuals, 75% of which were brown planthoppers. In Dapu, Guangdong, cumulative catches over two days (August 28–29) totaled 14,688 individuals, with brown planthoppers making up 40.7%. In Xianju, Huangyan, and Linhai, Zhejiang, peak daily catches on August 30 were 19,520, 8,576, and 7,040 individuals, respectively, all with 100% brown planthopper composition.
Third, in eastern South China, central Jiangnan, and the rice-growing regions along the middle and lower reaches of the Yangtze River, field populations of planthoppers are high, with a particularly elevated proportion of brown planthoppers. Following earlier control measures, planthopper populations in the mid- and late‑season rice areas of southern China have been brought under effective management, with average counts generally ranging from 200 to 500 insects per 100 hills. However, recently, in Fujian’s single‑crop rice areas, Jiangxi’s mid‑season rice regions, the central and southern parts of Anhui’s rice‑growing zones, northern Zhejiang, and Shanghai’s lower‑Yangtze rice areas, pest densities have risen sharply; in some locales, average counts have exceeded 1,000 insects per 100 hills, surpassing the threshold for intervention. Moreover, in Shanghai, Jiangxi, Hunan, and Fujian, the proportion of brown planthoppers in fields has reached 90%, 85%, 76%, and 55%, respectively, posing a significant risk of resurgence.
Fourth, localized control measures were inadequate, leading to severe outbreaks in some fields. In eastern South China, central Jiangnan, and the middle and lower reaches of the Yangtze River, pest populations in certain rice-growing areas exceeded critical thresholds, with some fields experiencing complete crop damage. For example, in Shunchang, Jianning, and Ninghua in Fujian, heavily infested fields recorded 10,000–30,000 pests per hundred tillers; in Wuyuan, Fuliang, Poyang, and Yongxiu in Jiangxi, peak densities in mid-season rice fields exceeded 50,000 pests per hundred tillers; in Quzhou, Zhejiang, severely affected fields accounted for 31% of the total, with average densities of 10,533 and 3,905 pests per hundred tillers in Kaihua and Jiangshan, respectively; in Chongming, Shanghai, and Yancheng, Jiangsu, uncontrolled or poorly managed fields averaged 9,700 and 7,500 pests per hundred tillers, respectively; and in the central and southern rice‑growing regions of Anhui, fields with inadequate or ineffective management harbored 3,000–7,000 pests per hundred tillers, with some reaching over 20,000, while in localized areas, short-winged adult insects numbered as high as 50–180 per hundred tillers.
II. Forecast for the Next Phase
According to forecasts from the National Climate Center, temperatures in southern rice-growing regions are expected to be near or above normal for this time of year, with southern Zhejiang, eastern and southern Jiangxi, Fujian, and northeastern Guangdong experiencing anomalies 1–2°C higher. Meanwhile, the middle and upper reaches of the Yangtze River and the Jianghuai rice‑growing areas are likely to see above‑normal precipitation. Favorable temperatures and regionally concentrated rainfall will promote an increase in the number of generations of rice planthoppers and extend their period of damage. Over the next 10 days, typhoon activity is expected to be frequent over the South China Sea and the northwestern Pacific, with one additional typhoon forming in these waters. Rainfall in southeastern Southwest China and western Jiangnan is projected to exceed normal levels by 30%–80%, with some localized areas seeing 100%–200% more precipitation, creating conditions conducive to the southward migration and subsequent infestation of rice planthoppers.
In the coming period, brown planthoppers are expected to pose a high risk of severe outbreaks in areas with large pest populations—such as the double-cropping late‑rice regions of South China and the Jiangnan region, as well as the single‑cropping late‑rice areas along the middle and lower reaches of the Yangtze River and the Jianghuai Plain—where the proportion of brown planthoppers is high and host plants are at growth stages conducive to infestation. All localities must remain highly vigilant, strengthen light‑trap monitoring and field surveys, comprehensively track the dynamics of planthopper populations, issue timely short‑term forecasts and alerts, and provide effective guidance on prevention and control measures.

Source: Pest and Disease Monitoring Division, National Agricultural Technology Center; Author: Pest and Disease Monitoring Division, National Agricultural Technology Center