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

At present, in South China and the middle reaches of the Yangtze River, mid-season rice is in the grain-filling to harvest stage, while in Southwest and Northeast China, single-season rice is at the grain-filling to heading stage. In the middle and lower reaches of the Yangtze River, late-season single-crop rice is in the booting to heading stage. Due to a high initial pest population and frequent recent typhoon activity, brown planthopper populations—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 region, and the Jianghuai rice-growing area.
I. Recent Developments
Currently, the nationwide area affected by rice planthoppers during the mid- and late‑rice growing season 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 classified as moderate (Level 3), with heavier to severe outbreaks (Levels 4–5) observed 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 time of year. 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 period, 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, recent surveys in the rice-growing regions along the southeastern coast have revealed peak moth‑attracting activity dominated by the brown planthopper. Affected by Typhoon Maysak, from late August to early September, multiple monitoring sites across southeastern coastal areas—including Fujian, Guangdong, and Zhejiang—recorded daily trap catches exceeding 10,000 individuals, with a high proportion of brown planthoppers. For example, at 19 monitoring stations in Fujian, the average daily catch per light from August 27 to September 2 reached 1,497 insects, with brown planthoppers accounting for 60% of the total; in Jianning, a single light captured 10,080 insects on August 25, with brown planthoppers making up 95%, while in the field, a single light recorded 12,800 insects on August 28, with brown planthoppers comprising 75%. In Dapu, Guangdong, cumulative catches from a single light on August 28–29 totaled 14,688 insects, with brown planthoppers representing 40.7%. In Xianju, Huangyan, and Linhai, Zhejiang, peak daily catches on August 30 were 19,520, 8,576, and 7,040 insects, respectively, with brown planthoppers accounting for 100% of the catch.
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- to late‑maturing 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‑cropping rice areas, Jiangxi’s mid‑season rice zones, the central and southern parts of Anhui’s rice region, 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 full‑scale infestations. 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 surpassed 50,000 pests per hundred tillers; in Quzhou, Zhejiang, 31% of fields experienced severe outbreaks, with average densities in Kaihua and Jiangshan reaching 10,533 and 3,905 pests per hundred tillers, 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 regions of Anhui, fields with inadequate or ineffective control harbored 3,000–7,000 pests per hundred tillers, with some exceeding 20,000, while in localized areas, short-winged adult populations reached 50–180 pests 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 area 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 overwintering 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 favorable for their development. All localities must remain highly vigilant, strengthen monitoring at light traps 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