At present, the medium rice in South China and Jiangnan and the single-cropping rice in Southwest and Northeast China are in the stage of harvesting to filling and milking, the single-cropping rice in the middle and lower reaches of the Yangtze River is in the jointing to the gestational panicle stage, and the double-cropping late rice in South China and Jiangnan is in the tillering stage. Since mid-August, rice planthoppers have been in the western southwest and eastern Jiangnan rice areas, and rice longitudinal leaf borers have been monitored in the middle and lower reaches of the Yangtze River in the rice areas of the Yangtze River to achieve a significant peak of adult insects, and the amount of insects in the field is higher than that of the same period last year, and the overall incidence is moderate, heavier than that of the previous year. According to statistics, the current occurrence area of rice planthopper and rice longitudinal leaf borer is 88.81 million mu and 72.98 million mu respectively, an increase of 1.9% and 7.2% year-on-year. In the next stage, there is more precipitation in the southern rice area, the high temperature range is reduced, the intensity is weakened, and the weather conditions suitable for the "two migrations" of pests return to land and breed. It is expected that rice planthoppers will occur more heavily in the middle rice area of Jiangnan (grade 4) and locally (grade 5); rice longitudinal leaf borer will occur more heavily in the middle and lower reaches of the Yangtze River and the eastern rice area of Jiangnan (grade 4), and locally occur along the river (grade 5), and the severity of occurrence has rebounded compared with the past two years.
1. Rice planthopper
Since mid-August, according to the monitoring of 246 stations of the national rice pest monitoring regional station, the total number of rice planthopper attractants has been 119,000 heads, a year-on-year decrease of 20.7%, of which the amount of brown planthopper attractants is 77,000 heads, an increase of 28.8% year-on-year, accounting for 64.7% of the total number of rice planthopper attractants, and the proportion of brown planthoppers increased by 25 percentage points over the same period last year. According to local monitoring, rice planthoppers have been monitored in the western southwest and eastern Jiangnan rice areas to detect obvious insect attraction peaks, of which The number of single-lamp insects in Mangshi, Yunnan Province, exceeded 1,000 for many consecutive days from August 11 to 15, and as high as 11,200 on August 14; Fujian Jian'ou and Datian monitored the peak of insect attraction on August 14-20, with 18,757 and 9,497 insects at the peak, respectively. From the perspective of insect attraction in various provinces, the amount of insect attraction in the northern part of the southwest and Jiangnan rice areas was high year-on-year, of which Sichuan and Hubei were 2-3.5 times that of the same period last year, and Jiangxi, Zhejiang, Hunan and Fujian increased by 70.1%, 40.5%, 24.6% and 13.7% respectively year-on-year; other provinces decreased by 20%-90% year-on-year.
At present, the overall occurrence of rice planthoppers is moderate, and the occurrence of local leakage prevention plots of rice in Jiangnan is relatively heavy. Among them, the density of insect populations in the fields of south China, Jiangnan middle rice and southwest china has decreased slightly after effective prevention and control, but it is still higher than that of the same period last year, and the amount of insects in 100 bushes is generally 200-900 heads, and the high is 2500-7500 heads, and the local leakage prevention field block has appeared "impervious" phenomenon. For example, the occurrence of some fields in Xianyou and Shunchang in Fujian is relatively heavy, and the amount of 100 bush insects is generally 2500-3500 heads, and the high is 8000-12000 heads, and the highest is 17150 heads; the average number of 100 bush insects in Hunan Chaling, Yuanling, Yongding and other places exceeds 1,000 heads, and the local prevention effect is poor or the phenomenon of "impervious penetration" occurs in the field block. The short-winged adult insects in the field are generally 1-10 in 100 bushes, and the local insect volume is large, and more than 10 in Yiyang, Xiangxi Prefecture and Xiangtan in Hunan Province; it occurs in Anhui along the river, of which the average number of 100 bush insects in Jixi County, Pujiwei Farm and Shexian County is 115, 107 and 38 respectively, and the early warning indicators are super large. The field density of late rice planthoppers in south China and Jiangnan continued to increase, and the number of 100 bush insects was generally 70-450 heads, and the high ones were 550-900 heads; among them, the hunan short-winged adult insects were generally 1-8.8 heads, and more than 10 in Xiangtan City. Rice planthoppers occur lightly in the single-cropping rice areas of the middle and lower reaches of the Yangtze River (Grade 2), and the amount of 100 bush insects is generally less than 200 heads, and the number of 100 bush insects in Huangzhou, Macheng and Chibi in Hubei Province is more than 1000 heads.
2. Rice longitudinal curl leaf borer
Since mid-August, the amount of moths in the field of rice longitudinal curling leaf borer in China has been generally low, and the amount of moths in the rice areas of the middle and lower reaches of the Yangtze River has been high. According to the monitoring of 246 stations in the national rice disease and pest monitoring regional station, the total number of moths under the lamp was 16,000, a year-on-year decrease of 39.6%. Among them, from August 12 to 15, due to the dual influence of typhoons and local insect source feathering, the rice longitudinal leaf borer appeared in the middle and lower reaches of the Yangtze River with obvious moth peaks, and the peak daily moth volume was generally 500-1500 heads, and the high was 2000-3000 heads, higher than the same period in recent years. For example, the number of moths per mu in the field was 2240 in Xiangcheng District of Suzhou, Jiangsu Province on August 12, which was 6 times that of the previous day; the amount of moths in the field in Jiangdu and Rudong on August 13 was 500-1000 heads, which was 3-4 times that of the previous day. The number of moths per mu in the paddy areas of South China and Jiangnan is generally 10-100 heads, and the high is 400-800 heads, which is lower than the same period last year.
At present, the overall occurrence of rice longitudinal leaf borer is moderate, and the occurrence of rice in the lower reaches of the Yangtze River and the eastern part of Jiangnan is more serious. Among them, the amount of field insects in the single-cropping rice areas of South China, Jiangnan Middle Rice and Southwest China has decreased through effective prevention and control, but it is still higher than the same period last year, and the number of larvae per mu is generally 600-3000 heads, and the high is 4000-7000 heads. For example, the average number of larvae per mu in Chongqing was 1328, which was 5.4 times that of the same period last year; the average number of larvae per mu in Hunan was 1486, an increase of 38.7% year-on-year. The number of larvae per mu of late rice in South China and Jiangnan was lower than that of the same period last year, generally 400-2000 heads, and the high was 3000-5000 heads. The amount of field insect eggs in the single-season rice area in the middle and lower reaches of the Yangtze River increased significantly, and the amount of larvae per mu was generally 500-3000 heads, and the high ones were 4000-8000 heads. For example, the amount of insect eggs in the field in Anhui is 24%-75% higher than that in the same period in recent years; the number of eggs in the 100 clusters of insects in the Jintan Observation Garden in Jiangsu Is as high as 1950 heads (grains), which is far larger than the occurrence index. The leaf curl rate in the field is generally 0.5%-5.6%, the high rate is 9%-15%, and the re-emergence of plots in eastern Guizhou is as high as 40%.
Third, the trend will occur in the next stage
According to the forecast of the Central Meteorological Observatory, due to the combined influence of tropical low pressure and cold and warm air after the weakening of the typhoon, there will be heavy to heavy rain in most parts of South China, southern and western Jiangnan, and eastern parts of the southwest region in the next 10 days; affected by high-altitude troughs and low eddy shear, there will be moderate to heavy rain in some areas of Jianghuai, Jianghan, Jiangnan and other places, with more rainfall than the same period of the year, and 50% to 1 times more in some areas, and the weather conditions are conducive to the return and landing of "two migration" pests. At the same time, with the reduction of high temperature range and intensity in the southern rice area, the weather conditions of suitable temperature and high humidity are conducive to the occurrence and reproduction of rice planthoppers and rice longitudinal leaf borers, which are unfavorable to the prevention and control work, and the "two migrations" of pests will further aggravate the occurrence of pests. All localities should strengthen monitoring and investigation in a timely manner, issue short- and medium-term prevention and control forecasts at an appropriate time, scientifically guide prevention and control, effectively control harm, and reduce disaster losses.
Source: Pest and Disease Monitoring Office