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Prediction of occurrence trend of second generation armyworm

Release time: 2023-06-19

      Recently, the adult armyworm of the first generation has appeared successively in Huanghuai, North China, Northeast China and Northwest China, with high moth quantity and obvious moth peak in some parts of South China, but low moth quantity in Huanghuai, North China and Northeast China, and second-generation eggs and young larvae found in many fields in Northeast China。Combined with weather conditions and crop planting conditions, it is expected that the second-generation armyworm will occur in an area of 25 million mu in China, and the overall occurrence will be light to moderate, and high-density fields will appear in local areas with high moth abundance and abundant rainfall. The peak period of occurrence is from late June to early July。

      First, the first generation of armyworm occurrence is light, the amount of residual insects is low

      The area of first-generation armyworm infestation in the middle and lower reaches of the Yangtze River, Jianghuai and Huanghuai wheat areas was 4.99 million mu, an increase of 43% compared with 2022, but it was still a small year.The average number of insects per square meter in wheat fields is 0.5, a 25 percent increase from 2022。The national control or control area of 5.44 million mu, the amount of residual insects after control is low, are 0 per square meter.Below 3 heads。

      Second, the number of first-generation moths is higher in southern areas and lower in northern areas

      Since mid to late May, the cumulative moth attractance of the first generation of adult insects of the aerial warning lamp at each monitoring point showed the characteristics of high in the south and low in the north。The attractance of moths in Guangxi, Hunan and other southern regions was high, 2-3 times higher than that in the same period of last year。Among them, 1,589 head in Hunan Lixian County, 2 higher than the same period last year (437 head).6 times;Hunan Jiangyong 586 head, higher than the same period last year (165 head) 2.6 times;Guangxi Yizhou 1255 head, higher than the same period last year (398 head) 2.2倍。The amount of moths in Huanghuai, North China and Northeast China was lower than that in the same period of last year by more than 40%。Among them, Shanxi Wanrong 43 head, close to the same period of last year, 63 less than the same period in 2021.9%;There were 36, 40, 4, 25 and 28 head in Zhengding, Kangbao, Hebei, Zhangwu, Liaoning and Changling, Jilin, respectively, 62 fewer than the same period last year.0%、47.4%、85.2%、56.9%、69.2%;Xingping in Shaanxi Province and Shuangcheng in Heilongjiang Province accounted for 70 head and 107 head, an increase of 79 over the same period last year.5%、2倍。

      In most of Huang-Huai-hai area, the number of moths attracted by the common light was lower than that of the same period last year, and the moth peak appeared in central and eastern Henan。其中,From May 21 to June 13 in Pingyu, Huaiyang, Changge, Dancheng, Yongcheng and Ye County of Central and eastern Henan, the cumulative number of moths attracted by single lamp was 4453, 2555, 1407, 997, 435 and 402, respectively,Moth Peak days are generally in late May to mid-June,The maximum number of moths attracted by a single light on May 29 was 1700.The total number of moths attracted at other monitoring sites was below 400,The overall moth attractors in the province decreased by 30% compared with the previous year。In Shanxi Province, 20 monitoring stations from June 1 to 12 accumulated 331 moths, 65% less than the same period last year。No significant moth peak was found at all monitoring sites in Hebei。

      Third, second generation eggs and young larvae are seen in the fields of Northeast China

      Since the end of May, more eggs have been seen in the fields in Northeast China。Among them, Jilin began to see eggs on May 23, a total of 8 counties (cities) to attract egg blocks, the cumulative number of egg blocks 28, the cumulative number of eggs 2113, about 20% higher than the same period last year。In Liaoning, eggs began to be seen on May 26, and a maximum of 3 eggs were attracted in a single day, with an average number of 80 eggs。On June 7, the number of egg attractor of 20 grain and grass bars in Tongliao, Inner Mongolia was 1-3, and the average egg number was 42-88。

      Young larvae have been found in northeast China since early June。In Jilin Province, second generation larvae were found in 11 counties (cities) in early June, and the average larvae amount per square meter of corn field was 0.1 larva, mainly 1-3 instars。In early June, the young larvae were seen in the fields of Liaoning Province, and the number of 100 plants was 5。Young larvae were found in wheat and corn fields of Kezuohouqi in Inner Mongolia, and the insect quantity per square meter was less than 0.5头。The harm of young larva was found in some fields in Shuangcheng, Heilongjiang Province。

      Fourth, the weather conditions are favorable to the occurrence of armyworm in North and northeast China

      According to the National Meteorological Center forecast,Next 10 days,The accumulated precipitation in eastern Inner Mongolia, Northeast China, North China, Huanghuai and eastern Northwest China is 10-30 mm,More than 40 mm in one place,It is beneficial to the occurrence of second-generation armyworm.Most of Inner Mongolia, eastern North China, northern Henan, northern Shandong, northern Jiangsu, Anhui, western Liaoning and other places will have a daily maximum temperature above 35℃ high temperature weather process,The daily maximum temperature in some areas exceeded 37℃,It has certain inhibitory effect on the occurrence of second-generation armyworm。

      In view of the characteristics of strong migration and flight ability of adult armyworm and hidden damage of young larva,All localities should make full use of conventional monitoring lights, high-altitude monitoring lights, sex traps, straw and other monitoring tools,Do a good job of dynamic monitoring of adult population occurrence,Pay close attention to the migration dynamics of surrounding areas;meanwhile,Do a systematic survey of eggs and larvae in millet fields and weedy corn fields,Early prevention of high-density concentration harm。

      (Source: Pest Survey Office)