小麦抽穗期与麦红吸浆虫成虫发生期的同步性及其受害程度

The synchronization of ear emerging stages of winter wheat with occurrent periods of the orange wheat blossom midge,Sitodiplosismosellana(Gehin)(Diptera: Cecidomyiidae) adults and its damaged level

通过2012年在麦红吸浆虫发生田对小麦不同生育期进行套袋保护,明确了小麦抽穗期为麦红吸浆虫侵害的敏感期。采用生态位重叠率的计算方法,统计2012—2013年不同品种的抽穗期与麦红吸浆虫发生期的同步性,结果表明,同步性越高,产量损失越重,具有显著的相关关系。同时,品种抽穗期的成虫累计发生量与产量损失有显著的相关性。成虫发生期与抽穗期同步或吻合导致小麦受害而不是扬花期,所以在缺乏抗虫品种的情况下,应采取抽穗期化学保护进行防治。

The orange wheat blossom midge（ OWBM）,Sitodiplosis mosellana（ Gehin）,is one of the most important pests of winter wheat in North China. It often feeds on developing wheat kernels and can cause a serious yield loss of this cereal.There were 2. 4 million hectares with OWBM occurrence in 2013 in China. On the other hand,from the 1950 s to the present time,the northern boundary of the OWBM occurrence area has shifted towards the pole by about four degrees of latitude（440 km） in North China. The northern area of North China,including Hebei,Beijing,Tianjin and northwestern Shandong,has become a novel occurrence region.This investigation was carried out on bagged ears of flag leaf,ear emergent and flowering stages of the winter wheat cultivar,Luomai 24,protected from the OWBM in fields in 2012 at Jiaozhaivillage,Luolong district,Luoyang city,Henan.The OWBM adults were monitored in April and May with yellow sticky traps,and the adult period of OWBM was found to overlap with the ear emergent and flowering stages of the cultivar. There were no damaged bagged ears in the flag leaf stage.The yield losses in bagged ears from 1 /4 to 3 /4 ear emergence were significantly less than in the fully ear emergent stage,but there were no significant differences between bagged early and late flowering stages. However,the yield loss in bagged flowering ears（ average 10. 79%） was significantly higher than in the bagged ear emergent stage（ average 3. 48%）. The result revealed that emerging ears are susceptible to OWBM infestation. The damage level was evaluated in terms of synchronization of ear emergence stages of winter wheat cultivars with occurrence periods of OWBM adults in the 2012 and2013 crop growing seasons. More than 400 susceptible cultivars were evaluated. Because of a 2℃ lower temperature on 19 April 2013,the adult period ran from 4 May to 13 May that year. Synchronization was calculated using the niche overlap formula（ Geange et al 2011）. In the 2012 growing season,the maximum synchronization value for 23 cultivars was 0. 628 when the ear emergent stage ran from 22 April to 28 April,and the average yield loss was 78. 1%. The minimum synchronization value was 0. 307 for three cultivars when the ear emergent stage ran from 28 April to 2 May,and the average yield loss was 11. 7%. In the 2013 growing season,the maximum synchronization value for three cultivars was 0. 783 when the ear emergent stage ran from 4 May to 11 May,and the average yield loss was 2. 41%. The minimum value for 11 cultivars was 0. 062 when the ear emergent stage ran from 15 April to 25 April,and the average yield loss was 0. 04%. The results obtained indicate that higher synchronization values led to more serious yield losses and there was a significant relationship between them. The yield losses of wheat cultivars showed a significant positive correlation with the total number of OWBM adults during the ear emergent stage. This conclusion indicates that the control strategy should be aimed at chemical protection of the ear emergent stage in China until resistant wheat cultivars are planted,because the infestive OWBM occurrence period is in the ear emergent stages of winter wheat,and not the flowering stage. At the same time,the result may help to explain why the OWBM occurrence area has shifted towards the pole because the average winter and spring temperature has risen by 1. 5℃ since the 1950 s in the northern area of North China,and there might now be an synchronous or matched status between wheat ear emergent stage and OWBM adults in the northern area of North China.