水稻對褐飛蝨抵抗性研究：特別論及寄主與生物小種間之相互作用
Other Title
Studies on Varietal Resistance to the Brown Planthopper in Rice with Special Emphasis on the Interaction Between Host and Biotypes
Start Page
293
End Page
322
Date Issued
1984-12
Date
1984-12
Author(s)
鄭清煥
C.H. Cheng
Abstract
褐飛蝨為本省第二期稻作之主要害蟲，栽培抗蟲品種為防治該蟲最經濟有效方法之一。目前水稻抗褐飛蝨育種工作雖己在本省奠下良好基礎，但鑑於褐飛蝨生物小種在東南亞栽值抗蟲品種地區造成危害，如何防患未然，仍成為目前之重要研究課題。木項研究以配合木省抗褐飛蝨育種之進展及針對預防褐飛蝨生物小種之產生為目的，進行各項試驗。在配合本省褐飛蝨育種方面，新引入及檢定抗蟲優良新種源32品種（系），以及引入〞田間抗蟲型〞稻種及釐定檢定此類型抗蟲品種之方法，以供育種及檢定之需要。另一方面測定本省新育成高級品系對褐飛蝨之抵抗程度，以供將來新品種推廣及對褐飛蝨防冶之參考。
在預防生物小種之產生方面，觀察含不同抗蟲因子稻種與4種生物小種褐飛蝨之相互作用，生物小種在抗蟲及感蟲品種之取食行為，生物小種在抗蟲品種存活能力之遺傳行為以及觀察輸值及混植不同抗蟲因子品種對新有害生物小種產生抑制效果等。其結果顯示含不同抗蟲因子稻種對不同生物小種褐飛蝨之寄主偏好，存活率及危害程度均有極顯著之差異。由含Bph-1及Bph-3抗蟲因子品種所汰選出來之生物小種較由含有bph-2抗蟲因子選汰者具較大之危害能力。任何抗蟲品種對生物小種之危害均無組織之機械障礙足以妨碍其取食。生物小種不喜好在抗蟲品種取食可能因抗蟲品種缺乏昆蟲取食之刺激物質所致。生物小種存活於抗蟲品種之能力受隱性之數量因子所支配，利用輪值或混植不同抗蟲因子稻種證明可有效地抑制有害新生物小種之產生。
本省以往推廣之抗褐飛蝨品種均為含bph-2因子之中等抗性品種，栽植此類品種在褐飛蝨大量發生時雖無法完全抑制褐飛蝨之危害，但可減少一半以上之施藥次數。此類品種對褐飛蝨汰選壓力較低，又無影響天敵之活動，很適用於害蟲綜合防治體系。然而為防患大面積栽植同一抗蟲因子品種而汰選新有害之生物小種，育成不同抗蟲因子品種提供輪流或混合栽植乃成為急待努力之課題。
The brown planthopper (BPH) is the most destructive insect pest of rice in Taiwan especially in the second rice crop. A cultivation of resistant varieties is considered as the most economic measures for control of the hopper. During past decade, a program for breeding rice resistance to the hopper have been well established in Taiwan and six resistantt varieties have been named and released for commercial cultivation. Recently, in view of the occurrence of biotypes of BPH in southeast Asia only two to three years after resistant variety JR 26 was cultivated extensively. In order to avoid a monoculture of monogenic resistant varieties to induced the occurrence of virulent bio-types of the hopper as which have happened in southeast Asia, it is considered importance to breed rice for resistance in diverse genetic basis. For this purpose, three hundred and ninety eight variety (lines) with different resistance genes were introduced from the International Rice Research Institute (IRRI) and identified both in laboratory and field in this study. Among them 32 improved resistant lines with Bph-3, bph-4, or genes combination of Bph-3 or bph-4 with Bph-1 or bph-2, and the progenies of Ptb 33 (with two unidentified reistance genes) were selected as good sources for breeding resistance to BPH (Table 1). In addition, three “field resistance” varieties (resistance is possibly conditioned by polygenes), Triveni, Utri-Rajapan and Kencana were also introduced from the IRRI, and a method for identification of such type of resistance was also established by infestation of 30-day-old seedings planting in a plate and infestation with a density of 4 seedlings per mated-female of BPH. By using this method, the ¡§field resistance¡¨ varieties could be identified from the susceptible varieties during the nymphal stage of following generation.
The interactions between varieties with different resistance genes and four biotypes of BPH. were also investigated at present study. It indicated that the host preference, survival rate, population development and degree of damage of different biotypes on varieties with different resistance genes differed significantly. The biotypes developed from varieties with Bph-1 and Bph-3 . resistance genes were more virulent than that was developed from variety with bph-2. No mechanical barrier was observed in the tissues of rice plant to disturb the feeding of biotypes from resistant varieties. However, when every biotpye was caged to feed on resistant variety, the insect changed feeding sites frequently, and more branch of stylet sheath produced in each feeding was observed. A significantly less amount of honeydew excreted when the insect caged on resistant varieties, that is considered as mainly due to a lack of feeding stimulant involved in the resistant varieties.
The ability and inability of biotypes to survive and infest on varieties with different resistance genes was observed to be polygenic in nature. The results of reciprocal crosses between biotypes I and II, and between biotypes I and III showed that the inability of biotype I to survive on Mudgo was partial dominant to those of biotype II, and the inability of biotype I to survive on H 105 was partial dominant to those of biotype III. Reciprocal crosses between biotype II and III indicated that the inability of biotype III in survival and infesting Mudgo was over dominant to those of biotype II.
The experiment conducted to assess whether or not the evolution of new biotypes can be prevented or retarded by use of a rotative or mixed planting of resistant varieties with different resistance genes, the survival rate of the nymphs of BPH on such planting systems was compared with those which were reared continously on a fixed resistant variety. The results showed that BPHs were easy to shift their ability to survive on resistant variety when they were forced to feed on the variety continously for more then 6 generations. However, when the resistant varieties with different resistance genes were grown in rotation or grown in mixture, then the survival of BPHs on a particular resistant variety were evidently lower than that was forced to feed on a particular resistant variety continously. This indicate that rotative or mixed cultivation of resistant varieties having different resistance gene in an area could slow down the evolution of new biotypes.
The resistant varieties having released for commercial cultivution in Taiwan are all with bph-2 resistance genes and belong to moderate resistant ones. These varieties tested in an outbreak of BPH conditions showed that the resistant varieties alone could not suppress the BPH population below the level of economic threshold. However, by cultivation of resistant varieties could reduce more than a half of insecticidal application. Since the selection pressure of these varieties to BPH are lower than that of 1R26, they migh not overcome by the new virulent biotypes as easy as that of 1R26 in southeast Asia countries. In addition, a cultivation of morderate resistant varieties were observed to be compatible with biological control since they did not reduce the natural enemies of the pest inhabiting on them. Accordingly, the varieties with bph-2 resistance-gene were considered as an important element of an integrated rice-insect pests manager-ment program. Nervethiess, as mention above when resistant varieties are planted extensively in a big area, planting resistant varieties with different resistance genes would be more effeictve in preventing the prevalence of virulence biotypes of the BPH than that of monoculture with monogenic resistant varieties. Therefore, breeding for resistance to BPH in diverse gonetic basis is urgent needed.
Publisher
臺灣省農業試驗所
Type
book part
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