Influence of Diversity in Rice, BPH and Humans on BPH management Strategies
Principal Scientist (Retired), Directorate of Rice Research (Presently Indian Institute of Rice Research), Rajendranagar, Hyderabad-500030,Telengana State, India
Molecular Entomology, 2015, Vol. 6, No. 5 doi: 10.5376/me.2015.06.0005
Received: 27 Jun., 2015 Accepted: 15 Jul., 2015 Published: 27 Jul., 2015
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Preferred citation for this article:
Krishnaiah N.V., 2015, Influence of Diversity in Rice, BPH and Humans on BPH management Strategies, Molecular Entomology, Vol.6, No.5 1-13 (doi: 10.5376/me.2015.06.0005)
Rice Brown Plant hopper, Nilaparvata lugens (Stal) (BPH) is the most economically important insect pest causing damage to rice crop. Apart from normal brown colored individuals, presence of black colored variants of BPH is the common phenomenon in almost all places. Development of higher concentration of the pigment “melanin” in the body wall of such individuals could be the most probable cause. Physiological diversity in BPH can exist as virulence to a set of varieties with known resistance genes, virulence pattern with regard to transmission of virus diseases, developmental pattern of morpho-forms and Spectrum of insecticide resistance. All these can be intelligently used for understanding migration patterns and also devising management strategies.
Existence of “diversity” in rice is the result of evolution and domestication. Within the species of cultivated rice in Asia (Oryza sativa), there are three subspecies viz., Indica, Japonica and Javanica. Indica is represented by thousands of varieties which are traditionally tall in stature, lodging when grown under high nutrition, weak culm and in general puffy in grain quality after cooking. Japonica varieties are relatively shorter in stature, with more tillers, better responsiveness to nitrogen application, do not lodge to the extent of traditional tall Indicas and rice is sticky after cooking. The people living in tropical world are generally habituated for eating puffy rice and those in temperate countries for sticky rice that led to perpetuation of varieties with similar grain quality over thousands of years of domestication of rice in Asia. Javanica varieties in general possess lower yielding capability than even traditional tall Indica varieties. The rice revolution in tropics has started with the establishment of International Rice Research Institute (IRRI) in Philippines and later All India Coordinated Rice Improvement Project (AICRIP) by Government of India at Hyderabad. IR8 is the starting point for HYVs from IRRI. Later “Jaya” from AICRIP followed by a score of other varieties laid a strong foundation for further advancements in rice cultivation from 1973 onwards in all tropical rice tracts. It is also the starting point of BPH attacks to rice crop. Lot of diversity in rice existing in the entire tropical rice belt before green revolution era in the form of thousands of varieties has got eroded by cultivation of few HYVs with their origin from TN1 and IR8.
Diversity in human management systems can have tremendous influence on rice production technology and BPH management strategies as evidenced by the success of hybrid rice in China and not to that extent in India. Development and adoption of duck rice and fish rice in China which has direct relevance to BPH management and nonexistence of the same in India is influenced by human management systems and food habits. In technologically advanced Japan where human time and effort are used based on their economic value, BPH management strategy is almost always different from the tropical world. Thus understanding the whole of these as a component of human existence and survival and moderating human thinking in population control and lowering the exploitation of nature including rice production can lead to real and truthful BPH management which will certainly be long lasting and sustainable.
Brown plant hopper; BPH management; Rice ecosystem; Diversity