19
Rice Brown Planthopper
and Jhansi Lakshmi, 2012).
Migration of East Asian BPH Biotype:
Migration of East Asian BPH biotype has been extensively studied. In fact the most
fundamental details of the whole long range migration of BPH have come into light
through the efforts of Japanese rice scientists first and later by Chinese scientists. BPH
migration here is mainly aided by East Asian Monsoon. The East Asian monsoon
affects large parts of Indo-China, The Philippines, China, Korea and Japan. It is
characterized by a warm, rainy summer monsoon and a cold, dry winter monsoon. The
rain occurs in a concentrated belt that stretches east-west except in East China where
it is tilted east-northeast over Korea and Japan. The seasonal rain is known as Meiyu
in China, Changma in Korea, and Bai-u in Japan. The onset of the summer monsoon
is marked by a period of pre-monsoonal rain over South China and Taiwan in early
May. From May through August, the summer monsoon shifts through a series of dry
and rainy phases as the rain belt moves northward, beginning over Indo-China and the
South China Sea (May), to the Yangtze River Basin and Japan (June) and finally to
North China and Korea (July). When the monsoon ends in August, the rain belt moves
back to South China. East Asian biotype of BPH migrates from southern tip of China to
eastern states of China by May end and then to Japan and Korea by June first fort night
along the Bai-u monsoon. In Japan and Korea rice crop is available in transplanted
condition by May end. BPH settles, multiples, damages rice crop up to August end or
September first fort night or September end. When rice crop is harvested in Japan and
Korea by September end BPH migrates back to southern tip of China via the eastern
states of China (Otuka, 2009).
Migration of South-East Asian Biotype:
There is no published information available about long range migration of South East
Asian biotype of BPH prevalent in The Philippines, Myanmar, Vietnam, Cambodia,
Laos, Thai Land, Malaysia and Indonesia. However, there is vast scope for long range
migration of BPH in this region. This migration is probably aided by Indo-Australian
monsoon. This consists of the Indian and South-East Asian summer monsoon that
occurs from June to September, and the Australian and Maritime Continent monsoon
that occurs in austral summer (October to February). During June to September,
monsoon winds move from southern hemisphere to northern hemisphere usually from
