Vergara - 1976 - Physiological and morphological adaptability of ri

CLIMATE AND RICE INSECTS 385
Duitydhluultpintnpw
Jmliil
1 1 |
MI Apr May All uimiqlsapilouiuw m;
7. Armunl trends of temperature and occurrence of the
brown Plilfll-hllpptfif. Mlaparvuru fugens. ln Nlanila the
brown planthitpper breeds all year round; in Taichung it
has two cycle of population growth on two crops of rice;
in Japan. one cycle of population growth on one crop
of rice.
April the continental anticyelone gradually weakens and incursions of warm,
moist tropical air from between south and east replace the cold northeasterlies
(Arakawa. 1969). In l9?2 a trough oflow pressure lay from the south ofKy-‘ushu
to the South China Sea. Considerable rainfall was observed on April 6 to 8. and
a few days later there was an inflow ole warm and humid tropical air mass. It is
plausible that inunigrattts were carried to Hongkoilg by the tropical air mass.
Collection ofplanthoppers unfortunately was terminated on April l4, and further
immigratiorts were not surveyed
According to this hypothesis. the two planthopper species, and possibly other
planthoppcrs. spread out armually from the tropical zone to the subtropical zone
in March and April, and then from the subtropical zone to the temperate zone