2
Rice Brown Planthopper
by piercing the leaf sheath with their ovipositor in batches of 30-80 per day (Plate 4,
Page 9).Oviposition period and number of eggs laid per female vary depending on
temperature and nutritional status of the plants on which they are feeding. Egg period
vary from 5-8 days and small whitish nymphs of about 1mm (Plate 3 Page 9) emerge.
These nymphs as well as adults suck plant sap usually from nutritionally rich phloem
and occasionally on xylem mainly for their water requirement. Nymphs molt 5 times,
each time increasing in size and finally becoming adults. Total nymphal period vary
from 15-22 days depending on temperature. Adult life span may vary from 7-15 days
again depending on temperature and food availability.
Evolutionary status of BPH WBPH and SBPH:
There are certain basic differences in the evolutionary status of these plant hoppers.
Both BPH and WBPH are insects of tropical origin and appear to have co-evolved
along with rice since its domestication. These are typically mono-phagous and can
complete their life cycle only on Oryza sativa. These have optimum temperature
requirement of 22-27°C and cannot survive at a temperature below 10°C. BPH and
WBPH can survive up to 45°C if allowed to feed continuously with host plant rice. But
die within an hour if removed from feeding at such high temperatures. All their normal
biological functions like feeding, speed of development and longevity are lowered
while nymphal duration is prolonged if the temperatures are lower than the optimum
range. More or less similar effects are observed if temperature increases above optimum
range. However, speed of nymphal development may remain similar up to 33-35°C.
BPH and WBPH are not known to over winter in any stage of their life cycle. Similarly
Plate 1: BPH female-brown colored, macro-
pterous, evolved to fly long distances
Plate 2: BPH female-black colored,brachy-
pterous, evolved for high reproduction
