The stem borers, generally considered
the most serious pests of rice
worldwide, occur and infest plants
from seedling stage to maturity. Fifty
species in three families-Pyralidae,
Noctuidae (Lepidoptera), and Diopsidae
(Diptera)—are known to attack
the rice crop (Table 3). Thirty-five
pyralids belonging to 12 genera,
10 noctuid species belonging to
3 genera, and 5 diopsid species
belonging to the genus Diopsis have
been recorded as rice stem borers.
The pyralid borers are the most
common and destructive, and usually
have high host specificity. The
noctuid borers are polyphagous and
only occasionally cause economic
losses to the rice crop. In Asia, the
most destructive and widely distributed
are yellow stem borer
Scirpophaga incertulas (Walker),
striped stem borer Chilo suppressalis
(Walker), white stem borer
Scirpophaga innotata (Walker), darkheaded
stem borer, Chilo polychrysus
(Meyrick), and pink borer Sesamia
inferens (Walker). In Asia, Scirpophaga
incertulas and Chilo suppressalis are
responsible for a steady annual
damage of 5-10% of the rice crop,
with occasional localized outbreaks
of up to 60%.
