Abstract:
The Rice Yellow Stem Borer (YSB), Scirpophaga
incertulas (Lepidoptera: Crambidae), is a major
pest that poses significant yield losses in Sri
Lankan paddy cultivation. Synthetic chemical
insecticides are the primary control method.
However, their long-term effectiveness is limited
due to negative impacts on biodiversity and risk
to human health. This study aims to characterize
the pheromone components of the local YSB
population and assess their behavioral responses
to different Sri Lankan rice varieties. Pheromone
components were collected from female YSB
using
dynamic headspace collection (30
individuals per replicate) and solvent extraction
(15 individuals per replicate). A varietal
preference test was conducted using a dual
choice olfactometer for eight rice varieties: BG
366, AT 311, BG 257, AT 362, BG 251, AT 313,
BG 360 and BG 377. The collected volatile
compounds were analyzed using Gas
Chromatography-Mass Spectrometry (GC-MS).
The
GC-MS analysis identified (Z)-11
Hexadecenal as a major sex pheromone
compound in YSB. The varietal preference test
shows significant differences (p = 0.001) among
the rice varieties. Notably, AT 313 is the most
attractive rice variety (13.2 ± 0.33), and BG 251
is the least attractive rice variety (3.8 ± 0.22) to
the female YSB. S. incertulas most prefers to
damage paddy cultivation after the pre-booting
stage (early panicle initiation). The optimum
laboratory rearing conditions for S. incertulas
were determined as 26 ± 2 0C temperature, 75 ±
5% relative humidity, and a 10-12 hours light:
12-14 hours dark cycle. Further studies are
necessary regarding laboratory bioassays and
field evaluations to develop a sustainable and
effective semiochemical-based pest management
strategy (pheromone trap) to manage the rice
yellow stem borer more effectively.
