Abstract:
Rhinoceros beetle (RB) (Oryctes
rhinoceros L.) is one of the devastating pests of
coconut and other palm species. The main strategy
for the management of RB is the use of highly toxic
synthetic pesticides. However, banning of toxic
pesticides in Sri Lanka urges finding alternative
repellant materials. The use of semiochemicals
especially behaviour-modifying plant volatiles is a
recent trend in agriculture pest management.
Therefore, this study was conducted to identify the
repellent plant volatiles to formulate a
semiochemical-based pest management strategy.
Electroantennographic (EAG) technique
employed to explore the antennal response of male
and female RB to 12 plant volatiles using a
commercially available EAG system. Results
revealed that mean antennal responses were
significantly higher (p<0.05) on both males and
females to plant volatiles than control. The
largest response evoked by aggregation
pheromones (Male 0.7698 ± 0.130 mV, Female
0.9504 ± 0.232 mV) then evoked the higher
responses by the male to Ethyl butyrate, Limonene
(+), 1-Octane-3-ol, α-pinene, and Propyl
butyrate. Whereas female evoked higher
responses to 1-Octane-3-ol, Limonene (+),
Citronella, and 3-Hexene-1-ol. The dose-response
study indicated the male responses had decreasing
trend with increasing doses from 1% to 10%,
while the female was erratic. Moreover, dual
choice olfactometer studies revealed that males
and females were attracted to RB aggregation
pheromone, Limonene (+), Ethyl propionate, and
β-Myrcene where they were repelled by
Citronellol, 2-hexane-ol, 1-Octane-3-ol, and α-
Pinene. Therefore, Citronellol, 2-hexane-1-ol, α-
Pinene and 1-Octane-3-ol, can be used as a
potential plant volatile to formulate the repelling
compounds to manage the O. rhinoceros.
