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Lures of aggregation pheromones of the Australian and Hawaiian populations of New Guinea sugarcane weevil, Rhabdoscelus obscurus (Boisduval), with other semiochemicals were used to
clarify the identity of the weevil population in Guam.
In a field experiment at eight different locations (Dededo, Tumon, Yigo,
Hagåtña, Mangilao, Yona, Agat and Malesso), plastic bucket traps baited with
the lure of the Australian R. obscurus population in combination with a food volatile compound (ethyl acetate) and
cut sugarcane captured significantly more weevils (total of 348) than traps
baited with pheromone lure of the Hawaiian R. obscurus population in combination with food volatile and cut
sugarcane which caught a total of 128 weevils. Traps baited with lure containing
only the food volatile and cut sugarcane or only cut sugarcane captured
significantly fewer weevils (total of 36 and 30, respectively) than those
baited with pheromone compounds. Data from trap catches indicate that the Guam
population of R.
obscurus responded
significantly more to the pheromone lure of the Australian population than to pheromone
lure of the Hawaiian population indicating that the Guam
R. obscurus
population is related more
closely to the Australian population. Trap catches at the Tumon and Dededo
locations were greater than those in Yigo, Yona, Mangilao, Hagåtña, Agat, and
Malesso. Rainfall had a low correlation with trap catches at all locations
except at Yigo where it positively correlated to the Australian population lure
treatment. Semiochemical based trapping in weevil management has potential either
in mass trapping or as part of an IPM program. A future line of work is also
proposed for the control of weevil borers based on these initial results.