Sugarcane weevil borer resistance: Breeding strategy development using survey data

Damage from sugarcane weevil borer has increased significantly in recent years in the Gordonvale to Tully region. Research was conducted to determine whether selection for genetically based weevil borer resistance was feasible. Two groups of 197 parental Clones each in two repeated plantings at Meringa in 1994 and 1995, 186 clones in two replicated farm.trials in Mulgrave in 1994, and 278 clones in three similar trials in Mourilyan in 1995 were surveyed. Eighteen stalks per plot were sliced in the Meringa and Mourilyan surveys. The Mulgrave data were collected from 6-stalk sub-samples taken for laboratory analyses. Average infestation was low at Meringa (11.6% and 8.2% bored stalks), marginally higher in the Mulgrave trials (16.3% and 24.3%), and moderate in the Mourilyan trials (51.2%, 50.3%, and 39.0%). Ample genetic variation was revealed in all populations. Analyses indicated selection for resistance would be successful. Susceptible clones revealed under low infestation pressure could be discarded safely, but "resistant" clones from the same screen could not be guaranteed resistant under high infestation pressure. Early generation screening in a high infestation environment, followed by screening for agronomic productivity, is recommended as a cost effective strategy if the industry requires weevil borer resistant commercial clones.