Apple cultivar preferences by Hoplocampa testudinea (Hymenoptera: Tenthredinidae) in the Annapolis Valley of Nova Scotia, Canada

The European apple sawfly, Hoplocampa testudinea (Klug) (Hymenoptera: Tenthredinidae), is an economically important pest in eastern Canada. Growers can experience significant crop losses as management of this species is difficult because it is present during bloom. As a result,management strategies other than pesticides are required for this pest. Eleven commercial and experimental apple (Malus pumila Miller; Rosaceae) cultivars were studied to evaluate host resistance as a potential management strategy. Preferences were determined using field surveys of adult visitation, larval infestation of apples, damage at harvest, behavioural bioassays, and electrophysiological tests. Significant differences in visitation and infestation were observed. H. testudinea preferred "Zestar!", "s23-06-153", and "Pinova" over other cultivars examined. Comparison with subsequent larval counts and damage also suggest differential performance of larvae in several cases, irrespective of the adult preference. Y-tube bioassays and electroanntennography results indicate that olfaction plays a role in cultivar discrimination for this species.