Parasitoid complex and bionomics ofApanteles polychrosidis(Hymenoptera: Braconidae) on the ash leaf-cone roller (Lepidoptera: Gracillariidae)

Abstract

AbstractThe ash leaf-cone roller,Caloptilia fraxinella(Ely) (Lepidoptera: Gracillariidae) is an introduced leaf-mining moth of horticultural ash trees (FraxinusLinnaeus; Oleaceae) in Western Canadian Prairie cities. Here, we identify the dominant parasitoid of this leaf-mining moth asApanteles polychrosidisVierek (Hymenoptera: Braconidae) and document its emergence pattern, courtship, mating, and host acceptance behaviours.Apanteles polychrosidisadult emergence is protandrous and mating occurs soon after female emergence. MaleA. polychrosidiscan mate multiple times in short sequence with a mean copulation time of 49 seconds. It is likely thatA. polychrosidisoverwinters in an alternate larval host, after emergence fromC. fraxinella. Mated femaleA. polychrosidisreadily parasitise an alternate host, the obliquebanded leafroller (Choristoneura rosaceana(Harris); Lepidoptera: Tortricidae), known to overwinter as larvae. Through rearingC. fraxinellapupae, we describe the remainder of the parasitoid complex ofC. fraxinella, in order of parasitism rate, asDiadegmaFörster (nearDiadegmafenestrale(Holmgren)) (Hymenoptera: Ichneumonidae), threeSympiesisFörster species (Hymenoptera: Eulophidae) (Sympiesissericeicornis(Nees von Esenbeck), one nearSympiesisviridula(Thomson) and one unknown species), andPteromalus phycidis(Ashmead) (Hymenoptera: Pteromalidae) and show that severalSympiesisspecies can be hyperparasitic onA. polychrosidis.Caloptilia fraxinelladensity within the tree canopy is highest in the lower canopy. Host density and abiotic factors such as temperature and light intensity do not influence the within-canopy distribution of most parasitoids exceptSympiesisspecies, which preferred the northern canopy.