The abundance of mitochondria suggests an eccrine mechanism of secretion, although dictyosomal vesicles may contribute to a granulocrine process. Phloem sap evidently is the main contributor of nectar carbohydrates. From the sieve elements and companion cells, an apoplastic route via intercellular spaces and cell walls, leading to the pores of modified stomata, is available. A symplastic pathway, via plasmodesmata connecting sieve elements to companion, parenchyma and epidermal cells, is also feasible. Uncollected nectar was reabsorbed, and the direct innervation of the nectary by sieve tubes potentially serves a second important route for nectar-sugar reclamation. Microchannels in the outer cuticle may facilitate both secretion and reabsorption.

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Aster yellows (AY) is an important disease of Brassica crops and is caused by Candidatus Phytoplasma asteris and transmitted by the insect vector, Aster leafhopper (Macrosteles quadrilineatus). Phytoplasma-infected Aster leafhoppers were incubated at various constant and fluctuating temperatures ranging from 0 to 35 °C with the reproductive host plant barley (Hordium vulgare). At 0 °C, leafhopper adults survived for 18 days, but failed to reproduce, whereas at 35 °C insects died within 18 days, but successfully reproduced before dying. Temperature fluctuation increased thermal tolerance in leafhoppers at 25 °C and increased fecundity of leafhoppers at 5 and 20 °C. Leafhopper adults successfully infected and produced AY-symptoms in canola plants after incubating for 18 days at 0–20 °C on barley, indicating that AY-phytoplasma maintains its virulence in this temperature range. The presence and number of AY-phytoplasma in insects and plants were confirmed by droplet digital PCR (ddPCR) quantification. The number of phytoplasma in leafhoppers increased over time, but did not differ among temperatures. The temperatures associated with a typical crop growing season on the Canadian Prairies will not limit the spread of AY disease by their predominant insect vector. Also, ddPCR quantification is a useful tool for early detection and accurate quantification of phytoplasma in plants and insects.

The ash leaf-cone roller, Caloptilia fraxinella (Ely) (Lepidoptera: Gracillariidae) is an introduced leaf-mining moth of horticultural ash trees (Fraxinus Linnaeus; Oleaceae) in Western Canadian Prairie cities. Here, we identify the dominant parasitoid of this leaf-mining moth as Apanteles polychrosidis Vierek (Hymenoptera: Braconidae) and document its emergence pattern, courtship, mating, and host acceptance behaviours. Apanteles polychrosidis adult emergence is protandrous and mating occurs soon after female emergence. Male A. polychrosidis can mate multiple times in short sequence with a mean copulation time of 49 seconds. It is likely that A. polychrosidis overwinters in an alternate larval host, after emergence from C. fraxinella. Mated female A. polychrosidis readily parasitise an alternate host, the obliquebanded leafroller (Choristoneura rosaceana (Harris); Lepidoptera: Tortricidae), known to overwinter as larvae. Through rearing C. fraxinella pupae, we describe the remainder of the parasitoid complex of C. fraxinella, in order of parasitism rate, as Diadegma Förster (near Diadegma fenestrale (Holmgren)) (Hymenoptera: Ichneumonidae), three Sympiesis Förster species (Hymenoptera: Eulophidae) (Sympiesis sericeicornis (Nees von Esenbeck), one near Sympiesis viridula (Thomson) and one unknown species), and Pteromalus phycidis (Ashmead) (Hymenoptera: Pteromalidae) and show that several Sympiesis species can be hyperparasitic on A. polychrosidis. Caloptilia fraxinella density 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 except Sympiesis species, which preferred the northern canopy. Résumé-L'enrouleuseen cône des feuilles de frêne, Caloptilia fraxinella (Ely) (Lepidoptera: Gracillariidae), est un lépidoptère introduit, mineur des feuilles des frênes horticoles (Fraxinus Linnaeus: Oleaceae), dans les villes des Prairies de l'Ouest Canadien. Nous identifions Apanteles polychrosidis Vierek (Hymenoptera: Braconidae) comme le parasitoïde principal de ce papillon mineur de feuilles et décrivons son patron d'émergence et ses comportements de cour, d'accouplement et d'acceptation d'hôte. L'émergence des adultes d'Apanteles polychrosidis est protandrique et l'accouplement a lieu peu après l'émergence des femelles. Le mâle d'A.polychrosidis peut s'accoupler plusieurs fois en courte succession avec une durée moyenne des accouplements de 49 secondes. Il est probable qu'A. polychrosidis passe l'hiver dans une larve hôte d'espèce différente après son émergence de C. fraxinella. Les femelles accouplées d'A. polychrosidis parasitent volontiers un hôte de rechange après leur émergence de C. fraxinella, soit la tordeuse à bandes obliques (Choristoneura rosaceana (Harris); Lepidoptera: Tortricidae) qui passe l'hiver au stade larvaire. Des élevages de nymphes de C. fraxinella nous ont permis de décrire le reste du complexe parasitaire de C. fraxinella, soit par ordre de taux de paras...

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