title: Influence of temperature on patch residence time in parasitoids: physiological and behavioural mechanisms.
abstract: Patch time allocation has received much attention in the context of optimal foraging theory, including the effect of environmental variables. We investigated the direct role of temperature on patch time allocation by parasitoids through physiological and behavioural mechanisms and its indirect role via changes in sex allocation and behavioural defences of the hosts. We compared the influence of foraging temperature on patch residence time between an egg parasitoid, Trichogramma euproctidis, and an aphid parasitoid, Aphidius ervi. The latter attacks hosts that are able to actively defend themselves, and may thus indirectly influence patch time allocation of the parasitoid. Patch residence time decreased with an increase in temperature in both species. The increased activity levels with warming, as evidenced by the increase in walking speed, partially explained these variations, but other mechanisms were involved. In T. euproctidis, the ability to externally discriminate parasitised hosts decreased at low temperature, resulting in a longer patch residence time. Changes in sex allocation with temperature did not explain changes in patch time allocation in this species. For A. ervi, we observed that aphids frequently escaped at intermediate temperature and defended themselves aggressively at high temperature, but displayed few defence mechanisms at low temperature. These defensive behaviours resulted in a decreased patch residence time for the parasitoid and partly explained the fact that A. ervi remained for a shorter time at the intermediate and high temperatures than at the lowest temperature. Our results suggest that global warming may affect host-parasitoid interactions through complex mechanisms including both direct and indirect effects on parasitoid patch time allocation.
authors.affiliation: Institut de Recherche en Biologie Végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke Est, Montréal, Québec, H1X 2B2, Canada. joffrey.moiroux@gmail.com.|Centre de Recherche et de Développement en Horticulture, Agriculture et Agroalimentaire Canada, 430 boul. Gouin, Saint-Jean-sur-Richelieu, Québec, J3B 3E6, Canada. joffrey.moiroux@gmail.com.
authors.forename: Joffrey
authors.initials: J
authors.lastname: Moiroux
authors.affiliation: Institut de Recherche en Biologie Végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke Est, Montréal, Québec, H1X 2B2, Canada.|Centre de Recherche et de Développement en Horticulture, Agriculture et Agroalimentaire Canada, 430 boul. Gouin, Saint-Jean-sur-Richelieu, Québec, J3B 3E6, Canada.
authors.forename: Paul K
authors.initials: PK
authors.lastname: Abram
authors.affiliation: UMR CNRS 6282 Biogéosciences, Université de Bourgogne, 6 boulevard Gabriel, 21000, Dijon, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Louâpre
authors.affiliation: Centre de Recherche et de Développement en Horticulture, Agriculture et Agroalimentaire Canada, 430 boul. Gouin, Saint-Jean-sur-Richelieu, Québec, J3B 3E6, Canada.
authors.forename: Maryse
authors.initials: M
authors.lastname: Barrette
authors.affiliation: Institut de Recherche en Biologie Végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke Est, Montréal, Québec, H1X 2B2, Canada.
authors.forename: Jacques
authors.initials: J
authors.lastname: Brodeur
authors.affiliation: Centre de Recherche et de Développement en Horticulture, Agriculture et Agroalimentaire Canada, 430 boul. Gouin, Saint-Jean-sur-Richelieu, Québec, J3B 3E6, Canada.
authors.forename: Guy
authors.initials: G
authors.lastname: Boivin
mesh_terms: D000818:Animals; D001042:Aphids / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology*; D005260:Female; D057232:Global Warming; D006790:Host-Parasite Interactions / Q000502:physiology; D008297:Male; D012744:Sex Ratio; D013696:Temperature; D014863:Wasps / Q000502:physiology*
keywords: Anti-predator behaviours; Climate; Discrimination ability; Host-parasitoid interaction; Patch time allocation; Sex allocation