title: Impact of fluctuating temperatures on development of the koinobiont endoparasitoid Venturia canescens.
abstract: The effect of temperature on the biology of Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) is well understood under constant temperature conditions, but less so under more natural, fluctuating conditions. Herein we studied the influence of fluctuating temperatures on biological parameters of V. canescens. Parasitized fifth-instar larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) were reared individually in incubators at six fluctuating temperature regimes (15-19.5°C with a mean of 17.6°C, 17.5-22.5°C with a mean of 19.8°C, 20-30°C with a mean of 22.7°C, 22.5-27.5°C with a mean of 25°C, 25.5-32.5°C with a mean of 28.3°C and 28.5-33°C with a mean of 30°C) until emergence and death of V. canescens adults. Developmental time from parasitism to adult eclosion, adult longevity and survival were recorded at each fluctuating temperature regime. In principle, developmental time decreased with an increase of the mean temperature of the fluctuating temperature regime. Upper and lower threshold temperatures for total development were estimated at 34.9 and 6.7°C, respectively. Optimum temperature for development and thermal constant were 28.6°C and 526.3 degree days, respectively. Adult longevity was also affected by fluctuating temperature, as it was significantly reduced at the highest mean temperature (7.0 days at 30°C) compared to the lowest one (29.4 days at 17.6°C). Survival was low at all tested fluctuating temperatures, apart from mean fluctuating temperature of 25°C (37%). Understanding the thermal biology of V. canescens under more natural conditions is of critical importance in applied contexts. Thus, predictions of biological responses to fluctuating temperatures may be used in population forecasting models which potentially influence decision-making in IPM programs.
authors.affiliation: Aristotle University of Thessaloniki, Faculty of Agriculture, Laboratory of Applied Zoology and Parasitology, 54124 Thessaloniki, Greece.
authors.forename: Christos G
authors.initials: CG
authors.lastname: Spanoudis
authors.affiliation: Aristotle University of Thessaloniki, Faculty of Agriculture, Laboratory of Applied Zoology and Parasitology, 54124 Thessaloniki, Greece.
authors.forename: Christos S
authors.initials: CS
authors.lastname: Pappas
authors.affiliation: Technological Educational Institution of Thessaloniki, Crop Production Department, Laboratory of Entomology, 57400 Sindos, Thessaloniki, Greece.
authors.forename: Argyroula G
authors.initials: AG
authors.lastname: Delpisi
authors.affiliation: Aristotle University of Thessaloniki, Faculty of Agriculture, Laboratory of Applied Zoology and Parasitology, 54124 Thessaloniki, Greece. Electronic address: ssa18@psu.edu.
authors.forename: Stefanos S
authors.initials: SS
authors.lastname: Andreadis
authors.affiliation: Aristotle University of Thessaloniki, Faculty of Agriculture, Laboratory of Applied Zoology and Parasitology, 54124 Thessaloniki, Greece.
authors.forename: Matilda
authors.initials: M
authors.lastname: Savopoulou-Soultani
mesh_terms: D000064:Acclimatization; D000818:Animals; D007814:Larva / Q000254:growth & development; D008136:Longevity; D013696:Temperature; D014863:Wasps / Q000254:growth & development*
keywords: Adult longevity; Developmental threshold; Ephestia kuehniella; Fluctuating temperature; Survival; Venturia canescens