title: Diurnal temperature variations affect development of a herbivorous arthropod pest and its predators.
abstract: The impact of daily temperature variations on arthropod life history remains woefully understudied compared to the large body of research that has been carried out on the effects of constant temperatures. However, diurnal varying temperature regimes more commonly represent the environment in which most organisms thrive. Such varying temperature regimes have been demonstrated to substantially affect development and reproduction of ectothermic organisms, generally in accordance with Jensen's inequality. In the present study we evaluated the impact of temperature alternations at 4 amplitudes (DTR0, +5, +10 and +15°C) on the developmental rate of the predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor (Acari: Phytoseiidae) and their natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). We have modelled their developmental rates as a function of temperature using both linear and nonlinear models. Diurnally alternating temperatures resulted in a faster development in the lower temperature range as compared to their corresponding mean constant temperatures, whereas the opposite was observed in the higher temperature range. Our results indicate that Jensen's inequality does not suffice to fully explain the differences in developmental rates at constant and alternating temperatures, suggesting additional physiological responses play a role. It is concluded that diurnal temperature range should not be ignored and should be incorporated in predictive models on the phenology of arthropod pests and their natural enemies and their performance in biological control programmes.
authors: Laboratory of Agrozoology, Department of Crop Protection, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium.
authors: Dominiek
authors: D
authors: Vangansbeke
authors: PCS-Ornamental Plant Research, Schaessestraat 18, B-9070, Destelbergen, Belgium.
authors: Joachim
authors: J
authors: Audenaert
authors: Laboratory of Agrozoology, Department of Crop Protection, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium; Entomology Department, Vietnam National University of Agriculture, Trau Quy, Gia Lam, Hanoi, Vietnam.
authors: Duc Tung
authors: DT
authors: Nguyen
authors: PCS-Ornamental Plant Research, Schaessestraat 18, B-9070, Destelbergen, Belgium.
authors: Ruth
authors: R
authors: Verhoeven
authors: PCS-Ornamental Plant Research, Schaessestraat 18, B-9070, Destelbergen, Belgium.
authors: Bruno
authors: B
authors: Gobin
authors: Laboratory of Agrozoology, Department of Crop Protection, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium.
authors: Luc
authors: L
authors: Tirry
authors: Laboratory of Agrozoology, Department of Crop Protection, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium.
authors: Patrick
authors: P
authors: De Clercq
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D060434:Herbivory / Q000502:physiology*; D008018:Life Cycle Stages / Q000502:physiology*; D016014:Linear Models; D008925:Mites / Q000502:physiology*; D017711:Nonlinear Dynamics; D010572:Pest Control, Biological; D011235:Predatory Behavior / Q000502:physiology*; D013696:Temperature