Sørensen, Christian Hougaard3; Toft, Søren4; Kristensen, Torsten Nygård2
1 Department of Bioscience - Genetics, Ecology and Evolution, Department of Bioscience, Science and Technology, Aarhus University2 Department of Biological Sciences, Genetics and Ecology, Faculty of Science, Aarhus University, Aarhus University3 Department of Bioscience, Aarhus University4 Department of Bioscience - Genetics, Ecology and Evolution, Department of Bioscience, Science and Technology, Aarhus University
Ladybirds are used in integrated pest management and augmentative biological control programs all over the world. Typically, commercial rearing of the commonly used ladybird, Adalia bipunctata, takes place at a constant temperature (25 °C) which maximizes reproductive output and survival in the laboratory. However, insects are known to acclimate via physiological adjustments to their thermal environment and performance is often higher at temperatures to which they are acclimated. Thus rearing A. bipunctata at 25 °C may not be optimal if they are to effectively manage aphid pests under different thermal regimes. Here, we report on the effects of rearing temperature (15, 20 and 25 °C) of A. bipunctata on aphid predation at similar test temperatures and under cold semi-natural conditions. Furthermore we assessed the upper thermal critical limit of ladybirds from the three rearing temperatures using a heat knock down assay as well as the effects of rearing temperature on pupal survival and adult mass. We demonstrate that ladybirds acclimated to a certain temperature consume more aphids at that temperature than ladybirds acclimated to other temperatures. Acclimating ladybirds to cold temperatures also increased their body-size but reduced pupal survival and heat resistance, suggesting costs associated with acclimation. Our findings have implications for the application of ladybirds as bio-control agents in different thermal environments. The results can be used to improve the efficiency of pest management in biological control programs.