Cold-acclimation increases the predatory efficiency of the aphidophagous coccinellid Adalia bipunctata Christian Hougaard Sørensen a , Søren Toft a,⇑ , Torsten Nygaard Kristensen a,b a Department of Bioscience, Aarhus University, Ny Munkegade 116, DK-8000 Aarhus C, Denmark b Department of Molecular Biology and Genetics, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark highlights " Cold acclimation may increase the biocontrol efficiency of a ladybird. " Acclimated beetles had the highest biocontrol efficiency at all temperatures. " Cold acclimation increased body- size but reduced pupal survival and heat resistance. " Acclimation should be considered in augmentative release programs. graphical abstract Test temperature ( o C) 15 20 25 Rel. no. of aphids consumed (%) 70 75 80 85 90 95 100 Rearing temp. 15 o C 20 o C 25 o C article info Article history: Received 21 May 2012 Accepted 24 September 2012 Available online 16 October 2012 Keywords: Acclimation Biological control Coccinellidae Heat resistance Predation Sitobion avenae abstract 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 preda- tion 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 envi- ronments. The results can be used to improve the efficiency of pest management in biological control programs. Ó 2012 Elsevier Inc. All rights reserved. 1. Introduction Predaceous ladybirds (family Coccinellidae) have received attention from ecologists, because of their use in biological control as predators of agricultural pests e.g. aphids, diaspids, coccids, aleyrodids and mites (Obrycki and Kring, 1998; Omkar and Pervez, 2005). They have been used as a component of integrated pest management and in augmentative control programs since the early 20th century (Hodek, 1970). Today, ladybirds are commercially produced and sold as bio-control agents, in particular against aphids which damage for billions of dollars of crops annually worldwide (Oerke, 1994). Adalia bipunctata (L.) is one of the best 1049-9644/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.biocontrol.2012.09.016 ⇑ Corresponding author. Fax: +45 87154326. E-mail address: soeren.toft@biology.au.dk (S. Toft). Biological Control 65 (2013) 87–94 Contents lists available at SciVerse ScienceDirect Biological Control journal homepage: www.elsevier.com/locate/ybcon