Using high relative humidity and low air temperature as a long-term storage strategy for the predatory mite Neoseiulus californicus (Gamasida: Phytoseiidae) Noureldin Abuelfadl Ghazy a,b,⇑ , Takeshi Suzuki b,c , Maqsood Shah a , Hiroshi Amano d , Katsumi Ohyama a,b a Graduate School of Horticulture, Chiba University, Matsudo 648, Chiba 271-8510, Japan b Center for Environment, Health and Field Sciences, Chiba University, Kashiwanoha 6-2-1, Chiba 277-0882, Japan c Japan Society for the Promotion of Science, Japan d Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan highlights " The effect of RH during cold storage on Neoseiulus californicus was investigated. " Survival time was longer under high RH for all life stages. " The longest survival time was observed in the mated adult females. graphical abstract article info Article history: Received 23 March 2011 Accepted 15 December 2011 Available online 27 December 2011 Keywords: Cold storage IPM Life stages Natural enemy Neoseiulus californicus Survival curve abstract The survival time of an indigenous Japanese strain of Neoseiulus californicus (McGregor) was investigated at high and low relative humidities (RHs) of approximately 100% and 80%, respectively, at an air temper- ature of 5 °C. Five life stages, larva, protonymph, deutonymph and unmated and mated adult female, were tested in 1.5-mL polypropylene vials, in which the RH was adjusted by either adding or omitting a water-saturated filter paper. The survival curves and median survival time (LT 50 ) were significantly dif- ferent between high and low RHs, and the mean survival time (MST) was 1.6–2.3 times longer at high RH than that at low RH, except in larvae, in which tolerances to high RH and/or low air temperature were not well developed. At high RH, the MST of the mated adult females was 63.1 d and was 1.4 times longer than that of unmated adult females. These results indicate that the suitable water content in the body was probably maintained by increasing the RH at the low air temperature, which is considered to be a primary factor affecting the survival time of N. californicus. Moreover, the nutrient content in the body, such as eggs and male sperm in the mated adult females, could have positive effects on prolonging their survival time. These findings will help to construct an efficient long-term storage method for N. californicus. Ó 2011 Elsevier Inc. All rights reserved. 1. Introduction To cope with agricultural pest damage and their rapid adaptation to pesticides, an integrated pest management (IPM) that uses a combination of existing pest control methods, including chemical, physical and biological control, is absolutely imperative. Recently, biological control using indigenous natural enemies, considered envi- ronmentally benign agents, has become a core component of IPM. Phytoseiid mites are natural enemies that can efficiently sup- press some phytophagous pest insects and mites in greenhouses 1049-9644/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.biocontrol.2011.12.006 ⇑ Corresponding author at: Center for Environment, Health and Field Sciences, Chiba University, Kashiwanoha 6-2-1, Chiba 277-0882, Japan. E-mail addresses: noureldinghazy@yahoo.com, Ghazy@graduate.chiba-u.jp (N.A. Ghazy). Biological Control 60 (2012) 241–246 Contents lists available at SciVerse ScienceDirect Biological Control journal homepage: www.elsevier.com/locate/ybcon