ORIGINAL PAPER Temperature-dependent development of Diglyphus isaea (Hymenoptera: Eulophidae) on Liriomyza sativae (Diptera: Agromyzidae) on cucumber Mostafa Haghani Æ Yaghoub Fathipour Æ Ali Asghar Talebi Æ Valiollah Baniameri Received: 17 May 2006 / Revised: 23 October 2006 / Accepted: 6 November 2006 / Published online: 29 November 2006 Ó Springer-Verlag 2006 Abstract The development of Diglyphus isaea (Walker), a parasitoid of leafminers, was studied under laboratory conditions at seven constant temperatures (10, 15, 20, 25, 30, 35, and 40°C) on Liriomyza sativae Blanchard reared on cucumber (Cucumis sativus L.). The total development period (oviposition to adult emergence) decreased with increasing temperature between 15 and 35°C. In 10 and 40°C no development rate was found in D. isaea, so that it may be claimed that these temperatures fall outside the temperature range for development. Linear regression was used to describe the relationship between development rate and temperature. For egg to adult development, males of D. isaea required 153.8 degree-days (DD) above the theoretical threshold of 9.2°C and females required 161.3 DD above 9.4°C. Data were fitted to four non- linear temperature-dependent models. Evaluation of the models took place based on the following criteria: fit to data, number and biological value of the fitted coefficient, and accuracy on the estimation of the thresholds. It could be concluded that the Briere-1 and Briere-2 models are suitable for estimating the mini- mum, maximum and optimal temperature thresholds of D. isaea. Thermal requirements and temperature thresholds can be used to predict the occurrence, number of generations and population dynamics of D. isaea. Keywords Cucumber  Degree-day  Development  Diglyphus isaea  Liriomyza sativae  Temperature Introduction Temperature is a critical abiotic factor influencing the dynamics of insects. Temperature sets the limits of biological activities in arthropods, such that low and high temperature threshold and optimal temperature can be estimated for all major life processes. Thermal characteristics may vary between species, populations, development stages, and with other ecological factors such as food source (Gilbert and Raworth 1996; Roy et al. 2002, 2003). Cucumber (Cucumis sativus L.) is the main green- house vegetable in Iran and this crop is attacked by different pests such as leafminers (Fathipour et al. 2006). Agromyzid leafminers occur worldwide and are economically important pest of many agricultural crops (Kaspi and Parrella 2005; Lee et al. 2005; Hondo et al. 2006). Vegetable leafminer, Liriomyza sativae Blanchard is a major pest of a wide variety of vegetables and ornamental crops throughout the world (Parrella 1983; Reitz and Trumble 2002). Damage is caused mostly by larvae that feed their way inside the plant–host mesophyll, and by the female feeding behavior, (puncturing the leaf with its ovipositor, and feeding from the leaf sap), an action that decreases the plant photosynthesis (Parrella et al. 1983). Female flies may transmit plant pathogens M. Haghani  Y. Fathipour (&)  A. A. Talebi Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, P.O. Box 14115-336, Tehran, Iran e-mail: fathi@modares.ac.ir V. Baniameri Department of Agricultural Entomology, Plant Pests and Diseases Research Institute, P.O. Box 19395-1454, Tehran, Iran 123 J Pest Sci (2007) 80:71–77 DOI 10.1007/s10340-006-0154-5