Bulletin of Insectology 73 (1): 79-86, 2020 ISSN 1721-8861 eISSN 2283-0332 Preference and performance of Trichogramma embryophagum when parasitizing Cydia pomonella and two stored-product moths Fatemeh HAGHI GOLBAGHI 1 , Seyed Hosein GOLDANSAZ 2 , Shima RAHMANI 3 , Mohammad Reza ATTARAN 4 1 Department of Entomology and Plant Pathology, College of Aboureyhan, University of Tehran, Iran 2 Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran 3 Department of Plant Protection, Science and Research Branch, Islamic Azad University, Tehran, Iran 4 Biological Control Research Department, Iranian Research Institute of Plant Protection, Tehran, Iran Abstract Trichogramma species are polyphagous biocontrol agents most commonly used against the egg stage of various groups of insect pests. Host preference is a key trait in parasitoids and it is important to characterize the main hosts of parasitoids before using them in biocontrol programs. In the present study, the parasitism of Cydia pomonella (L.) (Lepidoptera Tortricidae) by Trichogramma embryophagum (Hartig) (Hymenoptera Trichogrammatidae) (a parasitoid species commonly distributed in Europe and Central Asia against the pest) was compared with parasitism on Sitotroga cerealella Oliver (Lepidoptera Gelechiidae) and Ephestia kuehniella Zeller (Lepidoptera Pyralidae) using choice and no-choice experiments. In the no-choice test, parasitism on C. pomonella was higher than on S. cerealella and E. kuehniella. In the parasitoid’s early life, parasitism on C. pomonella was four times greater than on the two other hosts. In addition, parasitoid emergence from C. pomonella was also higher than from the two other hosts on the first day of parasitism. In the choice test, C. pomonella eggs were preferred as hosts (vs. S. cerealella and E. kuehniella) during the first two days of the parasitism assay as well as during total parasitism assay overall. Furthermore, the production of females was higher in C. pomonella than in the other hosts (early in parasitism and during whole parasitism assay, both in non-choice and choice tests). Female longevity was greater on C. pomonella than on S. cerealella and E. kuehniella during the no-choice test and was even lower during the choice test. Female abnormality and preadult mortality were more frequent in S. cerealella and E. kuehniella than in C. pomonella during the choice test while no significant difference was detected for these traits when hosts were presented in the no-choice test. Overall, the results indicated that C. pomonella is a preferable host for T. embryophagum; these results may be useful for further development of biocontrol programs relying on T. embryophagum. Key words: parasitism, host preference, parasitoid specialization, no choice test, choice test. Introduction The codling moth, Cydia pomonella (L.) (Lepidoptera Tortricidae) is one of the most important pests of apple and pear around the world, capable of damaging up to 95% of these products. Quince, peach, walnut, and plum are other fruit crops that are damaged by this insect (Is- mail and Albittar, 2015; Basheer et al., 2016). Use of natural enemies such as pathogens, nematodes, predatory mites, insect predators and parasitoids is one strategy in managing codling moth populations (Blomefield and Giliomee, 2012; Ismail and Albittar, 2015; Ksentini and Herz, 2019). Among parasitoids, several Hymenopteran families have been reported, with the majority of species belonging to Braconidae and Ichneumonidae (Velcheva and Atanassov, 2016). In the family Trichogrammatidae, one species, Trichogramma cacoeciae Marchal (Hyme- noptera Trichogrammatidae) has been considered as a biocontrol agent of codling moth in several papers (Botto and Glaz, 2010; Ismail and Albittar, 2015; Basheer et al., 2016; Ksentini and Herz, 2019). In Denmark, alongside T. cacoeciae, mass release of Trichogramma evanescens Westwood was examined for reduction of C. pomonella (Sigsgaard et al., 2017). However, according to the Sigsgaard et al. (2017), further studies are required to assess the suitability of Trichogramma species against C. pomonella eggs. For more than 40 years, Trichogramma spp. have been used in many countries as biological control agents against various insect pests, mostly lepidopterans, on fruit trees and on crops such as vegetables, cotton, corn, rice, and sugarcane (Smith, 1996; Poorjavad et al., 2018). Indeed, Trichogramma species are one of the most commonly used groups of natural enemies. They can be cultured relatively easily and are able to manage the host before crop damage occurs (Smith, 1996; Yang et al., 2016). However, most parasitoids especially spe- cies of the Trichogramma genus possess different host preferences and performances when facing their varia- ble hosts (Godfray, 1994; Mansfield and Mills, 2004; Roriz et al., 2006; Desneux et al., 2009; 2012; Chail- leux et al., 2012; 2013a; Paraiso et al., 2013). Thus, it is essential to evaluate host ranges of parasitoids such as Trichogramma for possible use in biological control programs (Paraiso et al., 2013). Parasitism preference and fitness of parasitoid offspring such as demographic traits, larval survivorship, growth and development time, emergence rate, adult weight, and fecundity are the factors affected by the host quality (Godfray, 1994; Roriz et al., 2006; Iranipour et al., 2010; Pizzol et al., 2010; 2012; Chailleux et al., 2013b; Yang et al., 2016; Zhang et al., 2017). It is necessary to find the host range of a parasitoid to evaluate the potential worth of a biological control agent (Mansfield and Mills, 2004). No-choice and choice tests are the most common methodologies utilized for host range evaluation (Van Driesche and Murray, 2004). If the agent is not monophagous according to a no-choice