On the specific identity of specimens of Phytoseiulus longipes Evans (Mesostigmata: Phytoseiidae) showing different feeding behaviours: morphological and molecular analyses M.-S. Tixier * , M. Ferrero, M. Okassa, S. Guichou and S. Kreiter Montpellier SupAgro, Unite ´ Mixte de Recherche no. 1062 Centre de Biologie et de Gestion des Populations, ba ˆ timent 16, 2 Place Pierre Viala, 34060 Montpellier cedex 01, France Abstract This paper focuses on the differentiation of specimens, identified as Phytoseiulus longipes, collected in four countries: Argentina, Brazil, Chile and South Africa. Two of these populations are known to feed and develop on Tetranychus evansi, whereas the two others do not. As morphologically similar specimens can sometimes belong to different species and because differences in predatory behaviours exist among the four populations considered, we tested for the presence of cryptic species. Morphological and molecular experiments (12S rDNA) were carried out. The four studied populations of P. longipes could be morphologically differentiated thanks to a combination of characters. However, these morphological differences are very small. The two populations that feed and develop on T. evansi (from Argentina and Brazil) are morphologically closer to each other than to the two other populations. Genetic distances among the four populations of P. longipes were very low, suggesting that despite their different feeding habits, all specimens belong to the same species. However, the populations associated with T. evansi showed some genetic differentiation from those that do not use this pest. This is the first time that this type of differentiation has been reported for the family Phytoseiidae. These results are of primary importance to ensure the success of biological control programs and to develop strains adapted to both crops and prey species. Keywords: 12S DNA, taxonomy, specialization (Accepted 15 October 2009) Introduction Several species in the family Phytoseiidae are important natural enemies used to control mite pest outbreaks in many crops (McMurtry & Croft, 1997). Specific diagnostic is, thus, of primary importance for the success of biological control programs. This family is widespread all over the world and includes three sub-families and more than 2000 valid species (Chant & McMurtry, 2003a,b, 2004a,b, 2005a,b, 2006a,b, 2007; Moraes et al 2004; Kreiter & Tixier, 2006). Species of the genus Phytoseiulus Evans (sub-family Amblyseiinae) are the most frequently used for the biological control of mite pests, especially Phytoseiulus persimilis Athias-Henriot, a species * Author for correspondence Fax: 00 33 4 99 61 23 93 E-mail: tixier@supagro.inra.fr Bulletin of Entomological Research, Page 1 of 11 doi:10.1017/S0007485309990617 Ó Cambridge University Press 2010