Eugregarinida are a group of endoparasite that inhabit the intestine of a large number of invertebrates which belong to Apicomplexa taxon. Individuals of this order are known with large trophozoites, morphological and behavioral dissimilarity between the two stages of trophozoite and sporozoite, chronic pathogenic effect on the host and having the nucleus situated in its deutomerite part. In order to study this entomopathogenic group and their occurrence in natural populations of the white grub, Polyphylla adspersa (Col., Melolonthidae), several second and third larvae were collected through September 2011 from urban parks and landscapes of Mashhad (Razavi Khorasan province of Iran). The digestive tract of 105 larvae were dissected to detect any possible infection of entomopathogenic protists. During this work, parasite specimens from suborder Septatorina were observed in front and middle parts of intestine of second instar larvae. Different developmental stages of the eugregarine except oocyst and gametocyste stages were observed. This apicomplxan characterized as Stictospora sp and its idendity confirmed by Richard E. Clopton from Peru State College, USA. Morphometric parameters of adult trophozoite and gamont (including Primite and Satellite) were measured according to Clopton & Hays (2006) with some modifications. The data showed that trophozoites are as long as 2176 6m (1100-2800±92.06) including three parts: epimerite, protomerite and deutomerite. The gamonts are differentiated from each other according to nucleus location in deutomerite part. Gamonts normally have couple processes, syzygy type of zygosis. For molecular characterization and phylogenetice analysis, amplification of 18S gene (SSU) by PCR and subsequently interpretaion of their DNA sequences are undergoing. Exposure of infected white grub to stress condition killed the host by destroying the front parts of digestive system. Therefore its role as natural biocontrol agent in fluctuations of pest population density via increasing larval susceptibility as well chronic infection is significant.The current study is the first global report on natural infection of the white grub, P. adspersa to Stictospora and includes the first record of this genus from Iran.

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