Eugregarinidae, an endoparasite group, the members of which inhabit the intestine of a
large number of invertebrates, belong to Apicomplexa taxon. Individuals of this order are
known by their large trophozoites, morphological and behavioral dissimilarity between the two
stages of trophozoite vs sporozoite, chronic effect on the host and having the nucleus being
situated in its deutomerite part. To study this entomopathogenic pathogen and its occurrence in
natural populations of white grub, Polyphylla adspersa (Col., Melolonthidae), sampling was
conducted to collect from both the second and third larval stages of the white grub (during
September 2011) from urban parks and landscapes of Mashhad (Khorasane Razavi Province,
Iran). The digestive tracts of 105 larvae were dissected to detect any possible infection of the
entomopathogenic protists. During this process, parasitc specimens from suborder Septatorina
were observed in the foregut as well as midgut portions of the second instar larvae. Different
developmental stages of the eugregarine (except oocyst and gametocyste stages) were
observed. This apicomplexan was characterized as Stictospora sp. Morphometric parameters of
adult trophozoite and gamont (including Primite and Satellite) were assessed. The data
revealed that a trophozoite,s length is 2176 μm (1100-2800±92.06) including the three parts of
epimerite, protomerite and deutomerite. The gamonts are differentiated from each other as
according to the nucleus location in their deutomeritic parts. Gamonts are normally of the
couple process, syzygy type of zygosis. Exposure of the infected white grub to stress
conditions caused the death of the host by destroying the front parts of the digestive system.
Impact of the protist was exacerbated when accompanied by the activity of some species of an
Oxyurida nematode. The nematode was found out as belonging to Cephalobellus genus from
Thelastomatidae family,a new genus of nematode reported from Iran. Sporadic and local
impact of the protist in fluctuations of pest population density via an increase in larval
susceptibility as well as the incidence of chronic infection could be significant.The current
study is the first global report on the natural infection of white grub, P.
adspersabyStictospora.In the meantime, it presents the first record of the genus Stictospora
from Iran.