Genetic similarity among Agistemus pallinii Matioli et al (Acari: Stigmaeidae) found in citrus orchards in Viçosa, Minas Gerais State, Brazil.

Stigmaeidae are very important predators of mite and insect pests on several crops in Brazil. It is considered the second most important family of predatory mites in citrus orchards in Brazil. However, their identification, especially that of the members of the genus Agistemus, is rather difficult based only on morphology. Hence, this study describes the use of random amplified polymorphic DNA (RAPD-PCR) markers to determine the genetic similarity of an Agistemus pallinii Matioli et al population found in 2004 in a citrus orchard in Viçosa, Minas Gerais State, Brazil, preying on Panonychus citri (McGregor). Amplifi cations were performed with 12 random primers (OPAA8, OPAA19, OPAB1, OPAB5, OPAB18, OPAC9, OPAC17, OPAC19, OPAD10, OPAE9, OPAE12 and OPAE17), which generated 119 bands, with 53.8% polymorphism. The coefficients of genetic similarity among the individuals ranged from 0.68 to 0.99, indicating a high genetic similarity among them. The 3D projection analysis clustered the majority of individuals confirming their high similarity. Though individuals of A. pallinii are minute (+/- 360 microm long), the PCR-RAPD technique can still be used for their identification, complementing morphological analyses or for comparison of populations collected in different geographic regions. This is the first molecular study carried out with stigmaeid mites.