title: Comparative cytogenetic study of three Macrolophus species (Heteroptera, Miridae).
abstract: Macrolophus pygmaeus (Rambur, 1839) (Insecta, Heteroptera, Miridae) is a predator of key vegetable crop pests applied as a biocontrol agent in the Mediterranean region. Macrolophus pygmaeus and Macrolophus melanotoma (A. Costa, 1853) are cryptic species with great morphological similarity which results in their misidentification and negative consequences for the conservation of their populations on greenhouse and outdoor crops. In order to find out specific markers for their separation we studied the karyotype, male meiosis and heterochromatin composition of these species and additionally of a third species (as a reference one), Macrolophus costalis Fieber, 1858. We demonstrate here that all the three species share achiasmate male meiosis and sex chromosome pre-reduction. On the other hand, the species differ in karyotype, with 2n=28 (26+XY) in Macrolophus pygmaeus, 2n=27 (24+X1X2Y) in Macrolophus costalis, and 2n=34 (32+XY) in Macrolophus melanotoma, and heterochromatin distribution and composition. In addition, the species differ in sperm morphology: sperm cells of Macrolophus costalis are significantly longer with longer head and tail than those of Macrolophus melanotoma and Macrolophus pygmaeus, whereas sperm cells of Macrolophus melanotoma have a longer tail than those of Macrolophus pygmaeus. All these characters can be used as markers to identify the species, in particular the cryptic species Macrolophus melanotoma and Macrolophus pygmaeus.
authors.affiliation: University of Lleida, Department of Crop and Forest Sciences. Alcalde Rovira Roure, 177, 25198 Lleida (Spain).
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Jauset
authors.affiliation: University of Lleida, Department of Crop and Forest Sciences. Alcalde Rovira Roure, 177, 25198 Lleida (Spain).
authors.forename: Eva
authors.initials: E
authors.lastname: Edo-Tena
authors.affiliation: IRTA, Ctra. Cabrils Km 2, 08348 Cabrils (Barcelona), Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Castañé
authors.affiliation: IRTA, Ctra. Cabrils Km 2, 08348 Cabrils (Barcelona), Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Agustí
authors.affiliation: IRTA, Ctra. Cabrils Km 2, 08348 Cabrils (Barcelona), Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Alomar
authors.affiliation: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 1 Tsar Osvoboditel Blvd., 1000 Sofia, Bulgaria.
authors.forename: Snejana
authors.initials: S
authors.lastname: Grozeva
keywords: Heteroptera; Macrolophus; Miridae; achiasmate meiosis; karyotype; sex chromosome pre-reduction; sex chromosomes; sperm morphology