Localization of HSP single-copy genes by inexpensive, permanent non-fluorescent in situ hybridization on meiotic chromosomes of the grasshopper Schistocerca pallens (Acrididae).

There have been many studies on Schistocerca gregaria and Locusta migratoria, which are important grasshopper pests in many parts of the world. However, the main pest grasshopper species in Brazil, S. pallens, Rhammatocerus schistocercoides and Stiphra robusta, are very poorly characterized genetically. We adapted a permanent in situ hybridization method to extend the genetic characterization of S. pallens by mapping the single-copy genes Hsp70, Hsp83, Hsp27, and Ubi on meiotic chromosomes. Hsp70 was mapped on the L2 chromosome, in which 82% of the signals were observed. Hsp83 was mapped on a medium-sized chromosome, on which 81% of the signals were observed, tentatively identified as M7. The hybridization signals for the Hsp27 gene were detected on the L1 chromosome at a frequency of 58%. The main hybridization site of the Ubi probe was on the L2 chromosome, with 73% of the signals. All mapped genes also presented secondary hybridization signals, always at frequencies below 30%. These are the first single-copy genes mapped for S. pallens and also for the Acrididae family. Since the Acrididae generally present very similar karyotypes, these data are useful as new landmarks for chromosome identification and as a tool for phylogenetic studies on the genus Schistocerca and for comparison with other insects.