Chromosome studies in southern Brazilian wheat pest aphids Sitobion avenae, Schizaphis graminum, and Methopolophium dirhodum (Homoptera: Aphididae)

Abstract

We examined the chromosome set of the aphid species Sitobion avenae, Schizaphis graminum and Methopolophium dirhodum by means of conventional staining and C, NOR, AluI and HaeIII banding methods. These species are considered important pests to several plants of economic interest in Brazil. No variation was observed in the number of chromosomes of S. avenae, whereas there was intraspecific variation in the other two species. Interspecific differences in the response to the banding treatments were observed. Whereas these techniques allowed the identification of several S. graminum chromosome pairs, only the AluI treatment was capable of inducing differential staining in the M. dirhodum chromosomes and no clear patterns emerged when the S. avenae preparations were treated<br>Por meio de coloração convencional e de métodos de bandamento C, NOR, AluI e HaeIII, foi feita uma tentativa de caracterizar o cariótipo e a variação no número cromossômico das espécies de afídeos Sitobion avenae, Schizaphis graminum e Methopolophium dirhodum, que são considerados como pragas importantes para várias plantas de interesse econômico no Brasil. Não foi encontrada variação no número cromossômico de S. avenae, enquanto que as outras duas espécies apresentaram variação numérica intra-específica. Diferenças interespecíficas quanto à resposta aos tratamentos de bandamento foram observadas. Através dos métodos utilizados, foi possível a identificação de vários pares cromossômicos de S. graminum, mas só o tratamento com AluI foi capaz de induzir coloração diferencial nos cromossomos de M. dirhodum, enquanto que nenhum padrão claro de bandamento apareceu nos preparados de S. avena

Cytogenetic Analysis of the Holocentric Chromosomes of the Aphid Schizaphis Graminum

“…This may explain the high diffusion of chromosomal polymorphism known for many aphid species (BLACKMAN 1978(BLACKMAN , 1980(BLACKMAN , 1990KHUDA-BUSH and KAR 1990). For example, in S. gruminum mitotic plates ranging from 2n = 6 and 2n = 8 have been observed (RUBIN DE CELIS et al 1997). Moreover, a variation in chromosome length among five s. graminum biotypes has been reported (MAYO et al 1988).…”

Heterogeneity in the Second Internal Transcribed Spacer (ITS2) of rDNA in the Genetically Distinct Metopolophium dirhodum Isofemale Lineages (Hemiptera: Aphididae)

“…In another study, the genetic variability of introduced populations of M. dirhodum in New Zealand is low when compared with populations from Scotland [5]. However, in southern Brazil, the presence of two karyotypes within populations of M. dirhodum (2n = 16 and 2n = 18) was reported, showing an important genetic divergence caused by chromosomal rearrangements [6].…”