Karyotype variation in the corn leaf aphid, Rhopalosiphum maidis (Fitch), species complex (Hemiptera: Aphididae) in relation to host-plant and morphology

Abstract

Rhopalosiphum maidis (Fitch) collected on barley in the northern hemisphere usually has a ten-chromosome karyotype, whereas samples from maize, sorghum and Johnson grass (Sorghum halepense) from all parts of the world commonly have 2n = 8. Samples with other karyotypes (2n = 9, 2n = 11 and 2n = 8 heterozygous for an interchange between the X chromosomes) occur less frequently on these and other species of Gramineae. Multivariate morphometric analysis, principally by the method of canonical variates, indicated that the ten-chromosome form may be regarded as a single clone of R. maidis recognizable by its karyotype and host-plant relationships, although not completely separable by morphology alone from all other clones of this permanently parthenogenetic species complex.

Chromosomal location of rDNA clusters and TTAGG telomeric repeats in eight species of the spittlebug genus Philaenus (Hemiptera: Auchenorrhyncha: Aphrophoridae)

“…In phytophagous insects, host plant shifting might be an important factor in sympatric divergence and speciation (Berlocher & Feder, 2002;Horn et al, 2006;Loxdale, 2010). In some aphids, another group of the order Hemiptera, polymorphism for chromosome number was found to be correlated with change of host plants (Brown & Blackman, 1988;De Barro et al, 1995;Hales et al, 2000). Such karyotypic divergence in relation to host plant is known to occur in the genus Amphorophora where A. idaei Börner, which feeds on raspberry (Rubus idaeus) has 2n = 18, whereas A. rubi (Kaltenbach), which feeds on blackberry (Rubus fruticosus agg.)…”

“…In this species there is a strong association between chromosome number and host plant. Specimens with 2n = 8 are found on Sorghum and Zea mays, whereas on northern hemisphere barley, Hordeum vulgare, 2n = 10 is common (Brown & Blackman, 1988).…”

Karyotype Variation in the Aphid Sitobion rosaeiformis (Das) (Homoptera: Aphididae).

“…In this species 2n=8 is associated with samples from maize, sorghum and Johnson grass, whereas 2n=10 is associated with barley (Brown and Blackman 1988). Earlier, Chattopadhay et al (1982) also observed differences in number and size of chromosomes in samples of R. maidis (2n=8 and 10) collected from Triticum vulgare and Zea mays respectively.…”

“…The relationship between karyotype variation and association with host plant has been reported in Rhopalosiphum maidis (Brown and Blackman 1988). In this species 2n=8 is associated with samples from maize, sorghum and Johnson grass, whereas 2n=10 is associated with barley (Brown and Blackman 1988).…”

“…Structural heterozygosity and variation in chromosome number within species have been reported in some aphid species (Blackman 1971, Chattopadhay et al 1982, Brown and Blackman 1988 , Blackman et al 1990). These studies indicate that there is association between karyotypes and host plant in aphids .…”