Karyotype studies on grape phylloxera (Daktulosphaira vitifoliae FITCH)

: A cytogenetic technique was developed to produce suitable chromosome spre ads for phylloxera karyotype analysis. The karyotype for pathogenetic phyll oxera was 2 n = 10. Karyotypes from haploid sex cells were found to vary be tween n = 5 and n = 6, the latter possibly indicating an aneuploidic aberra tion. Tetra- and polyploid cells were detected in somatic trophocytes. Prep aration of phylloxera sex and somatic cells for chromosomal analysis report ed here enables the study of genetic variation on a chromosomal scale.