Cytogenetics of Blattella germanica: comparison of an insecticide-resistant and an insecticide-susceptible field strain

Abstract

Meiotic chromosomes of a cockroach field strain that is highly resistant to several insecticides were compared with those of a susceptible field strain. The resistant strain was characterized by extensive autosome–autosome associations. They resulted in fragmentation, deletions, and insertion or attachment of segments in novel positions. The distribution pattern of chiasma frequency was also aberrant. One individual was heterozygous for an interchange between chromosomes 6 and 12. Properties of the susceptible strain were generally similar to those described earlier from a laboratory susceptible strain, except that a terminal knob on chromosome 4 was frequently present.Key words: Blattella, cockroach, chromosome, resistance.