GENETICS AND EXPRESSION OF MOTTLED BODY - MOSAIC MUTANT OF THE GERMAN-COCKROACH (DICTYOPTERA, BLATTELLIDAE) WITH POSSIBLE CYTOPLASMIC INHERITANCE

Mottled body (Mt) is a mutant of the German cockroach, Blattella germa nica (L.), which is characterized by extensive color variegation on th e surface of the body. Irregular light patches appear in the integumen t of wild-type black color. Mottling is more conspicuous on abdominal segments than on thoracic segments. The character is clearly observed in the nymphal stage but also can be seen on the small dorsal tergites of adults. Expression of mottling is variable. The trait is mostly ma ternally inherited, and cytoplasmic factor(s) may be involved. A metho d for judging the degree of mottling was established. Degree of mottli ng was scored on the surfaces from 1st to 3rd thoracic and 1st to 7th abdominal segments. Mottling patterns did not change during late nymph al development. Mottling expression did not decrease from the Mt stock to the F-1 (Mt female x wild-type male), and F-2 (F-1 Mt female x wil d-type male). Mottling patterns were often different between left and right sides. Patterns were often discontinuous across the median line of the body and sometimes one side was mottled and the other side almo st wild-type color. Separate scoring between left and right surfaces a nd also between dorsal and ventral surfaces revealed that the degree o f mottling was more correlated dorsoventrally than laterally. This sug gests that mottling patterns were determined before dorsal closure dur ing embryogenesis and are influenced by the shape peculiar to cochroac h embryos packed in the ootheca, which is broad dorsoventrally and com pressed laterally.