IRRADIATION OF SPERM AND OOCYTES INONCOPELTUS FASCIATUS(HEMIPTERA: LYGAEIDAE): SEX RATIO, FERTILITY, AND CHROMOSOME ABERRATIONS IN THE F1PROGENY

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Abstract
Adult Oncopeltus fasciatus were irradiated as 7- to 8-day-old males, and as 3- to 4- or 10- to 12-day-old females with doses of 8 and 20 krad of gamma irradiation and 200 R of X-rays, respectively. Treated bugs were outcrossed to untreated bugs, and F1progeny derived from irradiated sperm and from prophase and metaphase oocytes were studied. All treated bugs were less fertile than the controls, but none of the treatments produced full sterility. Among the F1generation from the three types of crosses, there was no significant deviation from a 50:50 sex ratio.When F1males were outcrossed to untreated females, only the males derived from irradiated sperm were semisterile; F1males derived from the treated oocytes were as fertile as the controls. The semisterility of the F1males was correlated with chromosome translocations and fragments in the spermatocytes. The virtual absence of these aberrations in the testes of F1males derived from irradiated oocytes suggests that these aberrations are not induced in oocytes, are repaired, or are not included in the maternal pronucleus after irradiation of meiotic oocytes.