Modification of fecundity and fertility during oogenesis by gamma radiation and/or ozone with a cytological analysis in the ectoparasitic wasp, Habrobracon juglandis (Ashmead)

Ofuoku, Edith
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In Experiment I, adult female wasps were exposed to 44.1 ppm ozone for 0, 2, 4, 6, 8, 10, 12, 16, 24, and 27 h. The results indicated that the 27 h of ozone exposure produced 100% lethality on the first day. Exposures below 27 h progressively decreased life span with increasing length of exposure.

In Experiment II A, adult virgin Habrobracon females were exposed to 44.1 ppm ozone for 0, 2, 4, 6, 8, 10, 12, 16, and 24 h to determine the effects of ozone on fecundity (egg laying ability) and fertility (egg hatching ability). The results showed that ozone significantly decreased fecundity and fertility in all meiotic stages except metaphase I.

In Experiment II B, adult virgin Habrobracon females were exposed to 0, 25, 35, 45, and 65 Gy of Co-60 gamma radiation. All treated wasps showed significant progressive decreases in fecundity and fertility with increases in radiation dose; females given 45 and 65 Gy experienced temporary infecundity and permanent sterility, respectively. The results indicated the differential sensitivity of the various meiotic stages.

In Experiment II C, adult virgin Habrobracon females were exposed to 0, 22.5, or 45 Gy of Co-60 gamma radiation; to 0, 8, or 16 h of 44.1 ppm ozone; or to combinations thereof to determine the effects of these insults on fecundity and fertility. Together or singly ozone and radiation reduced fecundity and fertility. The co-insult treatments resulted in additive or synergistic effects.

In Experiment III, adult virgin Habrobracon females were exposed to the conditions of Experiment II C to correlate by cytological examination of the ovarioles the effects of ionizing radiation and/or ozone on the germ cells at specific meiotic stages. The ovarioles from females exposed to 8 and 16 h ozone had gaps in the series of developing reproductive units and these abnormalities increased with time. Radiation doses above 22.5 Gy caused destruction of germ cells and degeneration or atrophy of the ovarioles; while, the co-insult treatments resulted in more adverse effects on the ovarioles than the single insults. Results obtained from the cytological study explain the fecundity and fertility observations.

Radiology, Medical imaging