TEMPERATURE CONTROL OF MALE EMBRYO VIABILITY OF THE APHID MEGOURA-VICIAE

Early stages of gametogenesis were observed in embryos of Megoura vici ae Buckton at two temperatures, 24-degrees-C and 27-degrees-C. The hig her temperature is lethal for male embryos but not for female embryos. Spermatogenesis proceeds to the synizesis contraction stage at both t emperatures but goes no further at 27-degrees-C. All the spermatocytes degenerate prior to undergoing metaphase I and gamete degeneration is followed by the death of the male embryos. In oogenesis, synizesis la sts for much longer and no differential viability at the two temperatu res can be observed. A possible explanation, related to the different timing of meiosis in the two sexes, is proposed and discussed.