Influence of daylength on the production of parthenogenetic and sexual females of aphis fabae at 17.5°
1977
TSITSIPIS, J.A. | MITTLER, T.E.
When apterous virginoparae of Aphis fabae and their progenies were raised at 17.5° on leaf discs of Vicia faba under photoperiods of 12 h or less per day, more alatae occurred among the progenies than under longer photoperiods. The alatae developed exclusively into gynoparae at 4, 10 and 12 h light per day and almost all did so at 2 h. At 13 h 45 min, 14 h, 16 h, and 24 h all the alatae developed into virginoparae. At transitional photoperiods ranging from 13 h 6 min to 13 h 28 min, both alate morphs occurred. They could both be deposited by a single apterous virginopara and produce intermorphs containing eggs and embryos. Under most light regimes, a proportion of the gynoparae (generally < 10%) produced some apterous virginoparae, gynoparae, and males after producing a number of oviparae. Alate virginoparae produced almost three times as many larvae as did the gynoparae. By transferring alatiform larvae produced by apterae raised at short day (SD: 10 h light) to long day (LD: 16 h light) or vice versa, a strong prenatal influence of SD on gynopara production was demonstrated. SD also had a postnatal influence on presumptive virginoparous alatiforms, if they were transferred to SD already in the 1st instar. Alatiform larvae could be influenced by SD or LD as late as in the 3d instar if they and their mothers had been maintained under a weak short (13 h 6 min) or a weak long day (13 h 45 min). The results are discussed in relation to possible hormonal mechanisms of morph determination.
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