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Effect of abscisic acid on vitellogenesis in sarcophaga bullata
- MAN, W., LOOF, A., BRIERS, T., HUYBRECHTS, R.
- Entomologia experimentalis et applicata 1981 v.29 no.3 pp. 259-267
- Sarcophaga bullata, abscisic acid, carnivores, cis-trans isomers, ecdysterone, fecundity, hemolymph, host plants, lipid content, liver, molting, phytophagous insects, protein content, radioimmunoassays, sugars, topical application, vitellogenesis, vitellogenin
- In the carnivorous dipteran Sarcophaga bullata Parker, vitellogenesis was partially inhibited by injection of two doses of 12 μg abscisic acid (ABA), There was no significant difference between injections on day 2 and 4, or on day 4 and 6. Higher and lower doses were less effective, The mixture of isomers inhibited vitellogenesis more than the cis-trans isomer. ABA had no effect on the total lipid concentration of the haemolymph but it inhibited the sharp increase in total protein concentration of the haemolymph and particularly that of vitellogenin, which normally occurred within 24 hr following liver feeding on day 4, Since vitellogenin synthesis is under the control of moulting hormone (MH), the MH activity was measured by radioimmunoassay to find out whether ABA might interact with vitellogenin synthesis via its hormonal inductor. Eight hours after liver feeding, there was a MH peak in the control groups while following ABA treatment this peak occurred after 18 hr, The inhibitory effect of ABA on vitellogenesis could be overruled by feeding sugar impregnated with ecdysterone (5 mg/g), not by topical application of JH. Our results suggest that ABA might interact with a mechanism which phytophagous and non-phytophagous insects share in common. If in phytophagous insects the same amount of ABA per gram weight, as was effective in Sarcophaga (about 200 μg/g), is needed to reduce fecundity, it is not probable that this plant hormone plays a role in the seasonal synchronisation of the growth and reproduction of insects with the senescence of their host plants.