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The effect of phytosterols on tsetse reproduction

Published online by Cambridge University Press:  19 September 2011

D. L. Whitehead
D. L. Whitehead
Affiliation:
International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, Kenya
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Abstract

The phytosterols inokosterone, makisterone A, ecdysterone and ecdysone were effective growth regulators and abortifacients (70%) at estimated doses of 1.4 × 10−4 M, 6.8 × 10−4 M, 5.2 × 10−5 M, and 7.8 × 10−5 M respectively when fed to female tsetse Glossina morsitans morsitans. The sterols, added to defibrinated cow or pig blood, were fed to the flies in an in vitro system through a silicone rubber membrane. Cyasterone and ponasterone A were only slightly effective, therefore the hydroxyl groups on the side chain appear to confer activity. Evidence is presented to support three hypotheses which may be advanced to describe the mode of action of the sterols, namely:

(a) Synthesis and/or release of the ‘milk’ secretion from the uterine gland is significantly retarded.

(b) Although the size of the blood-meal is normal, digestion of the in vitro meal is very slow.

(c) Development of the larva itself may be affected by the presence of the hormonally active sterol (or a metabolite) in the ‘milk’.

Effective dose of sterol causing 70% abortion in flies is very much lower than that dose required when injected into the haemolymph. The Malpighian tubules very rapidly excrete the sterol. Therefore, either (1) a slow release of sterol or metabolite into the haemolymph is necessary to disrupt ‘milk’ production, or (2) digestion of the treated in vitro meal itself (and subsequent meals as well) is so retarded that the larva in utero is effectively starved.

Keywords

Tsetseabortifacientecdysteroidin vitro feedinguterine glanddigestionexcretionlarval development
Type
Research Article
Information
International Journal of Tropical Insect Science , Volume 1 , Issue 3 , September 1981 , pp. 281 - 288
Copyright
Copyright © ICIPE 1981

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References

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