Effects of pyrimidine-2-thiol on the ovarian histology of Epilachna vigintioctopunctata (Fabr.) (Coleoptera: Coccinellidae).

V Sood, H Kaur, R Sandhu

Index: Folia Morphol. (Praha.) 37(4) , 402-6, (1989)

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Abstract

The telotrophic ovary of Epilachna vigintioctopunctata is composed of 32-40 ovarioles, each with an apical germarium and a basal vitellarium. The germarium encloses mononucleate and binucleate trophocytes, prefollicular tissue and oogonia, while the vitellarium contains 2-5 oocytes arranged in order of maturity. Definite nutritive cords are absent. When females are exposed to 75 mg 4,4,6-trimethyl-1h, 4H-pyrimidine-2-thiol by contact, the trophocytes and the follicular epithelial cells disintegrate to form dark-staining clumps and thus fail to supply nourishment to the developing oocytes, which consequently remain yolk-less and are ultimately reduced to shrunken masses.