THE POSTEMBRYONIC DEVELOPMENT OF THE FEMALE REPRODUCTIVE SYSTEM IN LIMOTHRIPS CEREALIUM HALIDAY (THYSANOPTERA: THRIPIDAE)

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Abstract

In the early second-instar larva the reproductive system comprises a pair of undifferentiated ovary-rudiments, each produced posteriorly into a solid strand of cells—the mesodermal lateral oviduct rudiments. Later in the second instar a spermathecal rudiment arises from the epidermis of the eighth abdominal segment and ovipositor valve rudiments from the eighth and ninth sterna. By the early prepupa the lateral oviducts acquire ampullae and the ectodermal structures are supplemented by a common oviduct rudiment (from the seventh sternum) and an accessory gland rudiment (from the ninth sternum). Further growth of these is followed in the pupa by the development of the vagina through ventral closure of a mid-sternal groove on the eighth segment and by the division of the ovary rudiment into ovarioles. Meanwhile the ovipositor valves have increased in length and some of their muscles have arisen by differentiation of previously unorganized masses of myoblasts; the remaining ovipositor muscles are formed from larval muscles which change their positions but are otherwise unaltered. Though the reproductive system of Limothrips is morphologically comparable to that of less specialized Exopterygota, its development is shown to be delayed in a manner more reminiscent of the endopterygote insects.

Ancillary