Ranendra Nath Sinha

Bio: Ranendra Nath Sinha is an academic researcher. The author has contributed to research in topics: Spermatheca. The author has an hindex of 1, co-authored 1 publications receiving 14 citations.

The spermatheca in the flour beetle (tribolium castaneum herbst)1

Abstract: The( histology of the spermatheca of the Tenebrionid beetles has been very poorly studied. The structure of the spermatheca of Triboliu?, castaetur, IIHerbst differs greatly from the Coleop teran spermath ece described by previous authors (see Snodgrass, 1935; In mls, 1934). It is characterized by being unrecognizable in gross anatomcial dissection. The descriptive terms used in this paper are those employed by Snodgrass (1935). IATIRIALS AND M!IETHODS Adult females of Triboliinl castanJeum Herbst were fixed in Mukerji's fluid (Miukerji, 1937; Sinha, 1953, in press) and serial sections of the entire body, 8 micra in thickness, were made in transverse and longitudinal planes. The technique employed for sectioning the sclerotized beetles was that of Mukerji with the author's modification. Some dissections of the organ were also made in normal saline solution and later sectioned by the ordi nary, paraffin method. Sets of the serial sections of tlhe insects were stained in Mallory's triple stainl and Delafield's lemlatoxy li1 and Eosin, whereas the sets from the dissected organs were stained only in'the latter. DESCRIPTION The spermatheca of the Tribolium, castaneulr I-Herbst is a blunt, apical, anterior swelling of the vagina:t which is totally unrecog nizable from outside. It is 0.08 nmn. long and 0.1.3 mnm. in diam eter and is located 0.13 m11n. above the juncfion of the fifth and the sixth abdominal sterla (third and fourth visible sterna) in natural position. A study of the serial sections reveals that the organ is a rectangulatr mImus:cular chamber iomposcd- of four long

Sperm Utilization Strategies in Nonsocial Insects

Abstract: It is postulated that the sperm precedence characteristics of most insect populations have resulted primarily from selection on females (1) to optimize the genetic composition of their progeny; (2) to discourage or encourage multiple matings for reasons other than genetic considerations; (3) to optimize their sperm storage capacity and utilization. In addition, selection on males to maximize egg fertilization by reduced displacement of their sperm and increased displacement of other sperm to the extent that these can be achieved without sacrificing the optimal mating strategy (Parker 1970a) probably has been important in some species. Parker's (1970a) hypothesis that the amount of sperm displacement in a population should stabilize at the value which yields the optimal overall male fertilization rate is accepted as the optimal male strategy; however, it is suggested that females often largely determine, by their behavior and by the structure and functioning of their reproductive tract, the optimal male st...

The incidence of sperm displacement in insects: four conjectures, one corroboration

Abstract: The paper tests, by the comparative method, four hypotheses to explain why the degree of sperm displacement differs in different insect species. It summarizes evidence for 57 species. Here are the four hypotheses: species with mating plugs should show low sperm displacement, and species without plugs high displacement (Boorman & Parker); species with spheroid spermathecas should show low displacement, species with elongate spermathecas high displacement (Walker); species with low paternal investment should show low sperm displacement, species with high paternal investment high displaycement (Gwynne); and species with low natural mating frequencies should show low displacement, species with high mating frequencies high displacement (this paper). The spermathecal shape hypothesis is of limited theoretical plausibility; but the other ideas are theoretically possible. The evidence, if numbers of species are counted, generally fits all four theories; but, in a statistically more rigorous cladistic test, it significantly supports only the mating frequency theory.

Insecticide resistance enhances male reproductive success in a beetle

Abstract: Malathion-specific resistance in the red flour beetle, Tribolium castaneum, is widespread and stable in natural populations even in the absence of pesticide exposure. To understand this stability, both resistant and susceptible males were placed in competition for susceptible female fertilization. Females were then isolated and their progeny was tested for malathion susceptibility. Male reproductive success was estimated for populations originating from different geographic areas and for isogenic strains. In most cases, resistant males had a greater reproductive success rate than susceptibles. The results suggest that male reproductive success is not traded against the selection for malathion resistance, even resistant individuals are at an advantage for this fitness trait. This absence of fitness cost may be the result of postselection of (1) modifier gene which ameliorate the fitness of resistant individuals or (2) nondeleterious resistance gene. Resistant phenotype superiority could be due to increased male mating success, improved ability of resistant males in sperm competition, female mate choice, and/or cryptic female choice of resistance gene(s). The effect of male phenotypic frequency on male reproductive success was also examined. We observed that male fertilization success is frequency dependent and inversely related to their frequency. However, this "rare male" advantage did not counteract the superiority of the resistant males.

Female role in sperm storage in the red flour beetle, Tribolium castaneum

Abstract: This study clarifies the role of female-controlled processes contributing to sperm storage in the red flour beetle, Tribolium castaneum. Evidence presented indicates that sperm motility is not affected by extreme hypoxia produced by anesthetization of the female with either carbon dioxide or nitrogen. Sperm location and motility in low-oxygen environments did not differ from that of sperm in reproductive tracts immersed in fully aerated saline. Sperm motility was unaffected by exposure to potassium cyanide, an aerobic respiratory system poison, but was inhibited by exposure to iodoacetic acid, a glycolysis poison. Based on the retention of sperm motility under extreme hypoxia, female control over sperm storage was then examined. Both anesthetized females and dead females had fewer stored sperm after mating than unanesthetized control females. These results suggest that female T. castaneum play an active role in moving sperm from the site of deposition into storage. © 1998 Elsevier Science Inc. All rights reserved.

Female influence over offspring paternity in the red flour beetle Tribolium castaneum

Abstract: In animals having internal fertilization, both sexes can potentially influence the post-copulatory processes of sperm transfer, sperm storage and sperm use for fertilization. In this experiment, we investigated whether Tribolium castaneum females can influence male paternity success following consecutive matings with two different males. We compared second male paternity success (P2) between females exposed to carbon dioxide (CO2) and control females kept in air, in both cases for 30 min between two matings. CO2 exposure inhibits muscular activity and has previously been shown to decrease sperm storage by T. castaneum females. Females exposed to CO2 after their first mating showed significantly higher P2 than control females during the later portion of a one-month oviposition period. These results are consistent with reduced storage of first male sperm by CO2-exposed females. Also, T. castaneum females showed considerable variation in spermathecal morphology, and P2 decreased with increasing spermathecal tubule volume. These results demonstrate that T. castaneum females can influence male paternity success, and suggest that differential sperm storage may be an important mechanism of post-copulatory female choice.