Reproductive system of the bruchid beetles bruchus quadrimaculatus Fabr., bruchus (callosobruchus) chinensis L., (bruchidae—Coleoptera)

Abstract

1)ITliGAUAS M U K E R J I A E D M. A. HAKTM HTIUYA Drpni t nimt of Zo,oloyy, Unzversity of Calcutta ELEVES TEXT FIGORES AND THREE PLATES (SEVENTEEN FIGKRES) .ITTHOIIS' .4l3CTRACT The reproductire organs of Ururhris quadrirnarulatus Fahr.. and R. ((Mlosohrurhus) chinensis L., iiirludiiig Iristolory are desrrihrd in detail. The role of the diffrrmt parts of the male and female copulatory apparatus i s discussed and the physical composition and fnnctiori of the srrretioris o f the accessory glands are indicated. The specific differences in the struzturr of thr genitalia of the two species are shown.

Evolution of Male and Female Genitalia Following Release From Sexual Selection

“…The genitalia ( N = 4 pairs) were then photographed under the MZ16A microscope, and one preparation was sectioned at intervals of 20 μm. Examination of these specimens confirmed previous observations (Mukerji and Bhuya 1937) that the parameres and flap remain outside the female genital tract during copulation (Cayetano 2010), and these traits were therefore considered to be nonintromittent appendages.…”

“…1). This small appendage could therefore be a sensory structure that functions in guiding the aedeagus into the female genital opening, or a stimulatory structure (“titillator”: Mukerji and Bhuya 1937) that induces females to allow intromission. We found some evidence of the evolution of OLS allometric slope (steeper in monogamous lines than in polygamous ones) for flap length.…”

“…1) that may support the aedeagus and guide it into the female genital opening. Mukerji and Bhuya (1937) observed that “males palpate the external genital aperture of the female by the apex of the parameres.” We did not detect any treatment effects on allometric slope for paramere length, but we found an interaction between mating system and ecological context for this trait, with the longest parameres occurring under delayed reproduction and polygamy.…”

“…Top panel: A diagrammatic representation of the male (left) and female (right) genitalia. Structures are labeled according to contemporary convention, with older terms (see Mukerji and Bhuya 1937; Southgate et al 1957) shown below in quotation marks. A transverse section of the male aedeagus (A) in everted state is depicted, with the dashed horizontal line representing the approximate extent of the intromittent portion (“endophallus” or “phallosome”) bearing genital spines (S) (denticles) that is everted inside the female copulatory tract.…”

“…In the seed beetle Callosobruchus maculatus , the tip of the male intromittent organ (aedeagus) is densely covered with spines (Mukerji and Bhuya 1937; Crudgington and Siva‐Jothy 2000). The spines may function in male–male competition by acting as an anchor that enhances males’ ability to cling to females (Edvardsson and Tregenza 2005), and thereby influencing male performance in sperm competition (Hotzy and Arnqvist 2009).…”