Ultrastructure and Transovarial Transmission of Endosymbiotic Microorganisms in Conomelus anceps and Metcalfa pruinosa (Insecta, Hemiptera, Fulgoromorpha)

Anna Michalik,Teresa Szklarzewicz,Władysława Jankowska

doi:10.3409/fb57_3-4.131-137

Abstract

Endosymbiotic microorganisms commonly occur in fulgoromorphans, as in other plant sap-sucking hemipterans. Large syncytial organs termed mycetomes are present in the body cavities of Conomelus anceps (Delphacidae) and Metcalfa pruinosa (Flatidae), in the close vicinity of the ovaries. The mycetomes are surrounded by a one-layered epithelium. The mycetome cytoplasm is filled with yeast-like symbiotic microorganisms (YLSs). The YLSs are transovarially transmitted to the next generation. The endosymbionts are released from the mycetomes and migrate towards the ovarioles containing vitellogenic oocytes. The YLSs pass through the cells of the ovariole stalk (pedicel) and enter the perivitelline space. Then, a deep depression is formed at the posterior pole of the oocyte. The YLSs accumulate in the oocyte depression and form a characteristic "symbiont ball". The mycetome cytoplasm of Metcalfa pruinosa as well as epithelial cells surrounding the mycetome contain small, rod-shaped bacteria.

Highlights

Endosymbiotic microorganisms commonly occur in fulgoromorphans, as in other plant sap-sucking hemipterans
Since hemipterans feed on phloem sap devoid of amino acids, their primary endosymbionts are responsible for amino acid synthesis and delivery to the host insect (e.g. SASAKI & ISHIKAWA 1995; WILKINSON & ISHIKAWA 2001)
The individual ovariole is subdivided into a terminal filament, tropharium, vitellarium and ovariolar stalk that joins the ovariole to the lateral oviduct (Fig. 1)

Summary

Introduction

Endosymbiotic microorganisms commonly occur in fulgoromorphans, as in other plant sap-sucking hemipterans. Fulgoromorphans, like other plant sap-sucking hemipterans, harbor obligate, intracellular symbiotic microorganisms (see BUCHNER 1965; HOUK & GRIFFITHS 1980; BAUMANN 2005, 2006, for further details). Most hemipterans have prokaryotic endosymbionts, eukaryotic microorganisms historically termed “yeast-like symbionts” (YLSs) occur in some aphids, scale insects, leafhoppers and fulgoromorphans (see BUCHNER 1965; ISHIKAWA 2003, for further details). Both bacterial and yeast-like endosymbionts are maternally inherited by transovarial transmission. In contrast to bacterial endosymbionts, the transovarial transmission of YLSs is poorly known, and there are only three published observations on this process (NODA 1977; CHENG & HOU 2001; SACCHI et al 2008), two of which consider members of the family Delphacidae

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