3.—The Cytology of the Parthenogenetic Australian Weevil Listroderes costirostris Schönh

Abstract

SynopsisKaryograms prepared from ovarian and blastoderm cells of the parthenogenetic Australian Brown Vegetable Weevil demonstrate a consistent triploid condition with 30 chromosomes which can be grouped into 10 sets of homologues. Meiosis is replaced by a single mitotic-like division in which 30 univalent chromosomes, each composed of two chromatids, divide equationally between an ootid nucleus and a single polar nucleus. Prior to the differentiation of the oocytes a peculiar bouquet stage occurs in the cells of the end chamber of each ovariole, but the significance of this phase is not known. Arrested development in eggs from individuals of low fertility is investigated and the relationship of body size and chromosome number is discussed.

Wolbachia infection in the tribe Naupactini (Coleoptera, Curculionidae): association between thelytokous parthenogenesis and infection status

“…Ploidies have been very scarcely studied in Naupactini. It is interesting however, that the only three parthenogenetic species whose ploidies are known are infected with Wolbachia [ Aramigus tessellatus and Naupactus peregrinus are 3× and Aramigus conirostris is 5× (Sanderson, 1973; Normark, 1996)]. Certainly, Wolbachia may have played an important role in ensuring the viability of the eggs, and consequently, in saving clones from extinction.…”

“…On the contrary, the reproductive biology of the Naupactini is poorly known. There is no direct evidence of parthenogenesis, except for Naupactus cervinus , Naupactus leucoloma , Naupactus peregrinus , Pantomorus ruizi and Aramigus tessellatus (Buchanan, 1939; Sanderson, 1973; Normark, 1996; Marvaldi, 1998). However, Lanteri & Normark (1995) proposed a list of about 30 presumably parthenogenetic species of Naupactini, on the basis of female‐biased sex ratios (ie males either absent or scarce in part of their geographical range).…”

Cytological investigations of parthenogenesis in gall wasps (Cynipidae, Hymenoptera)

“…mobilis Moore, the triploid weevil Listroderes costirostris Schon. and sawflies (Sanderson, 1960(Sanderson, , 1970(Sanderson, and 1973, all of which tolerate a high degree of chromosomal irregularity. Diploid nuclei are common in somatic cells of haploid gall wasp males as in other Hymenoptera and, where less than the haploid number of chromosomes appear as in loose spermatocyte cells, the loss can usually be attributed to breakage of the nuclear membrane.…”

“…The triploid Australian vegetable weevil, Listroderes costirostris Schon. has an enigmatic bouquet stage comparable to pachytene with the thirty chromosomes forming a haploid number of loops apparently by tandem linkage in threes, but reappearing after the diffuse stage as thirty univalents (Sanderson, 1973) which undergo a non-reductional maturation division. The triploid gynogenetic Ptinus clavipes f. mobilis Moore has a bouquet stage with the triploid number of loops (Sanderson, 1960) and therefore may be classed as pseudomeiotic.…”

A triploid race of the parthenogenetic Japanese weevil Blosyrus japonicus Sharp (Coleoptera: Curculionidae).

“…Most of these forms are characterized by the basic number of 11. The exception are 3 triploid species, Liophloeus tessulatus Mull., Eusomus ovulum Germ., and Listroderes costirostris Schon., with 30 chromosomes suggesting a basic number of 10 (Mikulska 1953;Suomalainen 1955;Takenouchi 1969;Sanderson 1973).…”