Wolbachia infections of tephritid fruit flies: molecular evidence for five distinct strains in a single host species

Endosymbiotic bacteria of the genus Wolbachia are widespread among arthropods and can induce cytoplasmic incompatibility, thelytokous parthenogenesis, male-killing or feminization in their hosts. Here, we report phylogenetic relationships of Wolbachia in tephritid fruit flies based on wsp gene sequences. We also report, for the first time, five distinct strains of Wolbachia in Bactrocera ascita sp. B. Four of the five Wolbachia strains found in this species were in the same groups as those found in other tephritid fruit flies, suggesting possible horizontal transmission of Wolbachia from other fruit flies into B. ascita sp. B. The unreliability of wsp-specific group primers demonstrated in this study suggests that these primers might be useful only for preliminary identification of Wolbachia. Final determination of group affiliation needs to be verified with wsp sequence data.

Wolbachia infections of phlebotomine sand flies (Diptera: Psychodidae)

Old and New World phlebotomine sand fly species were screened for infection with Wolbachia, intracellular bacterial endosymbionts found in many arthropods and filarial nematodes. Of 53 samples representing 15 species, nine samples of four species were found positive for Wolbachia by polymerase chain reaction amplification using primers for the Wolbachia surface protein (wsp) gene. Five of the wsp gene fragments from four species were cloned, sequenced, and used for phylogenetic analysis. These wsp sequences were placed in three different clades within the arthropod associated Wolbachia (groups A and B), suggesting that Wolbachia has infected sand flies on more than one occasion. Two distantly related sand fly species, Lutzomyia (Psanthyromyia) shannoni (Dyar) and Lutzomyia (Nyssomyia) whitmani (Antunes & Coutinho), infected with an identical Wolbachia strain suggest a very recent horizontal transmission.

Field evidence for mechanical transmission of rabbit haemorrhagic disease virus (RHDV) by flies (Diptera : Calliphoridae) among wild rabbits in Australia

Field collected flies were screened for the presence of rabbit haemorrhagic disease virus (RHDV) by applying reverse transcriptase PCR (RT-PCR) in which primers specific to the capsid protein of the virus were used. The virus was detected in flies from locations where rabbit haemorrhagic disease (RHD) was reported and also soon after the release of RHDV in a 'clean' area. Oral and/or anal excretions of flies (flyspots) were found to contain viable virus and oral inoculation of rabbits revealed that a single flyspot was able to cause RHD. We conclude that flyspots are a major potential source of the virus for oral or conjunctival transmission of the virus to rabbits. (C) 1998 Elsevier Science B.V. All rights reserved.

Quantification of Listeria spp. contamination on shell and flesh of cooked black tiger prawns (Penaeus monodon)

Aims: To quantify Listeria levels on the shell and flesh of artificially contaminated cooked prawns after peeling, and determine the efficacy of Listeria innocua as a model for L. monocytogenes in this system. Methods and Results: A L. monocytogenes and L. innocua strain were inoculated separately onto cooked black tiger prawns using two protocols ( immersion or swabbing with incubation). Prawns were peeled by two methods ( gloved hand or scalpel and forceps) and numbers of Listeria on shells, flesh and whole prawn controls were determined. Prawns were exposed to crystal violet dye to assess the penetration of liquids. Regardless of preparation method or bacterial strain there were ca 1log(10) CFU more Listeria per shell than per peeled prawn. Dye was able to penetrate to the flesh in all cases. Conclusions: Shell-on prawns may be only slightly safer than shell-off prawns. Listeria innocua is an acceptable model for L. monocytogenes in this system. Significance and Impact of the Study: Reduced risk from L. monocytogenes on prawns can only be assured by adequate hygiene or heating.

Genes, morphology and agreement: congruence in Australian anthracine bee flies (Diptera : Bombyliidae : Anthracinae)

Almost half of the 4547 described bee flies (Bombyliidae: Diptera) in the world belong to the subfamily Anthracinae, with most of the world's diversity in three cosmopolitan tribes: Villini, Anthracini and Exoprosopini. Molecular data from 815 base pairs of 16S mitochondrial DNA and morphological characters from species-groups of these tribes in Australia were analysed cladistically. The results show that the relationships between the anthracine tribes reflect those found in a previous morphological analysis. The genera of the Anthracinae in Australia are monophyletic, except for Ligyra Newman, and are assigned to tribes. Although simultaneous analysis of the combined molecular and morphological data produced clades found in both separate analyses, the different data sources are significantly incongruent. We use phylogenetic measures to examine support for the relationships among the Australian Anthracinae inferred by the molecular and morphological data.

Oscar Asche's Modernisms: Flesh, Colour and Light

The article examines the early 20th century Australian actor, theater director, and writer Oscar Asche and how various aspects of his work are expressive of an aesthetic modernism. His theatrical productions with his wife Lily Brayton are discussed, as well as his solo projects like the highly acclaimed musical "Chu Chin Chow." Asche is described as a "vitalist."

Australian Glow-worms in Caves

Glow-worms are the larvae of a fly from the family Keroplatidae. Their closest relatives are the “fungus flies” that seek out mushrooms for their larvae to consume. Glow-worms have gone out on an evolutionary limb, albeit a successful one. They have lost their association with fungi and have instead become carnivorous. The unique feature of glow-worms is their ability to bioluminesce—to produce light.

Evidence for a global Wolbachia replacement in Drosophila melanogaster

Wolbachia are maternally inherited intracellular α-Proteobacteria found in numerous arthropod and filarial nematode species [1, 2 and 3]. They influence the biology of their hosts in many ways. In some cases, they act as obligate mutualists and are required for the normal development and reproduction of the host [4 and 5]. They are best known, however, for the various reproductive parasitism traits that they can generate in infected hosts. These include cytoplasmic incompatibility (CI) between individuals of different infection status, the parthenogenetic production of females, the selective killing of male embryos, and the feminization of genetic males [1 and 2]. Wolbachia infections of Drosophila melanogaster are extremely common in both wild populations and long-term laboratory stocks [6, 7 and 8]. Utilizing the newly completed genome sequence of Wolbachia pipientis wMel [9], we have identified a number of polymorphic markers that can be used to discriminate among five different Wolbachia variants within what was previously thought to be the single clonal infection of D. melanogaster. Analysis of long-term lab stocks together with wild-caught flies indicates that one of these variants has replaced the others globally within the last century. This is the first report of a global replacement of a Wolbachia strain in an insect host species. The sweep is at odds with current theory that cannot explain how Wolbachia can invade this host species given the observed cytoplasmic incompatibility characteristics of Wolbachia infections in D. melanogaster in the field [6].