Significance of transovarial infections of Amblyospora sp. (Microspora: Thelohaniidae) in relation to parasite maintenance in the mosquito Culex salinarius

Andreadis, Theodore G.; Hall, Donald W.

doi:10.1016/0022-2011(79)90095-8

Cited by 71 publications

(35 citation statements)

References 11 publications

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“…no paternal-mediated vertical transmission). This is generally true for all species of Amblyospora (Andreadis and Hall 1979b, Andreadis 1985b, Sweeney et al 1988. Hurst (1991Hurst ( , 1993 and Sweeney et al (1989) have hypothesized that in those aquatic habitats where copepods are abundant, the most effective long- …”

Section: Evolutionary Strategies and Adaptations For Survivalmentioning

confidence: 99%

Evolutionary strategies and adaptations for survival between mosquito-parasitic microsporidia and their intermediate copepod hosts: a comparative examination of Amblyospora connecticus and Hyalinocysta chapmani (Microsporidia: Amblyosporidae)

Andreadis

2005

FOLIA PARASIT

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Abstract. The epizootiology, transmission dynamics, and survival strategies employed by two mosquito-parasitic microsporidia that utilize copepods as intermediate hosts are examined in relation to the biological attributes of their hosts and the environments in which they inhabit. Amblyospora connecticus Andreadis, 1988, a parasite of Ochlerotatus cantator (Coquillett) and Acanthocyclops vernalis (Fischer) is found in an unstable salt marsh environment that is subject to periodic flooding and drying. Both hosts have distinct non-overlapping generations. A. connecticus exhibits a well-defined seasonal transmission cycle that relies heavily on maternal-mediated transovarial transmission by female O. cantator during the summer, and horizontal transmission via the copepod host during the spring (copepod to mosquito) and fall (mosquito to copepod). Its survival strategies include: delayed virulence, low pathogenicity and high tissue specificity that allow for transstadial transmission of horizontally acquired infections and maximum spore production, reliance on living hosts throughout most of its life cycle with overwintering in the copepod, polymorphic development that is well synchronized with host physiology, and production and dissemination of infectious spores that are coincident with the seasonal occurrence of susceptible stages in each host. Hyalinocysta chapmani Hazard et Oldacre, 1975, a parasite of Culiseta melanura (Coquillett) and Orthocyclops modestus (Herrick) is found in a comparatively stable, subterranean habitat that is inundated with water throughout the year. Copepods are omnipresent and C. melanura has overlapping broods. H. chapmani is maintained in a continuous cycle of horizontal transmission between each host throughout the summer and fall but lacks a developmental sequence leading to transovarial transmission in the mosquito host. It relies on living hosts for most of its life cycle and overwinters in diapausing mosquito larvae. Transstadial transmission does not occur and there is no dimorphic development in the mosquito host. The spatial and temporal overlap of both mosquito and copepod hosts during the summer and fall affords abundant opportunity for continuous horizontal transmission and increases the likelihood that H. chapmani will find a target host, thus negating the need for a transovarial route. It is hypothesized that natural selection has favoured the production of meiospores in larval female mosquitoes rather than congenital transfer of infection to progeny via ovarian infection as a strategy for achieving greater transmission success. Analysis of the molecular phylogeny data suggest that (1) transovarial transmission and the developmental sequence leading to ovarian infection have been secondarily lost in H. chapmani, as they occur in all other closely related genera, (2) the ancestral state included complex life cycles involving transovarial transmission and an intermediate host, and (3) mosquito-parasitic microsporidia are adjusting their life cycles to accommodate host ecol...

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Section: Evolutionary Strategies and Adaptations For Survivalmentioning

confidence: 99%

Evolutionary strategies and adaptations for survival between mosquito-parasitic microsporidia and their intermediate copepod hosts: a comparative examination of Amblyospora connecticus and Hyalinocysta chapmani (Microsporidia: Amblyosporidae)

Andreadis

2005

FOLIA PARASIT

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“…A more widely observed distortion of allocation is the phenomenon of male killing by cytoplasmic elements. These have been characterized in diverse taxa including drosopholids (Magni, 1952), Lepidoptera (Clarke et at., 1983), Coleoptera (Lanier & Oliver, 1966;Gotoh & Niijima, 1986), Hemiptera (Leslie, 1984) and mosquitoes (Andreadis & Hall, 1979). The evolutionary dynamics of this behaviour have been the subject of recent discussion (Uyenoyama & Feldman, 1978;Werren, 1987;, and it is the postulated cause of sex ratio variation in Russian populations of Ada/ia bipunctata L. (the two spot ladybird) (Lus, 1947a).…”

Section: Introductionmentioning

confidence: 99%

Cytoplasmic male killing elements in Adalia bipunctata (Linnaeus) (Coleoptera: Coccinellidae)

Hurst¹,

Majerus²,

Walker³

1992

Heredity

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A wild sample of Ada/ia bipunctata larvae and pupae were collected from Surrey, and F1 virgin adults mated. The sex ratio produced by these pairs was found be be variable, 22 pairs produced a sex ratio consistent with a 1:1 sex ratio, but four produced a strong female bias. Daughters and males from biased broods were mated to adults from non-biased broods of different parentage.Males and females from unrelated families were crossed. Where the female was taken from a biased clutch, the biased sex ratio trait recurred in a high proportion of cases. Where males from such broods were crossed, or females from broods with no history of bias were mated, sex ratios consistent with 1:1 were obtained. Pairs producing a strong female bias showed hatch rates which were approximately half that of crosses producing non-biased sex ratios. Treatment with tetracycline in golden syrup cured females who showed the biased sex ratio trait. Daughters conceived after this treatment produced normal sex ratios. Females fed purely on golden syrup, as a control, continued to produce female biased sex ratios until treated with tetracycline. We therefore suggest that an unknown bacterium, transmitted through egg cytoplasm but not sperm, is responsible for the early mortality of male embryos and thus a bias in the secondary sex ratio. The contribution that the study of the Coccinellidae can make to theories concerning the incidences and evolution of male killing elements is discussed in relation to egg cannibalism.

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“…On the other hand, there are reports that microsporidiosis caused by Amblyospora spp. in some species of culicidae showed no evidence of reduction of fecundity (Andreadis & Hall 1979, Andreadis 1983, 1985, Sweeney et al 1989.…”

Section: Resultsmentioning

confidence: 95%

“…Consequently, epizootics of these pathogens do not usually result in dramatic suppression of host populations. Rather, such pathogens exert sublethal effects on their hosts such as reduced fecundity, shortened longevity and a general loss of vigor.Medically important insects and agricultural pests have been investigated for a long time with regard to sublethal effects caused by microsporidiosis (Gaugler & Brooks 1975, Andreadis & Hall 1979, Andreadis 1983, 1985, Sweeney et al 1989, Lockwood & Debrey 1990, Castello Branco Jr 1998. Blackflies represent an important family among the medically important insects due to their role as vectors of human and animal helminthiasis and because the nuisance caused by their biting habit (Crosskey 1990).…”

mentioning

confidence: 99%

Effects of Polydispyrenia simulii (Microspora; Duboscqiidae) on Development of the Gonads of Simulium pertinax (Diptera; Simuliidae)

Junior

1999

Mem. Inst. Oswaldo Cruz

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Microsporidial infections of insects are often chronic and nonlethal in nature. Consequently, epizootics of these pathogens do not usually result in dramatic suppression of host populations. Rather, such pathogens exert sublethal effects on their hosts such as reduced fecundity, shortened longevity and a general loss of vigor.Medically important insects and agricultural pests have been investigated for a long time with regard to sublethal effects caused by microsporidiosis (Gaugler & Brooks 1975, Andreadis & Hall 1979, Andreadis 1983, 1985, Sweeney et al. 1989, Lockwood & Debrey 1990, Castello Branco Jr 1998. Blackflies represent an important family among the medically important insects due to their role as vectors of human and animal helminthiasis and because the nuisance caused by their biting habit (Crosskey 1990). Simulium pertinax Kollar is the most antropophilic species occurring in southeastern Brazil and is the main target of government and other control programmes in these areas.Although microsporidia are considered the most common and worldwide blackfly pathogen, their ecology and epizootiology are poorly known in this host group. The aim of this work is to evaluate the effects of the infection caused by the microsporidium Polydispyrenia simulii in the gonads of both sexes of the blackfly S. pertinax reared from heavily infected larvae. MATERIALS AND METHODSLarvae of S. pertinax were collected from their natural breeding sites and kept in a laboratory rearing system adapted from Raybould and Grunewald (1975) (Fig.). Separate rearing systems were stocked with blackfly larvae infected and not-infected with P. simulii. Adults of both sexes originating from healthy and infected larvae were obtained from the system and then transfered to glass holding chambers of 0.29 m³. The rearing system and the chambers were maintained at room temperature without photoperiod control. The adults originated from healthy and infected larvae were kept separate.Human bait (nude forearm) was offered to the female flies twice a day (40 min each one). Filter paper bands soaked in 20% sucrose solution were also provided for the adults to feed. After blood feeding, each S. pertinax female was maintained in glass vials of 40 ml containing filter paper bands soaked with sucrose solution.S. pertinax males and females were dissected in 0.85% saline solution at regular intervals. Females were dissected after the seventh day from the first blood meal while males were dissected after the fourth day from the adult fly emergence. The testes and ovaries were examined under the microscope (100x up to 1,000x). The motility of

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Significance of transovarial infections of Amblyospora sp. (Microspora: Thelohaniidae) in relation to parasite maintenance in the mosquito Culex salinarius

Cited by 71 publications

References 11 publications

Evolutionary strategies and adaptations for survival between mosquito-parasitic microsporidia and their intermediate copepod hosts: a comparative examination of Amblyospora connecticus and Hyalinocysta chapmani (Microsporidia: Amblyosporidae)

Evolutionary strategies and adaptations for survival between mosquito-parasitic microsporidia and their intermediate copepod hosts: a comparative examination of Amblyospora connecticus and Hyalinocysta chapmani (Microsporidia: Amblyosporidae)

Cytoplasmic male killing elements in Adalia bipunctata (Linnaeus) (Coleoptera: Coccinellidae)

Effects of Polydispyrenia simulii (Microspora; Duboscqiidae) on Development of the Gonads of Simulium pertinax (Diptera; Simuliidae)

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