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PubMedDate not supplied

[Effect of temperature on longevity and infection with the nematode Strelkovimermis spiculatus (Nemata: Mermithidae), a parasite of mosquitoes].

Strelkovimermis spiculatus is a common parasite of culicid species in Argentina. Effect of temperature on longevity and infectivity of juvenile preparasites of S. spiculatus was determined at 4, 10, 20 and 27 degrees C. Three containers with 100 ml of dechlorinate water and 300 preparasites (12 hour-old), were placed for each day and temperature, during 40 days (total = 480 containers). Survived preparasites were counted on 12 containers per day (three for each temperature). When number of survived preparasites was determined, second instar larvae of Aedes aegypti were added to each container in a 10:1 ratio (preparasites:mosquito) to determine infectivity of daily survived preparasites. Longevity of preparasites decreased at higher temperatures. Maximum longevity of preparasites maintained at 4, 10, 20 and 27 degrees C were 35, 30, 25 and 27 days, respectively. Survivorship of preparasites, exposed to the same temperatures, varied from 57% to 100% at day two, from 21% to 77% at day five and from 9% to 33% at day ten. Infectivity of preparasites maintained at temperatures from 4 to 27 degrees C was always higher than 70%. Extended longevity with maintenance of the infectivity capacity of preparasites, are important attributes to consider S. spiculatus an effective mean of controlling a large number of culicid species between 4 and 27 degrees C.

Animals↗
PubMed1991

Mermithid nematode parasites of Coquillettidia perturbans in Massachusetts.

We surveyed 792 larval and 12,400 adult Coquillettidia perturbans for mermithid nematodes in 1990. Collections were made from cattail marshes in the greater Boston area. No mermithids were found in the adult mosquitoes, nor in larvae collected in mid-season, but 3 were found in larvae collected during September and October. This is only the second recorded occurrence of mermithids in Cq. perturbans.

Animals↗
PubMedDate not supplied

[The infective capacity of the nematode Romanomermis culicivorax Ross et Smith, 1976 (Rhabditida: Mermithidae) in mosquito larvae of the species Anopheles albimanus Wiedemann, 1821 (Diptera: Culicidae) under natural conditions].

An experimental study was carried out in two natural breeding sites of Anopheles albimanus Wiedemann, 1821 in Havana City, in order to test the effectiveness of the nematode Romanomermis culicivorax Ross and Smith, 1976. In one of the breeding sites fresh preparasiticals from eggs recently hatched in cultures were applied at a 10:1 dose, a mean infestation rate being found of mean = 3 with a 97 +/- 0.86% mortality. The second breeding site was treated with preparasiticals 30 hours after their obtention, and a decrease was seen in the larva infestation levels mean means = 1.1 and 76 +/- 0.76% mortality rate.

Animals↗
PubMed1991

Infectivity of a mermithid nematode Romanomermis iyengari (Welch) in different conductivity levels under laboratory and field conditions.

Infectivity of R. iyengari was examined by exposing mosquito (Culex quinquefasciatus) larvae to the preparasite at different conductivity levels. The preparasite infected 63.5, 30, 11, 1.5 and 0.5% of the mosquito larvae respectively at 2000, 2500, 3000, 3300 and 3600 mu ho/cm. Although, 62-69% of the preparasite survived at 4000-5400 mu ho/cm, it did not infect. Application of preparasite to tree-holes resulted in 53-63% infection of Aedes albopictus larvae initially. On 6th day the infection level was 40% which decreased further to 7% by 15th day. The infection reappeared on 38th day indicating that R. iyengari has not only infected mosquito larvae as soon as they were applied to tree-holes in which the conductivity was 600-2800 mu ho/cm but also got established there.

Animals↗
PubMedDate not supplied

[The prospects for using Romanomermis culicivorax and R. iyengari (Nematoda: Mermithidae) for mosquito control in Azerbaijan].

The parasitic nematodes Romanomermis culicivorax and R. iyengari, were evaluated as a means of bloodsucking mosquito larvae control in Apsheron Peninsula (the city of Baku) and Lenkoran Lowland (Masally District) in Azerbaijan. Being once brought, mermithids got acclimatized in 12 shallow freshwater nonpolluted pools with aquatic flora and inhibited the emergence of 13-97% of mosquitoes during the summer period. R. culicivorax successfully survived the temporary drying (up to 2 weeks) in 3 and spent a winter in 2 water reservoirs. The possibility of R. iyengari settling via transmission of infected mosquito larvae from a "nursery" pool to a mermithid free water pool was proved. The larvae Cx. modestus, Cx. theileri, Ae. caspius and Ur. unguiculata are first registered as hosts of R. culicivorax and An. sacharovi, Cx. theileri and that of R. iyengari. Both mermithid species may be considered as a means of prolonged inhibition of mosquito emergence in the shallow nonpolluted fresh-water reservoirs in the Azerbaijan SSR.

Acclimatization↗
PubMedDate not supplied

[An evaluation of the possibility of using Romanomermis iyengari Welch mermithids for mosquito control in Uzbekistan].

Mermithid nematodes Romanomermis iyengari were released into 13 natural water bodies of various types at a ratio of 300-8000 invasive preparasites per 1 m2 of water surface in Tashkent region of Uzbekistan. Infected larvae of Anopheles martinius, An. hyrcanus, Culex modestus were found in 6 water bodies with low content of dissolved salts (Ca2+ + + Mg2(+)-3.8-6.7 mg equivalent/l, Cl(-)-38.3-160.2 mg/l). The infection rates of mosquito larvae were 9-67%. In laboratory tests mermithids infected up to 100% of mosquito larvae of the above-mentioned species as well as An. superpictus and Cx. pipiens from natural populations. Aedes caspius were resistant to mermithid infection. It is expected that in Tashkent region these mermithids can be used only in water bodies with low salt content.

Animals↗
PubMedDate not supplied

[Trials to introduce Romanomermis culicivorax (Nematoda: Mermithidae), mosquito larva parasites, into the reservoirs of Voronezh and Moscow Province].

Possibility of using Romanomermis culicivorax for mosquito control in the town of Voronezh and Moscow Province has been assessed. The infection rate of mosquito larvae didn't exceed 26% when preparasitic juveniles were released into water bodies at a ratio of 1-3 thousand per 1 m2 and temperature 18-25 degrees C. There were no evidences of mermithid settlement and hibernation in the water bodies of Voronezh. High efficacy of using R. culicivorax in mosquito larvae control can only be expected in these regions under hot summer conditions.

Animals↗
PubMedDate not supplied

[A trial of Romanomermis iyengari and R. culicivorax mermithids as a means for controlling blood-sucking mosquitoes in the Tadzhik SSR].

Field trials of R. iyengari and R. culicivorax in the biological control for the mosquito larvae were conducted in Parkhar, Kuibyshevsk, Gissar districts and the outskirts of the city of Dushanbe, the Tadjik SSR. Larvae of Anopheles superpictus, An. pulcherrimus and An. hyrcanus in a dosage of 1-5 thousand intact larvae per sq. m were invaded by mermithids. The mean infection rate was 46 per cent. The maximum infection rate was 98 per cent. It depended on several factors: the dosage of intact larvae, temperature, water salinity, water flowage in the waterbodies and their overgrowth with plants. Slow-flowed rice paddies and flow-free fresh waterbodies turned to be the proper sites for mermithids. The effect was higher in Anopheles than in Culex mosquitos.

Animals↗
PubMedDate not supplied

[The mass rearing of the mermithid nematode Romanomermis culicivorax].

The procedure of mass laboratory rearing of mermithid nematode Romanomermis culicivorax, a parasite of mosquito larvae, is described. Culex pipiens molestus larvae are used as a host for cultivation at the host: preparasites ratios of 1:4-1:6, enabling to obtain the greatest mass of nematodes (over 500 mg per 1 thousand of infested mosquito larvae) when the male female ratio in culture was 1:1. This rearing technique allows to obtain on average 350 thousand invasive mermithid preparasites per 1 g of adult mermithids. The above-proposed method is compared to the procedure rearing described earlier by Petersen, Willis (1972).

Animals↗
PubMed1990

Persistence of mermithidae (Nematoda) infections in black fly (Diptera: Simuliidae) populations.

Data on the persistence of mermithid infections in black fly populations over several years indicate mermithid infection rates are relatively stable over several years in a stream. These data were from specific sites in a variety of streams all having the same simuliid fauna present each season. This suggests that the suitability of the stream bed for the free living phase is very important in regulating mermithid populations.

Animals↗
PubMed1990

Observations on the biology of Romanomermis sp. (Nematoda: Mermithidae) parasites of Aedes in western Wyoming.

Univoltine Aedes mosquito larvae infected by Romanomermis sp. were found at 2 localities in Yellowstone National Park, Wyoming. Aedes nevadensis, Ae. impiger, Ae. pullatus and Ae. punctor were the predominant host species. Only Ae. nevadensis was common to all sites. Rates of parasitism ranged from 55 to 93% and differed significantly between localities. Significant annual variation in the rate of parasitism occurred within populations, but neither infection rate nor mean parasite load differed among host species. Parasite populations were distributed among host species in proportion to abundance, but distributions of parasites within host species were over-dispersed. Inter-specific variation in survival of infected larvae was associated with the degree to which immune responses were manifested in different host species.

Aedes↗
PubMed1990

Effect of temperature and host-parasite ratio on sex differentiation of Romanomermis iyengari (Welch), a mermithid parasite of mosquitoes.

The effect of temperature and host-parasite ratio on the percentage infection and sex differentiation of R. iyengari was studied. Significant differences were observed in the percentage infection due to different host-parasite ratios and temperatures. At 25 degrees and 30 degrees C, the host parasite ratio of 1:3 resulted in 86-92% infection of Culex quinquefasciatus larvae. At 20 degrees and 35 degrees C, a higher host-parasite ratio was required to get this level of infection. More number of post-parasites per mosquito larva emerged at 20 degrees (1.5-5.8) and 25 degrees C (1.9-6.3) than at 30 degrees (1.5-3.9) and 35 degrees C (1.6-3.6). More than 50% of the post-parasites were females at 20 degrees and 25 degrees, 30 degrees and 35 degrees C at 1:1-1:10, 1:1-1:4 and 1:1-1:3 host-parasite ratios, respectively.

Animals↗
PubMed1985

Susceptibility of Romanomermis culicivorax (Nematoda: Mermithidae) postparasites to agrichemicals used in Louisiana rice production.

Susceptibility of Romanomermis culicivorax postparasites to riceland agrichemicals was evaluated during 1983. Nematode mortalities for all agrichemicals at 2 days posttreatment ranged from 0 to 11.4% with fentin hydroxide + urea responsible for the highest mortality. Fertilizers were significantly more toxic to nematodes at 2 and 25 days posttreatment than were insecticides. Carbofuran and methyl parathion produced less than 1% mortalities at 2 days and less than 5% mortalities at 25 days posttreatment. Approximately 80-84% of the surviving females exposed to insecticides as postparasites became gravid. Infectivity of the subsequent F1 generation preparasites resulted in greater than 92% parasitism in Culex quinquefasciatus larvae, except those produced by nematodes exposed to carbofuran (76.4%), 2,4-D (70.9%) and fentin hydroxide (67.4%).

Agriculture↗