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G N Fritz

Publications and source records attributed to G N Fritz.

13 recordsLinked to original sources
PubMed2006

Prevalence of Thelohania solenopsae infected Solenopsis invicta newly mated queens within areas of differing social form distributions.

Newly mated queens (NMQs) originating from monogyne red imported fire ant (Solenopsis invicta) colonies and following a mating flight, initiate new colonies by sealing themselves in a nuptial chamber and relying solely on their own fat and crop reserves, as well as no longer needed wing muscles to rear their first workers (claustral colony foundation). This method of colony-founding is rarely successful for polygyne-derived NMQs, whose low weight critically limits the number of first workers they are able to produce. However, this observation may be confounded by the parasitic microsporidium, Thelohania solenopsae, thus far found to persist only in association with polygyne colonies. Infections of this microsporidium reduce the weight of female alates and may explain why polygyne NMQs are unlikely to successfully found colonies claustrally. NMQs collected following mating flights in Gainesville and Ocala, Florida were sorted by weight, checked for insemination and T. solenopsae infection. Insemination levels were greater than 90% for all weight classes at both collection sites and were not related to infection. Infection levels were lower in Gainesville than Ocala, averaging 1.67% and 14.14%, respectively. Polygyne-derived NMQs collected in Ocala, defined here as weighing 12mg (social form correctly assigned in 85% of samples examined by PCR), had the highest infection levels, 25.37% (17/67) in 2003 and 21.43% (6/28) in 2004. We conclude that infection by T. solenopsae cannot be completely responsible for the inability of polygyne NMQs to claustrally establish colonies.

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PubMed2004

Dentification of four vectors of human Plasmodium spp. by multiplex PCR: Anopheles rangeli, An. strodei, An. triannulatus, and An. trinkae (Diptera: Culicidae: Nyssorhynchus).

One of the major obstacles for studies of the biology, ecology, and behavior of Neotropical vectors of human Plasmodium has been the lack of reliable and efficient means of identifying many species. Although the subgenus Nyssorhynchus includes most species responsible for human transmission in South America, there are no polymerase chain reaction (PCR)-based techniques for identifying members of this taxon. We describe the first multiplex PCR for identifying four species in the subgenus Nyssorhynchus that are vectors of human Plasmodium spp. Four species specific primers, together with a universal primer that anneals to the 5.8S rDNA region, produce amplicons of the internal transcribed spacer two with base pair sizes of 131,308,371, and 441 for An. triannulatus, An. trinkae, An. strodei, and An. rangeli, respectively.

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PubMed1998

Morphological, molecular, and chromosomal discrimination of cryptic Anopheles (Nyssorhynchus) (Diptera: Culicidae) from South America.

Based on similarity of male genitalia, the malaria vector Anopheles trinkae Faran from the eastern Andean piedmont of Colombia, Ecuador, Peru, and Bolivia was determined by Peyton (1993) to be a junior synonym of An. dunhami Causey, then known from a single locality in Amazonian Brazil. Following an appraisal of molecular, chromosomal, and morphological characters, we conclude herein that the 2 taxa are specifically distinct and remove An. trinkae from synonymy with An. dunhami. Eggs of the 2 species are distinguished easily by the anterior crown, long floats, and closed deck that occur only in An. trinkae. The X chromosome of larval polytenes is divisible into R and L arms in An. dunhami, but not in An. trinkae. A phenogram based on banding pattern scores from 18 random amplified polymorphic DNA primers separated with 100% resolution An. dunhami, An. trinkae, Anopheles nuneztovari Gabaldón and Anopheles darlingi Root. In the ITS2 region of rDNA, 25% of base sites distinguished An. trinkae from An. dunhami and 21% from the related An. nuneztovari; males of these 3 species had accessory glands of significantly different sizes. Preliminary isoenzyme screening indicated that 3 of 11 loci were diagnostic for separating An. trinkae from An. dunhami. The results indicate that An. dunhami is related more closely to An. nuneztovari than to An. trinkae and illustrate the merits of a multidisciplinary approach to mosquito systematics.

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PubMed1998

Sequence analysis of the rDNA internal transcribed spacer 2 of five species of South American human malaria mosquitoes.

The rDNA internal transcribed spacer 2 (ITS2) was sequenced for 5 species of mosquitoes that may be important vectors of human malaria in certain regions of South America and are difficult to distinguish by morphology: Anopheles evansae, An. nuneztovari, An. rangeli, An. strodei and An. trinkae. ITS2 sequences from samples collected in Ecuador, Bolivia, Venezuela and Brazil were aligned and compared in order to determine the usefulness of this spacer for the elaboration of species specific primers and DNA probes. The ITS2 was found to be different in size (ranging from 333 to 397 bp) and sequence between all pairs of species. Highly variable regions were found primarily at the 3' end of the spacer and were interspersed with relatively conserved sites. Instraspecific sequence variation was limited to a single transversion between specimens of An. rangeli from distant geographic locations suggesting concerted evolution and homogenization of the ITS2.

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PubMed1998

Lake Vera revisited: parity and survival rates of Anopheles punctipennis at the site of a malaria outbreak in the Sierra Nevada foothills of California.

Parity and survival rates of Anopheles punctipennis were studied at the site of a 1952 outbreak of malaria in the Sierra Nevada foothills of California with the purpose of estimating blood feeding frequency and survivorship of such populations. Anopheles punctipennis was the dominant species in landing collections conducted for 20 consecutive nights in August and September 1990. The mean parity rate of An. punctipennis was 0.82. The gonotrophic cycle was estimated to last three days based on time series analysis of the number of nulliparous and parous mosquitoes collected each day. Survivorship was estimated to be 0.79 per gonotrophic cycle and 0.92 per day. Ovarian dilatation data indicated that some females had completed eight gonotrophic cycles prior to being collected and 45% of the females completed two or more cycles. The high prevalence of multiparous individuals, high parity rate, long survivorship and a short three-day gonotrophic cycle estimate indicates that this population is long lived and has a capacity to be an efficient vector of malaria.

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PubMed1995

Genetic differentiation and diagnostic loci of Anopheles nuneztovari, An. trinkae, and An. rangeli (Diptera: Culicidae).

Samples of Anopheles rangeli Gabaldon, Cova Garcia & Lopez, An. trinkae Causey, and An. nuneztovari Gabaldon from Venezuela, Ecuador, Brazil, and Bolivia were analyzed for genetic variability at 24 enzyme loci. Estimates of genetic variability for An. rangeli and An. trinkae from Ecuador and for An. nuneztovari in Venezuela had the following ranges: 46-58% polymorphic loci, 1.7-2.0 (SEM = 0.1-0.3) mean number of alleles per locus, and 0.069-0.113 (SEM = 0.03-0.04) expected mean heterozygosity. Genetic variability estimates of An. rangeli from Bolivia were 20.8-29.2% polymorphic loci, 1.2-1.6 (SEM = 0.1-0.2) mean number of alleles per locus, and 0.037-0.054 (SEM = 0.02-0.03) expected mean heterozygosity. The estimated genetic distance between An. rangeli and An. trinkae ranged from 0.149 to 0.197. The genetic distance between these 2 species and An. nuneztovari ranged from 0.319 to 0.440. Although there were allele frequency differences at some loci between samples of An. nuneztovari sampled from either side of the Andes Mountains in Venezuela, there were no diagnostic loci and the estimated genetic distance was only 0.023. Seven enzyme loci were diagnostic between An. nuneztovari and one or both of its sister species: Acon-2, Ao, Hk-1, Idh-2, Me, Pgi, and Pgm. The diagnostic loci Hk-1 and Acon-2 were not polymorphic in any species. An. rangeli and An. trinkae can be distinguished by the diagnostic loci Ao, Idh-2, and Me-1, and with a 97% probability by Pgm. Distance Wagner and unweighted pair-group method with arithmetic averaging analyses support a close phylogenetic relationship between An. trinkae and An. rangeli.

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PubMed1994

Sequence analysis of the ribosomal DNA internal transcribed spacer 2 from populations of Anopheles nuneztovari (Diptera: Culicidae).

Sequence variation of the ribosomal DNA internal transcribed spacer 2 (ITS2) was examined for populations of the malaria vector Anopheles nuneztovari collected in Colombia, Venezuela, Bolivia, Suriname, and Brazil. Mosquitoes from Colombia and Venezuela had identical ITS2 sequences and were distinguished from sequences in other populations by three insertion/deletion events (indels) and by one transversion. The length of the ITS2 was 363-369 bp, and it had a G+C content of 55.3%-55.7%. Variation in the length of the ITS2 between and within populations was due to indels in simple repeats. ITS2 consensus sequences were similar or identical for samples from the following three groups: (1) Colombia, Bolivia, and Venezuela; (2) Suriname and northern Brazil; and (3) eastern and central Brazil. The presence of two different consensus sequences from a single location near Manaus, Brazil, suggests that populations from eastern Brazil and those from Suriname converge in this region of the Amazon Basin. These data show that putative cryptic species of An. nuneztovari are distinguished by very minor differences in DNA sequence of the ITS2 region.

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PubMed1993

Anopheles hermsi, probable vector of malaria in New Mexico.

Samples of Anopheles freeborni s.1. were collected from areas of New Mexico where malaria had once been common and sporozoites had been isolated from this species. Specimens were identified by analysis of polytene chromosome banding patterns and by specific rDNA fragments generated through the polymerase chain reaction. All samples collected in New Mexico were identified as An. hermsi, which was the probable vector of malaria in this region during the early 20th century.

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PubMed1992

Evidence of seasonal eggs in Anopheles punctipennis (Diptera: Culicidae).

Anopheles punctipennis (Say), collected in October from resting sites in Illinois, deposited two morphologically distinct types of egg batches. One type was similar to the seasonal "winter" egg of Anopheles walkeri Theobald, with an extensive exochorion that covered all except the tip of the egg. Laboratory rearing of isofemale lines, under two different light-dark and temperature cycles, demonstrated that both types of eggs were intraspecific variants. F1 females from all "winter" egg batches deposited only normal eggs when reared under a 12:12 (L:D) cycle and at 25 degrees C. Most An. punctipennis reared under a 8:16 (L:D) cycle with variable temperature exhibited gonotrophic dissociation or accumulated fat body.

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PubMed1991

Diagnostic characterization of Anopheles freeborni and An. hermsi by hybrid crosses, frequencies of polytene X chromosomes and rDNA restriction enzyme fragments.

A polytene chromosome analysis was prepared from Anopheles freeborni collected from 25 locations in north and central California, and parts of Washington and Oregon. The X chromosome banding pattern, thought previously to be specific to An. hermsi, was common in mosquitoes collected from foothill regions in California, and in all samples from Washington and Oregon. At some of these locations, many mosquitoes had heterokaryotypes for the inversion that distinguishes the X chromosome of An. freeborni from that of An. hermsi. Use of rDNA restriction site analysis, and the results from crossing of different strains bearing either type of X chromosome, showed that An. hermsi does not have a unique or diagnostic X chromosome. Anopheles hermsi was collected in San Mateo County, CA, which is now the northernmost known limit of this species. Crossing studies, or the examination of rDNA restriction enzyme profiles, are presently the only means of identifying An. hermsi.

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PubMed1989

Improved techniques for rearing Anopheles freeborni.

Techniques are described for mass rearing Anopheles freeborni. Eggs were incubated overnight at ca. 28 degrees C and then dried. Measured quantities of dried eggs were placed into styrofoam rings floating on the water surface of rearing trays. Water levels in larval rearing trays were kept shallow, and temperature was maintained with heat tapes at ca. 28 degrees C. Larvae were fed once a day on a slurry containing a 3:1:1:1 mixture of guinea pig chow, liver powder, yeast and hog chow. Pupation began on the 7th day after egg hatch, and pupae were harvested on the 8th, 9th and 10th days; ca. 1,700 pupae were harvested/tray. Adults emerged from 85% of the pupae, and about 40% were female. Individual males held in gallon-sized containers inseminated as many as 10 females. Although most sugar-fed males died within 2 weeks after emergence, over 35% of sugar-fed females survived for 3 weeks. Colonies were maintained on defibrinated bovine blood provided in natural membrane prophylactics. There were no significant differences in the number of blood-fed females or in the number of eggs they produced when mosquitoes were offered either guinea pigs or defibrinated bovine blood. Eggs were collected in plastic cups placed in cages. There was less than 6% mortality of eggs when these were dried and stored at 10 degrees C for 6 days.

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