Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

175,122 Full-Text Articles 204,741 Authors 28,865,135 Downloads 375 Institutions

All Articles in Life Sciences

Faceted Search

175,122 full-text articles. Page 3337 of 4334.

Population Genetics And Gene Variation In Secondary Screwworm (Diptera: Calliphoridae), David B. Taylor, Richard D. Peterson II 2012 University of Nebraska-Lincoln

Population Genetics And Gene Variation In Secondary Screwworm (Diptera: Calliphoridae), David B. Taylor, Richard D. Peterson Ii

David B Taylor

Allozyme variation in 4 populations of secondary screwworm, Cochliomyia macellaria (F.), representing North, Central, and South America was examined . Variability was observed in 12 of 13 enzyme loci, and the frequency of the most common allele was IS statistics indicated random mating within populations . Wright's FST statistics and chi-square contingency analyses indicated homogeneous gene frequencies among the populations. These data suggest that C. macellaria is a panmictic species with high levels of gene flow between populations.


Susceptibility Of House Fly (Diptera: Muscidae) Larvae To Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae, Steinernematidae, David B. Taylor, Allen L. Szalanski, Byron J. Adams, Richard D. Peterson II 2012 University of Nebraska-Lincoln

Susceptibility Of House Fly (Diptera: Muscidae) Larvae To Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae, Steinernematidae, David B. Taylor, Allen L. Szalanski, Byron J. Adams, Richard D. Peterson Ii

David B Taylor

The potential for entomopathogenic nematodes to control flies in cattle feedlots was determined by screening 40 strains representing 8 species of Heterorhabditis Poinar and 5 species of Steinernema Travassos for virulence toward 3rd-instar house flies (maggots), Musca domestica L. None of the 22 strains of Heterorhabditis infecting maggots caused significant levels of mortality in a filter paper assay. Ten strains of Steinernema infected maggots, of which 7 strains--4 S. carpocapsa (Weiser), 2 S. feltiae (Filipjev), and 1 S. scapterisci (Nguyen & Smart) caused significant mortality. Ten Heterorhabditis strains and 10 Steinernema strains successllly reproduced for 22 generations in maggots. No difference ...


Response Of Screwworms (Diptera: Calliphoridae) To Changes In The Concentration Of Blood, Egg, And Milk In The Larval Diet, David B. Taylor 2012 University of Nebraska-Lincoln

Response Of Screwworms (Diptera: Calliphoridae) To Changes In The Concentration Of Blood, Egg, And Milk In The Larval Diet, David B. Taylor

David B Taylor

Larvae of screwworm, Cochliomyia hominivorax (Coquerel), were reared on diets with varying concentrations of whole dried bovine blood, whole dried egg, and nonfat dried milk. Pupal weight, egg to pupal survival, adult emergence, sex ratio, fecundity, and fertility were significantly affected by one or more of the dietary components. Curvilinear models for the effect of dietary component concentration on life history parameters were derived by multiple regression. Most models resulted in bell-shaped curves that were used to calculate optimal diet component concentrations. Biomass, survival, emergence, and fecundity were maximized at 6% blood, 5% egg, and 1.3% milk.


Stable Fly Population Dynamics In Eastern Nebraska In Relation To Climatic Variables, David Taylor, Dennis Berkebile, Philip Scholl 2012 USDA-ARS

Stable Fly Population Dynamics In Eastern Nebraska In Relation To Climatic Variables, David Taylor, Dennis Berkebile, Philip Scholl

David B Taylor

Stable flies are among the most important pests of cattle and other livestock in North America. Their biting and annoyance reduce weight gains in cattle costing producers more than $1 billion per year in production losses. The factors that control population levels of this fly are poorly understood. A better understanding of these factors would permit producers to make informed decisions on when and where to implement control procedures based upon predicted populations levels. In this study, we evaluated the relationships between stable fly population levels and climatic variables. Temperature was the most important variable for the rise and fall ...


Mitochondrial Dna Variation Among Muscidifurax Spp. (Hymenoptera: Pteromalidae), Pupal Parasitoids Of Filth Flies (Diptera), David B. Taylor, Richard D. Peterson II, Allen L. Szalanski, James J. Petersen 2012 University of Nebraska-Lincoln

Mitochondrial Dna Variation Among Muscidifurax Spp. (Hymenoptera: Pteromalidae), Pupal Parasitoids Of Filth Flies (Diptera), David B. Taylor, Richard D. Peterson Ii, Allen L. Szalanski, James J. Petersen

David B Taylor

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing analyses were used to characterize an amplicon of ~625 bp in 4 of the 5 nominate species of Muscidifurax Girault & Sanders, pupal parasitoids of muscoid flies. A single polymorphic nucleotide site was observed among 2 samples of M. raptor Girault & Sanders. No sequence variation was observed among 3 samples of M. raptorellus Kogan & Legner. The sequence of M. uniraptor Kogan & Legner was identical to that of M. raptorellus. Nucleotide divergence among the Muscidifurax spp. ranged from 0.14 to 0.18 substitutions per nucleotide. Muscidifurax zaraptor Kogan & Legner exhibited multiple haplotypes ...


Population Genetics And Gene Variation In Primary And Secondary Screwworm (Diptera : Calliphoridae), David Taylor, Richard Peterson II 2012 University of Nebraska at Lincoln

Population Genetics And Gene Variation In Primary And Secondary Screwworm (Diptera : Calliphoridae), David Taylor, Richard Peterson Ii

David B Taylor

Allozyme variation in screwworm, Cochliomyia hominivorax (Coquerel), and secondary screwworm, C. macellaria (F.), populations from northwest Costa Rica was examined . Variability was observed in 11 of 13 enzyme loci and the frequency of the most common allele was <0.95 for 5 loci in screwworm . In secondary screwworm, 12 of 13 loci were variable and the frequency of the most common allele was <0.95 for 6 loci . Expected heterozygosities were 0.149 and 0.160 for screwworm and secondary screwworm, respectively. Goodness-of-fit statistics for Hardy-Weinberg equilibrium and Wrights F statistics indicated that both species are panmictic with no evidence ...


Population Genetics And Gene Variation Of Stable Fly Populations (Diptera: Muscidae) In Nebraska, Allen L. Szalanski, David B. Taylor, Richard D. Peterson II 2012 University of Nebraska-Lincoln

Population Genetics And Gene Variation Of Stable Fly Populations (Diptera: Muscidae) In Nebraska, Allen L. Szalanski, David B. Taylor, Richard D. Peterson Ii

David B Taylor

Genetic variation in stable fly, Stomoxys calcitrans (L.),populations from Nebraska, Canada, and Texas was sampled. Four of 12 allozyme loci were polymorphic, with an average of 1.7 alleles per locus. Observed and expected heterozygosities were 0.086 and 0.070,respectively. Nei's genetic distance between populations averaged 0.001 and ranged from 0.000 to 0.005. Wright's F statistics revealed greater variation within than among populations. Allele frequencies were homogeneous among temporal samples from a single population. Polymerasechain reaction—restriction fragment length polymorphism (PCR—RFLP) analysis of 6.4 kb of the mitochondrial DNA genome ...


Population Genetics And Gene Variation In Screwworms (Diptera: Calliphoridae) From Brazil, David B. Taylor, Richard D. Peterson II, Gonzalo E. Moya-Borja 2012 University of Nebraska, Lincoln

Population Genetics And Gene Variation In Screwworms (Diptera: Calliphoridae) From Brazil, David B. Taylor, Richard D. Peterson Ii, Gonzalo E. Moya-Borja

David B Taylor

Allozyme variation in New World screwworm, Cochliomyia hominivorax (Coquerel), populations from Brazil was examined. Variability was observed in 8 of 13 enzyme loci and the frequency of the most common allele was <0.95 for seven loci. Observed and expected heterozygosities were 0.159 and 0.165, respectively. Comparisons of the Brazilian populations with previously studied populations from Costa Rica resulted in Nei's genetic distances of between 0.000 and 0. 006, with the greatest distance being between populations within Brazil. Comparisons with Mexican populations using only three loci resulted in genetic distances ≤0.031. Goodness-of-fit statistics for Hardy-Weinberg ...


Genetic Relationship Among Diabrotica Species (Coleoptera: Chrysomelidae) Based On Rdna And Mtdna Sequences, Allen L. Szalanski, Richard L. Roehrdanz, David B. Taylor 2012 University of Nebraska-Lincoln

Genetic Relationship Among Diabrotica Species (Coleoptera: Chrysomelidae) Based On Rdna And Mtdna Sequences, Allen L. Szalanski, Richard L. Roehrdanz, David B. Taylor

David B Taylor

Corn rootworms of the genus Diabrotica (Coleoptera: Chrysomelidae) are the most serious pest of corn in midwestern United States. Despite their economic importance, phylogenetic relationships within the genus remain unclear. Phylogenetic analysis of five Diabrotica species and subspecies was undertaken using DNA sequences of the nuclear rDNA first internal transcribed spacer region (ITS1) and a portion of the mtDNA cytochrome oxidase I and II genes (COI/COII). Parsimony and maximum likelihood analysis indicated that southern corn rootworm is sister to banded cucumber beetle, whereas, northern corn rootworm forms a distinct clade with western and Mexican corn rootworm. ITS1 and COI ...


Gelled Diet For Screwworm (Diptera: Calliphoridae) Mass Production, David B. Taylor, Jimmy C. Bruce, Rene Garcia 2012 University of Nebraska-Lincoln

Gelled Diet For Screwworm (Diptera: Calliphoridae) Mass Production, David B. Taylor, Jimmy C. Bruce, Rene Garcia

David B Taylor

A rearing system based on a diet gelled with Water-Lock G400, a synthetic superabsorbent (poly(2-propenamide-co-2-propenoic acid, sodium salt))( WL), was compared with the standard rearing system (liquid diet suspended in acetate fibers) for the mass production of screwworms, Cochlomyia hominivorax (Coquerel). The WL rearing system yielded 2% heavier pupae, 32% higher egg to pupa survival, and required 54% less diet and 88% less labor than the standard rearing system. Other advantages of the WL system include reduced susceptibility to suboptimal environmental conditions and labor practices, and characteristics conducive to centralization and mechanization of rearing procedures.


Sugar Feeding In Adult Stable Flies, David B. Taylor, Dennis R. Berkebile 2012 University of Nebraska-Lincoln

Sugar Feeding In Adult Stable Flies, David B. Taylor, Dennis R. Berkebile

David B Taylor

Adult stable flies (Stomoxys calcitrans L.) are known to feed readily on sugars in the laboratory. However, little is known concerning the extent of stable fly sugar feeding in wild populations. We examined the frequency of sugar feeding in stable flies collected on Alsynite sticky traps in rural and urban environments. In addition, stable flies were visually examined to determine whether blood was present in the gut. In laboratory studies, sugars were detectable with the anthrone technique in stable flies for ~3 d after being imbibed, and blood could be visually detected in the gut for 24-48 h after feeding ...


Susceptibility Of House Fly (Diptera: Muscidae) Larvae To Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae, Steinernematidae), David B. Taylor, Allen L. Szalanski, Byron J. Adams, Richard D. Peterson II 2012 University of Nebraska-Lincoln

Susceptibility Of House Fly (Diptera: Muscidae) Larvae To Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae, Steinernematidae), David B. Taylor, Allen L. Szalanski, Byron J. Adams, Richard D. Peterson Ii

David B Taylor

The potential for entomopathogenic nematodes to control flies in cattle feedlots was determined by screening 40 strains representing 8 species of Heterorhabditis Poinar and 5 species of Steinemema Travassos for virulence toward 3rd-instar house flies (maggots), Musca domestica L. None of the 22 strains of Heterorhabditis infecting maggots caused significant levels of mortality in a filter paper assay. Ten strains of Steinemema infected maggots, of which 7 strains (4 S. carpocapsae (Weiser), 2 S.feltiae (Filipjev), and 1 S. scapterisci Nguyen & Smart) caused significant mortality. Ten Heterorhabditis strains and 10 Steinemema strains successfully reproduced for ≥ 2 generations in maggots. No ...


Watershed Scale Impacts Of Buffers And Upland Conservation Practices On Agrochemical Delivery To Streams, Thomas G. Franti, Dean E. Eisenhauer, Mary Carla McCullough, L. M. Stahr, Mike Dosskey, David D. Snow, Roy F. Spalding, Alan L. Boldt 2012 University of Nebraska - Lincoln

Watershed Scale Impacts Of Buffers And Upland Conservation Practices On Agrochemical Delivery To Streams, Thomas G. Franti, Dean E. Eisenhauer, Mary Carla Mccullough, L. M. Stahr, Mike Dosskey, David D. Snow, Roy F. Spalding, Alan L. Boldt

Daniel D Snow

Conservation buffers are designed to reduce sediment and agrichemical runoff to surface water. Much is known about plot and field scale effectiveness of buffers; but little is known about their watershed scale impact. Our objective was to estimate the watershed scale impact of grass buffers by comparing sediment and agrichemical losses from two adjacent 141-165 hectare watersheds, one with conservation buffers and one without. Rainfall derived runoff events from 2002-2003 were monitored for water runoff, TSS, phosphorous and atrazine loss. A conservation-watershed included 0.8 km of grass buffers and 0.8 km of riparian forest buffer, ridge-tilled corn, corn-beans-alfalfa ...


Occurrence And Biological Effect Of Exogenous Steroids In The Elkhorn River, Nebraska, Usa, Alan Kolok, Daniel Snow, Satomi Kohno, Marlo Sellin, Louis Guillette 2012 University of Nebraska at Omaha

Occurrence And Biological Effect Of Exogenous Steroids In The Elkhorn River, Nebraska, Usa, Alan Kolok, Daniel Snow, Satomi Kohno, Marlo Sellin, Louis Guillette

Daniel D Snow

Recent studies of surface waters in North America, Japan, and Europe have reported the presence of steroidogenic agents as contaminants. The current study has three objectives: 1) to determine if steroidogenic compounds are present in the Elkhorn River, 2) to determine if sediments collected from the Elkhorn River can act as a source of steroidogenic compounds to aquatic organisms, and 3) to determine if site-specific biological effects are apparent in the hepatic gene expression of fathead minnows. Evidence was obtained using three approaches: 1) deployment of polar organic chemical integrative samplers (POCIS), 2) deployment of caged fathead minnows, and 3 ...


Estrogenic Compounds Downstream From Three Small Cities In Eastern Nebraska: Occurrence And Biological Effect, Marlo K. Sellin, Daniel D. Snow, Debbie L. Akerly, Alan S. Kolok 2012 University of Nebraska Medical Center

Estrogenic Compounds Downstream From Three Small Cities In Eastern Nebraska: Occurrence And Biological Effect, Marlo K. Sellin, Daniel D. Snow, Debbie L. Akerly, Alan S. Kolok

Daniel D Snow

Recent studies have detected estrogenic compounds in surface waters in North America and Europe. Furthermore, the presence of estrogenic compounds in surface waters has been attributed, in some cases, to the discharge of wastewater treatment plant (WWTP) effluent. The primary objective of the current study was to determine if WWTP effluent contributes estrogens to the surface waters of Nebraska. A second objective of this study was to determine if estrogens were found in concentrations sufficient enough to manifest feminizing effects on fish. These objectives were satisfied by deploying polar organic chemical integrative samplers (POCIS) and caged fathead minnows at eight ...


Comparison Of Two Gelling Agents For Screwworm (Diptera: Calliphoridae) Larval Diets, David B. Taylor 2012 University of Nebraska-Lincoln

Comparison Of Two Gelling Agents For Screwworm (Diptera: Calliphoridae) Larval Diets, David B. Taylor

David B. Taylor

A sodium polyacrylamide polyacrylate gelling agent, Water-Lock G-400, and a galactan polysaccharide agent, carrageenan, were compared for solidifying larval diets of the screwworm, Cochliomyia hominivorax (Coquerel). Water-Lock diet produced larger pupae with less larval mortality than did carrageenan diet. Pupae from larvae reared on the Water-Lock diet exhibited higher emergence and produced adults with higher fecundity. Water-Lock diet also produced larger larvae at 56 h after oviposition. Densities in excess of 300 mg of eggs (16,200 eggs) per liter of Water-Lock gelled diet did not increase larval yield but did reduce larval weight and survival.


Mitochondrial Dna Variation Among Muscidifurax Spp. (Hymenoptera: Pteromalidae), Pupal Parasitoids Of Filth Flies (Diptera), David B. Taylor, Richard D. Peterson II, Allen L. Szalanski, James J. Petersen 2012 University of Nebraska-Lincoln

Mitochondrial Dna Variation Among Muscidifurax Spp. (Hymenoptera: Pteromalidae), Pupal Parasitoids Of Filth Flies (Diptera), David B. Taylor, Richard D. Peterson Ii, Allen L. Szalanski, James J. Petersen

David B. Taylor

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing analyses were used to characterize an amplicon of ~625 bp in 4 of the 5 nominate species of Muscidifurax Girault & Sanders, pupal parasitoids of muscoid flies. A single polymorphic nucleotide site was observed among 2 samples of M. raptor Girault & Sanders. No sequence variation was observed among 3 samples of M. raptorellus Kogan & Legner. The sequence of M. uniraptor Kogan & Legner was identical to that of M. raptorellus. Nucleotide divergence among the Muscidifurax spp. ranged from 0.14 to 0.18 substitutions per nucleotide. Muscidifurax zaraptor Kogan & Legner exhibited multiple haplotypes ...


Identification Of Screwworm Species By Polymerase Chain Reaction-Restriction Fragment Length Polymorphism, David B. Taylor, Allen L. Szalanski, Richard D. Peterson II 2012 University of Nebraska-Lincoln

Identification Of Screwworm Species By Polymerase Chain Reaction-Restriction Fragment Length Polymorphism, David B. Taylor, Allen L. Szalanski, Richard D. Peterson Ii

David B. Taylor

Restriction fragment length polymorphisms in polymerase chain reaction amplified fragments (PCR-RFLP) of mitochondrial DNA were used to differentiate species of New World screwworms (Diptera : Calliphoridae) . Twenty-seven restriction enzymes were screened on five regions of mtDNA . Eleven restriction fragment length patterns differentiated New World screwworm, Cochliomyia hominivorax (Coquerel), from secondary screwworm, Cochliomyia macellaria (F.) . Five restriction fragment length patterns were polymorphic in C. hominivorax while all fragment patterns were fixed in C. macellaria. Diagnostic restriction fragment length patterns were used for species diagnosis, whereas intraspecific variable patterns were used to characterize field samples and laboratory strains . The PCR-RFLP technique is flexible ...


Population Genetics And Gene Variation In Primary And Secondary Screwworm (Diptera : Calliphoridae), David B. Taylor, Richard D. Peterson II 2012 University of Nebraska-Lincoln

Population Genetics And Gene Variation In Primary And Secondary Screwworm (Diptera : Calliphoridae), David B. Taylor, Richard D. Peterson Ii

David B. Taylor

Allozyme variation in screwworm, Cochliomyia hominivorax (Coquerel), and secondary screwworm, C. macellaria (F.), populations from northwest Costa Rica was examined . Variability was observed in 11 of 13 enzyme loci and the frequency of the most common allele was <0.95 for 5 loci in screwworm . In secondary screwworm, 12 of 13 loci were variable and the frequency of the most common allele was <0.95 for 6 loci . Expected heterozygosities were 0.149 and 0.160 for screwworm and secondary screwworm, respectively. Goodness-of-fit statistics for Hardy-Weinberg equilibrium and Wrights F statistics indicated that both species are panmictic with no evidence ...


Genetic And Morphological Comparisons Of New And Old World Populations Of Spalangia Species (Hymenoptera: Pteromalidae), David B. Taylor, Roger Moon, Gary Gibson, Allen L. Szalanski 2012 University of Nebraska-Lincoln

Genetic And Morphological Comparisons Of New And Old World Populations Of Spalangia Species (Hymenoptera: Pteromalidae), David B. Taylor, Roger Moon, Gary Gibson, Allen L. Szalanski

David B. Taylor

The genetic similarity of New and Old World samples of Spalangia spp. (Hymenoptera: Pteromalidae) was examined using two ribosomalDNAregions. The species examined were Spalangia cameroni Perkins, Spalangia endius Walker, Spalangia gemina Bouček, Spalangia nigra Latreille, Spalangia nigroaenea Curtis, and Spalangia slovaca Bouček. Two species of Muscidifurax, Muscidifurax raptor Girault & Sanders and Muscidifurax zaraptor Kogan & Legner (Hymenoptera: Pteromalidae) were included as outgroup taxa. The internal transcribed spacer (ITS)-1 region was highly variable among Spalangia species with many insertions/deletions making alignment of the sequences difÞcult. The D2-D3 region of the 28s ribosomal gene and the nuclear rDNA 18s gene were ...


Digital Commons powered by bepress