Mercedes Ebbert | SUNY: Orange County Community College (original) (raw)

Papers by Mercedes Ebbert

Research paper thumbnail of Book Review:Evolution and Diversity of Sex Ratio in Insects and Mites. Dana L. Wrensch, Mercedes A. Ebbert

Quarterly Review of Biology, 1994

Research paper thumbnail of Drosophila (Diptera: Drosophilidae) Response to Changes in Ecological Parameters Across an Urban Gradient

Environmental Entomology, 2003

Understanding the changes in biodiversity correlated with urbanization is essential for monitorin... more Understanding the changes in biodiversity correlated with urbanization is essential for monitoring the complex effects of human activity on native ecosystems. We hypothesized that the Drosophila community native to temperate woodland forests would change along a gradient of urbanization, and could therefore serve as a model system in studies on urbanization. We used an urbanization gradient we had previously characterized in Southwest Ohio. Community composition gradually changed along the gradient, although community diversity did not. Abundance varied signiÞcantly among sites, with one species, Drosophila melanogaster, increasing in abundance from the least to the most urbanized sites. We used 28 parameters from three sets of environmental dataÑland cover, vegetation, and temperature and humidityÑto build a model with Canonical Correspondence Analysis and characterize the species-environment relationship. The most predictive variables explaining the distribution of the Drosophila community were maximum temperature, maximum saturation deÞcit, percent lawn cover, average diameter at breast height (dbh) of shrubs and trees, and number of tree species. We conclude that the presence of individual, easily identiÞable Drosophila species may serve as robust indicators of the habitat degradation brought about by urbanization, and as ideal models for exploring animal response to urbanization.

Research paper thumbnail of Factors influencing DTPA conjugation with antibodies by cyclic DTPA anhydride

Diethylenetriaminepentaacetic acid (DTPA) was conjugated with a practical concentration (300 micr... more Diethylenetriaminepentaacetic acid (DTPA) was conjugated with a practical concentration (300 micrograms/ml) of antibody to human albumin (Ab) and 1083 17-1A monoclonal colorectal antibody (MAb-17-1A) via an acylation reaction using cyclic DTPA anhydride (cDTPAA). The conjugation reaction was favored as pH increased. Bicarbonate buffer at pH 8.2 was chosen for studies of the effect of the cDTPAA-to-antibody ratio on DTPA conjugation with antibody because of its good buffer capacity at that pH. The reaction of cDTPAA with Ab at molar ratios of 2000, 1000, 500, and 100 in the bicarbonate buffer gave rise to 11, 9, 8, and 2 indium atoms incorporated per Ab with 47%, 55%, 59%, and 77% retention of the binding activity. For the conjugation reaction of MAb-17-1A, 29, 28, 31, 11, 4, and 1 indium atoms were incorporated, with the retention of less than 5%, less than 5%, less than 5%, 12%, 60%, and 93% of binding activity when the molar ratio was 5000, 2000, 1000, 500, 100, and 50.

Research paper thumbnail of Trypanosomatid Prevalence and Host Habitat Choice in Woodland Drosophila

Journal of Invertebrate Pathology, 2001

Although trypanosomatids (Trypanosomatidae: Kinetoplastida) are common inhabitants of dipteran gu... more Although trypanosomatids (Trypanosomatidae: Kinetoplastida) are common inhabitants of dipteran guts, prevalence in natural fly populations has not been studied. We investigated factors associated with trypanosomatid prevalence in eight species of woodland Drosophila (Drosophilidae: Diptera) collected from five sites in southwest Ohio. We collected infected flies from every site, over both years of our study, and from every Drosophila species. Prevalence differed with host species, but not between sites or with host sex. Prevalence was highest in the most abundant species, members of the subgenus Sophophora, species using decaying fruit as breeding sites, and those able to use more than one type of substrate for oviposition.

Research paper thumbnail of Lack of specificity in the interaction between two maize stunting pathogens and field collected Dalbulus leafhoppers

Entomologia Experimentalis Et Applicata, 2001

We tested hypotheses concerning the specificity of interactions between insect vectors and mollic... more We tested hypotheses concerning the specificity of interactions between insect vectors and mollicute plant pathogens in a 22-month study of leafhoppers collected at three agricultural field sites in Mexico. The common species collected, Dalbulus maidis, D. elimatus, D. gelbus, and D. guevari were equally likely to test positive for corn stunt spiroplasma (CSS) in ELISA, and to transmit maize bushy stunt phytoplasma (MBSP) to test maize seedlings. We documented intraspecific variation in the ability of D. maidis to transmit confirmed CSS infections. Dalbulus guevari and D. gelbus were less successful in transmitting CSS than D. maidis from the same population. Our results suggest this vector-plant pathogen interaction is not specific to a single Dalbulus-mollicute combination, and that both the range of potential vectors in agricultural fields, and intraspecific variation across populations of these vectors, should be the focus of future work.

Research paper thumbnail of Relative reactivity of DTPA, immunoreactive antibody-DTPA conjugates, and nonimmunoreactive antibody-DTPA conjugates toward indium-111

Anti-human serum albumin antibody {Ab) was reacted with cyclic DTPA dianhydride (cDTPAA) at vario... more Anti-human serum albumin antibody {Ab) was reacted with cyclic DTPA dianhydride (cDTPAA) at various cDTPAA/Ab molar ratios between 1 and 40. Using a carrier In titration method for DTPA and DTPA-antibody conjugate (Ab-DTPA), we determined that the above reactions produced between 0.1 and 11 DTPA molecules per either immunoreactive antibody (sAb) or nonimmunoreactive antibody (nAb). The percentage of sAb remaining after the above reactions was between 88 and 62%. The reaction of no-carrier-added 111 ln with the reaction mixture from cDTPAA/Ab molar ratios of 1 to 40 gave radiochemical yields <25% for the respective Ab-DTPA. The rest of the 111 ln activity was associated with free DTPA. Our results indicate that Ab-DTPA containing > 1 DTPA molecule per Ab is more reactive than that containing <1 DTPA but is about as reactive as free DTPA. This allows us to label in the presence of free DTPA and consequently prevent colloid formation. The percentage of 111 ln activity incorporated into sAb-DTPA from the reactions at these molar ratios was similar to that found from the uv analysis. This indicates that the reactivity of sAb-DTPA and nAB-DTPA from the same conjugation reaction is similar. As a result, we were able to conjugate about one DTPA molecule to the Ab without causing deactivation of the Ab and label it with 111 ln in the presence of excess DTPA. We obtained a specific activity of 6 /JLC\ 111 ln per /ug of Ab using research grade 111 ln without further purification.

Research paper thumbnail of HOST AGE, BUT NOT HOST LOCATION WITHIN A STREAM, IS CORRELATED WITH THE PREVALENCE OF GUT PARASITES IN WATER STRIDERS

Journal of Parasitology, 2003

We tested for correlations between the geographic, demographic, and temporal distribution of an a... more We tested for correlations between the geographic, demographic, and temporal distribution of an aquatic insect host and the prevalence of its gut parasites in southwestern Ohio. Trypanosomatids were present in Aquarius remigis collected from all 4 streams surveyed in the watershed. Prevalence declined dramatically from May to July and remained low through the fall. This pattern was consistent over all sites of our study, with no effect of stream, stream site (upstream vs. downstream), or host sex on prevalence. Stage, however, was strongly correlated with prevalence; adults were more likely to be infected than were nymphs. We argue that behavioral differences between the 2 age classes may account for the decline in prevalence; opportunities for transmission are highest in the spring, when mating activities increase adult host contact rates, and decline in the summer, when contact rates decrease.

Research paper thumbnail of Variable effects of crowding on Drosophila hosts of male-lethal and non-male-lethal spiroplasmas in laboratory populations

Heredity, 1995

Male-lethal, maternally inherited spiroplasmas occur in four species of Drosophila, and persist i... more Male-lethal, maternally inherited spiroplasmas occur in four species of Drosophila, and persist in natural populations despite imperfect vertical transmission rates. In the field, larval crowding is thought to be sporadic, but occasionally intense. To determine whether crowding affects host persistence, I compared the population dynamics of infected females (hosts) under crowded conditions to those expected from data collected on uncrowded females. I estimated host fitness components and maternal transmission rates for individual females under uncrowded conditions in both the artificial host D. pseudoobscura (this paper) and the native host D. willistoni (previously reported). Spiroplasma infection had no effect on lifetime production of daughters in D. pseudoobscura; however, as with some D. willistoni lines, hosts may produce more of their daughters earlier in life than nonhosts. Because individual contributions to relative rates of increase calculated from these fitness data were similar for hosts and nonhosts, I expected hosts to persist in laboratory populations. Instead, three patterns were observed: rapid extinction of D. willistoni females infected with male-lethal spiroplasmas, slow decline or persistence of hosts (depending on initial frequency) in both D. pseudoobscura infected with male-lethal spiroplasmas, and D. willistoni infected with non-male-lethal spiroplasmas. Population dynamics, then, depend on host species and bacterial isolate. Fitness estimates change with host line in uncrowded D. willistoni, but host genetic background did not affect population dynamics. These and previously published results show that the interaction phenotype changes with host and parasite isolate, and that host fitness can be affected by crowding. Crowding in natural populations may therefore decrease host fitness but, in expanding populations, early reproduction in hosts may be to their advantage. Possible effects of seasonal fluctuations in population density on the fitness of infected Drosophila are discussed.

Research paper thumbnail of Protozoan and intracellular fungal gut endosymbionts in Drosophila: prevalence and fitness effects of single and dual infections

Journal of Invertebrate Pathology, 2003

We report on the effect of single and mixed infections with two gut symbionts, trypanosomatids an... more We report on the effect of single and mixed infections with two gut symbionts, trypanosomatids and the intracellular fungus Coccidiascus legeri, on the life history of their host, Drosophila melanogaster. We also provide the first report on the prevalence of C. legeri in natural populations of Drosophila. Prevalence overall was low (3.4%), and differed with host species, but persisted from the first to the second year of our survey. We documented delayed pupation in flies exposed to trypanosomatids, but larvae exposed to the fungus eclosed more quickly than controls. Larvae exposed to mixed infections pupated more slowly, but eclosed more quickly than controls.

Research paper thumbnail of Survival in Dalbulus leafhopper vectors improves after exposure to maize stunting pathogens

Entomologia Experimentalis Et Applicata, 2001

Using D. maidis and pathogen isolates collected at three field sites along an altitudinal gradien... more Using D. maidis and pathogen isolates collected at three field sites along an altitudinal gradient in Mexico, we compared survival in leafhoppers exposed to healthy maize to those exposed to maize infected with one of four isolates of maize stunting pathogens: two isolates of the corn stunt spiroplasma (CSS, Spiroplasma kunkelii) and two of the maize busby stunt phytoplasma (MBSP). Survival improved after exposure to either plant pathogen under both the cooler and warmer environmental conditions D. maidis is likely to encounter during the dry season. Survival varied among leafhoppers from the different field sites, suggesting that gene flow between these populations is limited. The leafhoppers responded differently to the four isolates (i.e., we noted significant population by exposure interactions), but we found no difference between MBSP and CSS exposure. Finally, we found evidence of local adaptation in one leafhopper population to sympatric, as compared to allopatric, plant pathogens. We have shown with this and our earlier study that aspects of the interaction phenotype in the association between D. maidis and the plant pathogens are mutualistic and that this association has considerable potential as a model for studies of local adaptation.

Research paper thumbnail of Book Review:Evolution and Diversity of Sex Ratio in Insects and Mites. Dana L. Wrensch, Mercedes A. Ebbert

Quarterly Review of Biology, 1994

Research paper thumbnail of Drosophila (Diptera: Drosophilidae) Response to Changes in Ecological Parameters Across an Urban Gradient

Environmental Entomology, 2003

Understanding the changes in biodiversity correlated with urbanization is essential for monitorin... more Understanding the changes in biodiversity correlated with urbanization is essential for monitoring the complex effects of human activity on native ecosystems. We hypothesized that the Drosophila community native to temperate woodland forests would change along a gradient of urbanization, and could therefore serve as a model system in studies on urbanization. We used an urbanization gradient we had previously characterized in Southwest Ohio. Community composition gradually changed along the gradient, although community diversity did not. Abundance varied signiÞcantly among sites, with one species, Drosophila melanogaster, increasing in abundance from the least to the most urbanized sites. We used 28 parameters from three sets of environmental dataÑland cover, vegetation, and temperature and humidityÑto build a model with Canonical Correspondence Analysis and characterize the species-environment relationship. The most predictive variables explaining the distribution of the Drosophila community were maximum temperature, maximum saturation deÞcit, percent lawn cover, average diameter at breast height (dbh) of shrubs and trees, and number of tree species. We conclude that the presence of individual, easily identiÞable Drosophila species may serve as robust indicators of the habitat degradation brought about by urbanization, and as ideal models for exploring animal response to urbanization.

Research paper thumbnail of Factors influencing DTPA conjugation with antibodies by cyclic DTPA anhydride

Diethylenetriaminepentaacetic acid (DTPA) was conjugated with a practical concentration (300 micr... more Diethylenetriaminepentaacetic acid (DTPA) was conjugated with a practical concentration (300 micrograms/ml) of antibody to human albumin (Ab) and 1083 17-1A monoclonal colorectal antibody (MAb-17-1A) via an acylation reaction using cyclic DTPA anhydride (cDTPAA). The conjugation reaction was favored as pH increased. Bicarbonate buffer at pH 8.2 was chosen for studies of the effect of the cDTPAA-to-antibody ratio on DTPA conjugation with antibody because of its good buffer capacity at that pH. The reaction of cDTPAA with Ab at molar ratios of 2000, 1000, 500, and 100 in the bicarbonate buffer gave rise to 11, 9, 8, and 2 indium atoms incorporated per Ab with 47%, 55%, 59%, and 77% retention of the binding activity. For the conjugation reaction of MAb-17-1A, 29, 28, 31, 11, 4, and 1 indium atoms were incorporated, with the retention of less than 5%, less than 5%, less than 5%, 12%, 60%, and 93% of binding activity when the molar ratio was 5000, 2000, 1000, 500, 100, and 50.

Research paper thumbnail of Trypanosomatid Prevalence and Host Habitat Choice in Woodland Drosophila

Journal of Invertebrate Pathology, 2001

Although trypanosomatids (Trypanosomatidae: Kinetoplastida) are common inhabitants of dipteran gu... more Although trypanosomatids (Trypanosomatidae: Kinetoplastida) are common inhabitants of dipteran guts, prevalence in natural fly populations has not been studied. We investigated factors associated with trypanosomatid prevalence in eight species of woodland Drosophila (Drosophilidae: Diptera) collected from five sites in southwest Ohio. We collected infected flies from every site, over both years of our study, and from every Drosophila species. Prevalence differed with host species, but not between sites or with host sex. Prevalence was highest in the most abundant species, members of the subgenus Sophophora, species using decaying fruit as breeding sites, and those able to use more than one type of substrate for oviposition.

Research paper thumbnail of Lack of specificity in the interaction between two maize stunting pathogens and field collected Dalbulus leafhoppers

Entomologia Experimentalis Et Applicata, 2001

We tested hypotheses concerning the specificity of interactions between insect vectors and mollic... more We tested hypotheses concerning the specificity of interactions between insect vectors and mollicute plant pathogens in a 22-month study of leafhoppers collected at three agricultural field sites in Mexico. The common species collected, Dalbulus maidis, D. elimatus, D. gelbus, and D. guevari were equally likely to test positive for corn stunt spiroplasma (CSS) in ELISA, and to transmit maize bushy stunt phytoplasma (MBSP) to test maize seedlings. We documented intraspecific variation in the ability of D. maidis to transmit confirmed CSS infections. Dalbulus guevari and D. gelbus were less successful in transmitting CSS than D. maidis from the same population. Our results suggest this vector-plant pathogen interaction is not specific to a single Dalbulus-mollicute combination, and that both the range of potential vectors in agricultural fields, and intraspecific variation across populations of these vectors, should be the focus of future work.

Research paper thumbnail of Relative reactivity of DTPA, immunoreactive antibody-DTPA conjugates, and nonimmunoreactive antibody-DTPA conjugates toward indium-111

Anti-human serum albumin antibody {Ab) was reacted with cyclic DTPA dianhydride (cDTPAA) at vario... more Anti-human serum albumin antibody {Ab) was reacted with cyclic DTPA dianhydride (cDTPAA) at various cDTPAA/Ab molar ratios between 1 and 40. Using a carrier In titration method for DTPA and DTPA-antibody conjugate (Ab-DTPA), we determined that the above reactions produced between 0.1 and 11 DTPA molecules per either immunoreactive antibody (sAb) or nonimmunoreactive antibody (nAb). The percentage of sAb remaining after the above reactions was between 88 and 62%. The reaction of no-carrier-added 111 ln with the reaction mixture from cDTPAA/Ab molar ratios of 1 to 40 gave radiochemical yields <25% for the respective Ab-DTPA. The rest of the 111 ln activity was associated with free DTPA. Our results indicate that Ab-DTPA containing > 1 DTPA molecule per Ab is more reactive than that containing <1 DTPA but is about as reactive as free DTPA. This allows us to label in the presence of free DTPA and consequently prevent colloid formation. The percentage of 111 ln activity incorporated into sAb-DTPA from the reactions at these molar ratios was similar to that found from the uv analysis. This indicates that the reactivity of sAb-DTPA and nAB-DTPA from the same conjugation reaction is similar. As a result, we were able to conjugate about one DTPA molecule to the Ab without causing deactivation of the Ab and label it with 111 ln in the presence of excess DTPA. We obtained a specific activity of 6 /JLC\ 111 ln per /ug of Ab using research grade 111 ln without further purification.

Research paper thumbnail of HOST AGE, BUT NOT HOST LOCATION WITHIN A STREAM, IS CORRELATED WITH THE PREVALENCE OF GUT PARASITES IN WATER STRIDERS

Journal of Parasitology, 2003

We tested for correlations between the geographic, demographic, and temporal distribution of an a... more We tested for correlations between the geographic, demographic, and temporal distribution of an aquatic insect host and the prevalence of its gut parasites in southwestern Ohio. Trypanosomatids were present in Aquarius remigis collected from all 4 streams surveyed in the watershed. Prevalence declined dramatically from May to July and remained low through the fall. This pattern was consistent over all sites of our study, with no effect of stream, stream site (upstream vs. downstream), or host sex on prevalence. Stage, however, was strongly correlated with prevalence; adults were more likely to be infected than were nymphs. We argue that behavioral differences between the 2 age classes may account for the decline in prevalence; opportunities for transmission are highest in the spring, when mating activities increase adult host contact rates, and decline in the summer, when contact rates decrease.

Research paper thumbnail of Variable effects of crowding on Drosophila hosts of male-lethal and non-male-lethal spiroplasmas in laboratory populations

Heredity, 1995

Male-lethal, maternally inherited spiroplasmas occur in four species of Drosophila, and persist i... more Male-lethal, maternally inherited spiroplasmas occur in four species of Drosophila, and persist in natural populations despite imperfect vertical transmission rates. In the field, larval crowding is thought to be sporadic, but occasionally intense. To determine whether crowding affects host persistence, I compared the population dynamics of infected females (hosts) under crowded conditions to those expected from data collected on uncrowded females. I estimated host fitness components and maternal transmission rates for individual females under uncrowded conditions in both the artificial host D. pseudoobscura (this paper) and the native host D. willistoni (previously reported). Spiroplasma infection had no effect on lifetime production of daughters in D. pseudoobscura; however, as with some D. willistoni lines, hosts may produce more of their daughters earlier in life than nonhosts. Because individual contributions to relative rates of increase calculated from these fitness data were similar for hosts and nonhosts, I expected hosts to persist in laboratory populations. Instead, three patterns were observed: rapid extinction of D. willistoni females infected with male-lethal spiroplasmas, slow decline or persistence of hosts (depending on initial frequency) in both D. pseudoobscura infected with male-lethal spiroplasmas, and D. willistoni infected with non-male-lethal spiroplasmas. Population dynamics, then, depend on host species and bacterial isolate. Fitness estimates change with host line in uncrowded D. willistoni, but host genetic background did not affect population dynamics. These and previously published results show that the interaction phenotype changes with host and parasite isolate, and that host fitness can be affected by crowding. Crowding in natural populations may therefore decrease host fitness but, in expanding populations, early reproduction in hosts may be to their advantage. Possible effects of seasonal fluctuations in population density on the fitness of infected Drosophila are discussed.

Research paper thumbnail of Protozoan and intracellular fungal gut endosymbionts in Drosophila: prevalence and fitness effects of single and dual infections

Journal of Invertebrate Pathology, 2003

We report on the effect of single and mixed infections with two gut symbionts, trypanosomatids an... more We report on the effect of single and mixed infections with two gut symbionts, trypanosomatids and the intracellular fungus Coccidiascus legeri, on the life history of their host, Drosophila melanogaster. We also provide the first report on the prevalence of C. legeri in natural populations of Drosophila. Prevalence overall was low (3.4%), and differed with host species, but persisted from the first to the second year of our survey. We documented delayed pupation in flies exposed to trypanosomatids, but larvae exposed to the fungus eclosed more quickly than controls. Larvae exposed to mixed infections pupated more slowly, but eclosed more quickly than controls.

Research paper thumbnail of Survival in Dalbulus leafhopper vectors improves after exposure to maize stunting pathogens

Entomologia Experimentalis Et Applicata, 2001

Using D. maidis and pathogen isolates collected at three field sites along an altitudinal gradien... more Using D. maidis and pathogen isolates collected at three field sites along an altitudinal gradient in Mexico, we compared survival in leafhoppers exposed to healthy maize to those exposed to maize infected with one of four isolates of maize stunting pathogens: two isolates of the corn stunt spiroplasma (CSS, Spiroplasma kunkelii) and two of the maize busby stunt phytoplasma (MBSP). Survival improved after exposure to either plant pathogen under both the cooler and warmer environmental conditions D. maidis is likely to encounter during the dry season. Survival varied among leafhoppers from the different field sites, suggesting that gene flow between these populations is limited. The leafhoppers responded differently to the four isolates (i.e., we noted significant population by exposure interactions), but we found no difference between MBSP and CSS exposure. Finally, we found evidence of local adaptation in one leafhopper population to sympatric, as compared to allopatric, plant pathogens. We have shown with this and our earlier study that aspects of the interaction phenotype in the association between D. maidis and the plant pathogens are mutualistic and that this association has considerable potential as a model for studies of local adaptation.