Tabanus Nigrovittatus Research Articles

Effect of chitosan on adult longevity when fed, in no-choice experiments, to Musca domestica L., Tabanus nigrovittatus Macquart, and Phormia regina (Meigen) adults and its consumption in adult Musca domestica L.

The literature reports that more research needs to be done on using chitosan as an environmentally friendly bioinsecticide, especially against dipterans. Thus, we examined the effect of chitosan when fed, in no-choice experiments, to adult Musca domestica, Tabanus nigrovittatus, and Phormia regina. A 2% chitosan solution was fed, in no-choice experiments, to adults of Musca domestica, Tabanus nigrovittatus, and Phormia regina to study the effects on survivorship. In all species, the uptake of chitosan caused a significant decrease in survivorship. Examination of the digestive tract of house flies showed a thick material within the midgut, plus a shriveling of the midgut only in chitosan-treated flies. A survivorship curve of adult house flies fed a 10% sucrose and 2% w/v ascorbic acid-only solution showed that the effect of the chitosan solution was due to the chitosan and not the ascorbic acid. Intake experiments revealed that by day 2, chitosan treated house flies consumed significantly less of the diet compared to controls. Chitosan, a biopesticide, when fed in no-choice experiments to three species of adult flies produced severe mortality within 4-6 days of ingestion. A working hypothesis suggests that by day 2 of the chitosan diet there appears to be a malfunction of the digestive tract and possibly the midgut microbiome. © 2020 Society of Chemical Industry.

Recovery of horse fly populations in Louisiana marshes following the Deepwater Horizon oil spill

The Deepwater Horizon oil spill in April 2010 had unprecedented impact on the Gulf of Mexico. We established the greenhead horse fly (Tabanus nigrovittatus Macquart) as a bioindicator of marsh health. This species is bound to coastal marshes, since its larvae develop as top invertebrate predators in the marsh soil. Immediately after the oil spill (2010–2011), populations of this horse fly declined in oiled areas of Louisiana marshes with significant impacts on genetic structure. In this follow-up study five years after the catastrophic event (2015–2016), we now report signs of recovery of populations in formerly oiled areas. Fly numbers increased compared to previous counts. Previously detected genetic bottlenecks in oiled populations have disappeared. Migration into oiled areas began to replenish formerly depleted horse fly populations in impacted regions with populations from non-oiled areas as an important source of migrants. Parameters of family structure that had been impacted by the oil spill (number of breeding parents, effective population size, number of family clusters) rebounded to levels similar to or exceeding those in non-oiled control areas.

Impact of the 2010 Deepwater Horizon oil spill on population size and genetic structure of horse flies in Louisiana marshes.

The greenhead horse fly, Tabanus nigrovittatus Macquart, is frequently found in coastal marshes of the Eastern United States. The greenhead horse fly larvae are top predators in the marsh and thus vulnerable to changes in the environment, and the adults potentially are attracted to polarized surfaces like oil. Therefore, horse fly populations could serve as bioindicators of marsh health and toxic effects of oil intrusion. In this study, we describe the impact of the April 2010 Deep Water Horizon oil spill in the Gulf of Mexico on tabanid population abundance and genetics as well as mating structure. Horse fly populations were sampled biweekly from oiled and unaffected locations immediately after the oil spill in June 2010 until October 2011. Horse fly abundance estimates showed severe crashes of tabanid populations in oiled areas. Microsatellite genotyping of six pristine and seven oiled populations at ten polymorphic loci detected genetic bottlenecks in six of the oiled populations in association with fewer breeding parents, reduced effective population size, lower number of family clusters and fewer migrants among populations. This is the first study assessing the impact of oil contamination at the level of a top arthropod predator of the invertebrate community in salt marshes.

Complete Genome Sequence of Spiroplasma litorale TN-1T (DSM 21781), a Bacterium Isolated from a Green-Eyed Horsefly (Tabanus nigrovittatus).

Spiroplasma litorale TN-1T (DSM 21781) was isolated from the gut of a green-eyed horsefly (Tabanus nigrovittatus), collected at Ocracoke Island in North Carolina in 1983. Here, we report the complete genome sequence of this bacterium to facilitate the investigation of its biology.

Development of Microsatellites for Population Genetic Analyses ofTabanus nigrovittatus(Diptera: Tabanidae)

The greenhead horse fly, Tabanus nigrovittatus Macquart (Diptera: Tabanidae), is frequently found in coastal marshes of the Eastern United States. The females are autogenous (i.e., able to develop eggs without a bloodmeal),but they become a considerable pest to both humans and animals when they pursue a source of blood protein to produce additional eggs. In this study, we identified microsatellite markers to provide first insight into the population genetic structure of this notorious pest species. Because no prior genomic information was available for T. nigrovittatus, we used direct shotgun pyrosequencing technology to characterize microsatellite loci. Approximately 10% of the 105,634 short sequence reads generated from random genome sampling contained microsatellites with at least four repeats ofdi-, tri-, tetra-, penta-, and hexamers. Primers were designed for 36 different microsatellite loci with di-, tri-, and tetramer repeat units. After optimization, 20 primer pairs yielded consistent PCR products and were validated for population genetic application in six populations in Western Louisiana Ten loci were polymorphic with 2-9 alleles per locus and an average observed heterozygosity of 0.20 across populations. The horse fly populations from different trap sites (distance 50-144 km) or years of collection (2010 vs 2011) were genetically distinct from each other (FST = 0.05-0.39) and genetically diverse (gene diversity: 0.24-0.37) but considerably inbred (FIS: 0.22-0.47), with high mean relatedness among individuals (r = 0.27), suggesting the capture of a high percentage of sisters at the same trap location who were progeny of incest.

FMRFamide-like immunoreactivity in the central nervous system and alimentary tract of the non-hematophagous blow fly, Phormia regina, and the hematophagous horse fly, Tabanus nigrovittatus.

FMRFamide-related peptides (FaRPs) are a diverse and physiologically important class of neuropepeptides in the metazoa. In insects, FaRPs function as brain-gut neuropeptides and have been immunolocalized throughout the nervous system and alimentary tract where they have been shown to affect feeding behavior. The occurrence of FMRFamide-like immunoreactivity (FLI) was examined in the central nervous system and alimentary tract of non-hematophagous blow fly, Phormia regina Meigen (Diptera: Calliphoridae), and the hematophagous horse fly, Tabanus nigrovittatus Macquart (Diptera:Tabanidae). Although the central nervous system and alimentary anatomy differ between these two dipteran species, many aspects of FLI remain similar. FLI was observed throughout the central and stomatogastric nervous systems, foregut, and midgut in both flies. In the central nervous system, cells and processes with FLI occurred in the brain, subesophageal ganglion, and ventral nerve cord. FLI was associated with neurohemal areas of the brain and ventral nerve cord. A neurohemal plexus of fibers with FLI was present on the dorsal region of the thoracic central nervous system in both species. In the gut, processes with FLI innervated the crop duct, crop and anterior midgut. Endocrine cells with FLI were present in the posterior midgut. The distribution of FLI in these two flies, in spite of their different feeding habits, further supports the role of FaRPs as important components of the braingut neurochemical axis in these insects and implicates FaRPs as regulators of insect feeding physiology among divergent insect taxa.

Factors Affecting Engorgement Behavior in the Salt Marsh Horse Fly, Tabanus nigrovittatus Macquart (Diptera: Tabanidae)

Female Tabanus nigrovittatus were field collected and used in laboratory experimentation to explore physiological and behavioral factors that affect engorgement. Previous studies showed sulfakinins act as feeding satiety factors in insects. This study demonstrates that sulfakinins have differing effects on engorgement that is dependent on the feeding technique used in the laboratory. The satiety effect of sulfakinin on flies engorging using the blood-soaked Kimwipe® feeding technique is not in agreement with previous experiments using an alternate feeding technique with artificial membranes. This study is the first to demonstrate that the temperature of blood is a significant factor for engorgement in this species. Also, the percentage of flies engorging is significantly different depending on the feeding technique used.

Performance of Painted Plywood and Cloth Nzi Traps Relative to Manitoba and Greenhead Traps for Tabanids and Stable Flies

Experiments were conducted to adapt the cloth Nzi trap to a format suitable for fixed applications in biting fly sampling or control. Catches of tabanids [Tabanus L., Chrysops (Meigen), and Hybomitra Enderlein], and stable flies [Stomoxys calcitrans (L.)] in painted plywood traps were compared with those in standard phthalogen blue cloth traps, and in similarly painted cloth traps. The Manitoba horse fly trap and the Tabanus nigrovittatus Macquart "greenhead" box trap were used as additional standards during one tabanid season. Shiny features of traps reduced catches, e.g., paint on cloth instead of wood, or use of aluminum screening instead of netting. Nevertheless, appropriately painted plywood Nzi traps caught as many biting flies as did standard cloth Nzi traps, if paint finishes were matte, and with the use of phthalogen blue colorants. Nzi traps collected about the same tabanid fauna as the Manitoba and T. nigrovittatus traps, but with improved catches of Chrysops and Tabanus. Recommendations are provided on appropriate color matching, and selection of readily-available materials for trap construction.

Effect of Seasonality and Perisulfakinin on Engorgement by <I>Tabanus nigrovittatus</I> (Diptera: Tabanidae) in the Laboratory

The horse fly Tabanus nigrovittatus Macquart (Diptera: Tabanidae), a hematophagous insect, is a nuisance pest along the Atlantic Coast. A description of the engorgement pattern throughout the season is lacking in the literature for this species. The percentage of flies engorging a bloodmeal in the laboratory throughout the season was recorded, and here we demonstrate that the percentage of flies that are blood feeding fluctuates, leading to a decrease in flies engorging as the season ends. Additionally, three recent nonhematophagous insect studies demonstrated that sulfakinins, a vertebrate homologue of cholecystokinin, function in feeding inhibition as a satiety factor. We found that groups of flies injected with one nanomole of perisulfakinin were inhibited from blood feeding by 45–60%. The satiation of feeding reported here is in agreement with the previous research by using nonhematophagous species. When groups of flies were injected with 10 nmol of perisulfakinin, the percentage of flies engorging was increased relative to the sham-injected flies, although not significantly. The stimulation of engorgement by sulfakinin has not previously been demonstrated, and its mode of action remains unclear.

Effect of Octenol on Engorgement by Tabanus nigrovittatus (Diptera: Tabanidae)

Adult female Tabanus nigrovittatus Macquart (Diptera: Tabanidae) were field collected from a salt marsh in Essex County, Massachusetts. The horse flies were transported back to and tested in the laboratory to determine the effects of octenol (1-octen-3-ol) on engorgement. Flies exposed to octenol strips had a significantly higher engorgement response compared with control flies. To our knowledge, this is the first study to demonstrate an important link between an odor stimulus and the feeding response in Tabanidae. Research examining the link between odor attractants and repellents on the engorgement response is lacking or limited in most hematophagous Diptera. Understanding the role odors have on ingestion is essential to knowing how to interrupt feeding behavior of blood-feeding arthropods, especially for important vectors.

Effect of Octenol on Engorgement by <I>Tabanus nigrovittatus</I> (Diptera: Tabanidae)

Adult female Tabanus nigrovittatus Macquart (Diptera: Tabanidae) were field collected from a salt marsh in Essex County, Massachusetts. The horse flies were transported back to and tested in the laboratory to determine the effects of octenol (1-octen-3-ol) on engorgement. Flies exposed to octenol strips had a significantly higher engorgement response compared with control flies. To our knowledge, this is the first study to demonstrate an important link between an odor stimulus and the feeding response in Tabanidae. Research examining the link between odor attractants and repellents on the engorgement response is lacking or limited in most hematophagous Diptera. Understanding the role odors have on ingestion is essential to knowing how to interrupt feeding behavior of blood-feeding arthropods, especially for important vectors.

Occurrence of Serotonin Immunoreactivity in the Central Nervous System and Midgut of Adult Female Tabanus nigrovittatus (Diptera: Tabanidae)

Abstract Serotonin is an important neuromessenger used in a variety of signaling pathways throughout the animal kingdom. In insects, serotonin has been demonstrated to mediate feeding and feeding-related behaviors. In this study, serotonin antibody was localized in cells and processes throughout the central nervous system (CNS) and midgut of female horse fly Tabanus nigrovittatus Macquart. In the CNS, immunoreactivity was localized in cells and processes throughout the brain and ventral nerve cord. In the midgut, a fine network of immunoreactive processes was observed running along the outer surface of the midgut, with a decrease in innervation toward the posterior region of the midgut.

Occurrence of Serotonin Immunoreactivity in the Central Nervous System and Midgut of Adult Female <I>Tabanus nigrovittatus</I> (Diptera: Tabanidae)

Serotonin is an important neuromessenger used in a variety of signaling pathways throughout the animal kingdom. In insects, serotonin has been demonstrated to mediate feeding and feeding-related behaviors. In this study, serotonin antibody was localized in cells and processes throughout the central nervous system (CNS) and midgut of female horse fly Tabanus nigrovittatus Macquart. In the CNS, immunoreactivity was localized in cells and processes throughout the brain and ventral nerve cord. In the midgut, a fine network of immunoreactive processes was observed running along the outer surface of the midgut, with a decrease in innervation toward the posterior region of the midgut.

Bacterioplankton community composition in flowing waters of the Ipswich River watershed.

moptera), and the isopod Philoscia vittata were the most common invertebrates encountered in the marsh. In the marsh-grass-removal experiment we found a significant decrease in abundance of leafhoppers ( [2] 26.9, P 0.0001), as well as spiders (Order Araneae) ( [2] 8.72, P 0.013), greenhead fly larvae (Tabanus nigrovittatus) ( [2] 14.23, P 0.001), and O. grillus ( 2 [2] 26.9, P 0.0001) after clipping (Fig. 1). P. vittata was not significantly affected ( [2] 3.32, P 0.19, Fig. 1). The stepwise multiple regression indicated that percent S. alterniflora, percent bare space, percent Salicornia europaea, and temperature were correlated with patterns of leafhopper abundance (F[4,32] 40.02, P 0.0001). The positive correlation between leafhoppers and S. alterniflora cover is consistent since leafhoppers often feed on S. alterniflora (3). Spiders were positively related to dead above-ground biomass, and percent bare space (F[2,34] 8.25, P 0.001), which is consistent with their reduced abundance in our experimental marsh-grass-removal treatments. The measured environmental variables related to the abundance of T. nigrovittatus larvae were percent Juncus gerardi, sediment surface temperature, and proportion of tethered amphipods eaten (F[3,33] 8.04, P 0.0001). The abundance of T. nigrovittatus larvae was negatively correlated with sediment surface temperature. It is likely that temperatures in the newly clipped patches were higher than in the unclipped marsh. Abundances of T. nigrovittatus larvae were also positively correlated with the proportion of tethered amphipods eaten, which is consistent with our observations of predation by T. nigrovittatus larvae on tethered O. grillus specimens. O. grillus abundance was not significantly correlated with any variables, and the amphipod was widely distributed throughout the marsh. The lack of a significant correlation with aboveground biomass or haying frequency is noteworthy since the amphipods experienced a strong drop in abundance in the marsh-grass haying experiment. This finding suggests that the long-term effects of haying on O. grillus abundances are much less severe than the immediate response. Many invertebrate species may experience a strong reduction in abundance just after haying; however, many environmental variables in addition to haying had an effect on patterns of invertebrate abundance in the long-term. We thank Carl Noblitt, our research assistant. This research was supported by an REU fellowship through the Plum Island Sound LTER program to JPL.

Detection of cryptic species in the Tabanus nigrovittatus (Diptera: Tabanidae) complex in Massachusetts by morphometric and cuticular hydrocarbon analysis.

Greenhead flies of the Tabanus nigrovittatus complex from Massachusetts salt marshes were identified as T. nigrovittatus Macquart and T. conterminus Walker using the morphometric model developed by Sofield et al. Four body measurements from a total of 5,983 female flies collected over 2 consecutive years yielded canonical scores producing a unimodal rather than the expected bimodal distribution. The lack of bimodality indicated that both species were not present at the study site. This was substantiated by cuticular hydrocarbon (CHC) analysis of a subsample of these specimens. Fifteen, female flies of the Tabanus nigrovittatus complex from the same site were identified to species using the Sofield et al. morphometric model and validated using CHC analysis. Two individuals of the T. nigrovittatus complex were identified incorrectly as T. conterminus by the morphometric model. The tendency of this model to incorrectly classify some individuals of T. nigrovittatus as T. conterminus brings into question the identity of the Walker syntypes of T. conterminus. Based on CHC analysis, our study shows that both species coexist within our study area.

Cuticular Hydrocarbon Variation in the Tabanidae (Diptera): Tabanus nigrovittatus Complex of the North American Atlantic Coast

The horsefly Tabanus nigrovittatus Macquart consists of a cryptic species complex involving at least 1 other sibling species, T. conterminus Walker. Multivariate analysis of cuticular hydrocarbon patterns of members of this complex from the Atlantic coast of North America clearly showed 3 statistically disjoint chromatotypes. Type I, which included the largest individuals, represented T. conterminus, whereas type II patterns represented a different chromatotype found in smaller flies identified as T. nigrovittatus. Surprisingly, some small specimens exhibited a 3rd chromatotype (type III) that contained di- and trimethylalkanes not identified in types I and II. We believe that this 3rd chromatotype represents an undescribed member of the T. nigrovittatus complex.

Spiroplasma litorale sp. nov., from Tabanid Flies (Tabanidae: Diptera) in the Southeastern United States

Spiroplasma strain TN-1T (T = type strain), a strain serologically distinct from other spiroplasma species, groups, and subgroups, was isolated from the gut of a horsefly (Tabanus nigrovittatus) from a barrier island off the coast of North Carolina. Related strains were isolated from other Tabanus spp., T. atratus, T. americanus, T. gladiator, T. lineola, T. sulcifrons, and T. zythicolor, from coastal Georgia. Cells of strain TN-1T in culture were helical and motile with an average of 5 to 10 helical turns per cell. Electron microscopic studies determined that the cells of strain TN-1T were surrounded by a single cytoplasmic membrane, and there was no evidence of a cell wall. The spiroplasma grew well in MID and SP-4 liquid media. Serum fraction (1%) medium and conventional horse serum medium also supported growth of strain TN-1T. Fried-egg colonies were not produced; instead, the strain produced small diffuse colonies that were surrounded by satellite growth. The optimum temperature for growth was 32°C, but multiplication was observed at temperatures from 10 to 41°C. The doubling time at the optimum temperature (32°C) was 1.6 h. No growth was observed at 5 or 43°C. Spiroplasma strain TN-1T passed through 220-nm filter pores but failed to pass through 100-nm filter pores. Strain TN-1T catabolized glucose but hydrolyzed neither arginine nor urea. The guanine-plus-cytosine content of the DNA was about 25 ± 1 mol%, and the genome size was 1,370 kbp. Based on results from this study and previously published data, strain TN-1T (= ATCC 43211) (group XVIII) is designated the type strain of a new spiroplasma species, Spiroplasma litorale.

Spatial Distribution of Hovering Male Tabanus nigrovittatus (Diptera: Tabanidae)

Male Tabanus nigrovittatus Macquart hover as a premating strategy in the early morning over Atlantic coastal salt marshes. These males are distributed with peak densities near mosquito ditches and with fewer hovering males farther from the ditch. Multivariate analysis indicated that male density or the distance between individuals is an important factor in structuring hovering male spatial distribution. When compared with previously published data, male densities match peak emergence of females. T. nigrovittatus numbers are lowest directly adjacent to mosquito ditches, where Tabanus conterminus (Walker) tends to hover, suggesting that spatial separation may contribute to reproductive isolation in these two sibling species.

Mechanical control of greenhead flies (Diptera: Tabanidae) in a marsh environment.

The effectiveness of New Jersey box traps for the control of adult greenhead flies, Tabanus nigrovittatus, Macquart, T. conterminus Walker, was assessed at Wallops Island, Va. Trap shape and placement were tested. Shallow (0.45 m high) traps caught significantly fewer flies than cubic (0.60 m high) traps. Traps located in the inner two of four layers of traps caught fewer flies than traps in the outer layers.

Feeding behaviour of the horsefly Tabanus nigrovittatus (Diptera: Tabanidae): effects of dissolved solids on ingestion and destination of sucrose or ATP diets

Abstract Wild caught female horseflies, Tabanus nigrovittatus Macq. (Diptera: Tabanidae), were fed solutions containing either sucrose or ATP as a phagostimulant. The sucrose diets were presented as free liquids at room temperature. The ATP in the other diets was dissolved in 0.15 M NaCl, or in 0.3 M or 1 M cellobiose and was presented covered with a Parafilm membrane at 38oC. The content of dissolved solids in some diets was adjusted with added cellobiose, which had no phago‐stimulatory effect. Diets of 1 M or 0.6 M sucrose were ingested in large amounts and were directed to the crop. Diets of 0.3 M or 0.1 M sucrose induced lower levels of ingestion, and the diet was directed to the midgut. The addition of cellobiose to give a 1 M total concentration of dissolved solids in these sucrose diets induced many insects responding to the lower concentrations of sucrose to direct the diet to the crop. Diets of ATP in saline or in 0.3 M cellobiose were directed to the midgut. ATP in 1 M cellobiose caused many of the insects to put the diet in both the crop and the midgut. Two behavioural models are presented that integrate interactions between the level of phagostimulation, the concentration of dissolved solids, and an endogenous feeding factor. The dissolved solids effect is most likely a response to osmotic pressure.