Factors Influencing Dispersion of Larval Black Flies (Diptera:Simuliidae): Effects of Current Velocity and Food Concentration

1989 ◽  
Vol 46 (8) ◽  
pp. 1329-1341 ◽  
Author(s):  
Jan J. H. Ciborowski ◽  
Douglas A. Craig

Positioning and feeding of Simulium vittatum larvae were studied on a ceramic tile in a flume at three current velocities and two food concentrations. Locomotory activity and drift decreased with increasing current but were independent of food. Using nearest neighbor analysis, we detected significant aggregation at 15 cm∙s−1 that resulted from accumulation of individuals at upstream boundaries. Larvae also aggregated at 43 cm∙s−1, but independently of tile margins. Dispersion was random at 24 cm∙s−1. Gross pattern formation results from individual responses to prevailing flow conditions independently of food concentration. Relative ingestion rates decreased with increasing food concentration, larval size, velocity, and incidence of parasitism. Individual larvae avoided locations directly upstream or downstream of a nearest neighbor at 15 and 24 cm∙s−1 when food concentration was low (0.5 mg∙L−1), but not at higher food levels (3.5 mg∙L−1). These trends were reversed at high velocity. Larvae immediately downstream of neighbors had reduced ingestion rates. Larvae selected positions lateral to others under low food conditions. These animals had greater ingestion rates than did individuals in other locations. Results are consistent with hypotheses of flow disruption and/or food preemption by upstream larvae and of mutually induced beneficial flow between laterally adjacent individuals. Positioning within aggregations reflects complex behavior among conspecifics that varies with the interaction of flow and food concentration.

2016 ◽  
Author(s):  
Dick van Oevelen ◽  
Christina E. Mueller ◽  
Tomas Lundälv ◽  
Jack J. Middelburg

Abstract. Cold-water corals form prominent reef ecosystems along ocean margins that depend on suspended resources produced in surface waters. In this study we investigated food processing of 13C and 15N labelled bacteria and algae by the cold-water coral Lophelia pertusa. Coral respiration, tissue incorporation of C and N and metabolic-derived C incorporation into the skeleton were traced following the additions of different food concentrations (100, 300, 1300 µg C L−1) and two ratios of suspended bacterial and algal biomass (1:1, 3:1). Respiration and tissue incorporation by L. pertusa increased markedly following exposure to higher food concentrations. The net growth efficiency of L. pertusa was low (0.08 ± 0.03), which is consistent with their slow growth rates. The contribution of algae and bacteria to total coral assimilation was proportional to the food mixture in the two lowest food concentrations, but algae were preferred over bacteria as food source at the highest food concentration. We argue that behavioural responses for these small-sized food particles, such as tentacle behaviour and mucus trapping, are more likely to explain the observed food selectivity as compared to physical-mechanical considerations. A comparison of the experimental food conditions to natural organic carbon concentrations above CWC reefs suggests that L. pertusa is well adapted to exploit temporal pulses of high organic matter concentrations in the bottom water caused by internal waves and downwelling events.


1991 ◽  
Vol 69 (4) ◽  
pp. 1120-1123 ◽  
Author(s):  
Jan J. H. Ciborowski ◽  
Douglas A. Craig

Laboratory experiments were conducted to study aggregative responses of larvae of Simulium vittatum Zetterstedt on a ceramic tile to activity of a predatory perlid stonefly, Claassenia sabulosa (Banks). Nearest-neighbor analysis indicated that larvae became aggregated regardless of whether a predator was present. There was no significant difference in either number of larvae remaining on the tile or degree of black fly aggregation between trials that lacked a predator and those in which a stonefly could travel over the tile. Direct contact between predator and prey caused single simuliid larvae to release from the substrate, but daytime black fly behaviour was otherwise unaffected by stonefly activity.


2019 ◽  
Vol 49 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Yanli Lei ◽  
Chengchun Li ◽  
Tiegang Li ◽  
Zhimin Jian

Abstract The majority of sediment-dwelling foraminifera are thought to be deposit feeders. They use their reticulopodia to gather sediment with associated algae, organic detritus, and bacteria. Uptake of diatoms by foraminifera have been observed but rarely quantified. We measured the clearance (gathering) rate and ingestion rate of diatoms by the common benthic foraminifer Quinqueloculina seminula using Nitzschia closterium as prey under laboratory culture conditions. Grazing experiments were performed to evaluate the effects of temperature (at 12, 15, 18, 21, and 24°C) and food availability (10 to 800 cells mm−2) on uptake rates of diatoms. The clearance rates, estimated from the disappearance of food items, were variable (0.59–4.4 mm2 foram−1 h−1) and did not show a clear relationship with food availability. The maximum clearance rates increased from 1.80 ± 0.21 to 2.69 ± 0.32 mm2 foram−1 h−1 when temperature increased from 12 to 18°C and decreased to 2.28 ± 0.25 mm2 foram−1 h−1 at 24°C. Ingestion rates varied from 1.0 to 43 × 103 diatoms foram−1 h−1, following a hyperbolic response to food concentrations at all experimental temperatures. The maximum individual ingestion rates increased from 842 ± 180 to 1648 ± 480 (mean ± SE) cells foram−1 h−1 and then decreased to 316 ± 54 cells foram−1 h−1 as temperature increased from 12 to 24°C. Experimental results revealed that 12–18°C was the optimal temperature range for Q. seminula feeding for specimens adapted to local conditions. Our study indicates that Q. seminula plays an ecological role by feeding upon benthic diatoms in marine benthic ecosystems.


1981 ◽  
Vol 113 (3) ◽  
pp. 223-234 ◽  
Author(s):  
A. R. Westwood ◽  
R. A. Brust

AbstractTen species of black flies were collected from the Souris River, Manitoba between April 1977 and October 1978. Adults of Simulium luggeri Nicholson and Mickel, Simulium meridionale Riley, Simulium venustum Say, Simulium verecundum Stone and Jamnback, and Simulium johannseni johannseni (Hart) were collected feeding on livestock and humans, and are well known pest species. Simulium vittatum Zetterstedt was the most abundant species, but was not a pest on man or domestic animals. Simulium tuberosum (Lundström) and Simulium johannseni duplex Shewell and Fredeen were the least abundant species. Simulium j. johannseni, S. j. duplex, S. venustum, S. verecundum, S. tuberosum, and Cnephia dacotensis (Dyar and Shannon) appeared to be univoltine species while S. luggeri, S. meridionale, Simulium decorum Walker, and S. vittatum were multivoltine in the Souris River.An evaluation of cone, plate, rope, and wire cage sampling devices for black fly larvae and pupae indicated that cone samplers provided a more representative sample for population assessment.In a black fly control program, of the Souris River, Manitoba two separate larvicide treatments in spring may be necessary. In the case of two treatments, the first should be aimed at late instar larvae of S. j. johannseni, S. venustum, and S. verecundum. Since the majority of S. luggeri and S. meridionale would be in the egg stage at this time, a second treatment, 10–14 days later, would be necessary to control late instar larvae of these species.


1998 ◽  
Vol 76 (3) ◽  
pp. 440-447 ◽  
Author(s):  
X Zhu ◽  
K P Pruess ◽  
T O Powers

Mitochondrial DNA (mtDNA) was extracted from pooled field-collected samples representing six species of black flies (Cnephia dacotensis, Simulium bivittaum, S. johansenni, S. luggeri, S. piperi, S. vittatum) and compared by restriction fragment length polymorphism (RFLP) analysis. Morphospecies were molecularly distinct, with few shared restriction fragments. Eleven populations of S. vittatum were found that appeared to be homogeneous for a single mitochondrial haplotype. Ten other populations of S. vittatum showed extensive mitochondrial heterogeneity. In part, these samples contained mixtures of two cytologically recognized siblings: IIIL-1 and IS-7. About 70% of the mitochondrial genome of a population pure for sibling IIIL-1 was cloned as five HindIII fragments, which were used as hybridization probes to examine individual black flies. Thirteen mtDNA haplotypes involving permutations of 10 HindIII restriction sites were identified in individual black flies examined from 26 populations. DNA from 168 larvae cut with both EcoR1 and HindIII revealed five additional haplotypes. One HindIII haplotype was present in 84% of 390 larvae examined and predominated in every population examined from New York to California and in both the IIIL-1 and IS-7 siblings. Nebraska populations had individuals with nearly all known haplotypes. The most common haplotype was usually the only form present in warm, silty streams with organic enrichment. Rarer haplotypes were found in cool, spring-fed streams but without clear geographic or phylogenetic components.


2020 ◽  
Author(s):  
Sandra Klintworth ◽  
Eric von Elert

Abstract In aquatic systems, organisms largely rely on chemical cues to perceive information about the presence of predators or prey. Daphnia recognize the presence of the predatory larvae of Chaoborus via a chemical cue, emitted by the larvae, a so-called kairomone. Upon recognition, neckteeth, an alteration of the carapace, are induced in Daphnia that reduce predation rates of Chaoborus. Neckteeth induction was often reported to entail costs. In a previous study, food quantity affected the level of neckteeth induction, with stronger neckteeth induction at low food concentrations and weak induction at high food concentrations. However, reducing neckteeth induction at high food quantities seems to be maladaptive and not in accordance with the concept that inducible defenses are associated with costs. Here, we hypothesized that weaker neckteeth induction at high food concentrations is caused by increased bacterial degradation of the kairomone. More specifically, we assume that higher algal food concentration is associated with higher bacterial abundances, which degrade the kairomone during the experiment. We tested our hypothesis by treating food algae with antibiotics before providing them as food to Daphnia. Antibiotics reduced bacterial abundances at high and low food concentrations. Reduced bacterial abundances at high food concentrations led to the same level of neckteeth induction as at low food concentrations. A linear regression revealed a significant correlation of neckteeth induction to bacterial abundances. We therefore conclude that differences in neckteeth induction at different food concentrations are not caused by the food quantity effects but by differences in bacterial degradation of the kairomone.


2004 ◽  
Vol 61 (4) ◽  
pp. 596-616 ◽  
Author(s):  
Eileen E Hofmann ◽  
Eric N Powell ◽  
Eleanor A Bochenek ◽  
John M Klinck

Abstract A biochemically based model was developed to simulate the growth, development, and metamorphosis of larvae of the Pacific oyster (Crassostrea gigas). The unique characteristics of the model are that it: (1) defines larvae in terms of their protein, neutral lipid, polar lipid, carbohydrate, and ash content; (2) tracks weight separately from length to follow larval condition; and (3) includes genetic variation in growth efficiency and egg quality to better simulate cohort population dynamics. The model includes parameterizations for filtration, ingestion, and respiration, which determine larval growth rate, and processes controlling larval mortality and metamorphosis. Changes in larval tissue composition occur as the larva grows and in response to the biochemical composition of the food. Simulations of larval growth indicate that departures of temperature, salinity, or food content from optimum levels reduce larval cohort survival, either because of metabolic constraints that result in death, unsuccessful metamorphosis, or increased predation resulting from increased larval lifespan. Temperatures and salinities near optimal values improve larval survival at low food concentration by increasing ingestion rate or growth efficiency. Also, survival at a given food concentration can vary widely depending on food composition, which determines food quality. The simulations suggest that the ratio of carbohydrate + lipid-to-protein may best describe the overall food quality, with optimal food compositions being characterized by ratios near 1.2 to 1.4 over a range of food concentrations. In contrast, food compositions containing too much or too little protein reduce larval survival, even at saturating food concentrations. In simulations emphasizing genetic variability within the cohort, larvae with high growth efficiency originating from large eggs out-perform other egg quality–growth efficiency combinations over a wide range of temperature, salinity, and food contents. As a consequence, suboptimal temperature, salinity, or food content compresses genetic variation by uniformly favouring larvae from large eggs with a high growth efficiency. However, the larval survival obtained from simulations that use a range of food qualities is representative of a much broader range of genetic types. Thus, the simulations support the supposition that food quality is an important variable controlling the survival and genetic variability of C. gigas larval cohorts.


2016 ◽  
Vol 13 (1) ◽  
pp. 1
Author(s):  
Biange Maria Cezário de Carvalho ◽  
Raquel Leite Wainfas ◽  
Tayanna Rodrigues ◽  
Lidiane Coelho Berbert ◽  
Thaiane Franklin ◽  
...  

According to Bergmann’s Rule, individuals who inhabit higher altitudes tend to be larger in body mass or size, when compared with individuals of the same taxon who inhabit lower altitude places. Black flies are insects of great medical and veterinary importance due to its blood-sucking habit, becoming subject of studies regarding its bionomics, ecology and taxonomy. Studies approaching the influence of the altitude gradient in the morphology of Diptera: Simuliidae larvae are scarce in the literature, therefore, this study aimed to investigate the influence of altitude gradient in the morphology of Diptera: Simullidae larvae in Itatiaia National Park, RJ, and thus verify if Bergmann’s Rule is applicable to these organisms. Black fly larvae were sampled from four sites during periods of March and May 2013. From each site 30 larvae were measured, and these lengths were later compared between sites using Kruskal-Wallis, which showed a significant difference (P<.05) among sites from lower altitudes in relation to those of higher elevations, what was corroborated using a cluster analysis. The altitude was related to larval size using a linear regression, showing a positive correlation between these variables, thus corroborating Bergmann’s rule for Black flies.


1993 ◽  
Vol 44 (5) ◽  
pp. 761 ◽  
Author(s):  
CR King ◽  
RJ Shiel

The functional response of D. carinata feeding on M. granulata was determined from laboratory trials conducted at 20-22�C, using a range of food concentrations (F) from 0.14 to 33.8�g (dry weight) mL-1. The functional response could be described by an lvlev model: I (ingestion rate, ng �g-1 h-1) = 200 - 205 × exp (- 0.036 × F). The ingestion rate at the highest food concentration (33.8 �g mL-1) was 140 ng �g-1 h-1, and there was no evidence to suggest that M. granulata either interfered with feeding at high densities or was a difficult food item for D. carinata to handle.


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