Tabanidae (Diptera: Insecta) attacking Tapirus terrestris (Linnaeus) (Mammalia: Tapiridae) in Central Amazon, Brazil

Abstract

Tabanidae (Diptera) is a cosmopolitan family of flies with a wide distribution in South America. Female flies feed on various hosts, including domestic animals, wildlife, and humans, based on host specificity. This study used a tapir, Tapirus terrestris, to assess the activity patterns of female Tabanidae, their feeding preferences on the host’s body, and the host’s defensive behaviors. From April 1997 to March 1998, monthly observations recorded 243 individuals from 20 species. Stenotabanus bequaerti, Tabanus occidentalis, Phaeotabanus cajennensis, and Chlorotabanus inanis were the most abundant. Activity peaks varied by species and time of day, with most attacks targeting the tapir’s hip, flank, back, and snout. The tapir responded to multiple attacks by contracting its skin and seeking refuge in water. This study highlights the pioneering discovery of the tapir, the largest wild terrestrial mammal in South America, as a host for blood-feeding Tabanidae species in the Amazon region.

Key words
Amazon; hematophagy; horseflies; insects; mammal; Tapir

INTRODUCTION

Tabanidae Latreille are abundant and diverse, with 4,402 known species worldwide (Pape & Thompson 2019). In the Neotropical region, more than 1,200 species are found (Henriques et al. 2012), with 475 occurring in Brazil and 250 species documented in the Amazon region (Krolow & Henriques 2023). Females of various Tabanidae species primarily feed on mammals (Magnarelli & Anderson 1980, McKeever & French 1999, D’Angelo et al. 2016), leading to several issues for the hosts, including blood loss, endo- and ectoparasitic infections, and stress (McKeever & French 1999). Domestic animals subjected to Tabanidae attacks may disrupt rest and foraging activities, potentially compromising their reproductive success (Keiper & Berger 1982) and promoting weight loss (Perich et al. 1986, Phelps & Holloway 1990, Foil et al. 1991). Tabanidae has been documented feeding on some animals, such as horses (Equidae; Gorayeb & Ribeiro 2001, Zamarchi et al. 2023), cattle (Bovidae; Mullens & Gerhardt 1979), and ducks (Anatidae; Limeira-de-Oliveira et al. 2002; Ferreira & Rafael 2004).

Instances of Tabanidae attacks have also been recorded in wild animals, expanding their behaviors beyond domestic settings. These incidents include attacks on camels (Camelidae; Dirie et al. 1989), moose (Cervidae; Gruell & Roby 1976), deer (Cervidae; Collins & Urness 1982), capybaras (Caviidae; D’Angelo et al. 2016), pigs, rodents, and even hippopotamuses (Hippopotamidae; Gouteux et al. 1989). Besides mammals, Tabanidae have also been documented engaging in hematophagy on reptiles, including lizards (Gouteux et al. 1989, Philip 1983, Gorayeb & Campos 2018), turtles (Cheloniidae; Fretey 1989) alligators (Alligatoridae) and snake Boa constrictor L. (Boidae; Philip 1976, 1986, Medem 1981, Barros 1996, Henriques et al. 2000, Ferreira et al. 2002). This expanded range of hosts underscores the versatility and adaptability of Tabanidae in their pursuit of sustenance.

Studies conducted in South America on horses reveal the diversity, abundance, prevalence, seasonal variability, attack behavior of Tabanidae, and the extent of their mechanical and biological transmission (Bassi et al. 2000, Barros 2001, Luz-Alves et al. 2007, Miletti et al. 2011, Krüger & Krolow 2015, Lucas et al. 2020, Costa et al. 2023, Corrêa-Neto & Henriques 2023, Zamarchi et al. 2023). In the Central Amazon, certain species have been documented to appear exclusively during specific times of the year (Rafael & Charlwood 1980, Rafael 1982, Henriques & Rafael 1999). A higher abundance and richness of Tabanidae is observed between July and December, coinciding with the drier and hotter period of the year. Some species, such as Tabanus occidentalis L. and Philipotabanus stigmaticalis Kröber, are particularly prevalent during this period (Oliveira et al. 2007, Ferreira-Keppler et al. 2010). In addition to seasonal variation, Tabanidae species can also show differences in their abundance throughout the day, corresponding to periods of heightened flight activity (Harley 1965, Joseph-Marie et al. 2019). For instance, throughout the day, Acanthocera marginalis Walker displayed increased activity during the morning, whereas Phi. stigmaticalis exhibited greater activity in the afternoon (Oliveira et al. 2007). In the eastern Amazon, Chlorotabanus inanis (Fabricius) and T. occidentalis (Gorayeb 1999) were observed throughout the collection period, exhibiting one or more peaks in abundance during the day that correspond to periods of increased flight activity.

The present study extends the existing knowledge about Tabanidae host preferences within the Central Amazon Forest, focusing on the tapir (Tapirus terrestris L.), a vulnerable species experiencing population declines in many areas (Flesher & Medici 2022). We aimed to contribute to understanding the daily and yearly activity patterns and attack behavior of Tabanidae species that utilize T. terrestris as a host. Given its large body size and ecological importance, the tapir plays a key role in maintaining parasitic networks involving hematophagous insects. Its decline could disrupt these networks, highlighting the need to preserve this species and its ecological interactions in tropical ecosystems.

MATERIALS AND METHODS

The study was carried out in collaboration with the “Centro de Instrução de Guerra na Selva” (CIGS) at Instruction Base 2, located at AM 010 highway at kilometer 4 of the Puraquequara Road, approximately 54 km from Manaus, Amazonas, Brazil (02°45’33” S, 59°51’03” W; Figure 1). The experiment took place along the banks of the Candiru stream, within an anthropogenic clearing bordered by a primary forest rich in Amazonian fauna and flora. The climate in the region is tropical equatorial humid, with distinct rainy (November–May) and dry (June–October) seasons. The mean annual temperature is 27oC (Ribeiro et al. 1999).

Figure 1
Sampling point location of Tapir at the Centro de Instrução de Guerra na Selva (CIGS) Base of Instruction (BI-2) in Manaus, Amazonas, Brazil.

Tapirus terrestris is characterized by a gray-dark brown color and short hair. The tapir was placed inside an iron cage measuring 3.5 × 2.5 × 2 m, lined with an aluminum screen with a spacing of 3 × 3 cm, which allowed the entry of insects. Sampling was conducted by three people for 13 hours per day (5:30 AM to 6:30 PM) over two consecutive days each month, totaling 26 hours of sampling per month. Over the 12-month study period (April 1997 to March 1998), a total of 312 hours of sampling was completed. Tabanid collection followed a methodology adapted from Mullens & Gerhardt (1979), originally developed for cattle. We used entomological nets to sample all Tabanidae that were actively feeding on Tapir. Horseflies that were merely perching on the tapir without attempting to feed were not collected. Moreover, we recorded the location of horsefly attacks on the tapir’s body using photographs, videos and field notes. The identification process was based on morphological characteristics using previous literature (e.g., Gorayeb 1985, Henriques & Rafael 1999). Moreover, Dr. Augusto Henriques, a recognized specialist in Tabanidae taxonomy, directly assisted with the identification and verification of the collected specimens. Identification of the Tabanidae specimens was conducted based on morphological characteristics observed during feeding on specific anatomical regions of covering. The sampled individuals were placed in the Invertebrate Collection at INPA, Manaus, Amazonas.

During samples, we divided the tapir body into 14 anatomical regions for analysis (e.g., hip, flank, back, snout). This division was performed in a preliminary study that served as a reference model for consistently identifying and delineating body parts. The tapir spent most of the observation period standing. However, it exhibited a range of behaviors, including walking, feeding, turning, and entering water, which occasionally influenced the accessibility of certain body parts to the horseflies. Periodically, the tapir would lie down in a lateral position, during which it protected its legs and reduced exposure of certain regions to horseflies. Variations in posture can result in a higher concentration of samples from more exposed body parts, which could introduce bias by underestimating or overestimating feeding activity in body parts.

Descriptive circular statistics were employed to analyze the daily attacking activity of horseflies. A Rayleigh z-test, specifically suited for assessing the uniformity of circular data, such as daily activity patterns, was used with a significance level of α < 0.05 (Oriana–Kovach Computing Services 2009). Spearman’s rank correlation test (α < 0.05) was applied to examine the relationship between the daily and annual abundance of Tabanidae species and environmental variables, including temperature, relative humidity (both recorded at the experiment site), and precipitation. This test was chosen for its robustness in handling non-parametric data and potential non-linear relationships, characteristics commonly observed in ecological datasets. To assess differences in the abundance and richness of Tabanidae across different body parts of Tapirus terrestris, we used linear mixed-effects (LME) models. In these models, the response variables (abundance and richness) were log-transformed [log(x+1)] to meet model assumptions. Body parts were included as fixed effects, while sampling months were treated as random effects. Additionally, we conducted a Canonical Correspondence Analysis (CCA) to examine the relationships between Tabanidae species and specific body regions of the tapir. All statistical analyses were performed in R using nlme (Pinheiro et al. 2021) and vegan packages in R.

Abbreviations in the text were differentiated as cited in this study: S. – Stenotabanus, T. – Tabanus, Pha. – Phaeotabanus, Chl. – Chlorotabanus, Chr. – Chrysops, D. – Diachlorus, Cat. – Catachlorops, L – Leucotabanus, F. – Fidena, P. – Pityocera, Phi. – Philipotabanus, Ca. – Cairina, C. – Caiman, E. – Eunectes.

RESULTS AND DISCUSSION

Species collected on the tapir host

We collected 243 Tabanidae specimens feeding on tapir, comprising 18 species and two morphospecies from 10 genera (Supplementary Material - Table SI). To our knowledge, there are no prior publications on Tabanidae species associated with Tapirus terrestris, highlighting the importance of investigating host-specific interactions to better understand the ecology and behavior of Tabanidae in tropical ecosystems. The most abundant Tabaninae species were Stenotabanus bequaerti Rafael, Fairchild and Gorayeb (32%), T. occidentalis (19%), Phaeotabanus cajennensis (Fabricius) (15%), and C. inanis (14%) (Table SI). S. bequaerti is restricted to the Central Amazon (Henriques 2004, Henriques & Rafael 1999), while the latter three species are widely distributed in the Neotropical region (Henriques & Rafael 1999, Rafael & Charlwood 1980). A previous study in the same area at CIGS recorded a higher number of species (66 species) using flight interception traps (Malaise and suspended traps), which were left in the field for 10 consecutive days monthly (Ferreira-Keppler et al. 2010). T. occidentalis was the second most abundant species in both Malaise and suspended traps (15.4%) and in our study. Conversely, P. cajennensis (3.48%), S. bequaerti (1.25%), and C. inanis (0.08%) were reported in low abundances in trap collections but were significantly more abundant on the tapir. Notably, Tabanus fortis (0.41%) was exclusively recorded on the tapir and not detected in Malaise or suspended traps, suggesting its potential host specificity or a unique ecological niche. It is important to note, however, that the presence of T. fortis could also be incidental, and further studies are needed to confirm whether its association with the tapir is consistent or opportunistic.

In the same CIGS area of our study, tapirs exhibited higher abundance and richness of Tabanidae species compared to other hosts, such as Cairina moschata L. (abundance = 51; richness = 3) (Ferreira & Rafael 2004), Caiman crocodilus (L.) (abundance = 214; richness = 4), and Eunectes murinus (L.) (abundance = 40; richness = 4) (Ferreira et al. 2002). According to Baldacchino et al. (2014), factors influencing host selection by Tabanidae include animal size, higher carbon dioxide emission, and feeding site preferences based on traits like short hair, large body size, color intensity, and glossiness. Additionally, tabanid density often provokes defensive responses in animals, such as skin trembling, leg stamping, head shaking, and tail flicking, which serve to deter these hematophagous insects (Raymond & Rousseau 1987).Among the species collected in our study, 11 species were associated with humans in clearing area of CIGS, of which eight were common to tapirs and humans (Chlorotabanus laetus Fabricius, Diachlorus falsifuscistigma Henriques and Rafael, Fidena loricornis Kröber, Pha. cajennensis, Pityocera cervus (Wiedemann), S. bequaerti, T. occidentalis, and Tabanus piceiventris Rondani (Ferreira et al. 2010).

Tabanidae activity throughout the day

The activity patterns of most Tabanidae species exhibited non-uniform trends throughout the day (Table SI). This section focuses on the most abundant species. S. bequaerti exhibited a peak in activity during the hottest hours of the day, between 1:00 PM to 4:00 PM (Figure 2a). This activity peak showed a strong positive correlation with temperature (r = 0.74; p = 0.002; Table SII) and a negative correlation with humidity (r = -0.78; p = 0.001). S. bequaerti showed peak activity between 10:00 AM and 4:00 PM when associated with alligators and anacondas, with two peaks in the afternoon. When attacking humans, peak activity occurs from 11:00 AM to 12:00 PM and 3:00 PM to 4:00 PM (Ferreira et al. 2002).

Figure 2
Circular histograms depict the diurnal activity patterns of the most abundant Tabanidae species collected from tapirs (Tapirus terrestris). a: Stenotabanus bequaerti. b: Tabanus occidentalis. c: Phaeotabanus cajennensis. d: Chlorotabanus inanis. e: Total Tabanidae. Samples were performed between 5:30 AM to 6:30 PM (total collection time: 312 hours over one year).

Tabanus occidentalis was present throughout the entire day, with heightened activity between 3:00 PM and 6:00 PM (Figure 2b). This species displayed moderate correlations with temperature (r = 0.42) and humidity (r = -0.44). Conversely, activity remained steady throughout the day during attacks. Rafael & Charlwood (1980) recorded a similar density pattern in the Central Amazon, where this species, then referred to as T. dorsiger var. dorsovittatus and var. modestus, was collected from horses. Their study showed comparable densities between 6:00 AM and 12:00 PM, escalating to peak density between 5:00 PM and 6:00 PM, aligning with our findings. In the eastern Amazon, T. occidentalis exhibited increased afternoon flight activity when using horses as bait (Gorayeb 1985, 2000). Associated with anacondas and alligators, it showed three peak activity periods: two in the morning and one from 1:00 PM to 4:00 PM. Peak activity when attacking humans occurred between 3:00 PM and 6:00 PM (Oliveira et al. 2007, Ferreira et al. 2002, 2010).

Phaeotabanus cajennensis exhibited a small peak of activity in the morning and was particularly prevalent between 2:00 PM and 6:00 PM, diminishing as darkness fell (Figure 2c). Previous studies documented morning and afternoon activity of this species (Rafael & Charlwood 1980, Gorayeb 1985, 2000). In the CIGS area Pha. cajennensis attacked birds between 10:00 AM and 11:00 AM (Ferreira & Rafael 2004) and on humans in both the morning and afternoon (Ferreira et al. 2010). This species demonstrated weak correlations with temperature (r = 0.27; p = 0.342) and humidity (r = -0.31; p = 0.289).

Chlorotabanus inanis exhibited two activity peaks, consistent with those reported by Guimarães et al. (2016) in horses. This species is known to approach animals in search of a blood meal, with flight activity primarily occurring during the morning and evening crepuscular periods (Rafael & Charlwood 1981, Gorayeb 1985, 2000) in both forest and pasture habitats. It can also be observed during the daytime in shaded areas (Lane 1936, Philip & Fairchild 1956). Our results showed that abundance patterns peaked during periods of higher humidity and lower light levels at dawn and dusk (Figure 2d), with strong correlations observed between abundance and temperature (r = -0.79; p = 0.001) and humidity (r = 0.79; p = 0.001).

Variability in Tabanidae activity throughout the year

The abundance of Tabanidae species varies across the seasons (Table SIII). S. bequaerti was observed predominantly during the drier months (Figure 3a), exhibiting negative correlation with precipitation (r = -0.59; p = 0.045) and humidity (r = -0.44; p = 0.152), and weak positive correlation with temperature (r = 0.27; p = 0.394; Table SIV). This species has been recorded exclusively in the state of Amazonas (Parque Nacional do Jaú), where it was dominant during the dry season (August) using suspended traps over the stream in shrubby campina areas (Henriques 2004). This trend aligns with previous findings for S. bequaerti when attacking tapirs (July – September), alligators and anacondas (July – October; Ferreira et al. 2002), and humans (August; Ferreira et al. 2010).

Figure 3
Radar chart of monthly abundance of the most abundant Tabanidae species collected from Tapirus terrestris over 12 months of study (total collection time: 312 hours). a: Stenotabanus bequaerti. b: Tabanus occidentalis. c: Phaeotabanus cajennensis. d: Chlorotabanus inanis. e: Total Tabanidae.

Tabanus occidentalis exhibited increased abundance in December (Figure 3b), correlating weakly positively with temperature (r = 0.38; p = 0.226) and negatively with precipitation (r = -0.39; p = 0.211) and humidity (r = -0.42; p = 0.177; Table SIV). Seasonal studies on the Central Amazon have shown that T. occidentalis subspecies exhibit distinct activity patterns. T. occidentalis dorsovittatus peaks in December (Rafael & Charlwood 1980) and during the dry season months (Gorayeb 1985, 2000), while T. occidentalis modestus peaks in July, both subspecies present year-round. In Mato Grosso do Sul, Barros (2001) observed T. occidentalis year-round with peaks in July, and similar patterns were noted in Rondônia (Zamarchi et al. 2023) and northern Tocantins (Costa et al. 2023). However, there is a lack of records regarding T. occidentalis on tapirs, which would be a valuable addition to further studies in this area.

Phaeotabanus cajennensis was present throughout the year, except in September and February (Figure 3c), showing negative correlation with precipitation (r = -0.10; p = 0.750) and humidity (r = -0.44; p = 0.147), and a positive correlation with temperature (r = 0.37; p = 0.238). The species exhibits a preference for large mammals (Bouvier 1952, Medem 1981, Raymond & Rousseau 1987).

Chlorotabanus inanis appeared in April, with subsequent sightings from July to February (Figure 3d), showing weak correlations with precipitation (r = -0.35; p = 0.261), humidity (r = -0.03; p = 0.930), and temperature (r = 0.12; p = 0.699). Rafael (1982) documented higher abundance of this species, particularly during the dry season in peripheral areas of Manaus (AM), revealing a negative correlation with precipitation. Gorayeb ( 1993) observed year-round occurrence with one or more peaks using equine bait in the eastern Amazon.

Tabanid Attack Behavior and Host Defense in the Amazon Rainforest

According to Baldacchino et al. (2014), factors influencing host selection include animal size and higher carbon dioxide emission, as well as feeding site preferences based on characteristics such as short hair, large size, color intensity, and glossiness. Tabanid density elicits defensive reactions in animals, such as skin trembling, leg stamping, head shaking, and tail flicking, which are used to deter tabanids (Raymond & Rousseau 1987).

Tabanidae attacks were recorded on 14 parts of the tapir’s body (Figures 4 and 5), with the hip being the most frequently targeted area (34%), followed by the flank (12%), dorsal region (9%), and snout (8%). Abundance (F₁₃,₁₄₃ = 36.50; p < 0.001) was 3 to 28 times higher in the hip (6.83 ± 9.44) than in other regions, while richness (F₁₃,₁₄₃ = 4.96; p < 0.001) was 1.4 to 11 times higher (2.25 ± 1.60). The hip provides a large, exposed feeding site with minimal defensive interference from the host. While the tapir deters attacks through head shaking and skin contractions, these behaviors are less effective in posterior regions, where visual and physical access is limited. This likely reduces disturbance and facilitates repeated feeding events by horseflies.

Figure 4
Tapir (Tapirus terrestris) body parts (a) and % of attack by various Tabanidae species (b).

Figure 5
Body parts involved in the attack on Tapiridae (Tapirus terrestris) by most abundant Tabanidae species. a: Stenotabanus bequaerti. b: Tabanus occidentalis. c: Phaeotabanus cajennensis. d: Chlorotabanus inanis. e: Total Tabanidae.

The first two CCA axes explained 50.6% of the total variation in the assemblage composition on T. terrestris (CCA1 = 33.4%; CCA2 = 17.2%; Figure 6). C. laetus and C. variegatus were strongly associated with the positive CCA1 axis, indicating a preference for ears. In contrast, P. nigriflavus, P. cajennensis, and D. falsifuscistigma exhibited strong positive associations with the CCA2 axis, reflecting a preference for the snout and forehead regions. Conversely, L. exaestuans, P. cervus, T. fortis, and S. bequaerti displayed the strongest negative associations with the CCA2 axis. Notably, the hip was the tapir´s body part that was most closely associated with the negative CCA2 axis. In addition, CCA results highlight distinct patterns of body part colonization by most abundant species (Stenotabanus bequaerti, Tabanus occidentalis, Phaeotabanus cajennensis, and Chlorotabanus inanis). The tapir’s hip and flank were the most targeted areas, predominantly by S. bequaerti and T. occidentalis, driven by their preference for high blood flow regions and accessibility. P. cajennensis exhibited a preference for the snout, while C. inanis demonstrated a broader distribution across the body.

Figure 6
Canonical correspondence analysis (CCA) of Tabanidae attack on Tapiridae (Tapirus terrestris). Tapir´s body parts: BA = Back; BE = Belly; EA = Ears; EY = Eyes; FL = Flank; FO = Forehead; FL = Fore legs; FT = Fore Thigh; HL = Hind leg; HT = Hind Thigh; HI = Hip; NE = Neck; SH = Shoulder; SN = Snout. Tabanidae species: Chal = Catachlorops halteratus; Cina = Chlorotabanus inanis; Csp1 = Chlorotabanus sp. 1; Csp2 = Chlorotabanus sp. 2; Clae = Chrysops laetus; Cvar = Chrysops variegatus; Dfal = Diachlorops falsifuscistigma; Flor = Fidena loricornis; Lexa = Leucotabanus exaestuans; Ljan = Leucotabanus janinae; Lpau = Leucotabanus pauculus; Pcaj = Phaeotabanus cajennensis; Pnig = Phaeotabanus nigriflavus; Pcer = Pityocera cervus; Sbeq = Stenotabanus bequaerti; Tang = Tabanus angustifrons; Tant = Tabanus antarcticus; Tfor = Tabanus fortis; Tocc = Tabanus occidentalis; Tpic = Tabanus piceiventris.

Tabanus species generally preferred the tapir’s posterior region for feeding (Table SV). They landed quickly and initiated feeding, often remaining mobile without noticeably disturbing the tapir. Occasionally, groups of three or four individuals feeding concurrently could agitate the animal, interrupting their feeding sessions. Gorayeb ( 1985) noted that these species synchronized their flight and landing with the movement of horses before settling to feed. In contrast, Gorayeb ( 1985) observed that T. occidentalis and other Tabanus species (e.g., T. antarcticus Linnaeus, T. fortis, T. glaucus Wiedemann, and T. piceiventris) were more efficient at landing and feeding on the legs. Guimarães et al. (2016) reported that T. occidentalis preferred to bite the lower legs and body parts of horses. Observations by Raymond & Rousseau (1987) on T. occidentalis dorsovittatus in cattle also noted attacks on the front and hind legs where the fur is shorter. More recently, Zamarchi et al. (2023) described a slightly different pattern for T. occidentalis specimens and its subspecies dorsovittatus and modestus, noting attacks on the front and hind legs as well as the ears, muzzle, chest, and belly. These varying attack sites on the tapir are likely influenced by their lack of a long tail like horses and their relatively shorter legs. This preference ensures that these Tabanus species choose sites that are less accessible on horses due to constant tail movement, which hinders immediate feeding success for most of them.

Chlorotabanus inanis (24%) targeted the tapir’s hip, flank, and belly with equal frequency (Table SV). Chlorotabanus sp. 1 and sp. 2 consistently exhibited similar landing and feeding patterns, avoiding the head and neck region (Table SV). These species often circled rapidly before settling on the belly or back, sometimes causing discomfort to the tapir, particularly when multiple individuals arrived, especially when the tapir was already somewhat fatigued. In horse, Gorayeb ( 1985) observed Ch. inanis showing a preference for the front legs, muzzle, neck, belly, and anterior and posterior thighs. Guimarães et al. (2016) reported initial hematophagy on the horse’s legs.

Phaeotabanus cajennensis showed a distinct preference for the tapir’s snout region (44%; Table SV), frequently circling swiftly before alighting. This species consistently exhibited a focused landing pattern and fed quickly, covering most of the tapir’s body except for the eyes, ears, and front legs. Multiple individuals did not attack simultaneously, and their feeding appeared to be non-disruptive. This species has been noted to preferentially target horses’ foreheads (Bouvier 1952, Gorayeb 1985) and cattle (Raymond & Rousseau 1987).

The less numerous Tabaninae species (Table SV) fed without provoking a response from the host, except for Tabanus fortis, which emitted a continuous buzzing sound upon arrival while circling the animal to locate a feeding site. Chrysopsinae species were observed making rapid movements around the head before landing and feeding on the ears, seemingly without disturbing the animal. Similar behavior was documented by Gorayeb ( 1985) for Chrysops laetus, C. variegatus (De Geer), C. incisus Macquart, and C. varians Wiedemann, which attacked the ears and nostrils of horses. Other species swiftly flew around the head to feed on their hosts in open areas; for instance, Phorcotabanus cinereus (Wiedemann) on domestic ducks (Limeira-de-Oliveira et al. 2002), T. occidentalis on alligators and anacondas (Ferreira et al. 2002). The Pangoniinae targeted the hind regions of the animal, including the belly, flank, and hip (Table SV). They approached with persistent noise before settling on the feeding site, darting back and forth as the agitated animal attempted to avoid being landed upon and fed upon. Fidena auripes Ricardo, F. eriomeroides Lutz, and F. aurulenta Gorayeb attempted to feed on horses but were unsuccessful (Gorayeb 1985). During periods of high Tabanidae density or when multiple individuals attempt to feed simultaneously, tapirs respond by contracting their skin, leaping, and seeking refuge in water to avoid attacks. Tabanidae attacks can even lead to host migration in natural conditons; for instance, the increased abundance of horseflies during the dry season at lower altitudes has been observed to drive tapirs toward higher-altitude paramos as an avoidance strategy (Acosta et al. 1996).

Little attention has been given to biological, ecological, and behavioral strategies concerning wild animals as food sources for hematophagous insects. In this study, we found that native tapirs serve as a host for various Tabanidae species in a forest clearing surrounded by primary forest in the Central Amazon. The activity of the most abundant species occurred throughout the day, peaking with rising temperatures and decreasing towards dusk, including Chl. inanis, which feeds during specific low-light periods in the morning and evening twilight. Throughout the year, these species were mainly present during months with high temperatures, aligning with the predominant seasonal dynamics in the Central Amazon. Preferences in feeding areas included the back, flank, hip, and hind leg, likely due to the tapir’s short tail. Defensive responses and escape routes observed included head shaking, skin contraction, changing location, and seeking refuge in water.

SUPPLEMENTARY MATERIAL

Table SI-SV.

Table SI-SV.

Acknowledgements

We thank the Jungle Warfare Instruction Center (Centro de Instrução de Guerra na Selva - CIGS) for permitting sample in Instruction Base (BI-2). Lieutenant Roberto Stieger provided advice, infrastructure, and support throughout the transportation period that allowed fieldwork. To João Vidal, valuable field work assistance. To Dr. Augusto Henriques for the identification and collection of the material. We also acknowledge the Programa de Pós-Graduação em Entomologia for laboratory support the fieldwork. Our gratitude to FAPEAM Programa Posgrad and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001” /Pro-equipamentos - DCEN for laboratory support. For the projects “Sistemática Integrada de Insetos Aquáticos na América do Sul” financed by MCTIC/ INPA. To Instituto Nacional de Pesquisas da Amazônia (INPA) by the laboratorial and research financial support 1995-1997, PPI 3400. To Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), by the financial support, research fellow, processes 52.1239/95-8 and 35.0677/93-0 and, research financial project 52.1239/95-8.

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Publication Dates

• Publication in this collection
  20 Oct 2025
• Date of issue
  2025

History

• Received
  22 Nov 2024
• Accepted
  24 Feb 2025