Taxonomic review of Gasterophilus (Oestridae, Gasterophilinae) of the world, with updated nomenclature, keys, biological notes, and distributions

Gasterophilus in horses from Romania: diversity, prevalence, seasonal dynamics, and distribution

This is the first study that targets the epidemiology of Gasterophilus spp. in slaughtered horses from Romania. Previously to our research, there were five recorded species: Gasterophilus haemorrhoidalis, Gasterophilus inermis, Gasterophilus intestinalis, Gasterophilus nasalis, and Gasterophilus pecorum with a dispersed distribution throughout the country, the data being recorded more than 73 years ago. The collection of Gasterophilus larvae was carried out from the digestive system (stomach, duodenum, and rectum) of horses in three abattoirs, monthly between January 2023 and December 2023. Following dissection, all larvae were stored in absolute ethanol until morphological and molecular identification. The larvae were counted and identified according to morphological keys. Overall, 394 horses were examined, of which 211 (53.6%) were infected with L2 or L3 of Gasterophilus spp. Only two species were found: G. intestinalis (prevalence 52.0%) and G. nasalis (14.0%). Coinfection with both species occurred in 49 horses (12.4%). In total, 9759 larvae were collected (7916 L3 and 1843 L2). Larvae were localized in the stomach (G. intestinalis) and duodenum (G. nasalis) of horses. There was a strong seasonal variation in the mean intensity and mean abundance for both G. intestinalis and G. nasalis larvae and also for coinfections (p < 0.05). There were no significant differences between prevalence and mean intensity across gender, group age, or horse colour. Our findings show that Gasterophilus infection is widespread within Romania territory, being a possible cause of illness and welfare issues in horses.

Gasterophilus intestinalis infestation in lion (Panthera leo) and plains zebra (Equus quagga) in the Serengeti ecosystem: Morphological and molecular profiling

This study was conducted to clarify the host specificity and the geographical distribution of Gasterophilus species (Diptera, Oestridae) in the Serengeti ecosystem. A total of 317 larvae were recovered from two common zebras (Equus quagga, formerly Equus burchellii) in Maswa Game Reserve, and 58 larvae were recovered from an African lion (Panthera leo) in the Serengeti National Park. The study emphasizes the rare occurrence of Gasterophilus sp. in lions, shedding light on the broader life cycle and physiological implications for hosts. Genetic analysis of cox2 genes from Gasterophilus species, sourced from a single geographic location, reveals significant genetic distinctions and host specificity. This study reports the first case of G. intestinalis infestation in an African lion in the Serengeti ecosystem, extending its known range from zebras and other equids, and highlighting ecological and veterinary implications. This unusual prey-predator transmission highlights the value of molecular taxonomic tools in clarifying host-parasite dynamics and guiding targeted conservation strategies.

A new bot fly species of Cuterebra (Diptera: Oestridae) from Ecuador

A new species of cuterebrine rodent bot fly, Cuterebra yanayacui sp. nov., is described from the cloud forest of Ecuador, and it is argued that the species mimics a range of aculeate hymenopterans, including euglossine orchid bees of the genera Eufriesea Cockerell and Eulaema Lepeletier and bumble bees of the subgenus Cullumanobombus Vogt. Montemyia bureni Dalmat, 1942 is proposed as a junior synonym of Cuterebra ornata Bau, 1928, syn. nov., and an updated identification key to the species of the Metacuterebra species group within Cuterebra Clark is provided. The 5'-end of the Cytochrome c oxidase subunit I gene is sequenced for the new species and compared with published Cuterebra sequences.

Developmental dynamics and survival characteristics of the common horse bot flies (Diptera, Gasterophilidae, Gasterophilus) in desert steppe

The genus Gasterophilus (Diptera, Gastrophilidae) is an obligate parasite of the equine family that causes widespread myiasis in desert steppe. Based on four common naturally excreted Gasterophilus larvae collected systematically in the Karamaili Ungulate Nature Reserve from March to September 2021, this paper studies the population dynamics and ontogenetic laws of horse flies, and discuss the coexistence pattern and population dynamics prediction of horse flies. The results showed that the Gasterophilus larvae had obvious concentrated development period, and the time of population peaks was different, the earliest was G. nigricornis (late March), followed by G. pecorum-Ⅰ (mid-April), G. nasalis (late April), G. intestinalis (early May), G. pecorum-Ⅱ (mid-August). The order of development threshold temperature "C_nigricornis < C_pecorum-Ⅰ ≤ C_pecorum-Ⅱ < C_nasalis < C_intestinalis" is consistent with the peak order of different larval populations. The life history survival rate (L) was as follows: L_nigricornis (83.97%) ≥ L_intestinalis (81.25%) > L_nasalis (72.42%) ≥ L_pecorum-Ⅱ (71.65%) > L_pecorum-Ⅰ (39.23%). This study combined indoor experiments and field surveys revealed the development of horse fly populations with different life strategies in desert grasslands. Based on the different development threshold temperatures of several horse flies, the staggered population dynamics of Gasterophilus form continuous infection stress on the host. In addition, G. pecorum exhibited a univoltine bimodal population distribution in this area and led to two high-intensity host infections, which is one of the important reasons why it has become the dominant species of myiasis in desert steppe.

Host feces, olfactory beacon guiding aggregation of intestinal parasites Gasterophilus pecorum (Diptera: Gasterophilidae)

The aim of this study was to identify the aggregation sites and transmission characteristics of Gasterophilus pecorum, the dominant pathogen of endangered equines in desert steppe. Therefore, we tested with a four-arm olfactometer the olfactory response of the G. pecorum adults to the odors that have a great impact on their life cycle, and also investigated the occurrence sites of the adults in the area where the Przewalski's horse (Equus przewalskii) roam frequently during the peak period of G. pecorum infection. The results of four-directional olfactory test showed that the fresh horse feces had a stronger attraction rate on both male (50.4%) and female flies (38.2%). Stipa caucasica, the only oviposition plant where G. pecorum lay eggs, had a better attraction effect on females than that on males. And the attraction rates of S. caucasica to G. pecorum females in the early growth stage (Stipa I) and mid-growth stage (Stipa II) were 32.8% and 36.8%, respectively. In addition, the two-directional olfactory test showed that the attraction rate of males to fresh horse feces (68.90%) was higher than that to Stipa II (31.10%), and females also showed similar olfactory responses. Moreover, in our field investigation, 68.29% of G. pecorum adults were collected from around the horse feces. The results of laboratory test and field investigation implied that the location mechanism of G. pecorum aggregation for mating is related to the orientation of horse feces. The horse feces and the vicinity are the key contamination areas of G. pecorum, and it is also the areas where horses are seriously infected with G. pecorum. Those fresh feces, which gather abundant information about the host, naturally had the greatest chance of contacting with the host; G. pecorum adults create the opportunity to enter directly into the host's mouth and infect the host by laying eggs on S. caucasica, which is the most favorite plant of the host in this area. These characteristics are one of the main reasons why G. pecorum has become the dominant species under the condition of sparse vegetation in desert steppe.

Three-dimensional characterization of first instar horse and rhinoceros stomach bot fly larvae (Oestridae: Gasterophilinae: Gasterophilus, Gyrostigma): novel morphology and evolutionary implications

Larval characters are of importance in systematic and evolutionary studies of Diptera but lag behind characters of adults due to difficulties in obtaining relevant information. Larvae of stomach bot flies are obligate parasites completing development exclusively in the alimentary tract of equids and rhinoceroses. They possess diversified morphological adaptations, providing remarkable examples to further our understanding of larval evolution. Herein, three-dimensional structures of first instar Gasterophilus pecorum and Gyrostigma rhinocerontis are compared using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). We suggest CLSM has a large potential for exploiting cryptic character systems of micro fly larvae, as spectral range and intensity of autofluorescence emitted by sclerotized structures and soft tissues are distinct, presenting a high-contrast mechanism for multistructural visualization with non-destructive sample preparation. Five new potential synapomorphies are proposed to corroborate the sister-group Gasterophilus and Gyrostigma. The upward curving mouth-hooks of first instar Gasterophilus and Gyrostigma are distinctive in Cyclorrhapha and possibly serve to facilitate the larval subcutaneous migration within the host. Three types of mouthhooks are recognized in first instar Oestridae, with the gently curved and gradually tapered type optimized as the ancestral state, from which the gasterophiline and hypodermatine types evolved independently.

Parasitic diseases of equids in Iran (1931-2020): a literature review

Parasitic infections can cause many respiratory, digestive and other diseases and contribute to some performance conditions in equids. However, knowledge on the biodiversity of parasites of equids in Iran is still limited. The present review covers all the information about parasitic diseases of horses, donkeys, mules and wild asses in Iran published as articles in Iranian and international journals, dissertations and congress papers from 1931 to July 2020. Parasites so far described in Iranian equids include species of 9 genera of the Protozoa (Trypanosoma, Giardia, Eimeria, Klossiella, Cryptosporidium, Toxoplasma, Neospora, Theileria and Babesia), 50 helminth species from the digestive system (i.e., 2 trematodes, 3 cestodes and 37 nematodes) and from other organs (i.e., Schistosoma turkestanica, Echinococcus granulosus, Dictyocaulus arnfieldi, Parafilaria multipapillosa, Setaria equina and 3 Onchocerca spp.). Furthermore, 16 species of hard ticks, 3 mite species causing mange, 2 lice species, and larvae of 4 Gastrophilus species and Hippobosca equina have been reported from equids in Iran. Archeoparasitological findings in coprolites of equids include Fasciola hepatica, Oxyuris equi, Anoplocephala spp. and intestinal strongyles. Parasitic diseases are important issues in terms of animal welfare, economics and public health; however, parasites and parasitic diseases of equines have not received adequate attention compared with ruminants and camels in Iran. The present review highlights the knowledge gaps related to equines about the presence, species, genotypes and subtypes of Neospora hughesi, Sarcocystis spp., Trichinella spp., Cryptosporidium spp., Giardia duodenalis, Blastocystis and microsporidia. Identification of ticks vectoring pathogenic parasites, bacteria and viruses has received little attention, too. The efficacy of common horse wormers also needs to be evaluated systematically.

The family Oestridae in Egypt and Saudi Arabia (Diptera, Oestroidea)

All known taxa of the family Oestridae (superfamily Oestroidea) in both Egypt and Saudi Arabia are systematically catalogued herein. Three oestrid subfamilies have been recorded in Saudi Arabia and/or Egypt by six genera: Gasterophilus (Gasterophilinae), Hypoderma, Przhevalskiana (Hypodermatinae), Cephalopina, Oestrus, and Rhinoestrus (Oestrinae). Five Gasterophilus spp. have been recorded in Egypt, namely, G. haemorrhoidalis (Linnaeus), G. intestinalis (De Geer), G. nasalis (Linnaeus), G. nigricornis (Loew), and G. pecorum (Fabricius). Only two of these species have also been recorded in Saudi Arabia, namely: G. intestinalis (De Geer) and G. nasalis (Linnaeus). The subfamily Hypodermatinae is represented in the two countries by only four species in two genera, namely, H. bovis (Linnaeus) and H. desertorum Brauer (in Egypt only), and H. lineatum (Villers) (in Saudi Arabia only) and Przhevalskiana silenus (Brauer) (in both countries). The subfamily Oestrinae is represented by two widely distributed species in both countries, namely, C. titillator (Clark) and O. ovis (L.), in addition to another species represented in Egypt only, R. purpureus (Brauer). For each species, synonymies, type localities, distribution, Egyptian and Saudi Arabian localities with coordinates, and collection dates are presented.