Biological control of sheep gastrointestinal nematodiasis in a tropical region of the southeast of Brazil with the nematode predatory fungi Duddingtonia flagrans and Monacrosporium thaumasium

Formulations in matrix of sodium alginate (pellets) of the nematode predatory fungi Duddingtonia flagrans and Monacrosporium thaumasium were evaluated in the biological control of sheep gastrointestinal nematodiasis. Three groups (1, 2, and 3), each one with eight sheep of the Santa Inês breed, at the ages of 15–48 months, were placed in paddocks of Brachiaria decumbens for 5 months. In group 1, each animal received 1 g/10 kg of live weight (l.w.) of pellets of D. flagrans (0.2 g of fungus/10 kg l.w.). In group 2, each animal received 1 g/10 kg of l.w. of pellets of the fungus M. thaumasium (0.2 g of fungus/10 kg l.w.), twice a week, for 5 months. In group 3 (control), the animals received 1 g/10 kg of live weight of pellets without fungus. The monthly averages of the egg countings per gram of feces of the animals of groups 1 and 2 treated were 71.6% and 61.1% smaller, respectively, in comparison to the animals of group 3 (control). The treatment of sheep with pellets containing the nematophagous fungi D. flagrans and M. thaumasium may be used as an alternative for the control of sheep gastrointestinal nematodiasis.     

Efficacy of Duddingtonia flagrans and Arthrobotrys robusta in controlling sheep parasitic gastroenteritis

The aim of this study was to evaluate the efficacy of formulations of sodium alginate matrix (pellets) of the nematode predatory fungi, Duddingtonia flagrans (AC001 isolate) and Arthrobotrys robusta (I-31 isolate), in the biological control of sheep gastrointestinal nematode infections. Thirty young Bergamacia ewes were allocated into three groups: In group 1 (control), the animals received 2 g/10 kg of live weight (l.w.) of pellets without fungus; in group 2, each animal received 2 g/10 kg of l.w. of pellets of D. flagrans (0.2 g of fungus/10 kg l.w.); and in group 3, each animal received 2 g/10 kg of l.w. of pellets of A. robusta (0.2 g of fungus/10 kg l.w.). The animals of each group were kept separately under rotational grazing. Pellets, with or without fungi, were mixed with 1 kg animal food and administered twice a week for 6 months. There was no significant difference in mean live weight and packed cell volume among groups (P > 0.05). Mean nematode fecal egg counts (FEC) did not significantly differ between the control and the remaining groups, except in one or two collections, when FEC was higher in the control group than in group 2 and group 3, respectively. The group that received A. robusta pellets needed less salvage anthelmintic treatments. Haemonchus contortus was the predominant species recovered from tracer lambs. The nematophagous fungi, D. flagrans and A. robusta, did not provide satisfactory results in the prophylaxis of parasitic gastroenteritis in sheep, under the conditions of the present study.     

In vitro predatory activity of nematophagous fungi and after passing through gastrointestinal tract of equine on infective larvae of Strongyloides westeri

Three isolates of predator fungi Duddingtonia flagrans (AC001), Monacrosporium thaumasium (NF34), and Arthrobotrys robusta (I-31) were assessed in in vitro test regarding the capacity of prey infective larvae (L₃) Strongyloides westeri. Compared to control, without fungus, there was a significant decrease (P < 0.01) of 80.4%, 67.9%, and 72.8% in means of infective larvae S. westeri recovered from treatments with isolates AC001, NF34, and I-31, respectively. All tested isolates were efficient in the capture of S. westeri (P > 0.01) in vitro test. Linear regression coefficients of treated and control groups were −0.21 for control, −0.32 for D. flagrans, −0.34 for M. thaumasium, and −0.22 for A. robusta. In the following, isolates AC001 and NF34 were assessed in vivo regarding the capacity of supporting the passage through equine gastrointestinal tract without loss of ability of preying infective larvae S. westeri. Fungal isolates survived the passage and were efficient in preying L₃ since the first 12 h of collection (P < 0.01) in relation to the control group (without fungus). Compared to control, there was a significant decrease (P < 0.01) of 76.4% and 76.7% (12 h), 86.4% and 85.9% (24 h), 88.3% and 87.7% (48 h), and 89.9% and 87.2% (72 h) in means of infective larvae S. westeri recovered from treatments with isolates AC001 and NF34, respectively. Linear regression coefficients of L₃ of recovered S. westeri regarding the collections due to time were 1.93 for control, −3.52 for AC001, and −2.64 for NF34. Fungi D. flagrans and M. thaumasium (NF34) have demonstrated to be promising for use in the biological control of equine parasite S. westeri.     

Resistance of different fungal structures of Duddingtonia flagrans to the digestive process and predatory ability on larvae of Haemonchus contortus and Strongyloides papillosus in goat feces

The dynamics of the passage of conidia, chlamydospores, and mycelia of the fungus Duddingtonia flagrans through the digestive tracts of goats was evaluated. Four groups with five goats each were formed. In the group conidia, each animal received 1 × 10⁶ D. flagrans conidia per kilogram of live weight. In the group chlamydospore, each animal received 1 × 10⁶ chlamydospores per kilogram of live weight. In the group mycelia, each animal received 1 g of mycelium mass per kilogram of live weight. In the control group, the animals received no fungal structure. Feces were obtained 3 h before and 12, 24, 30, 36, 42, 48, 60, 72, 84, and 96 h after the inoculation. The feces were placed in Petri dishes containing water-agar. The Petri dishes were examined to detect the fungus and trapped nematodes. A second trial evaluated the effect of the fungal structures on the number of gastrointestinal larvae of Haemonchus contortus and Strongyloides papillosus harvested from the fecal cultures of the goats. The feces were obtained from the goats in the 12–24, 24–30, 30–36, 42–48, 60–72, 72–84, and 84–96 intervals after the inoculation. D. flagrans survived the digestive process of the goats and maintained its predatory activity, being observed from 12 to 96 h before inoculation in the animals that received chlamydospores and conidia.     

Predatory activity of the fungus <Emphasis Type="Italic">Duddingtonia flagrans</Emphasis> in equine strongyle infective larvae on natural pasture in the Southern Region of Brazil

Biological control is an alternative method to reduce the population of parasites through natural predators. A promising option of biological control in the reduction of infective larvae on pasture is the use of nematophagous fungi. In this study, the efficacy of the nematophagous fungus Duddingtonia flagrans in controlling gastrointestinal nematode parasites in field-raised horses was tested. Ten foals with an average age of 12 months were divided in two groups: five males constituted the treated group and five females constituted the control group. Each group was introduced in a field of mixed pasture with approximately 5 ha. The treated group received the fungus D. flagrans at a concentration of 10⁶ chlamydospores per kilogramme of animal body weight daily, mixed with horse food for 5 months. The control group did not receive the fungus. Samples were collected to perform eggs per gramme (EPG) counts weekly. Coproculture and collection of pasture were done monthly for larvae counting. No significant difference was observed in the EPG counting and in the number of larvae recovered from coprocultures, where cyathostomines, Strongylus and Trichostrongylus spp. were found after monthly larvae counting. No significant difference was observed in the EPG counts, and Trichostrongylus sp. was identified. The number of recovered larvae on pasture was significantly lower in the treated group in the last month of treatment, showing a reduction of 73.5% (p < 0.05). As such, the fungus was able to reduce the number of infective larvae in the pasture. Nevertheless, this did not reflect in a decrease of parasitic infection during the 5-month study period.     

Growth rate and trapping efficacy of nematode-trapping fungi under constant and fluctuating temperatures

The effect of temperature on radial growth and predatory activity of different isolates of nematode-trapping fungi was assessed. Four isolates of Duddingtonia flagrans and one isolate of Arthrobotrys oligospora were inoculated on petri dishes containing either corn-meal agar (CMA) or faecal agar and then incubated for 14 days under three different constant and fluctuating temperature regimes. The radial growth was similar on the two substrates at each temperature regime. All fungal isolates showed a higher growth rate at a constant 20 °C. At 10° and 15 °C, all D. flagrans isolates showed very similar patterns of radial growth at both constant and fluctuating temperatures. At 20 °C, they grew significantly faster at constant than at fluctuating temperatures. A. oligospora grew significantly faster than all D. flagrans isolates except when incubated at a fluctuating 20 °C. Spores of each fungal isolate were added to faecal cultures containing eggs of Cooperia oncophora at a concentration of 6250 spores/g faeces. The cultures were incubated for 14 days at the same temperature regimes described above. Control faeces (without fungal material) were also cultured. More larvae were recovered from the fungus-treated cultures incubated at a constant 10° or 15 °C than from those incubated at the respective fluctuating temperatures, except for one D. flagrans isolate. Incubation at 20 °C showed the opposite effect. The general reduction observed in the number of nematode larvae due to fungal trapping was 18–25% and 48–80% for a constant and fluctuating 10 °C, 70–96% and 93–95% for a constant and fluctuating 15 °C, and 63–98% and 0–25% for a constant and fluctuating 20 °C, respectively. Received: 15 December 1998 / Accepted: 16 February 1999     

Morphological and molecular evidence for a new species of the genus <Emphasis Type="Italic">Raphidascaris</Emphasis> (Nematoda: Anisakidae) from marine fishes from the South China Sea

A new anisakid nematode, Raphidascaris (Ichthyascaris) longispicula sp. nov., is described from the intestine and stomach of the marine fish Uroconger lepturus (Richardson) (Anguilliformes: Congridae) from the South China Sea (Guangdong and Hainan Province, respectively). The new species differs from all congeners in the subgenus Ichthyascaris by the short ventricular appendix (0.36–0.49 mm long), the number and arrangement of caudal papillae (25–28 pairs of preanal, 1–2 pairs of paranal, and 6–8 pairs of postanal), and the very long spicules (1.13–1.32 mm long, representing 9.34–10.3% of body length). The sequences of the internal transcribed spacer of ribosomal DNA of R. (I.) longispicula sp. nov. are analyzed and compared with the closely related nematode sequences. Molecular analyses seem to support the validity of this new nematode species based on morphological observation.     

Efficacy of an energy block containing Duddingtonia flagrans in the control of gastrointestinal nematodes of sheep

The efficacy of the nematode-trapping fungus Duddingtonia flagrans incorporated into an energy block was evaluated for the control of gastrointestinal nematodes in sheep. Four naturally parasitised sheep with average nematode egg counts of 2,470 eggs per gram grazed by pairs on two similar parasite-free paddocks for 30 days. During that period, one pair of sheep (treated animals, T1) received an energy block containing chlamydospores of D. flagrans at a dose of 200,000 chlamydopores/kg bw/day, while the second pair (control animals, C1) received a fungus-free energy block. The animals in both groups were taken off the paddocks after contaminating the pastures for a month with either nematode eggs plus fungal chlamydospores (T1) or nematode eggs alone (C1). Twelve parasite-free sheep were divided into two groups of six animals each, the treated group (T2) was placed on the paddock previously contaminated with parasites and fungus, while the control group (C2) was placed on the parasite-only paddock. These two groups grazed on their respective paddocks during 30 days and were then housed for 15 days, after which period they were slaughtered in order to determine the parasite burden present in each animal. Results showed that animals in group T2 harboured significantly less nematodes than their counterpart in group C2. The efficacy of D. flagrans was 92% against the total parasite burden, 100% against Haemonchus contortus and Teladorsagia circumcincta, 89.9% against Trichostrongylus colubriformis, 87.5% against Cooperia onchopora, and 90% against Trichostrongylus axei. No efficacy was detected against Nematodirus spathiger, Trichuris ovis and T. skrjabini.     

In vitro evaluation of physicochemical variables on the nematophagous fungus Duddingtonia flagrans

Duddingtonia flagrans is a biological alternative to the use of anthelmintic drugs in ruminants. This fungus must be ingested by the animal, pass through the cavities of the digestive tract and reach the feces where it develops traps that capture the nematodes. The severe conditions encountered in this process negatively affect the fungus, which is reflected in the low recovery rates compared to the amount administered. The aim of this study was to evaluate independently the in vitro effect of typical physical and chemical conditions of the gastrointestinal cavities of ruminants on the concentration, viability, and the in vitro nematode predatory ability of the chlamydospores of D. flagrans. The factors evaluated individually were pH (2, 6, and 8), temperature (28 ± 2°C and 39 ± 2°C), exposure to artificial saliva, and milling. The results showed that the concentration and viability of D. flagrans were not affected by the action of pH, temperature, milling, or exposure to artificial saliva. Regarding the in vitro nematode predatory ability, a reduction was observed after the milling process and the exposure for 24 h at different pH.     

Morphological variability,molecular phylogeny,and biological characteristics of the nematophagous fungus Duddingtonia flagrans

This study aims to investigate the molecular phylogenetic analysis, morphological variability, nematode‐capturing ability, and other biological properties of Chinese Duddingtonia flagrans isolates. We isolated 13 isolates of D. flagrans and found features that have never been reported before, such as two to three septa incluing club‐shaped conidia. Meanwhile, we conducted molecular phylogenetic analysis of the seven isolates and tested the radical growth of the isolates under different pH values, temperatures, and media. The capturing ability against infective larvae (L3) of Cooperia spp. in yak was detected in vitro. Finally, one isolate was selected for scanning electron microscopy (SEM) to investigate the trap formation process. The fungal sequence was obtained and submitted to GenBank (Accession no. KY288614.1, KU881774.1, KP257593.1, KY419119.1, MF488979.1, MF488980.1, and MF488981.1), and the tested isolates were identified as D. flagrans. Except for three isolates, the radial growth of the other isolates on 2% corn meal agar and 2% water agar exhibited faster growth than on other media. The fungus could not grow at 10 and 40°C but grew within 11 to 30°C. Moreover, it did not grow at pH 1–3 and 13–14, but instead at pH 4–12. In the in vitro experimental, L3s were reduced by 94.36%, 88.15%, and 91.04% for SDH035, DH055, and F088, respectively. SEM results showed that at 8 hr post addition of nematodes, some of the latter were captured. In the later stages of the interaction of the fungus with nematodes, a large number of chlamydospores were produced, especially on the predation trap. Results of the present study provided information about the molecular phylogenetic analysis, morphological variability, nematode‐capturing ability, and other biological properties of Chinese Arthrobotrys flagrans isolates before administering them for biocontrol.     

In vitro evaluation of the effect of the nematophagous fungi Duddingtonia flagrans, Monacrosporium sinense, and Pochonia chlamydosporia on Ascaris suum eggs

The in vitro effect of four isolates of the nematophagous fungi Duddingtonia flagrans (AC 001), Monacrosporium sinense (SF 53), and Pochonia chlamydosporia (VC 1 and VC 4) on eggs of Ascaris suum was evaluated. One hundred thousand A. suum eggs were plated on 2% water–agar with the grown isolates and control without fungus. After 7, 14, and 21 days, 100 eggs were removed and classified according to the following parameters: type 1, lytic effect without morphological damage to eggshell; type 2, lytic effect with morphological alteration of embryo and eggshell; and type 3, lytic effect with morphological alteration of embryo and eggshell, besides hyphal penetration and internal egg colonization. P. chlamydosporia showed ovicidal activity (p < 0.01), mainly of the type 3 effect, on A. suum eggs in the studied intervals of 13.3% (isolate VC 1) and 17.3% (isolate VC 4), 13.9% (VC 1) and 17.7% (VC 4), and 19% (VC 1) and 20% (VC4), respectively, at 7, 14, and 21 days. The other fungi showed no type 3 effect. P. chlamydosporia is a potential biological control agent of A. suum eggs.     

Power-cadence relationship in endurance cycling

In maximal sprint cycling, the power–cadence relationship to assess the maximal power output (P _max) and the corresponding optimal cadence (C _opt) has been widely investigated in experimental studies. These studies have generally reported a quadratic power–cadence relationship passing through the origin. The aim of the present study was to evaluate an equivalent method to assess P _max and C _opt for endurance cycling. The two main hypotheses were: (1) in the range of cadences normally used by cyclists, the power–cadence relationship can be well fitted with a quadratic regression constrained to pass through the origin; (2) P _max and C _opt can be well estimated using this quadratic fit. We tested our hypothesis using a theoretical and an experimental approach. The power–cadence relationship simulated with the theoretical model was well fitted with a quadratic regression and the bias of the estimated P _max and C _opt was negligible (1.0 W and 0.6 rpm). In the experimental part, eight cyclists performed an incremental cycling test at 70, 80, 90, 100, and 110 rpm to yield power–cadence relationships at fixed blood lactate concentrations of 3, 3.5, and 4 mmol L⁻¹. The determined power outputs were well fitted with quadratic regressions (R ² = 0.94–0.96, residual standard deviation = 1.7%). The 95% confidence interval for assessing individual P _max and C _opt was ±4.4 W and ±2.9 rpm. These theoretical and experimental results suggest that P _max, C _opt, and the power–cadence relationship around C _opt could be well estimated with the proposed method.     

Length Adaptation of the Passive-to-Active Tension Ratio in Rabbit Detrusor

The passive and active length–tension (L–T _p and L–T _a) relationships in airway, vascular, and detrusor smooth muscles can adapt with length changes and/or multiple contractions. The present objectives were to (1) determine whether short-term adaptation at one muscle length shifts the entire L–T _a curve in detrusor smooth muscle (DSM), (2) compare adaptation at shorter versus longer lengths, and (3) determine the effect of adaptation on the T _p/T _a ratio. Results showed that multiple KCl-induced contractions on the descending limb of the original L–T _a curve adapted DSM strips to that length and shifted the L–T _a curve rightward. Peak T _a at the new length was not different from the original peak T _a, and the L–T _p curve shifted rightward with the L–T _a curve. Multiple contractions on the ascending limb increased both T _a and T _p. In contrast, multiple contractions on the descending limb increased T _a but decreased T _p. The T _p/T _a ratio on the original descending limb adapted from 0.540 ± 0.084 to 0.223 ± 0.033 (mean ± SE, n = 7), such that it was not different from the ratio of 0.208 ± 0.033 at the original peak T _a length, suggesting a role of length adaptation may be to maintain a desirable T _p/T _a ratio as the bladder fills and voids over a broad DSM length range.     

How the vestibular system modulates tactile perception in normal subjects: a behavioural and physiological study

Caloric vestibular stimulation (CVS) is a physiological technique demonstrated to transiently improve hemianaesthesia in right brain-damaged patients (Bottini et al. in Exp Brain Res 99(1):164–169, 1994, Nature 376:778–781, 1995, Neurology 65(8):1278–1283, 2005). Recent studies suggest that these effects are based on the anatomical overlapping between vestibular and tactile projections (Bottini et al. in Nature 376:778–781, 1995) in the human brain. However, much less is known about behavioural effects of this manipulation on normal subjects. We aimed to explore tactile perception during left ear CVS in normal subjects. We administered seventeen right-handed normal subjects with different types of tactile stimuli (above and below threshold) during left ear CVS. To further ensure standardized procedure, tactile stimulation was delivered through a tool-developed ad hoc for the experiment. The experiment was divided in 3 conditions: (1) Baseline, (2) PostCVS and (3) Delayed CVS. We found a main effect of stimulus type (F _(2,32) = 907.712; P = 0.000) and condition (F _(2,32) = 55.505; P = 0.000). Moreover, post hoc comparisons revealed that below threshold stimuli are most affected by CVS (t ₍₁₆₎ = −11.213; P = 0.000). Left ear CVS modulates tactile perception also in normal subjects. Moreover, this modulation seems to be selective for below threshold stimuli and not caused by attentive processes. A multisensory phenomenon is possibly the best explanation for this interaction between touch and vestibular systems, corroborated also by the anatomical evidence and by the previous knowledge about interaction with the environment.     

Mechanical recovery of inhibited cyathostomin larvae from equine intestinal tissue

The Stomacher? is very widely used in food and medical research for extracting tissues. To determine whether nematode larvae were disrupted by the Stomacher?, L₃ larvae of Haemonchus contortus were homogenised for up to 40 min at full power but no larval disruption occurred. Therefore, tissue from the mucosa and submucosa of the caecum of horses collected from a licenced abattoir was treated to determine whether inhibited cyathostomin larvae could be extracted. The optimum time on full power for a 10-g sample was 20 min, and in three out of five caecal samples from different horses, significantly more larvae were recovered than with 6 h pepsin HCl digestion. It is concluded that the Stomacher? provides a simple fast method of extracting inhibited nematode larvae from gastrointestinal tissues in the horse that could replace digestion with pepsin HCl.     

Adulticidal and larvicidal activity of Beauveria bassiana and Metarhizium anisopliae against housefly, Musca domestica (Diptera: Muscidae), in laboratory and simulated field bioassays

The susceptibility of the adult and larval stage of housefly, Musca domestica L. (Diptera: Muscidae), to two entomopathogenic fungi, Metarhizium anisopliae (Metsch.) Sor. and Beauveria bassiana (Bals.) Vuill., was evaluated under laboratory and simulated field bioassays. Bioassays on adult houseflies were carried out at different conidial concentrations ranging from 10³ to 10⁹ conidia/ml in petri plate and minichamber assays. Absolute mortality was observed within 4–5 days at all the concentrations tested. M. anisopliae was found to be more effective with LC₅₀ of 6.75 × 10⁷ conidia/ml compared with 1.21 × 10⁸ conidia/ml of B. bassiana in petri plate bioassay. Similar trend was observed in minichamber bioassay. Larvicidal activity evaluated through petri plate bioassay also indicated that M. anisopliae was more effective larvicide with LC₅₀ of 4.1 × 10⁸ conidia/ml as against 3.31 × 10⁹ conidia/ml of B. bassiana. Larvicidal activity was further evaluated in simulated field condition of decaying waste matrix using dry conidial formulations (10⁸ conidia/g) of both the fungi. Larval mortality obtained in this assay was 43% (B. bassiana) and 63% (M. anisopliae). Remarkably better performance of M. anisopliae as an adulticidal and larvicidal agent over B. bassiana in laboratory bioassays as well as simulated field conditions suggests that it may have good potential to become part of an integrated housefly control program.     

<Emphasis Type="Italic">Angiostrongylus costaricensis</Emphasis> (Nematoda: Protostrongylidae): migration route in experimental infection of <Emphasis Type="Italic">Omalonyx</Emphasis> sp. (Gastropoda: Succineidae)

Angiostrongylus costaricensis can infect several mollusks, and its migration route in intermediate hosts has been studied only in Sarasinula marginata. To verify the susceptibility of Omalonyx sp. as an intermediate host of A. costaricensis and to analyze the nematode migration route, individuals were infected with stage 1 larvae. Obtained stage 3 larvae were orally inoculated in mice, and after 30 days, adult worms and stage 1 larvae were recovered, demonstrating Omalonyx susceptibility and suitability to infection. To define the parasite migration routes, specimens of Omalonyx with 30 min, 1 h, 2 h, 4 h, 6 h, 8 h, 2 days, 5 days, 10 days, 12 days, 15 days, 20 days, 21 days, 25 days, 28 days, and 30 days of infection were fixed and serially sectioned. Histological sections were stained with hematoxylin–eosin. The results were compared to those described in S. marginata. Oral and cutaneous infections were noted. After the penetration, larvae were retained, mainly in the fibromuscular tissue, by hemocytes, or they spread to the whole organism through the circulation, following the anatomical structure of the vasculature. The perilarval hemocyte reaction in Omalonyx was more intense until stage 2 larva instar, decreasing in the presence of stage 3 larvae. Differences in some aspects of hemocyte reaction between S. marginata and Omalonyx exemplify interspecific peculiarities in snail response to the same parasite. Fapemig, FIOCRUZ, and Pibic UFMG.     

Pre-dive normobaric oxygen reduces bubble formation in scuba divers

Oxygen pre-breathing is routinely employed as a protective measure to reduce the incidence of altitude decompression sickness in aviators and astronauts, but the effectiveness of normobaric oxygen before hyperbaric exposure has not been well explored. The objective of this study was to evaluate the effect of 30-min normobaric oxygen (O₂) breathing before diving upon bubble formation in recreational divers. Twenty-one subjects (13 men and 8 women, mean age (SD) 33 ± 8 years) performed random repetitive open-sea dives (surface interval of 100 min) to 30 msw for 30 min with a 6-min stop at 3 msw under four experimental protocols: “air–air” (control), “O₂–O₂”, “O₂–air” and “air–O₂” where “O₂” corresponds to a dive with oxygen pre-breathing and “air” a dive without oxygen administration. Post-dive venous gas emboli were examined by means of a precordial Doppler ultrasound. The results showed decreased bubble scores in all dives where preoxygenation had taken place (p < 0.01). Oxygen pre-breathing before each dive (“O₂–O₂” condition) resulted in the highest reduction in bubble scores measured after the second dive compared to the control condition (–66%, p < 0.05). The “O₂–air” and “air–O₂ “conditions produced fewer circulating bubbles after the second dive than “air–air” condition (–47.3% and –52.2%, respectively, p < 0.05) but less bubbles were detected in “air–O₂ “condition compared to “O₂–air” (p < 0.05). Our findings provide evidence that normobaric oxygen pre-breathing decreases venous gas emboli formation with a prolonged protective effect over time. This procedure could therefore be beneficial for multi-day repetitive diving.     

Infection of Anopheles gambiae mosquitoes with entomopathogenic fungi: effect of host age and blood-feeding status

Physiological characteristics of insects can influence their susceptibility to fungal infection of which age and nutritional status are among the most important. An understanding of host–pathogen interaction with respect to these physiological characteristics of the host is essential if we are to develop fungal formulations capable of reducing malaria transmission under field conditions. Here, two independent bioassays were conducted to study the effect of age and blood-feeding status on fungal infection and survival of Anopheles gambiae s.s. Giles. Mosquitoes were exposed to 2 × 10¹⁰ conidia m⁻² of oil-formulated Metarhizium anisopliae ICIPE-30 and of Beauveria bassiana I93-825, respectively, and their survival was monitored daily. Three age groups of mosquitoes were exposed, 2–4, 5–8, and 9–12 days since emergence. Five groups of different feeding status were exposed: non-blood-fed, 3, 12, 36, and 72 h post-blood feeding. Fungal infection reduced the survival of mosquitoes regardless of their age and blood-feeding status. Although older mosquitoes died relatively earlier than younger ones, age did not tend to affect mosquito susceptibility to fungal infection. Non-blood-fed mosquitoes were more susceptible to fungus infection compared to all categories of blood-fed mosquitoes, except for those exposed to B. bassiana 72 h post-blood feeding. In conclusion, formulations of M. anisopliae and B. bassiana can equally affect mosquitoes of different age classes, with them being relatively more susceptible to fungus infection when non-blood-fed.     

Contamination of the environment by strongylid (Nematoda: Strongylidae) infective larvae at horse farms of various types in Ukraine

Analysis of the influence of horse-keeping conditions by contamination of the environment (pastures, paddocks, and stalls) by the strongylid infective larvae (L₃) was carried out at various types of horse farms, hippodromes, and riding clubs in Ukraine. A total of 1,237 horses from three types of horse-keeping conditions were examined. Epidemiological studies of stall and grazing area (pasture and paddocks) contamination by L₃ were performed at hippodrome (stalled horse-keeping) and horse farms with stall/paddock-keeping and stall/pasture-keeping conditions. Grass and stall litter samples were examined by the Baermann procedure. It was found that horses of stall-keeping conditions had the lowest level of strongylid infection (prevalence 46.4–77.8%, average infection 25.6–92.9 eggs per gram of feces (EPG)) and lowest proportion of large strongyle L₃ in coprocultures (1.6–11.3%). Horses of stall/pasture-keeping conditions were the most infected (prevalence 95.1–100%, average infection 198.2–453.7 EPG), and the proportion of large strongyle L₃ was 17.3–24.7%. Strongyle L₃ were found in litter of all parts of individual stalls; areas at the stall center, “toilet”, and entrance were the most contaminated. The highest L₃ number in stall litter was registered in summer. Contamination of permanent pasture grass by L₃ was notably lower than grass in paddocks (86.3–161.4 L₃/kg compared with 305.9–409.1 L₃/kg). The highest level of pasture grass contamination was observed in the middle of summer (July)—up 970.7 L₃/kg. The results obtained confirmed importance of environmental contamination in epidemiology of horse strongylidosis at various types of horse-keeping conditions.