Number Of Infective Larvae Research Articles

First Record of Microsporidia Infection in the Damselfly Ischnura elegans Larvae: Temperature and Predator Cue Effects on the Host’s Life History

Here, we report, for the first time, a microsporidian infection in laboratory-reared larvae of the damselfly Ischnura elegans. Infected larvae originated from field-collected adult females, which were caught in southern Poland in August 2020 (the second half of the flight season). Higher rearing temperatures and the presence of predator cues from the invasive alien signal crayfish (Pacifastacus leniusculus) increased the number of infected larvae. Infected larvae had distorted wing development, and all individuals died before emergence. Hence, microsporidian infection in I. elegans larvae impacted damselfly morphology and life history. We propose that warming temperature and stress caused by non-consumptive effects triggered by invasive alien predators are possible factors that produce negative fitness consequences following microsporidian infection in a key amphibious ectotherm.

Field Efficacy of Metarhizium rileyi Applications Against Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize.

The efficacy of the fungus Metarhizium rileyi (Farlow) Kepler, S. A. Rehner & Humber (Hypocreales: Clavicipitaceae) against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and the impact on the community of epigeans predators as well as the natural occurrence of native fungal strains were evaluated after sequential sprays in maize. In the first season, the infestation was lower than 0.2 larvae per plant throughout the three fungal sprays and no significant difference was observed in the number of infected larvae among treatments. In the second season, insect population reached an average of 0.8 larvae per plant between the second and third sprays and the number of larvae succumbed by M. rileyi was higher in fungal-treated plots in the following weeks. Molecular characterization of the collected isolates on mummified larvae revealed the introduction of a new isolate did not eliminate the native strain on the fungal-treated plots. In both seasons, the diversity and abundance of predator species in the plots were not affected by any of the treatments. We showed that applications of selected strains of M. rileyi early in the season have no significant impact on the occurrence of natural enemies in maize.

Correlation of subclinical gastrointestinal nematode parasitism with growth and reproductive performance in ewe lambs in Ontario

Infection with gastrointestinal nematode parasites (GINs) is an important cause of productivity loss on sheep farms in Ontario and worldwide. However, efforts to quantify the effect of GIN infection on growth have demonstrated mixed results. Furthermore, there has been limited investigation of their effect on reproductive performance. This study evaluated the effect of subclinical GIN parasitism on growth and reproductive performance of ewe lambs under Ontario grazing conditions. Rideau cross ewe lambs (n = 140) born in spring 2016 on a farm in central Ontario were followed for two years from before weaning through to November 2017, including their first lambing and lactation. These animals grazed from May to November of each year and were sampled every 6−8 weeks during both grazing seasons and once at mid-gestation in March 2017. At each sampling the ewe lambs were weighed, body condition scores assigned, fecal egg counts (FECs) performed, and pasture samples collected to assess number of infective GIN larvae. Study animals with a FEC of 500 eggs per gram or higher were selectively treated with anthelmintics to prevent morbidity and mortality. Fecal samples were cultured to determine infecting GIN species, and climate data were obtained from a weather station 26 km away from the farm. Precipitation levels and numbers of infective larvae on pasture were low during the first grazing season but were more typical of Ontario conditions in the second grazing season. The three most common GIN species were Haemonchus contortus, Teladorsagia circumcincta, and Trichostrongylus spp. General linear mixed models were generated for weight change over time, litter size at lambing, and weaning weights of offspring. Despite moderate peak GIN burdens in both grazing seasons, FEC was not significantly associated with weight change or litter size, apart from periparturient egg rise in study ewe lambs with larger litters (p = 0.05). Significant positive quadratic and negative linear associations were identified between late lactation FECs and offspring weaning weights; the association between FECs and weaning weights changed from negative to positive at a FEC of 361 eggs per gram. These results indicate that when GIN burdens are moderate as evidenced by fecal egg counts and infection is subclinical, there appears to be low to no impact on growth and reproductive performance in ewe lambs in the first 18 months of life. This suggests that when GIN parasitism is regularly monitored and controlled using targeted selective treatment, animal performance is minimally affected.

Climate change is likely to increase the development rate of anthelmintic resistance in equine cyathostomins in New Zealand

Climate change is likely to influence livestock production by increasing the prevalence of diseases, including parasites. The traditional practice of controlling nematodes in livestock by the application of anthelmintics is, however, increasingly compromised by the development of resistance to these drugs in parasite populations. This study used a previously developed simulation model of the entire equine cyathostomin lifecycle to investigate the effect a changing climate would have on the development of anthelmintic resistance. Climate data from six General Circulation Models based on four different Representative Concentration Pathways was available for three New Zealand locations. These projections were used to estimate the time resistance will take to develop in the middle (2040–49) and by the end (2090–99) of the century in relation to current (2006–15) conditions under two treatment scenarios of either two or six yearly whole-herd anthelmintic treatments. To facilitate comparison, a scenario without any treatments was included as a baseline. In addition, the size of the infective and parasitic stage nematode population during the third simulation year were estimated. The development of resistance varied between locations, time periods and anthelmintic treatment strategies. In general, the simulations indicated a more rapid development of resistance under future climates coinciding with an increase in the numbers of infective larvae on pasture and encysted parasitic stages. This was especially obvious when climate changes resulted in a longer period suitable for development of free-living parasite stages. A longer period suitable for larval development resulted in an increase in the average size of the parasite population with a larger contribution from eggs passed by resistant worms surviving the anthelmintic treatments. It is projected that climate change will decrease the ability to control livestock parasites by means of anthelmintic treatments and non-drug related strategies will become increasingly important for sustainable parasite control.

Saccharomyces cerevisiae (YT001) supplementation for the control of Haemonchus contortus and modulation of the immune response of sheep.

Studies aiming at the development and evaluation of alternative methods to minimise losses caused by the gastrointestinal nematode Haemonchus contortus are extremely important. Such research is essential, given the high morbidity rates among sheep and the significant mortality rates of lambs, allied to the low efficacy of commercial products for the control of this parasite. The purpose of this study was to evaluate the effect of the Saccharomyces cerevisiae (YT001 - YEASTECH) on the control of H. contortus and its modulation of the immune response in experimentally infected sheep. Eighteen sheep were divided into two groups. Group 1, the control group, comprised animals infected with H. contortus and supplemented with distilled water, while Group 2, the treated group, consisted of animals infected and supplemented with S. cerevisiae (400 million cfu/day of suspension for 49 days). The following parasitological parameters were evaluated: number of eggs per gram of faeces, number of infective larvae (L3) recovered per faecal culture, and parasitic load of the abomasum. The following immunological parameters were quantified: immunoglobulin (Ig)A in the mucous secretions and serum IgG; cytokines interleukin (IL)-4, IL-5 and IL-10; number of eosinophils in the abomasal mucosa and groups of cells positive for the markers: MHCII, CD4+CD25+, CD5+CD8+, WC4, CD5+CD4+, CD8+CD11b+ and CD5+WC1 by whole blood flow cytometry. The results revealed a significant decrease (P<0.05) in the number of larvae and significantly higher serum IgG levels (P<0.05) in the group supplemented with S. cerevisiae. The supplemented animals showed significantly larger numbers of eosinophils (P<0.05), as well as more cells positive for MHCII, CD4+CD25+, CD5+CD8+ than the control animals. This study confirmed the beneficial action of S. cerevisiae on the host immune response to H. contortus, as evidenced mainly by the smaller number of L3 recovered from the faeces of sheep supplemented with S. cerevisiae.

Biological control on gastrointestinal nematodes in cattle with association of nematophagous fungi

ABSTRACTThis study aimed to evaluate the efficacy of the association of the nematophagous fungi (Duddingtonia flagrans-AC001); (Pochonia chlamydosporia-VC4) and (Arthrobotrys robusta-I31) in a pelletised formulation of a sodium alginate matrix. The viability and activity of pellet germination and fungal activity (after encapsulation) were evaluated using in vitro and in vivo tests. Next, 12 heads of cattle, Dutch mestizo x zebu, with an average age of 12 months were dewormed with an anthelmintic. Next, 20 days after treatment with the anthelmintic, the animals were randomly divided into two groups of six animals each, and placed in two paddocks with 7.0 ha each of Brachiaria decumbens with historical grazing by animals naturally infected by gastrointestinal nematode parasites. At first, each animal was treated with 2 g of pellets per 10 kg of animal, containing the associated fungi (AC001 + VC4 + I31) administered twice a week in conjunction with commercial feed. Each animal in the control group received 2 g of pellets without mycelia added to the feed. The percentage reduction of infective larvae in the in vitro test was 94% (p < .01). In the in vivo test, the treated animals with fungal association had lower egg counts per gram of faeces (p < .01) compared to the control group animals – a reduction of 91.8%. The reduction in the number of infective larvae recovered from the pasture was 27.5% at a distance of 0–20 cm from the stool bulk, and 26.7% at a distance of 20–40 cm. This association (AC001 + VC4 + I31) of nematophagous fungi was effective in nematode control.

Effect of the integrated livestock–forest system on recovery of trichostrongylid nematode infective larvae from sheep

Trichostrongylids nematodes are capilliform worms that parasitize the gastrointestinal tract of ruminants that frequently cause serious injuries such as severe gastroenteritis and acute anemia. Sheep breeds are highly susceptible to these parasites, including adult animals as well. In sheep herds, this parasitic disease is traditionally controlled through the use of antihelminthics; however, some possible auxiliary methods of control have been suggested, and among them is the adoption of the integration livestock–forest system. The aim of the present study was to evaluate comparatively the recovery of trichostrongylid nematode larvae (L3) from sheep in a integration livestock–forest system and in grass monoculture, also analyzing the climatic influence in the four seasons of the year. The study was carried out from December 2013 to September 2014 in the experimental field of Embrapa Agrosilvopastoral located in the municipality of Sinop/MT, Brazil. In each season of the year, each treatment received thirty samples of feces weighing 20 g and containing approximately 60,000 eggs of trichostrongylid nematodes. At the end of 14 days, the remaining feces from the soil surface, as well as soil below the deposition area, and the adjacent forage near the feces were collected and taken to the laboratory where the number of infective larvae per kilogram of dry matter (L3/kg DM) in each collected material was determined. The recovery of L3 larvae was possible in all seasons and in all samples collected. There was a significant interaction between treatments and seasons of the year (p < 0.05). The silvopastoral system showed greater counts of L3/kg DM in the forage during the spring, summer, and winter collections. The feces collected in the winter were the material with highest counts of L3/kg DM in the study, with 30,199 in silvopastoral area, and 22,020 in grass monoculture, which differed significantly (p < 0.05). The soil also showed the same response, with 6112.74 L3/kg DM in silvopastoral system and 4847.56 L3/kg DM in grass monoculture, which were also significantly different (p < 0.05).

Duddingtonia flagrans in the control of gastrointestinal nematodes of horses

Horses can harbor a large amount of parasites that may cause serious clinical signs even death. The aim of this study was to evaluate the predatory activity of the fungus Duddingtonia flagrans against infective larvae (L3) of gastrointestinal nematodes of horses in fecal culture. The experimental design was completely randomized with three treated groups (G1, G2 and G3) and one control (CG), using eight animals/group. The treated animals received G1: 1.5 × 105; G2: 3 × 105 and G3: 6 × 105 chlamydospores of D. flagrans/kg body weight during 21 days. The fungi preparation was given at every other three-day interval. Faecal samples were collected during 30 days, on the same interval, to perform the fecal egg counts (EPG) and fecal culture for each horse. All groups demonstrated similar results for the EPG (P > 0.05) counts. D. flagrans significantly reduced (P < 0.05) the number of infective larvae after 72 h-interval between treatments. The G2 and G3 promoted higher results (P < 0.05) of L3 reduction compared to the CG. The biological control with the predacious fungi D. flagrans is still a promising free-living parasite regulator alternative to be use in livestock.

Differences between female and castrated male lambs in susceptibility to natural, predominantly Teladorsagia circumcincta infection

The difference between castrated male lambs and entire female lambs in susceptibility to gastrointestinal nematode infection was investigated in a flock of Scottish Blackface sheep. Castrated male lambs had higher faecal egg counts, higher body weights, lower parasite-specific plasma IgA activity and more adult nematodes. There were no detectable differences in the length of adult Teladorsagia circumcincta. Heavier egg shedding by males was associated with greater worm burdens. The difference in plasma IgA activity may have been a consequence of larger numbers of adult nematodes inhibiting the transfer of mucosal IgA to the plasma. At least part of the sex difference in egg production could be a consequence of males ingesting larger amounts of grass and hence numbers of infective larvae because of their larger size. The differences between castrated males and females contribute to the observed variation in nematode egg production in naturally infected lambs.

Entomopathogenic fungi isolated in the vicinity of Szczecin

The spectrum and occurrence of entomopathogenic fungi in litter beech forest. meadow soil and arable soil were evaluated using an "insect bait method". Soil and litter samples taken in autumn and spring from each stand were baited with &lt;i&gt;G. mellonella&lt;/i&gt; larvae at 22°C. Six species of entomopathogenic fungi infected these larvae. In the litter &lt;i&gt;Beauveria bassiana&lt;/i&gt; was the dominant species. Besides &lt;i&gt;B. bassiana&lt;/i&gt;, 23% of &lt;i&gt;G. mellonella&lt;/i&gt; larvae were infected by &lt;i&gt;Paecilomyces farinosus&lt;/i&gt; in autumn. In the forest soil the dominant entomopathogenic fungus was not found. In this stand the number of infected larvae was the lowest. &lt;i&gt;Metarhizium anisopliae&lt;/i&gt; was the dominant species in the meadow soil in both sampling periods. In the soil taken from a rye field&lt;i&gt; P. fumosoroseus&lt;/i&gt; and &lt;i&gt;B. bassiana&lt;/i&gt; infected &lt;i&gt;G. mellonella&lt;/i&gt; larvae almost to the same degree. It was established that &lt;i&gt;B. bassiana&lt;/i&gt; and &lt;i&gt;M. anisopliae&lt;/i&gt; infected more &lt;i&gt;G. mellonella&lt;/i&gt; larvae in spring than in autumn. In the case of &lt;i&gt;P. farinosus&lt;/i&gt; and &lt;i&gt;P. fumosoroseus&lt;/i&gt; an opposite tendency was observed.

Effect of nucleopolyhedrovirus infection of Spodoptera litura larvae on host discrimination by Microplitis pallidipes

The behaviour and oviposition of solitary endoparasitoid Microplitis pallidipes Szepligeti (Hymenoptera: Braconidae) were monitored to investigate the ability of the parasitoids to distinguish between nucleopolyhedrovirus (NPV)-infected and noninfected Spodoptera litura Fabricius (Lepidoptera: Noctuidae) larvae. The results indicated that the parasitoid searching time and the time until the first parasitoid attack on infected larvae were greater than those recorded on noninfected larvae; the number of infected larvae attacked by parasitoids, the percent of first attacks and parasitism rate in infected larvae were lower than those on noninfected larvae; and these differences were all significant 3 to 5 days postexposure of the larvae to a dose of 1.6 × 108 occlusion bodies (OB)· ml−1 and significant 4 and 5 days postexposure of the larvae to a dose of 1.6 × 107 OB·ml−1. The lowest dosage (1.6 × 106 OB·ml−1) had no significant effect on the above index values. In a field cage experiment, we found that the percentage of infected larvae parasitized by M. pallidipes gradually decreased as the time after NPV inoculation (1.6 × 108 OB·ml−1) increased, and that M. pallidipes significantly preferred to oviposit in healthy larvae from day 3 to day 5 after virus inoculation. Our research concluded that this parasitoid's ability to discriminate between healthy and infected hosts increased as virus concentration increased and as the time between exposure of hosts to virus and subsequent exposure to parasitoids increased.

A Review of the Epidemiology of Gastrointestinal Nematode Infections in Sheep and Goats in Ghana

In this paper, the gastrointestinal nematode parasites infecting small ruminants (sheep and goats) in Ghana and the epidemiological factors influencing their prevalence are reviewed and discussed. Twelve nematode species belonging to six families have been reported to infect these livestock in the country with Haemonchus contortus being the most prevalent helminth parasite in both animals. Parasitic gastroenteritis is caused by mixed infection of several nematode species. Management /husbandry practices, climate and host influence are found to be the main factors that affect gastrointestinal nematode infections in sheep and goats. Seasonal changes in the level of infective strongylate nematode larvae on pasture in the different agro-ecological zones of Ghana are reviewed. The number of infective larvae on pasture is reported to be directly related to the pattern of rainfall. Consequently, rainfall could be relied on to predict the rate of transmission of infection in grazing animals. Finally, the relevance of epidemiological knowledge in the development of efficient measures for controlling gastrointestinal nematode infections in sheep and goats in Ghana is discussed.

Evaluation of the effectiveness of Duddingtonia flagrans and Monacrosporium thaumasium in the biological control of gastrointestinal nematodes in female bovines bred in the semiarid region

Brazil has a herd of 212 million cattle and 171 million hectares of pastures that produce approximately 96% of Brazilian beef. The Brazilian production system enables animal infection by endoparasites, which are considered one of the main obstacles for the development of this industry and are responsible for considerable economic losses. The control of parasitic diseases is performed via the administration of antiparasitic drugs, but they leave residues of the products in the treated animal, affect non-target organisms and select resistant strains of the parasites. The species D. flagrans and M. thaumasium are promising and sustainable alternatives for controlling gastrointestinal helminths of ruminants and other herbivores. In this study, we evaluated the efficacy of isolates of these species, formulated in a sodium alginate matrix and administered twice a week, to reduce the number of environmental infective larvae of gastrointestinal nematodes that affect prepubescent zebu females. The treated animals presented fewer eggs and a lower number of infective larvae per gram of faeces (p < 0.05). The pastures occupied by treated animals showed a statistically significant reduction (p < 0.05) of the number of L3 and, furthermore, the genera Cooperia sp., Haemonchus sp., and Oesophagostomum sp. were the most prevalent. The average weight of the animals did not differ statistically (p > 0.05) among the treated and control groups. The use of sodium alginate pellets as vehicle for delivery of the fungus mycelia D. flagrans (isolate AC001) and M. thaumasium (isolate NF34A) proved effective in controlling trichostrongylids in prepubescent cows bred in the semi-arid region, with an effective reduction in the number of infective larvae in the pastures.

Comparative ultrastructural studies of the alterations to mouse lung parenchyma during Trichinella spiralis or Toxocara canis infection

Trichinella spiralis and Toxocara canis larvae migrated through the lung and induced many alterations in the lung parenchyma. Using electron microscopy, we identified and described the histopathological changes. These changes resulted from mechanical damage or from local inflammatory reactions provoked by larvae. The pattern of changes was described between 6 and 12 days post-infection (DPI) with T.spiralis larvae, and between 21 and 28 DPI with T.canis. The ultrastructural studies demonstrated that T.spiralis larvae migrating through the lungs evoked mainly destruction of type I epithelial cells, destruction of lamellar bodies of epithelial cells or extracellular alveolar lining layer. The severity of these changes was dependent on the number of infective larvae (400 or 800 T.spiralis larvae) and possibly the result of mechanical damage in the lung parenchyma. In contrast, infection with T.canis larvae initiated mainly eosinophilic perivasculitis and vasculitis as well as macrophage accumulation in the lung, which were additionally impacted by numerous crystalloid inclusions in macrophages. Trichinella spiralis larvae and T.canis larvae induced different pathological changes in the lungs of infected mice.

The spectrum and occurrence of entomopathogenic fungi in soils from apple orchards

The spectrum and occurrence of entomopathogenic fungi in orchard soil and arable soil were evaluated using an "insect bait method". Soil samples taken in autumn and spring from sward, herbicides fallow and arable soil were baited with &lt;i&gt;Galleria mellonella&lt;/i&gt; larvae. Entomopathogenic fungi &lt;i&gt;Beauveria bassiana&lt;/i&gt; (Bals.) Vuill., &lt;i&gt;Metarhizium anisopliae&lt;/i&gt; (Metsch.) Sorok. and &lt;i&gt;Paecilomyces fumosoroseus&lt;/i&gt; (Wize) Brown et Smith were isolated from three species of orchards soil and adjacent arable soil. Infection levels of &lt;i&gt;G. mellonella&lt;/i&gt; larvae were depended from species of soil . &lt;i&gt;M. anisoopliae&lt;/i&gt; caused most frequent infections of bait insects in light loamy sand and &lt;i&gt;P. fumosoroseus&lt;/i&gt; in alluvial silt and coarse sand. &lt;i&gt;B. bassiana&lt;/i&gt; was dominated in alluvial silt. It was established that &lt;i&gt;M. anisopliae&lt;/i&gt; and &lt;i&gt;B. bassiana&lt;/i&gt; infected more larvae in autumn than in spring. In case of &lt;i&gt;P. fumosoroseus&lt;/i&gt; an opposite tendency was observed. Generaly in arable soil and sward number of infected larvae was higher than other stands. In case of light loamy sand more infections of &lt;i&gt;G. mellonella&lt;/i&gt; larvae were found in samples from herbicides fallow. Irrespective of soil type &lt;i&gt;B. bassiana&lt;/i&gt; was the dominated species isolated from herbicides fallow, &lt;i&gt;M. anisopliae&lt;/i&gt; from sward and &lt;i&gt;P. fumosoroseus&lt;/i&gt; - from arable soil.

VERMINOSE EM CAPRINOS E OVINOS MANTIDOS EM PASTAGENS DE Panicum maximum Jacq. NO PERÍODO CHUVOSO DO ANO

The objective of this work was to evaluate the worm disease on goats and sheep kept on Panicum maximum Jacq. pastures, in the rainy season of the year. The dry matter density (DM) of different layers (0-15, 15-30 and above 30 cm) of Panicum maximum Jacq. pastures, and the forage contamination by gastrintestinal nematode infective larvae (L3) were quantified. Forty animals were submitted monthly to coproparasitological examinations (ECG and coproculture) during the rainy season. The experiment was carried out in Barreiras-Bahia-Brazil, in a split-plot design, with 10 replications on pastures and 20 replications on animals, from October of 2003 to March of 2004, and samples were taken from December to February. The number of infective larvae per kg/DM did not change with the grass layer, with average of 22.2 L3/kg DM. On the forage, Haemonchus sp. and Trichostrongylus sp. L3 larvae were indentified, reflecting the coproculture results. Goats showed higher ECG counting (2602) than Sheep (865), demanding more sanitary care.KEYWORDS: Coproculture, dry matter, ECG, nematodes.

Strongyloides rattiinfection induces transient nematode-specific Th2 response and reciprocal suppression of IFN-γ production in mice

Over one-third of the world population is infected with parasitic helminths, Strongyloides ssp. accounting for approximately 30-100 million infected people. In this study, we employ the experimental system of murine Strongyloides ratti infection to investigate the interaction of this pathogenic nematode with its mammalian host. We provide a comprehensive kinetic description of the immune response to S. ratti infection that was reflected by induction of antigen-specific IgM and IgG1, mast cell activation and a Th2-like cytokine response. T cells derived from infected mice displayed an increased IL-3, IL-4, IL-5, IL-13 and IL-10 response to CD3-engagement in comparison with T cells derived from naïve mice. The IFN-gamma response to CD3-engagement that was well detectable in T cells derived from naïve mice, however, was suppressed in T cells derived from infected mice. Both, the induction of the S. ratti-specific Th2 response and the suppression of pro-inflammatory cytokines were transient and observed in strict correlation to the course of infection and the number of infective larvae used. Finally, comparing artificial infections induced by subcutaneous injection of larvae to natural infections, we observed similar antigen-specific T cell responses although the natural infection led to a significantly lower worm burden.

Selection of entomopathogenic fungi for the control of the western corn rootworm Diabrotica virgifera virgifera

Abstract: The western corn rootworm Diabrotica virgifera virgifera Le Conte (Col., Chrysomelidae), a serious pest of maize, has been recently introduced into Europe. Several approaches for its control are presently under investigation including microbial agents. During a field survey in Hungary in 2005, naturally occurring entomopathogenic fungi were found to attack this pest. These novel isolates together with standard isolates were tested for virulence against D. v. virgifera larvae and adults. Twenty strains of Metarhizium anisopliae, Beauveria bassiana and Beauveria brongniartii were used in bioassays in the laboratory. Larvae and adults were dipped into a spore suspension with a concentration of 1 × 107 conidia (con.)/ml. They were kept for 14 days at 22°C (±2°C) and 70% relative humidity. The number of infected larvae and adults were counted and infection rates were calculated. Adults were significantly more susceptible to entomopathogenic fungi than larvae. The most virulent isolate infected about 47% of larvae (M. anisopliae Ma2277), whereas the infection rate in adults was up to 97% (M. anisopliae Ma2275). Isolates of M. anisopliae caused significantly higher mortalities than isolates of B. brongniartii and B. bassiana. Most of the adult beetles were killed within 12 days. Isolates from D. v. virgifera were more virulent than those from other hosts.

Effects of an algal biomass supplement on the periparturient rise in nematode egg output from ewes and the subsequent effects on their offspring

The periparturient rise in nematode eggs at lambing is a crucial part of the epidemiology of nematode infections as it allows a large number of infective larvae to be present in the pastures when the lamb is young and most immunologically naïve. With a rapidly rising level of anthelmintic resistance and increasing public concern over drug residues remaining in animal products, it is necessary to achieve more long-term, sustainable nematode control programmes. Some plant products could provide alternatives or adjuncts to conventional control with anthelmintics and ease the selection pressure for anthelmintic resistance. The polyunsaturated fatty acid, docosahexaenoic acid (DHA), which can be produced in high concentrations by some marine algae, has been shown to modify immune response in many species and decrease the production of proinflammatory cytokines (Calder, 2001). This action could reduce inflammation in the gut in response to parasite infestation and reduce the extent of associated hypophagia. The objective of this study was to investigate the long term effects of providing an algal DHA dietary supplement in late pregnancy, on the periparturient rise and the resulting effects on the infection levels and production consequences for their lambs.

STRONGYLOIDES RATTI INFECTION IN THE LARGE INTESTINE OF WILD RATS, RATTUS NORVEGICUS

The large intestine of a rat has been neglected almost completely as a site of Strongyloides sp. infection. We reported that adult Strongyloides ratti remained in the large intestine for more than 80 days, producing more number of infective larvae than small intestine adults, and therefore hypothesized that parasitism in this site could be a survival strategy. In wild rats, however, no study has focused on large intestine infections of Strongyloides. The present study revealed that 32.4% of 68 wild rats, Rattus norvegicus, had the infection of S. ratti in the large intestine, with an average of 4.7 worms. These worms harbored normal eggs in the uterus. In a laboratory experiment with S. ratti and Wister rats, daily output of infective larvae by 4.7 females in the large intestine was estimated to be 4,638.4, suggesting that a few parasites could play a role in the parasite transmission. Five species of nematode found in the wild rats showed seasonality in infection intensity, with highest intensities in March-May. The number of S. ratti in the large intestine was also highest in these months.