Spatial genetic pattern in an economically beneficial insect,the cyclical African wild silk moth (Gonometa postica)

The African wild silk moth (Gonometa postica) exhibits large inter-annual population size fluctuations in the Kalahari region of southern Africa. Spent cocoons from this species are currently being utilized in a local silk industry. An understanding of the recolonization dynamics of a particular harvested site, and of the population genetic effects of such dispersal, are crucial for designing a scientifically-based harvesting strategy. I link morphological estimates of flying ability to microsatellite genotyping in the determination of dispersal ability of this species. Morphological results suggest that the moth is a poor disperser with high wing loadings and males are better fliers than females. There is a significant effect of isolation-by-distance. Spatial population genetic analyses of microsatellite data further indicate lower and upper bounds on dispersal of 90 m and 50 km. The combined evidence suggests male-biased dispersal over several dozen kilometers with females that do not disperse over large distances. I discuss the potential influences of large population size fluctuations on patterns of genetic diversity and the implications for the inference of dispersal in my study species.     

Helminth parasites of dogs from two resource-limited communities in South Africa

Biological samples were collected from dogs in resource-limited communities in the North-West and Gauteng Provinces of South Africa to assess the prevalence of helminth parasitism. These samples included adhesive tape peri-anal skin swabs and fresh faecal samples for helminth examination, and thick and thin blood films (smears) and whole-blood samples in anticoagulant for examination of filarial nematode microfilariae and haemoprotozoa. The eggs of Ancylostoma caninum, Toxocara canis, Toxascaris leonina, Dipylidium caninum and taeniids were identified. None of the blood samples and smears tested positive for microfilariae of Dirofilaria immitis or Dipetalonema spp. or for haemoprotozoa. The adhesive tape swabs were negative for cestode eggs and segments. Most of the helminth parasites identified in this study are zoonotic and consequently are regarded as a public health hazard.     

Hair coat contamination with zoonotic helminth eggs of farm and pet dogs and foxes

Infections of dogs with Toxocara canis and Echinococcus multilocularis pose an infection-risk particularly for contact persons. We examined specimens of hair coat and faeces of 124 farm dogs, 118 household dogs, 49 kennel dogs, 15 puppies from two litters, and 46 red foxes. Microscopically identified eggs of Toxocara or taeniids were further investigated by species-specific PCRs. In farm dogs, eggs of E. multilocularis or T. canis were identified in each 2.4% of faecal samples, eggs of T. cati (gastrointestinal passage) in 7.3%, respectively. Household dogs excreted eggs of T. canis (0.8%) and of T. cati (2.5%). In kennel dogs, eggs of T. canis (4.1%), but not of T. cati were detectable. Coat samples contaminated with eggs of Toxocara spp. were found from farm dogs (5.6%), household dogs (1.7%) and kennel dogs (2.0%). Taeniid eggs were isolated from the coat samples from only two farm dogs (1.6%); a molecular species determination was not achieved. In six intrauterinely infected puppies, Toxocara-eggs were found in 17/38 samples taken within six weeks. No intact Toxocara eggs could be isolated from the coat of nine puppies from a second litter 13 days after deworming. Of the 46 red foxes investigated (dissection and faecal samples) 13 (28.3%) were infected with E. multilocularis and 20 (43.5%) with Toxocara. Eggs of taeniids and Toxocara were found in 13% (in three cases confirmed as E. multilocularis) and 21.7%, respectively, of the coat samples. None of the retrieved Toxocara eggs in the coat samples were embryonated. Thus, an infection of humans through the transmission of E. multilocularis eggs after direct contact with dogs or foxes is conceivable, whereas a corresponding infection risk by Toxocara eggs must be critically challenged.     

Observations of microtrash ingestion in Cape Vultures in the Eastern Cape,South Africa

Ingestion of man-made items by birds can reduce stomach volume and block the digestive track. In southern Africa, microtrash within the regurgitation of Cape Vulture nestlings was last documented in 1983. We present evidence of nestling microtrash ingestion after a 30-year gap. Vulture nestlings were captured at a breeding colony in the Eastern Cape, South Africa. One nestling regurgitated three microtrash fragments. Two pieces of microtrash were collected from the nest of another nestling. Neither nestling appeared to have skeletal deformities or feather stress bars. Our results highlight the persistence of microtrash ingestion by Cape Vulture nestlings, which could impact the species negatively.     

Occurrence of Baylisascaris transfuga in wild populations of European brown bears (Ursus arctos) as identified by a new PCR method

The European brown bear (Ursus arctos) is a species present in limited areas of Europe and several small populations are considered endangered. This species can be affected by a range of parasites. In particular, the genus Baylisascaris is an emerging parasite of wild animals which can cause severe larva migrans syndrome in aberrant hosts, which include 100 species of birds, mammals and also humans. Baylisascaris transfuga is the species reported from bears, and with the exception of a few laboratory trials, little is known about the capacity of this species to infect other animals. Furthermore, the identification of this species has traditionally been based on light microscopy, using either morphology of the adults at necropsy or detection of the eggs in faeces, which are methods limited by the experience and the efforts of the observer. The current work was aimed at developing a specific PCR to detect the parasite directly from faecal samples of naturally infected brown bears in the field, without the need for previous flotation. Using eggs and adults of B. transfuga collected in Croatia, we first developed a PCR to detect a portion of the second internal transcribed spacer region (ITS-2) of ribosomal DNA and then applied it to bear faecal samples spiked with a known number of B. transfuga eggs. We show here for the first time that this method allows the detection of a minimum of two Baylisascaris eggs in 25mg of faecal material, thus it demonstrates a high diagnostic capacity that could be applied to evaluate the prevalence of the parasite in faecal samples from wild populations of brown bears.     

Adjusting worm egg counts for faecal moisture in sheep

The number of eggs from gastrointestinal nematodes per gram of faeces (worm egg count WEC) is commonly used to determine the need for anti-parasite treatments and the breeding value of animals when selecting for worm resistance. Diarrhoea increases faecal moisture and may dilute the number of worm eggs observed. To quantify this effect, egg counts in sheep at pasture were simulated by dosing 15 animals with chromic oxide particles. The simulated WEC diminished as faecal moisture increased. When faeces were dried, simulated WEC per unit dry matter was not influenced by the amount of faecal moisture present prior to drying. The results suggest that adjustment for faecal moisture may provide an improved estimate of FEC. Drying faeces to calculate the WEC per unit dry matter would provide such an adjustment but may not be practical for industry application. In the past, the CSIRO McMaster Laboratory has used an adjustment factor developed by Gordon based on the classification of faecal consistency derived from the morphology of faeces. To examine the utility of an adjustment factor based on faecal consistency score (FCS), the relationships between FCS and simulated WEC and dry matter were examined. Dry matter and simulated WEC exhibited an exponential decline as FCS increased. The relationship between FCS and dry matter was further examined in 368 samples collected over 12 months from sheep at pasture, where it was observed that dry matter showed a linear decline as FCS increased. Adjustment factors based on dry matter were similar to those proposed by Gordon however adjustment factors predicted from simulated WEC diverged from the remainder for FCS>4. As no samples scored FCS 5 in the study of simulated FEC, the adjustment factors based on the larger study that included samples with FCS 5 was therefore considered more robust. Adjustment factors were given by the equation: WEC(estimated)=(WEC(observed)/(34.21-5.15 FCS))x29.06. This equation estimates for samples with FCS>1 the WEC that would be expected if the samples were FCS 1, the faecal consistency score for normal faeces. The impact of adjustment of observed WEC for faecal moisture predicted by FCS on decision points for treatment and on estimated breeding values requires further examination.     

浙江慈溪杭州湾湿地中心水鸟资源调查

湿地国际-中国办事处项目组水鸟专家于2009年8月21～22日对浙江杭州湾湿地中心项目区及其邻近湿地的水鸟进行了全面调查。本次调查,采用定点观测与路线调查相结合的方法,共统计到水鸟7科46种,数量超过1万只,其中迁徙的鸻鹬类为26种。描述了杭州湾湿地中心迁徙水鸟的种类、数量分布及其重要性。为全面评估和了解杭州湾湿地中心的水鸟资源,为杭州湾湿地中心正在建设的野生动物湿地管理提供本底数据和依据。并对将来改善杭州湾湿地中心迁徙水鸟的保护提出了建议。     

Fecundity of anthelmintic resistant adult Haemonchus contortus after exposure to ivermectin or benzimidazoles in vivo

A strain of Haemonchus contortus resistant to the benzimidazoles, ivermectin and salicylanilides was used to study the effect of exposure to ivermectin or oxfendazole on the number of eggs produced by adult female parasites. After anthelmintic administration there was a reduction in the faecal egg count of the infected lambs. Ivermectin caused a reduction in the number of eggs within adult parasites for up to 72 hours but this returned to higher than pre-treatment levels at 168 hours after treatment. After oxfendazole treatment there was an increase in the number of eggs stored in the adult parasites at 24 hours and then a significant reduction in the number of eggs for over 168 hours. This suggested that both ivermectin and oxfendazole have a deleterious effect on the reproductive potential of female H contortus although the parasites are resistant to these drugs. These results confirm the importance of allowing up to 10 days to elapse between the time of administration of an anthelmintic and the collecting of faecal samples when using the faecal egg count reduction test to identify anthelmintic resistance, especially when using benzimidazoles. The more prolonged effect on fecundity produced by oxfendazole may reflect the antimitotic action of the benzimidazole anthelmintics.     

Habitats and Dispersal of Southern African Anura

The data required to make it possible to relate dispersal of southern African Anura to the habitats occupied are considered. Habitat must be defined in terms of breeding populations; data on the breeding seasons of the taxon under consideration are needed, with comparative data on possible competitors in the breeding sites. Possible routes of dispersal under present conditions are considered; the distribution of the habitats of some taxa are considered in relation to presumed past conditions. Possible centres of origin and dispersal of genera and species endemic to southern Africa are discussed.     

中国升金湖水鸟系统监测方案:调查方法与初步结果

长江中下游湿地是中国东部最为重要的水鸟越冬地.由于长江中下游湿地面积与质量都发生了变化,迫切需要监测其越冬水鸟数量与分布的变化趋势,为有效开展保护计划奠定科学基础,以确保该区域水鸟的生存以及未来的种群恢复.然而,因统计质量受诸多因素影响,如何获得水鸟数量与分布的准确数据,同时确保这些数据可以在年度间和位点间进行比较,是非常复杂的.因此,建立一套有效的调查方法,最大程度地保证水鸟统计的精确性和准确性,并将统计产生的偏差最小化,是十分必要的.否则,调查结果准确性将受到影响,也无法用来进行比较分析.最近,我们探索建立了一套系统的水鸟调查方法,并于2008/2009年和2009/2010年冬在长江中下游的重要湿地升金湖开展了越冬水鸟调查,检验了该方法,取得了很好的结果.具体方法包括将湖泊划分为若干调查区域,每个调查区域又细分为若干亚区,区和亚区之间均有明确的分界线,最后分区域进行调查和记录.记录的数据包括物种数量、分布、环境和干扰情况等,记录的格式是统一的,以确保数据的准确性及尽可能地减少偏差.本文以这两年的冬季调查结果为例说明如何利用这些数据,获得水鸟数量、分布以及栖息地利用等详细信息.最后,讨论了在长江中下游湿地推广该方法、建立全流域水鸟监测项目的重要性.     

Trial by fire: social spider colony demographics in periodically burned grassland

Nature conservation authorities in southern Africa burn the grassland in nature reserves to reduce the incursion of woody plants and to encourage the growth of new grass for grazing. Studies have shown significant negative effects of burning on the abundance, species diversity and community composition of smaller vertebrates and invertebrates. Social arthropods are likely to suffer from repeated burning, as destruction of the colony means a permanent loss of the entire reproductive unit. Nests of social spiders of the genus Stegodyphus (Eresidae) are a prominent feature of African savannas and their size and visibility make them potentially good indicators of ecological consequences of fire. The colonies are sedentary and their nests may persist for several years, although individuals have an annual life cycle. We explored the mortality patterns and the effects of burning on survival of colonies of two species of social spider, Stegodyphus mimosarum and S. dumicola that live sympatrically. We compared colony mortality in burned and unburned areas to determine if colony mortality was due to burning or, alternatively, to natural senescence. Analysis of five years of nest mortality data together with information on the burning regime in Spioenkop Nature Reserve, KwaZulu Natal province (South Africa), indicates that colony extinction in S. mimosarum is independent of the burning regime, while burning is a significant cause of colony mortality in S. dumicola. The different responses of the two species are likely a result of different colony dynamics and nesting sites.     

Evaluation of a commercially available enzyme-linked immunosorbent assay for detecting antibodies to Fasciola hepatica and Fasciola gigantica in cattle, sheep and buffaloes in Australia

A commercially available ELISA for detecting antibodies to liver fluke was evaluated for use in Australia. Milk and serum samples from cattle and sheep in which infection with Fasciola hepatica was confirmed by detection of eggs in faeces were used to estimate sensitivity. Similar samples collected from cattle and sheep outside the F. hepatica-endemic area were used to estimate specificity. The ELISA was also evaluated for detecting antibodies to F. hepatica in milk from sheep and antibodies to Fasciola gigantica in sera from cattle and buffaloes, but with small numbers of samples. In cattle, the sensitivity and specificity of the ELISA were 98.2% and 98.3% using serum and 97.7% and 99.3% using milk. In infected herds, 41.4% and 41.5% of animals were positive in the serum and milk ELISAs, respectively, whereas F. hepatica eggs were found in faecal samples from 26.5% of animals. In sheep, the sensitivity of the ELISA was 96.9% and the specificity was 99.4%. In infected flocks, 60.2% of animals were positive in the serum ELISA and F. hepatica eggs were found in faecal samples 52.2% of animals. There was perfect agreement in the ELISA between paired serum and milk samples collected from ewes. The assay detected antibodies in sera from cattle and buffaloes with natural and experimental F. gigantica infections. In the experimentally infected animals, antibodies were detected 2 weeks post-infection. We conclude that the ELISA will be a valuable tool for diagnosing F. hepatica infections in cattle and sheep. The assay may also be useful for diagnosing F. gigantica infections but further studies are required to establish sensitivity and specificity.     

A note on endoparasites of wild ostriches (Struthio camelus) in the Mokolodi Nature Reserve,Gaborone, Botswana

A study was undertaken to investigate the prevalence of endoparasites of wild ostriches at Mokolodi Nature Reserve, Gaborone, over a 7-month period. Large numbers of strongyle eggs were recovered from faecal material in April and September and a decline in the strongyle egg counts was evident during June and July. Noteworthy was the absence of helminth eggs in faecal samples collected from chicks and coccidia oocysts from any of the ostriches.     

Regional variations in the nematode worm populations of breeding ewes in New Zealand

AIM: To determine whether the generic composition of nematode parasites in lactating ewes varies between geographic regions in New Zealand and whether age and fecundity of ewes affect nematode egg output. METHODS: Four ram breeding properties in each of the northern (NNI) and southern (SNI) North Island and the northern South Island (NSI) regions, together with six properties in the southern South Island (SSI) were investigated. Faecal samples were obtained on one occasion, 2-6 weeks after lambing, from at least 60 ewes on each property, stratified according to age and reproductive status. Nematode eggs were counted and coprocultures prepared to identify genera present. Information on the history of anthelmintic use on each property was also collected. RESULTS: Highest faecal egg counts (FEC) were observed from ewes in the NNI and SSI regions. Lambed hoggets and twin-rearing two-tooth ewes had higher FEC than their unlambed or single-lamb-rearing contemporaries, respectively. However, no significant effect of reproductive effort on FEC was demonstrated in mixed-aged ewes. Significant regional differences in generic composition of nematode parasites were observed: Teladorsagia spp (also referred to as Ostertagia spp) eggs made up 56% of total eggs shed from sheep in the SSI compared with14% in the NNI, and values for Haemonchus spp were 1%and 24% for these same regions, respectively. Trichostrongylus colubriformis and T. vitrinus together made up 7, 15, 13 and15% of eggs counted from sheep in the SSI, NSI, SNI and NNI, respectively. CONCLUSIONS: More comprehensive epidemiological information may suggest regional-specific approaches to the management of nematode parasites in ewes should be devised in the future.     

Efficacy of parenteral administration of ivermectin in the control of strongylidosis in donkeys

Investigations into the efficacy of parenteral ivermectin (Pandex) administration for strongylidosis control in donkeys were carried out. The preparation was applied subcutaneously at a dose of 0.2 mg/kg (1 ml/50 kg body weight). One day prior to the treatment and 14 days post-treatment, individual coprological samples were obtained for faecal nematode egg counts and larval culture. The study was performed on 263 donkeys originating from different regions of Bulgaria. Prior to the treatment and 20 days after that, blood samples were obtained from 64 previously infected animals for monitoring of changes in eosinophil leukocyte counts. The subcutaneous application of ivermectin had an efficacy of 96% in terms of reduction of faecal egg counts. In 92.2% of infected donkeys, a complete reduction of faecal eggs count occurred (0 eggs per gram of faeces epg), whereas in the remaining 7.8% of the infected donkeys, the egg counts were reduced by 72%. The reduction in faecal egg counts did not result in changes in eosinophil counts. The results obtained as well as the lack of local changes after the subcutaneous application of ivermectin in donkeys allow us to recommend its use for control of strongyles in donkeys.     

Quantifying the sources of variability in equine faecal egg counts: implications for improving the utility of the method

The faecal egg count (FEC) is the most widely used means of quantifying the nematode burden of horses, and is frequently used in clinical practice to inform treatment and prevention. The statistical process underlying the FEC is complex, comprising a Poisson counting error process for each sample, compounded with an underlying continuous distribution of means between samples. Being able to quantify the sources of variability contributing to this distribution of means is a necessary step towards providing estimates of statistical power for future FEC and FECRT studies, and may help to improve the usefulness of the FEC technique by identifying and minimising unwanted sources of variability. Obtaining such estimates require a hierarchical statistical model coupled with repeated FEC observations from a single animal over a short period of time. Here, we use this approach to provide the first comparative estimate of multiple sources of within-horse FEC variability. The results demonstrate that a substantial proportion of the observed variation in FEC between horses occurs as a result of variation in FEC within an animal, with the major sources being aggregation of eggs within faeces and variation in egg concentration between faecal piles. The McMaster procedure itself is associated with a comparatively small coefficient of variation, and is therefore highly repeatable when a sufficiently large number of eggs are observed to reduce the error associated with the counting process. We conclude that the variation between samples taken from the same animal is substantial, but can be reduced through the use of larger homogenised faecal samples. Estimates are provided for the coefficient of variation (cv) associated with each within animal source of variability in observed FEC, allowing the usefulness of individual FEC to be quantified, and providing a basis for future FEC and FECRT studies.     

Triploid Grass Carp Susceptibility and Potential for Disease Transfer when used to Control Aquatic Vegetation in Reservoirs with Avian Vacuolar Myelinopathy

Abstract

Avian vacuolar myelinopathy (AVM) is an often-lethal neurologic disease that affects waterbirds and their avian predators (i.e., bald eagles Haliaeetus leucocephalus) in the southern United States. Feeding trials and field surveys provided evidence that AVM is caused by a toxin-producing, undescribed cyanobacterium (UCB), which grows as an epiphyte on the leaves of submerged aquatic vegetation (SAV). Reservoirs with documented AVM epornitics support dense growth of nonnative SAV. Waterbirds ingest the toxin when feeding on aquatic plants with the epiphytic UCB, and secondary intoxication occurs when raptors consume these birds. Vegetation management has been proposed as a means to reduce waterbird exposure to the putative toxin. We fed aquatic vegetation with and without the UCB to triploid Grass Carp Ctenopharyngodon idella in laboratory and field trials. Only Grass Carp that ingested aquatic vegetation with the UCB developed lesions in the central nervous system. The lesions (viewed using light microscopy) appeared similar to those in birds diagnosed with AVM. Grass Carp that received aquatic vegetation without the UCB were unaffected. Grass Carp tissues from each treatment were fed to domestic chickens Gallus domesticus (an appropriate laboratory model for AVM) in a laboratory trial; the chickens displayed no neurologic signs, and histology revealed a lack of the diagnostic lesions in brain tissues. Results from our trials suggest that (1) triploid Grass Carp are susceptible to the AVM toxin, although no fish mortalities were documented; and (2) the toxin was not accumulated in Grass Carp tissues, and the risk to piscivorous avifauna is likely low. However, a longer exposure time and analysis of sublethal effects may be prudent to further evaluate the efficacy and risk of using triploid Grass Carp to manage aquatic vegetation in a system with frequent AVM outbreaks.

Received December 3, 2012; accepted August 2, 2013     

Amphistome infection of goats farmed under resource-poor conditions in South Africa

From December 1998 to April 2000, a longitudinal study was conducted of the pooled trematode faecal egg counts of samples collected from goats of resource-poor farmers at Rust de Winter, Gauteng Province, Impendle, KwaZulu-Natal Province, and Kraaipan, North-West Province, South Africa. The amphistome faecal egg counts followed a seasonal pattem, with an increase in the counts during the warmer months of the year (October to March). This is the first work concerning the seasonal cycling of amphistomes in ruminants in South Africa.     

Newcastle disease and avian influenza A virus in wild waterfowl in South Africa

In an intensive ostrich farming area in South Africa with a history of ostrich influenza outbreaks, we conducted a survey of avian influenza virus (AIV) and Newcastle disease virus (NDV) in wild aquatic birds. During late autumn and winter 1998, the time of year when outbreaks in ostriches typically start to occur, 262 aquatic birds comprising 14 species were sampled and tested for both virus infections. From eight samples, AIV, serotype H10N9, could be isolated. All isolates were apathogenic as determined by the intravenous pathogenicity index (0.00). Conversely, none of 33 sera of these wild birds showed antibodies against H10. However, one bird was found serologically positive for H6 AIV. This AIV serotype was later isolated from ostriches during an avian influenza outbreak in this area. No NDV was isolated although 34 of 46 serum samples contained NDV-specific antibodies. This is the first H10N9 isolate to be reported from Africa. In addition, our data support the notion that wild aquatic birds may function as a reservoir for AIV and NDV in South Africa.     

Parasitology and urban livestock farming in nigeria: prevalence of ova in faecal and soil samples and animal ectoparasites in Makurdi

Domestic environmental pollution resulting from urban livestock farming was investigated in Makurdi using parasitological techniques. The test tube flotation technique was used for the parasitological analysis of animal faecal matter and soil samples collected from residential premises. Ectoparasitic fauna of dogs, goats, sheep and cattle cohabiting with humans within the same residential compound were also collected and identified. The hand-picking and body brushing methods were employed to search for ticks, fleas, lice and mites. Of the 150 soil samples examined, 55 (36.7 %) were positive for 1 or more eggs of helminth parasites. There was no significant difference in the distribution of eggs in the soil samples from the 3 areas sampled (Chi2 = 0.046, df = 2, P > 0.05). Ascaris species were the dominant parasite eggs found. Of the 180 faecal samples examined, 107 (59.4 %) were positive for 1 or more eggs of helminth parasites. Chi-square analysis showed no significant difference in the level of infection of different animal faeces sampled (Chi2 = 5.74, df = 4, P > 0.05). Ascaris species were again the dominating helminth parasite eggs found. There was also no significant difference in the prevalence of helminth eggs in the animal faecal samples from the 3 areas sampled (Chi2 = 5.99, df = 4, P > 0.05). A total of 1908 ectoparasites was recovered (ticks: 32.80 %; lice: 22.43 %; fleas: 22.06 % and mite: 22.69 %). There was no significant difference in infestation animals between sexes (Chi2 = 0.10, df = 4, P > 0.05). The predominant genus encountered for ticks were Amblyomma, while Linognathus (43.90 %), Ctenocephalides (97.38 %) and Sarcoptes (58.89 %) were most predominant for lice, fleas and mites respectively. The public health implications of the findings, especially as these relate to the increasing incidence and prevalence of zoonotic infections, are discussed.