In vitro entomopathogenic activity of Beauveria bassiana against Psoroptes spp. (Acari: Psoroptidae)

An indigenous strain (IHEM 18747) of Beauveria bassiana (Balsamo) Vuillemin (Deuteromycetes) was evaluated for its in vitro entomopathogenic activity against the parasitic mite Psoroptes ovis Hering (Acari: Psoroptidae) from rabbits. The following aspects were evaluated: (1) effects of conidial concentration on the viability of adult females; (2) influence of the infection on the fertility, and on the hatchability of eggs; (3) and transmission of infection between mites, and from contaminated surface. Adult females immersed into increasing concentrations of conidia (10(4)-10(9)conidia ml(-1)) showed a dose-related susceptibility. At the highest concentration of conidia, LT50 was 1.6 days while LT50 of the controls reached 5.8 days. The fungus was able to sporulate on the body surface and 100% of the mites were covered with mycelium after immersion in solutions containing 10(7)-10(9)conidia ml(-1). One hundred percent of healthy mites exposed to infected cadavers or surfaces acquired the infection (LT50 reached 1.9 and 1.73 days, respectively, versus 6.1 and 5.1 days in controls, respectively). Egg laying was not reduced by the fungal infection but both the hatchability of the eggs and the life span of the emerging larvae were significantly reduced. Eggs directly infected with the fungus did not show reduced hatchability but the life span of the larvae was shortened. It is concluded that B. bassiana has a high entomopathogenic activity against Psoroptes spp. The in vivo use of this biocontrol agent against Psoroptes spp. in rabbit, sheep and cattle deserves further attention.     

Role of host and environment in mediating reduced gastrointestinal nematode infections in sheep due to intensive rotational grazing

We have previously reported marked reductions in faecal worm egg counts (WECs) and drenching frequency in sheep on an intensive rotational grazing system (IRG) in a cool temperate environment with summer-dominant rainfall. These experiments were designed to determine the role of the host and environmental factors in mediating this. The role of host factors was investigated by administering a fixed larval challenge in each of the 4 seasons of the year to groups of 20 young sheep on three different management systems, including IRG. This comprised a mixed larval challenge containing infective larvae of Haemonchus contortus and Trichostrongylus colubriformis 7 days after short-acting anthelmintic treatment. A range of measurements was then made up to day 35 post-challenge. The role of environmental factors was determined by assessing pasture infectivity in four seasons using faecal worm egg counts (WECs) and pooled faecal culture of worm-free tracer sheep. The management systems were high input (HI) with high fertiliser inputs high stocking rate and relatively long grazing periods; typical New England management system (TYP) with moderate fertiliser inputs and stocking rate and relatively long grazing periods and; Intensive rotational grazing (IRG) with moderate fertiliser inputs and stocking rate but very short (mean 5 days) grazing periods and long (mean 103 days) rest periods. IRG sheep had higher mean WEC at 28 and 35 days after fixed larval challenge than HI and TYP sheep in spring (IRG: 9500 ± 1000; HI: 4000 ± 1000; TYP: 7200 ± 1000 eggs/g, P<0.01) and summer (IRG: 8400 ± 750; HI: 5300 ± 800; TYP: 4400 ± 700 eggs/g; P<0.001) and also had lower live weights during these seasons. There was no difference in WEC after the autumn challenge (IRG: 5100 ± 450 HI: 4500 ± 450; TYP: 4200 ± 450 eggs/g; P ≈ 0.36) but IRG had lower WEC than TYP following the winter challenge (IRG: 2900 ± 400; HI: 2300 ± 400; TYP: 4300 ± 400 eggs/g, P<0.01). The tracer sheep (used to determine pasture infectivity) on IRG had significantly lower WECs during winter, spring and summer than those under the other management systems. Faecal culture and larval differentiation revealed that faeces from tracers on IRG contained significantly lower proportions of H. contortus and significantly higher proportions of Trichostrongylus spp. and Teladorsagia circumcincta than faeces from tracers on the HI and TYP treatments. Thus, when IRG was most efficacious for worm control, during spring and summer when short graze and long rest periods were maintained, sheep on this system exhibited greater susceptibility to larval challenge while tracer sheep indicated lower pasture infectivity. This demonstrates that the effects of IRG on WEC are mediated by reduced larval challenge rather than increased host resistance to infection.     

On-host ecology and off-host survival of the sheep scab mite Psoroptes ovis

These studies were conducted to investigate the possible role of certain aspects of the on-host ecology and off-host survival of the sheep scab mite, Psoroptes ovis, in the dissemination of infestation. All developmental stages of the mite occurred in the fleece both proximally or distal to the skin of infested Merino and Dorper sheep. A larger proportion of mites was present in the fleece of Dorper sheep distal to the skin in the late afternoon and early morning than at other times during the day. Immature and adult mites readily transferred to tufts of wool or hair placed on infested sheep of both breeds. No mites could be found on wool or hair rubbed off onto tree trunks or branches or other structures in enclosures housing heavily infested sheep, nor could any mites be collected from the soil of these enclosures, whereas more than 80% of mites artificially seeded onto soil samples were recovered. The longest mean off-host survival times for larvae, nymphs, and male and ovigerous female mites were recorded at 10 degrees C, and were 9.25 days (RH = 90%), 15 days (RH = 33% and 75%), 10.5 days (RH = 75% and 90%) and 11.25 days (RH = 90%) respectively. Under natural climatic conditions ovigerous females in glass vials containing Merino wool survived for 17 days compared to 15 days for females in vials without wool; this difference was, however, not significant. The mean off-host pre-hatch period for eggs varied between 5.9 days (T = 25 degrees C and RH = 33%) and 22.1 days (T = 10 degrees C and RH = 75%), while the longest time individual eggs took to hatch at the latter temperature and RH was 31 days.     

Effects of Three Anthelmintic Treatment Regimes against Fasciola and Nematodes on the Performance of Ewes and Lambs on Pasture in the Highlands of Kenya

The efficacy of strategic anthelmintic control of liver flukes (Fasciola) and gastrointestinal (GI) nematodes on the performance of ewes and lambs on pasture was assessed on a farm in the highlands of Kenya. In May 1999, 45 Corriedale ewes, aged between 2 and 3 years, were ear-tagged, weighed and allocated randomly to three equal treatment groups based on body weight. Faecal samples taken at this time revealed low levels of strongyle-type eggs per gram of faeces (EPG) and the presence of liver fluke eggs in only a few of the animals. All the animals were then set stocked for 12 months on separate paddocks in an area endemic for both Fasciola and GI nematodes. The ewes in group 1 were given a combined anthelmintic treatment against Fasciola and GI nematodes during the periods recommended for the control of Fasciola in the area (February, June and October). The ewes in group 2 were given the combined treatments 3 weeks after the onset of both the short and long rainy seasons (November and April, respectively). Those in group 3 were given separate treatments for Fasciola (February, June and October) and nematodes (3 weeks after the onset of the rainy seasons). The anthelmintic treatment against Fasciola consisted of triclabendazole at 10 mg per kg body weight, and that against nematodes was levamisole at 10 mg per kg body weight.The nematode EPG for the ewes in group 1 were higher than in groups 2 and 3 during both rainy seasons. The nematode EPG did not differ significantly between groups 2 and 3. The prevalence of Fasciola eggs (number of ewes shedding eggs in a group) in the ewes in groups 1 and 3 remained very low throughout the study period compared to those in group 2. The highest birth weights and the weight gains of lambs were recorded for the group of ewes given separate anthelmintic treatments for Fasciola and nematodes (group 3). The results of this trial indicated that, in an area like Nyandarua District, where liver flukes and GI nematodes are important constraints to sheep production, the best practice is to give separate treatments for the two groups of parasites at the recommended times.     

Effect of host resistance on the feeding and reproductive performance of Haemaphysalis punctata and Ixodes ricinus ticks

A study was made to assess the influence of host response on Haemaphysalis punctata and Ixodes ricinus biology by comparing the effects of feeding ticks on previously uninfested hosts with those fed on previously sensitised hosts. Adult H punctata were fed on sheep; larvae and nymphs of H punctata and I ricinus were fed on rabbits. The engorgement weights of all instars studied that fed on sensitised hosts fell very gradually with successive infestations. These weight reductions were greater at high than at low levels of infestation. In previously sensitised hosts, the engorgement period of all instars was prolonged: the percentage of instars which completed engorgement and engorgement weights were reduced. The host's clinical and immune response markedly affected the fecundity of adult female ticks and the viability and hatchability of the laid eggs. Eighty per cent of female H punctata successfully laid eggs following the first infestation and the hatchability of eggs was 85 per cent. The numbers successfully laying eggs decreased to 60 per cent during the fifth and sixth infestations and was less than 20 per cent following the seventh infestation; the hatchability decreased similarly. There was no marked effect on the development of immature instars when fed on sensitised rabbits.     

Examination of possible transmission of sheep scab mitePsoroptes ovis between host species

Examination of possible transmission of the Irish strain of the sheep scab mite (Psoroptes ovis) of ovine origin between host species involved calves and goats being placed with infected sheep and also directly challenged with live mites. Although mites remained on recipient species for up to a week, they failed to produce disease in either of these species. Calves and goats that had live mites placed on them likewise failed to infect sheep with which they were housed.     

冷藏时间对两广二号越年种孵化率影响试验初报

为探索两广二号蚕种冷藏期限问题,2018—2019年进行了冷藏时间、繁育期对两广二号越年种孵化率的影响试验。试验表明:冷藏时间与两广二号孵化率呈极显著负相关,与皓月×菁松孵化率相关不显著;两广二号不同繁育期、冷藏时间及二者交互作用的孵化率差异极显著;两广二号春制越年种冷藏安全期为111 d,秋制种冷藏安全期为162 d。     

家蚕滞育卵长期保存的研究

调查了不同温度保存的９个原种及２对杂交种的滞育性及多元醇量的变化，对长期保存卵进行了养蚕试验。结果表明：５℃保存卵在产卵１００日后滞育开始解除，１５０日左右孵化率达到最高峰，２００日后急剧下降。不同品种间无明显差异。１℃保存卵在产卵后１８０日左右开始解除滞育，原种在２００－３００日之间孵化率最高，３００日后显著降低，而杂交种产卵后４５０日孵化率仍在８０％以上。－１．５℃保存卵在产卵后５００日仍呈滞育状态，但转入５℃保存８０日后可获得孵化能力，到产卵后７００日孵化率大致在６０％左右。不同温度保存卵滞育的解除，与卵内山梨醇及甘油量的减少呈相同趋势。养蚕结果表明，用１℃保存４１０日以及－１．５℃保存７００日的杂交种，除孵化率比当年生产的冷藏浸酸种低外，其它饲育成绩无明显差异。     

Influence of the Laying Date on the Fertility and Hatchability of Red-Legged Partridge (Alectoris rufa) Eggs

In several countries, there is a well-developed market for Red-Legged partridge (Alectoris rufa) eggs for incubation. Although Red-Legged partridge eggs produced at game farms are sold with a guaranteed average hatchability, there is a marked seasonal variation in fertility and hatchability. Therefore, an average incubating hatchability value cannot be generalized across the whole breeding season. In this research, the influence that the laying date has upon the fertility and hatchability of incubated eggs and the hatchability of the fertile eggs incubated at a farm of Red-Legged partridge was analyzed. It was found that the laying date did indeed influence the fertility and hatchability of the incubated eggs. Fertility and hatchability were greater in the eggs set in the incubator between mid February and late March than those of the eggs set in late April and early May. Hatchability of fertile eggs was greater in the eggs set in the incubator in mid March and lower in the eggs set in late April. The higher values obtained during the middle of the laying period and the lower ones obtained at the end of the laying period cause the game farms’ need to inform their potential customers of the eggs’ expected hatchability as a function of their laying date.     

Factors affecting the hatchability of eggs from broiler breeders

1. Four experiments were carried out on eggs from broiler breeding flocks between 26 and 60 weeks of age. The effects of storage and incubation conditions on hatchability were tested.

2. Collecting eggs hourly rather than five hours after lay slightly reduced hatchability (P<0.10). Pre‐storage fumigation of almost un‐contaminated eggs had no effect on hatchability even after storage for 8 d. Storing eggs in unsealed polythene bags did not affect hatchability of eggs stored for 5 or 8 d.

3. Eggs stored for 2 d hatched better when held at 18 °C than at 15 °C (P<0.05). Eggs stored for 8 d at 15 °C hatched better than eggs stored for 8 d at 18 °C (P< 0.01). Best hatchability was in eggs stored in unsealed polythene bags at a room temperature of 15 °C. When older eggs were allowed 30 to 40 min more in the setter for each day of storage, the decline in hatchability was 0.5 to 0.6 percentage units per day in storage as compared with a decline of 1.2 percentage units per day when eggs of different storage times, up to 8 d, were set simultaneously.

4. Those eggs which showed a weight loss during incubation of near average for their relative humidity (RH) treatment tended to hatch better than others except under conditions of very low RH (0.36), when best hatchability was associated with lower than average weight loss.

5. In eggs from a young flock (28 to 44 weeks of age) hatchability of fertile eggs was depressed by 1 percentage unit with an increase in RH of 0.17, and by 1 percentage unit with each decrease of 0.06 in RH from a control RH of 0.53. In eggs from the same flock between 48 and 60 weeks of age hatchability was depressed by 1 percentage unit with each 0.037 increase in RH from 0.44 to 0.70.

6. Eggs from a young flock (34–49 weeks) hatched significantly better when maintained at 0.82 rather than at 0.66 (P<0.05) or 0.95 (P<0.10) RH during the hatching period from 19 to 21 d of incubation. Eggs from an older flock (51–61 weeks) hatched better at 0.82 and at 0.‐92 than at 0.72 RH during the same period, but the differences were not significant.     

Prevalence of anti-Toxoplasma gondii antibodies in serum and aqueous humor samples from cats with uveitis or systemic diseases in France

The present study sought to elucidate whether Schistosoma japonicum eggs could survive a passage through dogs and chickens. Three dogs and three chickens were used for the experiment. The dogs were allowed to eat goat faeces containing 80 S. japonicum eggs per gram. The chickens were given 2 ml of water containing more than 100 S. japonicum eggs per ml. The hatchability of the eggs was 51.8% prior to administration. All faeces were collected for 3 days from the dogs and for 2 days from the chickens and egg excretion and hatchability were measured. The results showed that nearly 50% of the eggs administered to the dogs were recovered in the faeces during the first 2 days and during the first 25 h 39% of the recovered eggs were viable and able to hatch. In the chickens 9% of the administered eggs were recovered within 27 h and within the first 3.5 h after administration 19% of the recovered eggs were viable and able to hatch. The results suggest that both dogs and chickens may act as transport hosts for S. japonicum in endemic areas.     

冀西北地区绵羊螨虫感染情况调查研究

为摸清冀西北地区绵羊螨虫的感染情况,选取冀西北地区坝上和坝下几个具有代表性的养殖场,通过临床症状、显微镜检查和统计学分析对绵羊感染螨虫的发病情况、不同年龄、不同季节感染情况进行试验研究。结果表明:冀西北地区绵羊螨虫阳性率44%,不同年龄、不同季节的绵羊螨虫阳性率均具有显著性差异(P<0.05)。     

季节和产蛋周龄对青脚麻鸡种蛋孵化性能的影响

试验选择600只青脚麻种母鸡,按24-28周龄、29-35周龄、36-42周龄及43周龄以上4个不同产蛋周龄和春夏秋冬4个不同季节分别收集种蛋进行孵化,研究不同季节和不同产蛋周龄对种蛋受精率和孵化率的影响。结果发现,不同产蛋周龄对青脚麻鸡种蛋的孵化性能有一定的影响,处于产蛋期29-35周龄的种鸡所产种蛋孵化性能最好;不同季节对青脚麻鸡种蛋的孵化性能也有一定的影响,秋季的孵化性能最好。     

Divergent selection for shape of growth curve in Japanese quail. 6. Hatching time,hatchability and embryo mortality

1. Hatching time, hatchability of fertile eggs and embryo mortality under standard egg storage (1 or 5 days at 12?±?1°C and 55% relative humidity) and incubation conditions (37·5?±?0·2°C and 50% relative humidity) were analysed in lines long-term selected for high (HG) and low (LG) relative weight gain between 11 and 28?d of age, respectively, and constant body weight at 49?d of age.

2. Egg storage duration did not have an effect on average hatching time. LG quail, characterised by a fast postnatal growth rate immediately after hatching, hatched earlier than HG quail with a low early growth rate (about 391 vs. 406?h after egg setting, respectively).

3. In contrast to hatching time, the hatchability of fertile eggs was influenced by line as well as egg storage duration. Extended storage decreased hatching success in both lines. However, LG eggs exhibited a higher hatchability than HG eggs (1?d storage: 96·0 vs. 82·5%; 5?d storage: 88·7 vs. 72·7%, respectively).

4. Lower hatchability resulted mostly from a higher frequency of embryo death during early (up to d 7) and late (d 14 and later) phases of incubation.

5. An inadequate nutrient supply to embryos in consequence of developmental delay seems to be a key factor decreasing viability of embryos during incubation.     

Correlation between the proportion of stained eggs and the number of mites (Dermanyssus gallinae) monitored using a ‘non‐parallel board trap’

The poultry red mite (Dermanyssus gallinae) is a serious problem for the poultry industry worldwide. However, the relationship between the mite population and the damage that they cause is still unclear. In this study, the mite population in poultry houses was examined using an established trap method, and the risk of blood‐stained eggs caused by the mites was assessed. Traps were placed once a week outside the egg channels and/or on the floor in two poultry farms in Fukuoka Prefecture, Japan, from April 2012 to July 2014. The numbers of blood‐stained eggs and total eggs were counted at weekly intervals. The results showed that the number of mites increased from April to May, and reached a peak around the beginning of June when the average temperature and humidity were >24°C and 70–90%, respectively. In the segmented model, the correlation between the proportion of blood‐stained eggs and the number of mites or temperature was positive over a threshold. In conclusion, our established trap method is useful for monitoring mites and can be used to predict when poultry farms should be treated to prevent appearance of blood‐stained eggs.     

The incidence of Chorioptes bovis (Acarina: Psoroptidae) on the feet of horses,sheep, and goats in the Netherlands

Summary

The feel of horses, sheep, and goats of different breeds and from many different localities were examined for Chorioptes bovis. In horses, mites were mainly found in the Belgian and Frisian breeds (40% and 62% infected, respectively). In sheep and goats, respectively 63% and 86% were infected. In horses as well as in sheep and goats, mange‐lesions were rarely seen. A number of sheep and goats were examined for mites and lesions quantitatively. In sheep all mites were restricted to the region close to the accessory digits and the claws. In goats the average number of mites was higher than in sheep, and mites could be found on all locations of the feet at least as far as the carpal and tarsal joint. Both in sheep and goats the biggest density of mites was found just below the accessory digits. When crusts were present, they were generally small and hidden under the coat. In sheep, which were housed for a long period, crusts were seen more often and were more distinct than in pastured animals. A negative correlation between the number of mites and the presence and extensiveness of crusts was observed A possible explanation for this phenomenon is suggested. From the results of this study it is clear that there is no necessity to list chorioptic mange in sheep and goats as a notifiable disease.     

Occurrence of waxy-textured yolk in the egg of the domestic hen (Gallus domesticus)

An unusual yolk material (waxy yolk) was identified in some hard boiled yolks of one strain of domestic hen. Its structure was consistent with it being formed from normal yolk through disruption of the yolk spheres. These are normally stable during even long periods of storage. Formation occurs mainly after ovulation, during passage of the egg down the oviduct; only rarely could it be found in the larger follicles of the ovarian hierarchy. In the flock of birds examined the incidence of eggs with waxy yolk was 75% of all eggs laid over a 7 d period. Of the 173 birds tested, the eggs of only 17 birds were totally unaffected; all eggs of 82 birds contained this material. The results of a hatchability trial indicated this material had no apparent influence on the embryo or hatchability.     

Evaluation of the bioequivalence of two formulations of deltamethrin for treatment of sheep with psoroptic mange

OBJECTIVE: To evaluate efficacy of 2 deltamethrin emulsifiable concentrates that differed on the basis of vehicle (methyl glycol acetate [AMG] or 2-propylene glycol 1-methyl ether acetate [AMP]) for the treatment of sheep with mange. ANIMALS: 30 ewes between 11 months and 7 years old that weighed 16 to 71 kg and were naturally infested with Psoroptes ovis. PROCEDURE: Sheep were randomly allocated into 3 groups (13 sheep in group AMP, 13 sheep in group AMG, and 4 negative-control sheep). Each sheep was dipped twice (10-day interval between dippings) in the assigned formulation. Assessment of efficacy was performed on days 3, 7, 14, 21, 28, 35, 42, 49, 56, and 63 after the first dipping. Efficacy was assessed by determining the number of eggs or live mites on those days, as well as regrowth of wool at the end of the study. RESULTS: Psoroptic mange infestation was maintained in the 4 control sheep throughout the study. We did not detect live Psoroptes mites in scrapings after day 7 (AMP group) or after day 14 (AMG group). No parasites were seen after day 14 in either treatment group. Therefore, efficacy was 100% for both treatment groups from days 14 to 63. CONCLUSIONS AND CLINICAL RELEVANCE: The 2 formulations of deltamethrin were equally able to eradicate Psoroptes infestation of sheep after 2 dippings performed in accordance with the label recommendations.     

温度对皖西白鹅种蛋孵化率的影响

选取存放4d的皖西白鹅种蛋5866枚,随机分为3组,在其他孵化条件相同的情况下,分别设定不同的孵化温度。结果表明:第1组受精蛋孵化率平均为75.30%,第2组平均为74.25%,第3组平均为62.85%,第1组与第2组受精蛋孵化率差异不显著,第3组受精蛋孵化率分别与第1组、第2组受精蛋孵化率均差异显著(P<0.05)。     

Survival and infectivity of Dicrocoelium dendriticum eggs under field conditions in NW Spain

A study was made of the survival of Dicrocoelium dendriticum eggs in sheep faeces in an area with a temperate climate (NW Spain). It appears that mortality is independent of the age of the eggs and that there is a marked seasonality within the period of time considered (20 months). A study was also carried out on the infectivity of D. dendriticum eggs by experimental infections of suitable intermediate hosts. The data show that no loss took place in infectivity during the period of study (15 months).