土壤温度和湿度对外来种蚯蚓Pontoscolex corethrurus 产茧和幼蚓孵化的影响

通过采用主处理为土壤温度,副处理为土壤湿度的裂区区组实验设计,在室内微生态条件下控制土壤温度和湿度培养蚯蚓,探讨了3种土壤温、湿度对热带外来种蚯蚓Pontoscolex corethrurus成蚓产茧和蚓茧孵化的影响。研究结果表明,P.corethrurus成蚓在20—30℃土壤温度范围、25%—35%土壤湿度环境中均可持续产茧和孵化幼蚓,培养时间、土壤温湿度对蚯蚓的产茧和孵化呈现显著影响。20%土壤湿度下成蚓休眠或死亡。35%土壤湿度下呈现最大蚓茧产量和幼蚓孵化量。在较好(35%)土壤湿度下产茧数表现为高温好于低温,反之亦然;在适宜(25%—35%)土壤湿度下幼蚓孵化率随温度升高而增加,但呈现高、低温的限制作用,即25℃土壤温度和35%土壤湿度时出现最高幼蚓孵化率。在适宜的土壤温湿度范围内,湿度较温度对蚯蚓繁殖具有更显著的控制作用,温度的影响在一定程度上可通过土壤湿度加以调节。     

中华绒螯蟹微卫星标记与生长性状相关性的初步分析

研究采用30个微卫星标记分析同池养殖的长江水系中华绒螯蟹群体,以筛选生长性状(体重、体长和体宽)相关的分子标记。结果表明,位点ESIN33、ESC29和ESC57与体重、体宽和体高呈极显著相关(P<0.01);位点ESC65与体高、体宽呈极显著相关(P<0.01),与体重呈显著相关(P<0.05)。不同基因型间的多重比较表明,ESIN33位点的AC基因型、ESC29位点的DD基因型、ESC65位点的BB基因型的平均体重、体宽和体高均高于其他基因型,且差异显著,是生长性状的优势基因型。研究结果可为中华绒螯蟹的分子标记辅助选育提供参考。     

外源促性腺激素处理后鸡产蛋及孵化研究

目的:探讨促卵泡素(FSH)对低产期肉用种母鸡在产蛋数量和孵化的影响,寻求较佳的用于提高低产期母鸡产蛋的激素剂量。方法:本试验采用同种激素不同剂量的处理方式,比较实验组和对照组产蛋量和孵化情况。结果:注射不同剂量的激素对鸡的产蛋有一定的影响,实验组一的平均产蛋数与对照组接近,其它四组均显著低于对照组(P<0.05),孵化率与健雏率与对照组无显著差异(P>0.05)。结论:小剂量激素处理对鸡产蛋量没有太大的影响,但大剂量会引起鸡生殖系统萎缩,激素处理对受精卵孵化及雏鸡生长并无负面影响。     

土壤温度和湿度对外来种蚯蚓Pontoscolex corethrurus 产茧和幼蚓孵化的影响

通过采用主处理为土壤温度,副处理为土壤湿度的裂区区组实验设计,在室内微生态条件下控制土壤温度和湿度培养蚯蚓,探讨了3种土壤温、湿度对热带外来种蚯蚓Pontoscolex corethrurus成蚓产茧和蚓茧孵化的影响。研究结果表明,P. corethrurus成蚓在20—30℃土壤温度范围、25%—35%土壤湿度环境中均可持续产茧和孵化幼蚓,培养时间、土壤温湿度对蚯蚓的产茧和孵化呈现显著影响。20%土壤湿度下成蚓休眠或死亡。35%土壤湿度下呈现最大蚓茧产量和幼蚓孵化量。在较好（35%）土壤湿度下产茧数表现为高温好于低温,反之亦然;在适宜（25%—35%）土壤湿度下幼蚓孵化率随温度升高而增加,但呈现高、低温的限制作用,即25℃土壤温度和35%土壤湿度时出现最高幼蚓孵化率。在适宜的土壤温湿度范围内,湿度较温度对蚯蚓繁殖具有更显著的控制作用,温度的影响在一定程度上可通过土壤湿度加以调节。     

单独隔离孵化对镇海林蛙蝌蚪生长发育、社交行为和运动表现的影响

两栖类胚胎呈卵群一起孵化在反捕食、维持胚胎间的温度平衡和促进胚胎的同步发育等方面具有重要作用。在实验条件下探究孵化条件(单独隔离孵化和卵群一起孵化)对镇海林蛙(Rana zhenhaiensis)蝌蚪的生长发育、社交行为及其运动表现能力的影响。结果表明,孵出2天后,单独隔离孵化组蝌蚪的体长和发育历期均显著大于卵群一起孵化组。以体长为协变量的协方差分析表明,特定体长的单独隔离孵化组蝌蚪的体宽和体重均显著大于卵群一起孵化组的个体。在蝌蚪的活动行为中,单独隔离孵化组蝌蚪在水体上层和中层出现的频次显著小于卵群一起孵化组,而在水体底层的出现频次显著大于卵群一起孵化组。单独隔离孵化组蝌蚪个体的分布面积率、最近邻个体的距离、个体间的距离均显著大于卵群一起孵化组,但个体间的接触频次显著小于卵群一起孵化组。在运动表现方面,单独隔离孵化组胚胎的摆尾搏动频次显著小于卵群一起孵化组。单独隔离孵化组蝌蚪的运动时长和运动频次均显著小于卵群一起孵化组。本研究结果将为无尾两栖类幼期的生长发育规律提供参考数据。     

几种生态因子对曼氏无针乌贼野生和养殖卵孵化的影响

比较了曼氏无针乌贼野生卵和养殖卵的区别,研究了不同温度、盐度、孵化密度、卵类型对野生和养殖曼氏无针乌贼孵化率和孵化时间的影响.结果表明：野生卵的质量较佳,养殖卵则以黑色小卵的质量为佳.野生卵的最佳孵化温度为27 ℃～29 ℃,最佳孵化盐度为24.5～32.0;孵化密度对野生卵孵化率的影响不显著.养殖卵在19 ℃～29 ℃下的孵化率为6.7%～30.0%,高于33 ℃和低于17 ℃均不能孵化;在盐度19.5～32.0范围内孵化率为18.3%～25.0%,盐度低于17.0不能孵化;充气情况下,孵化密度对养殖卵的孵化率影响不显著,而不充气情况下影响显著.     

不同土壤类型及其含水量对亚洲小车蝗卵孵化的影响

为明确不同土壤类型及其含水量对亚洲小车蝗Oedaleus decorus asiaticus Bey-Bienko卵孵化的影响,本实验选取棕钙土、黑土和砂土等3种土壤,在恒温28℃条件下设置5%、10%、15%和20%等4个土壤含水量,研究亚洲小车蝗卵的孵化前期、孵化历期、累积孵化率以及相对孵化率。结果表明,土壤类型、土壤含水量以及土壤类型与土壤含水量的交互作用对亚洲小车蝗卵孵化率影响极显著,而对卵孵化前期影响均不显著,卵孵化历期只受到土壤类型的显著影响。亚洲小车蝗卵在棕钙土中孵化率最高(42.5%～61.4%),其次为黑土,最低为砂土;孵化历期在棕钙土中(3.6±0.2 d)显著短于黑土和砂土。在棕钙土中,10%～20%含水量处理的卵孵化率(60.3%～61.4%)显著高于5%处理(42.5%);在黑土中,15%～20%处理的卵孵化率最高(49.8%～42.7%),其次为10%(28.4%),最低为5%处理(13.5%);在砂土中,5%处理的卵孵化率(38.7%)显著高于其他处理(12.9%～19.8%)。在3种不同土壤处理下,亚洲小车蝗卵的孵化均集中在前3 d,相对孵化率达到73.1%～98.0%;砂土的相对孵化率在第1天达到高峰,但与棕钙土和黑土的差异不显著;棕钙土和黑土的相对孵化率在第2天达到高峰,且显著高于砂土。因此,10%～20%含水量的棕钙土最适合亚洲小车蝗卵的孵化,孵化率高,孵化历期短,孵化时间更为整齐;其次为黑土;最次为砂土。     

福寿螺孵化条件的实验探究

福寿螺(Ampullaria gigas),又名大瓶螺,两栖淡水贝类软体生物,属软体动物门Mollusca,腹足纲Gasopoda,瓶螺科Pilaidae。成螺雌雄异体,爬行体长3．5～6cm,贝壳近似圆盘形,一般具6螺层;卵圆球形,直径2～2．5mm,初产时深红色、粘稠,孵化前变淡,卵成堆叠产,每卵块3～5层,约100～960粒不等;幼螺初孵体长2～2．5mm,软体部分呈深红色,初孵幼螺可在水中爬行,以后贝壳向右旋增加。     

胎仔数与父本缺失对棕色田鼠幼仔体重发育的影响

室内饲养条件下,测量了出生后不同发育阶段棕色田鼠Microtus mandarinus的体重,并探讨了胎仔数(分别为1只、2只、3只和4只)及父本缺失(母鼠单独抚育)对幼仔体重发育的影响.结果表明,棕色田鼠出生后第一周体重的瞬时生长率最高,此后逐步下降;出生后28～35 d,体重增益最大(P<0.05).出生后7 d,不同胎仔数的体重没有明显差异,但至断乳时(出生后21 d),胎仔数为2只的幼仔平均体重明显高于其它胎仔数的平均体重(P<0.05).与双亲抚育相比,母鼠单独抚育的幼仔在断乳时的体重明显下降(P<0.05).这些结果说明,哺乳期内棕色田鼠幼仔的体重发育与胎仔数有关.由于棕色田鼠是单配制,双亲育幼,父本雄鼠的缺失减少了亲本投资,影响了幼仔的身体发育.     

四川宝兴圈养绿尾虹雉的人工孵化技术研究

在四川宝兴蜂桶寨绿尾虹雉研究中心开展绿尾虹雉Lophophorus lhuysii卵人工孵化研究,用不同湿度孵化2组卵:梯度湿度组使用3种湿度,使卵失重率趋于15%;均衡湿度组始终使用50%～55%的湿度。观察记录卵质量、胚胎发育情况。结果显示:成功孵化雏鸟12只,孵化率70.6%,雏鸟3个月成活率100%;卵孵化期28.1～30.2 d,平均(29.5±0.6) d,卵失重率10.7%～17.6%,平均(14.0±2.0)%,啄壳时间26.1～28.3 d,平均(27.4±0.6) d,出壳持续时间36.5～58.5 h,平均(48.7±6.8) h;卵的日平均质量与孵化天数极显著负相关;梯度湿度组和均衡湿度组在卵的失重率和初始雏重上的差异有统计学意义,而啄壳时间和卵孵化期的差异无统计学意义;卵失重率越小,初始雏重越大;与家鸡Gallus gallus domesticus卵胚胎的发育特征相似。保持卵失重率10%～15%可做为绿尾虹雉卵孵化湿度设置的参考。     

A comparative survey of the Erpobdella octoculata (L.) populations in the Afon Crafnant,N. Wales,above and below an input of zinc from mine-waste

The life-cycle, growth, and reproductive success of a stream-dwelling Erpobdella octoculata (L.) were studied over a 19-month period at two sites, one above and one below an input of zinc pollution from mine-waste. Samples were collected monthly using quadrats. The blotted wet weight of all leeches was measured. An histological technique was employed to determine sexual maturity. Reproductive success was measured by estimating the numbers of cocoons and number of eggs per cocoon at each site. A wet ashing technique, followed by analysis using flame atomic absorption spectrometry, was used to determine the extent of bioaccumulation of zinc. Total zinc and other metals in the waters were similarly analysed.Differences were found between the populations at the two sites. The life-history of the Erpobdella above the contamination was comparable to that found for other stream-dwelling populations previously studied. Observed differences in densities of leeches between sites in the present and in previous studies by other workers may be due to recorded differences in the abundance of available food. At the polluted site, there was evidence that (a) there was a delay in cocoon deposition and hence hatching of young, (b) the adult leeches produced more misshapened and empty cocoons, (c) no relationship existed between the area of cocoons with eggs and number of eggs present, and (d) the proportion of young to adult leech was smaller at the polluted site. At the polluted site, higher levels of zinc were recorded in the tissues of Erpobdella and there was some evidence for the active intake of zinc by the leech.     

The effects of feeding regime on the growth and reproduction of the medicinal leech Hirudo medicinalis

1. The feeding frequency, the size of meals, the number of meals required to attain reproductive maturity and the number of meals taken between iteroparous reproductive bouts were determined in the laboratory under optimal conditions for the medicinal leech Hirudo medicinalis fed exclusively on mammalian (bovine) blood. In addition the number of bouts of reproduction and the numbers of cocoons and hatchlings per cocoon produced were determined.
2. The average time for H. medicinalis to reach reproductive maturity at 20°C was 289 days, at an average wet biomass of 8143 mg with two–nine separate bouts of cocoon production. The number of meals to first reproduction was 8.9 (mean meal size of 3066.7 mg), with a significant correlation between total mass of blood ingested and the numbers of reproductive bouts and number of cocoons produced. Mean lifetime cocoon production per individual was 12.43, with 3.9 hatchlings per cocoon.
3. The significant positive relationships between ingestion, fecundity and developmental rate observed support the hypothesis that declining abundances of field populations of H. medicinalis are the result of lower available energy for growth, reflecting leeches now feeding predominantly on amphibian blood of lower energetic value than mammalian blood.     

The influence of body size on immediate reproductive success in Dugesia gonocephala (Tricladida,Paludicola)

The individual reproductive output of the stream-dwelling flatworm Dugesia gonocephala was investigated. Various measures of reproductive success were related to body size. (I) For the first 30 days in the laboratory small individuals produced no cocoons, individuals of intermediate size produced unfertilized cocoons and large individuals usually produced fertilized cocoons. (II) In individuals that produced a cocoon, no correlation was found between the number of cocoons produced in one month and body size. (III) Large individuals, however, produced larger cocoons. This was not due to the fact that unfertilized cocoons were smaller. (IV) Large cocoons tended to contain more young. (V) The average size of young hatching from large cocoons was larger. (VI) Large individuals produced their first cocoon soon after their arrival in the laboratory and seemed to have a higher chance of producing a fertilized first cocoon. (VII) A trade-off existed between producing many small versus few large young.     

Reproduction efficiency of the Horse Leech,Haemopis sanguisuga (Linnaeus, 1758)

The aquaculture sector has recently focused on alternative food sources due to increased costs and limited resources. Live food sources, such as invertebrates, have important roles in digestion processes of fish. It was aimed to determine the reproduction efficiency of the horse leech, Haemopis sanguisuga, which is expected to be used as an alternative live nutritional source in aquaculture in this study. The study was conducted at ambient temperature in the laboratory conditions for three months. A total of 25 gravid leeches with an average body mass of 6.91 ± 2.20 g were used. The leeches lost up to 75% of their body mass and laid 4.30 ± 1.49 cocoons at 12.0 ± 8.2 days interval during cocoon laying period. Leeches stopped laying cocoon when the temperature fell to 16 °C. The average of offspring hatched from the cocoons was 6.45 ± 2.86. The length–body mass relationship of the offspring was exponential (W = 0.012L^2.809, R² = 0.898). The results from the current study indicate that the basic biological parameter affecting the reproduction efficiency of H. sanguisuga is the size of the broodstock leeches, and reproduction activity weakens the broodstocks.     

Reproductive potential of the earthworm Eisenia foetida

Summary Regression equations are provided for the earthworm Eisenia foetida with respect to age at which 50% of the population became clitellate at 25° C in relation to population density in activated sludge and in horse manure. Regression equations are provided for progeny per cocoon versus weight of cocoon, and weight of cocoon in relation to weight of parent; from these an equation is derived for progeny per cocoon relative to worm weight. Regression equations are given on (a) number of cocoons produced per adult in relation to age and population density from onset of adulthood to median peak production of cocoons, age 10 weeks, and from age 10 weeks to age 27 weeks, and (b) weight of worm in relation to population density and age between ages 5 and 27 weeks. From (a) and (b) a family of equations (c) are derived giving progeny per cocoon in relation to age of adult and population density. From equations (a) and (c) two families of equations are generated giving progeny per adult in relation to ascent to, and descent from, the median week of peak cocoon production in relation to population density. Data also are provided on age at which reproduction terminates in relation to population density, optimum population density for reproduction, and hatchability.     

Life history of the oligochaete Enchytraeus coronatus (Annelida, Enchytraeidae) in agar culture

Abstract. Life-history attributes and the reproductive biology of Enchytraeus coronatus (Oligochaeta, Enchytraeidae) were studied in agar cultures, as a basis for using this species in toxicity tests and other experimental studies. The use of agar allows daily examination of the behavior, reproduction, and mortality of the worms. At 20°C, E. coronatus had a generation time of 21–22 days and an embryonic period of 7–10 days. Hatch rate was high (>80%) and worms became sexually mature 8–10 days after hatching. Cocoon production and number of eggs per cocoon were positively correlated. Mortality in the first stages of the life cycle (embryonic period and first week after hatching) was about 38%. Three different periods of cocoon production were distinguished: a period characterized by a regular increase in the number of cocoons produced (weeks 4–9), a period of production at a constant high rate of ∼5 cocoons per week (weeks 10–20), and a period of decline in production rate (weeks 21–32), down to a mean value of 1.6 cocoons per adult in the last week. This study showed that synchronized agar cultures of cohorts can provide adults for long-term experimental tests, with the age for optimum reproduction being 8–20 weeks.     

The evolution of parental care in freshwater leeches

Summary The life-history strategies of a selection of the most common European freshwater leeches (Euhirudinea) are described. On the basis of this information and results from the literature, the probable phylogenetic development of parental care in the Euhirudinea is reconstructed. The jawless worm leeches (Erpobdellidae) secrete a protective cocoon, cement it to the substrate and sometimes ventilate it before they leave the egg capsules. This behaviour represents the most ancient state in leech evolution. Members of the jawed Hirudinidae deposit desiccation-resistant cocoons on land. All known Glossiphoniidae (leeches equipped with a proboscis) have evolved the habit of brooding the eggs and young. These unique parental care patterns within one family of extant freshwater leeches can be arranged schematically in a series of increasing complexity which may reflect the evolution of brooding behaviour. Glossiphoniid leeches of the genus Helobdella, which have a world-wide distribution, display the most highly developed parental care system: they not only protect but also feed the young they carry. This results in the young being much larger when they leave the parent and, presumably, in higher subsequent survival. Isolated cocoons of all aquatic leeches are rapidly destroyed by predators, primarily water snails. In erpobdellids (but not glossiphoniids, which protect the cocoons) a large portion of the cocoons are lost due to predatory attacks. We conclude that the major selective pressure driving the evolution of parental care in leeches may have been predation on eggs and juvenile stages. Dedicated to Professor Dr. G. Osche on the occasion of his 75th birthday     

The effects of feeding regime on the growth and reproduction of the medicinal leech Hirudo medicinalis

1. The feeding frequency, the size of meals, the number of meals required to attain reproductive maturity and the number of meals taken between iteroparous reproductive bouts were determined in the laboratory under optimal conditions for the medicinal leech Hirudo medicinalis fed exclusively on mammalian (bovine) blood. In addition the number of bouts of reproduction and the numbers of cocoons and hatchlings per cocoon produced were determined.
2. The average time for H. medicinalis to reach reproductive maturity at 20°C was 289 days, at an average wet biomass of 8143 mg with two–nine separate bouts of cocoon production. The number of meals to first reproduction was 8.9 (mean meal size of 3066.7 mg), with a significant correlation between total mass of blood ingested and the numbers of reproductive bouts and number of cocoons produced. Mean lifetime cocoon production per individual was 12.43, with 3.9 hatchlings per cocoon.
3. The significant positive relationships between ingestion, fecundity and developmental rate observed support the hypothesis that declining abundances of field populations of H. medicinalis are the result of lower available energy for growth, reflecting leeches now feeding predominantly on amphibian blood of lower energetic value than mammalian blood.     

Reproduction of Lumbricillus rivalis (Levinsen) in laboratory cultures and in decaying seaweed

The cocoon production of 144 Lumbricillus rivalis cultured in pairs at 10 ± 1 °C was high over the first 2 weeks of breeding activity and then declined, chiefly because of high mortality. Cocoon deposition lasted for between 1 and 16 weeks, eight pairs of worms producing cocoons for 9 weeks and one pair for 16 weeks. During the total period of cocoon deposition over 9000 eggs (mean 17·4 per cocoon) were deposited. Two decaying wrack bed populations of L. rivalis showed a low level of cocoon and egg production in autumn, rising to an annual maximum in late winter/early spring. In these populations the mean egg content varied seasonally from 17·1 to 47·8 eggs per cocoon. When cocoons in the laboratory were transferred from the site of deposition to incubation dishes 31% hatched, but those left in the substrate showed a 92% hatch. In the naturally occurring populations 19% of the cocoons detached from seaweed fronds hatched, but 62% of those left in situ. Eggs and worm embryos developed to relatively late stages in most cocoons, whatever the rate of hatching; development often continued for up to 2 months after deposition without hatching. Over 50% of the fertile eggs in cocoons from decaying wrack hatched and developed to 5 mm worms.     

Seasonal dynamics and emergence pattern of a tropical earthworm,Drawida calebi (Oligochaeta)

Cocoon morphology (shape, size, colour and ornamentation), hatching, and seasonal dynamics of cocoon and juveniles of D. calebi have been studied in an Indian pasture site. The average live weight of cocoon is 15.17 mg, length/diameter 0.94, and moisture content 72.5 g%. Just-hatched juveniles weigh on an average 10.4 mg, and are 10.5–17.5 mm in length. The incubation period lasts 56.33 ± 2 days during November—December in laboratory cultures (25°C, and moisture 15 g%). A maximum of 64.0 live cocoons/m² with a live weight of 0.971 g/m² were deposited during October—November 1977, but very few during summer months. A surface-living species, D. calebi shows single peak emergence pattern in December—January. It is estimated that 78 cocoons (live and dead)/m² (780,000/hectare), were produced in the field by D. calebi population in a year (1976–77). Thus the total cocoon production is 11.83 kg/hectare/year. It is estimated that 3 cocoons/individual/year are produced by D. calebi in field conditions.