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。     

牛蒡抗虫活性及抗虫成分的初步研究

在水温(23±0.5)℃、pH 7.0～8.0、溶解氧＞5 mg· L-1的条件下,研究孵化过程中不同盐度对拟目乌贼胚胎发育和孵化率的影响.结果表明,拟目乌贼卵透明略带奶油色,近椭圆形,短径为0.596～1.758 cm,长径为1.452～3.136 cm,刚产出的卵重约2g;孵化完成时,卵膜内的重量达到4.5g.在盐度为28‰时,经过28～30 d孵化,卵的短径和长径平均分别增加了0.601、0.615 cm,孵化率为57.0％;盐度为23‰时,卵的长径和短径也相应增加,增幅分别为0.567、1.263 cm,孵化率为13.5％;盐度为33‰时,经过28～30 d孵化,卵短径平均增长0.150 cm,而长径却缩短了0.141 cm,孵化率为9.5％;在盐度为13‰、18‰、38‰和43‰条件下,胚胎停止发育,孵化率为0.结果表明,拟目乌贼属于狭盐性种类,盐度变化对拟目乌贼胚胎发育和孵化有直接影响.     

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.     

体重、年龄和应激刺激对菲牛蛭繁殖性能的影响

采用单因素方差分析等方法探讨人工养殖条件下体重、年龄和环境应激对菲牛蛭繁殖性能的影响。结果表明,体重对卵茧大小和湿质量及幼蛭体长、体宽和湿体质量无显著影响(P>0.05),而亲蛭性腺系数、平均产茧数、孵化率和平均孵化数在各组间差异显著(P<0.05),其中体重10～15g组明显高于其他组(P<0.05);年龄对亲蛭平均产茧数、孵化率、平均孵化数和卵茧大小影响显著(P<0.05),其中2～3年龄亲本具有最高的平均产茧数、孵化率和平均孵化数,8月龄亲本所产卵茧个体明显大于其他年龄组(P<0.05),而卵茧湿质量及幼蛭体长、体宽和湿体质量在各年龄组间均无显著差异(P>0.05)。环境应激对亲蛭的平均产茧数、孵化率和平均孵化数影响显著(P<0.01),其中1～2次操作应激下的平均产茧数和孵化数最高,无操作刺激下的孵化率略高于1～2次操作刺激(P>0.05),而卵茧大小和湿质量及幼蛭体长、体宽和湿体质量在各应激处理组间无显著差异(P>0.05)。本研究获得了菲牛蛭繁殖的最佳体重和年龄,建议繁育生产中挑选10～15g和2～3年龄的个体作为亲本,期间进行1～2次操作刺激可提高其繁殖性能。     

温度变化对家蟋蟀卵孵化率的影响

对低温萌动温度和高温孵化温度变化条件下家蟋蟀Acheta domesticus卵的孵化率变化进行研究,旨在探讨温度变化对家蟋蟀卵孵化的影响,为温度影响昆虫卵孵化提供一个新的证据。在低温萌动温度(4℃和7℃)和高温孵化温度(25℃和29.5℃)下观察记录家蟋蟀卵孵化的个体数量,采用方差分析方法检验温度变化对卵孵化率的影响。结果表明,低温萌动温度显著影响家蟋蟀卵的孵化率,而高温孵化温度对家蟋蟀卵的孵化率则无显著作用,但二者存在显著的互作效应。在同一孵化时间内,不同温度处理下家蟋蟀卵孵化率之间的差异有统计学意义。在不同温度处理下,家蟋蟀卵达到最大孵化率的时间不同。说明低温萌动和高温孵化是家蟋蟀卵孵化的重要影响因素。本研究为家蟋蟀人工饲养的较有利的温度条件设置提供一定的理论指导。     

不同盐度下条石鲷胚胎及卵黄囊仔鱼的形态变化

为了研究盐度对条石鲷(Oplegnathus fascltus)胚胎及卵黄囊仔鱼生长发育的影响,将条石鲷的受精卵置于不同盐度的水体中, 观察盐度胁迫下条石鲷胚胎的沉浮情况、卵径、油球径、孵化率、畸形率, 以及孵化后卵黄囊仔鱼的形态变化和营养物质的消耗状况。结果表明:条石鲷受精卵在盐度25(含25)以下的水体中为沉性, 在盐度30(含30)以上的海水中全部漂浮于水表层, 在对照组盐度26的水体中大部分胚胎浮在水上层;在水温22.5 ℃～24.0 ℃的条件下, 条石鲷受精卵经24～30 h可孵化成仔鱼, 盐度对孵化时间影响不显著(P＞0.05);盐度为20～50都能孵出仔鱼, 但孵化率和畸形率因盐度不同而有显著差异;综合分析表明,条石鲷受精卵孵化的适合盐度范围为25～35,理论上的最适孵化盐度范围为28.5～30.5;受精卵卵径与孵化盐度呈反比,盐度与卵黄囊被吸收程度呈正比,与全长和体高呈反比,油球径不因盐度不同而改变。     

池塘桡足类休眠卵对浮游种群的潜在补充及其影响因素

休眠卵是桡足类的重要生存策略,其在沉积物中的丰度对水体种群的补充具有重要意义.干塘是池塘养殖管理的重要措施,对池塘生态系统具有重要影响.2014年2月15日(干塘前)和3月2日(干塘后),分别采集广州市南沙区养殖池塘内表层沉积物,研究沉积物中桡足类休眠卵对浮游种群的潜在补充及影响因素.结果表明: 干塘前未冷藏沉积物样品在盐度20时的潜在补充量和孵化率最高,4 ℃冷藏4周后最高值出现在盐度为15的处理组.干塘后未冷藏沉积物样品在盐度15时的潜在补充量和孵化率最高,冷藏4周后最高值出现在盐度为20的处理组.这说明干塘前桡足类休眠卵的潜在补充量显著高于干塘后,且干塘对沉积物中休眠卵的持续孵化时间有影响.     

影响西藏卤虫无节幼体在淡水中存活时间的几个因素分析

为对水产养殖育苗实践中活体饵料西藏卤虫(Antemia tibetiana)的应用提供参考, 研究不同钠盐对孵化率、无节幼体在淡水中存活时间的影响, 分析NaCl浓度、孵化液pH和淡水水温等因素对西藏卤虫无节幼体在淡水中存活时间, 记录各组无节幼体在淡水中50%和100%死亡所需时间。结果表明, 不同钠盐显著影响西藏卤虫的孵化率, Na₂SO₄组显著高于NaCl组(P<0.05), Na₂CO₃组显著低于NaCl组(P<0.01), 其他各组之间差异不显著(P>0.05)。以NaCl组孵化出的无节幼体在淡水中存活时间最长, 50%存活时间达13h, Na₂SO₄组孵化的无节幼体存活时间显著低于NaCl组(P<0.05), 而Na₂CO₃和NaNO₃组存活时间极显著低于NaCl组(P<0.01), 在Na₂CO₃中孵化的无节幼体死亡速度最快。孵化率高的实验组存活时间不是最长, 显示孵化率与存活率之间并无关联性。随着孵化液NaCl浓度升高, 无节幼体在淡水中存活时间逐渐延长, 至35‰时达到最高, 但当孵化液NaCl浓度达40‰时, 存活时间开始下降。随着孵化液pH从6.5—8.0逐渐升高, 存活时间逐渐延长, 至pH8.0时达到最高, 孵化液pH继续升高, 存活时间逐渐缩短, 到pH10.0时, 50%存活时间只有3.54h, 死亡速度最快, pH8.0组与其他实验组相比较差异显著(P<0.05)。在5℃淡水中无节幼体50%死亡时间为18.54h, 显著长于15℃水温组, 当水温≥20℃时, 所有组别50%存活时间短于水温15℃组, 差异显著(P<0.05)。孵化时钠盐的种类、NaCl浓度、孵化液pH和淡水水温对西藏卤虫无节幼体在淡水中存活时间有显著影响。     

Ovipositional and ovicidal effects of the microbial agent Bacillus thuringiensis israelensis on Culex quinquefasciatus say (Diptera: Culicidae).

The magnitude of oviposition as well as the size, shape and the number of eggs per of egg rafts egg raft were determined after gravid Culex quinquefasciatus Say oviposited on water treated with water dispersible granules (WDG) of Bacillus thuringiensis ssp. israelensis (Bti) and on untreated water. The mean number of eggs/raft was lower in the treated than in the untreated water. Bti concentrations from 0.5 to 2.0mg/L affected the shape of egg rafts and number of eggs in each raft. As the concentration of Bti increased from 0.5 to 2.0 mg/L the shape of egg rafts became more irregular with fewer eggs in each raft. Exposure to Bti at 2- and 26-h reduced the hatching rates, and fewer eggs hatched at 26-h of exposure to Bti. As the concentration of Bti WDG increased from 0.5 to 2.0 mg/L, the hatching rate decreased. Eggs exposed for 2-h to 2.0mg/ L Bti had a hatch of 30% after 24 h, the rate increasing to 57% after 72 h. In contrast, in 26-h exposed eggs to 2.0 mg/L Bti, the hatching rate after 24 h was only 12% and this rate increased to 39% after 72 h. In larvae from eggs exposed for 2 h, the survival rate was 40% at 2.0 mg/L Bti and 87% in untreated controls. In contrast, the survival rates of larvae from 26-h exposed eggs was 91% in controls while it was 30% at 2.0 mg/L Bti. As the concentration of Bti increased from 0.5 to 2.0 mg/ 1 the survival rates of larvae decreased. The combined effects of reductions of egg rafts, low number of eggs per egg raft, and reduced hatching and survival rates could have significant cumulative effects on the yield of adult mosquitoes, and this could result in a greater control potential of this microbial agent.     

Characterisation of proteases involved in egg hatching of the sheep blowfly, Lucilia cuprina

A number of proteases were identified in the egg shell washings (ESW) collected during the egg hatching of Lucilia cuprina (sheep blowfly). Characterization of these proteases indicated a pH optima in a similar pH range that was optimal for L. cuprina egg hatching. Mechanistic characterization of these proteases indicated that they were predominantly of the serine class. Several protease inhibitors were tested for their ability to inhibit L. cuprina egg hatching in vitro. Egg hatching was significantly (P<0.05) inhibited by PMSF (61%), 1,10-Phenanthroline (42%) and Pepstatin (29%). The inhibition of egg hatching by PMSF showed a strong concentration dependence, with its effects ranging from inhibition at high concentrations to enhancement of egg hatching at low concentrations. Addition of ESW to unhatched eggs, significantly (P<0.05) enhanced their rate of hatching above untreated control eggs. This enhancement of egg hatching was significantly (P<0.05) reversed by the protease inhibitors Elastatinal (40%), 1,10-Phenanthroline (40%) and PMSF (38%). These studies indicate a role for serine and/or metallo-proteases in facilitating L. cuprina egg hatch.     

CRYOPRESERVATION OF THE BEET ARMYWORM EGGS*

Abstract A protocol for cryopreservation of the eggs of beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) in liquid nitrogen was established after examining the effects of a number of factors on the survival of the eggs during various stages of cryopreservation. Over 95% of eggs incubated at 271) for 33 h were permeabilized and about 60% of them could hatch using the following permeabilization procedure: dechorionation of eggs in 15% sodium hypochlorite for 6 min followed by immersion in isopronol for 15 sec to remove surface water and then in n‐hexane for 30 sec to dissolve the wax layer. Immersion of the permeabilized eggs in 2 mol/L ethylene glycol for 30 min and then dehydration in 8.5 mol/L ethylene glycol solution containing 10% BSA for 5 min led to 55%? 60% survival and approximately 24% hatching rate. Eggs cryopreserved in liquid nitrogen using the recommended protocol have a survival rate of (16.3 ± 7.6)% and a hatching rate of (1.6 ± 1.1)%.     

Egg hatching of mosquitoes Aedes caspius and Ae. vittatus stimulated by water vibrations

Simple laboratory experiments with eggs of wild-caught Aedes caspius (Pallas) and Aedes vittatus (Bigot) mosquitoes (Diptera: Culicidae) demonstrated that egg hatch rates (i.e. percentage hatching daily) increased significantly in response to water vibrations caused by finger-tip drumming on containers of submerged eggs. When disturbed by daily vibrations for only 30 s, eggs hatched sooner than when they remained flooded or were periodically drained and reflooded without agitation. For autogenous Ae. caspius from saltmarsh, egg hatch rates were three- to four-fold greater for groups of 50 eggs than for solitary eggs, possibly due to chemicals (functional kairomones) emanating from other eggs or larvae. For anautogenous Ae. vittatus from freshwater rock-pools, tapping the container daily (for 30 s each 2 h in 8 h) hatched 93% of eggs, compared with only 42% hatch of eggs agitated only when first flooded or 55% hatch of eggs dried and reflooded three times during 17 days without other disturbance. It is concluded that, apart from flooding and other factors, vibrations - simulating the patter of rainfall provide a very significant hatching stimulus for Aedes eggs.     

The adaptive value of hatching towards the end of the night: lessons from eggs of the haematophagous bug Rhodnius prolixus

Abstract. The daily hatching rhythm of Rhodnius prolixus eggs is established under an LD 12 : 12 h photoperiod. The endogenous nature of this rhythm is demonstrated under continuous darkness. Hatching takes place during the last half of the night, when the maximum environmental relative humidity (RH) and minimum temperature (i.e. the combination that yields the lower water vapour saturation deficits) occur in wild habitats. This temporal window of approximately 7 h recurs at 24‐h intervals, producing a hatching rhythm in the population. The effects of the RH upon egg‐hatching are analysed. In agreement with previous studies, hatching success is strongly affected by environmental RH. Although 88% of eggs hatch at 75% RH, only 4% and 10% hatch at 0% or 100% RH, respectively. These results support the hypothesis that temporal synchronization is related to the avoidance of low environmental RHs, high environmental temperatures, or high water vapour saturation deficit during hatching, thus minimizing their deleterious effects. Given that eggs cannot choose optimum microclimatic conditions, selective pressures appear to have originated from an adaptive temporal rather than spatial hygropreference.     

Differences in egg size, shell thickness, pore density, pore diameter and water vapour conductance between first and second eggs of Snares Penguins Eudyptes robustus and their influence on hatching asynchrony

Brood reduction in birds is frequently induced by hatching asynchrony. Crested penguins (genus Eudyptes) are obligate brood reducers, but in contrast to most other birds, first‐laid eggs are considerably smaller in size than second‐laid eggs; furthermore, first‐laid eggs hatch after their siblings. The mechanisms underlying this reversal in size and hatching order remain unclear. In this study, we tested whether the second‐laid eggs of Snares Penguins Eudyptes robustus have a higher eggshell porosity allowing them to maintain a higher metabolic rate throughout incubation and to hatch before their first‐laid siblings. We investigated differences in egg size, shell thickness, pore density, pore diameter and water vapour conductance between first and second eggs within clutches and examined the influence of these shell characteristics on hatching asynchrony. First‐laid eggs of Snares Penguins were approximately 78% of the size of the larger second eggs. Second‐laid eggs had considerably thicker shells and more pores per cm² than first eggs, whereas pore diameter did not differ between eggs. Water vapour conductance was greater in second‐ (16.8 mg/day/torr) than in first‐laid eggs (14.9 mg/day/torr). The difference in water vapour conductance between first‐ and second‐laid eggs within clutches was related to hatching patterns. In nests where second eggs hatched before first‐laid eggs, second eggs had a considerably greater water conductance than their sibling, whereas in nests where both eggs hatched on the same day, the difference in water conductance between eggs was very small, and in a few nests where small first eggs hatched before their larger sibling, they had a greater water conductance than their larger second‐laid nestmate. Surprisingly few studies have investigated differences in shell characteristics between eggs within clutches and associated effects on hatching asynchrony. This study has demonstrated that such differences exist between eggs within clutches and that they can influence hatching patterns.     

广聚萤叶甲成虫交配时长对产卵量与孵化率的影响

【目的】明确不同交配时长对广聚萤叶甲雌虫产卵量和卵的孵化率的影响。【方法】在室内条件下,对不同交配时长下广聚萤叶甲的雌虫产卵量和卵的孵化率进行观察:(1)选取羽化第3d的广聚萤叶甲雌雄虫随机配对,观察24 h,记录交配情况和时长;(2)在交配开始1、5、15、30、60 min时,强行分开雌雄成虫,然后将不同交配时长的雌虫进行单独饲养,以正常交配一次的雌虫作为对照,每个处理选取23组;(3)将15～30 cm健壮豚草小苗插入注满水的塑料小瓶内,将配对的一组雌雄成虫和豚草小苗放入养虫盒中饲养,每天更换带卵的小苗并记录叶片上的产卵量;(4)将上述带卵的小苗至于适宜条件下培养,记录5～7 d内卵块孵化的情况。【结果】广聚萤叶甲正常交配一次的对照组的产卵水平显著高于各处理组,单雌产卵为889粒,交配时间15 min以下各组雌虫的产卵量明显低于交配30 min以上的各组雌虫。同时交配时长5 min以下雌虫产的卵基本不能孵化,而交配时间达到30 min以上的各组卵块的孵化率明显提高。【结论】雄虫转移雌虫受精所需精子量需要耗费的时间为30 min左右,且雄虫有延长交配时间的趋性。该结果为研究广聚萤叶甲的生态特性以及优化种群繁殖提供科学依据。     

Larval hatching in the horseshoe crab, Limulus polyphemus: facilitation by environmental cues

Female horseshoe crabs, Limulus polyphemus (Linnaeus), lay their eggs in nests on sandy beaches near the high water line. Embryos develop within the sand, hatch into trilobite larvae, and enter the water column when the nest is inundated. Given the diversity of tidal and shoreline inundation patterns that populations of L. polyphemus experience throughout their range (semidiurnal and diurnal tides, microtidal, and nontidal), hatching may also be facilitated by environmental triggers that serve to synchronize hatching and larval emergence with periods of high water. The objective of this study was to determine if larval hatching in L. polyphemus is triggered or facilitated by environmental cues. Stage 21 embryos were subjected to one of seven different treatments that simulated conditions experienced during inundation: (1) hydration, (2) agitation, (3) hydration and agitation, (4) hydration and agitation with sand, (5) osmotic shock, (6) terrestrial hypoxia, and (7) aquatic hypoxia. Hatching rates increased significantly under all simulated tidal conditions compared to controls and were highest (96%) for eggs simultaneously exposed to both hydration and agitation with sand. Measurements of the osmolarity of the perivitelline fluid of developing eggs collected from the field indicated that it is hyperosmotic to the ambient seawater and porewater. Thus, when inundated, eggs also experience a hypoosmotic shock, which would likely facilitate hatching by causing the eggs to swell, rupturing the egg membrane and thereby increasing the likelihood that larvae would hatch and enter the water column during periods of high water.     

To hatch or not to hatch? Egg hatch response to larval density and to larval contact in a treehole mosquito

Abstract.

• 1 We investigated the effect on egg hatch of exposure to: (1) varying larval density, and (2) larval contact in Aedes triseriatus Say (Diptera: Culicidae). For 2 days in the laboratory we submerged eggs into a treehole water medium containing 0 (control), 4, 12 or 24 larvae that could either contact the eggs directly or were separated from them by a screen. Following treatment, abundance of microorganisms on the egg surfaces, a food source for newly hatched larvae and a proposed hatching stimulus, was assessed by counts made from serial dilutions of samples.
• 2 We discovered a complex hatching response to larval contact and to larval density, and an interaction between these two factors in their effect on microbial growth. Hatching was inhibited in the 0-larva control, even though microorganisms grew abundantly on the eggs. Hatch rate, as well as microbial counts, were high for eggs in direct contact with 4 larvae. As density increased in the larval contact treatment, microorganisms disappeared from the egg surfaces and hatch rate declined.
• 3 When protected from larval grazing, eggs supported numerous microbial colonies irrespective of larval density. In contrast to the contact treatment group, egg hatch increased with increasing larval density. These observations suggest that the combination of microbial growth and a larval factor stimulates hatch. This hatching response may have evolved because both abundant microorganisms and numerous larvae reflect a habitat of good quality.