幼虫密度和温度对水芹叶象甲未成熟阶段生长发育的影响

[目的]为明确不同幼虫密度和不同温度条件对水芹叶象甲Hypera sp.未成熟阶段生长发育的影响.[方法]在室内条件下对不同幼虫饲养密度和不同温度条件饲养的水芹叶象甲未成熟阶段(卵、幼虫、预蛹和蛹)的存活和生长发育进行研究.[结果]幼虫密度对水芹叶象甲幼虫、预蛹和蛹的存活和生长发育均具有显著影响.水芹叶象甲幼虫、预蛹和蛹在50头/盒的密度条件下的存活率均显著高于其它密度条件,且发育历期显著短于其它密度条件.此外,各密度条件下的雌蛹重均显著重于雄蛹重,但性比(♀/♂)不受密度条件的影响.温度条件对水芹叶象甲卵、幼虫、预蛹和蛹的存活和生长发育亦均具有显著影响.27℃条件下的幼虫和蛹的存活率均显著高于其它温度条件,1龄幼虫在30℃条件下的存活率显著高于其它温度条件,而3龄幼虫在27℃条件下的存活率显著高于其它温度条件,但温度条件对2龄幼虫的存活率无显著影响.水芹叶象甲各龄期幼虫及各虫态的发育历期随着温度升高而显著缩短.[结论]幼虫饲养密度和温度是影响水芹叶象甲种群变化的重要因子,这将为分析水芹叶象甲种群动态变化规律,以 及提高该虫的预测预报和综合防控水平提供依据.     

幼虫密度对二点委夜蛾生长发育及繁殖的影响

【目的】在不同幼虫密度饲养条件下,研究二点委夜蛾Athetis lepigone生长发育及繁殖的情况,明确幼虫密度对该害虫的室内种群增长的影响。【方法】本实验设置5个幼虫饲养密度即1,5,10,20和30头/瓶(750 mL),分别观察5个饲养密度下该虫的各个龄期及整个幼虫发育历期及存活率、蛹重、蛹期以及成虫生殖情况。【结果】幼虫密度对该虫幼虫各龄期及整个幼虫发育历期及存活率、蛹重、蛹期以及成虫生殖情况均有显著性影响。整个幼虫发育历期随着密度的增加而缩短,10头/瓶达到最短(18.27 d),之后随着幼虫密度的增加而显著延长;幼虫至蛹的存活率随着密度增高而显著下降,30头/瓶最低(39.37%)。蛹期随着密度的增加而延长(10头/瓶除外)。蛹重和每雌产卵量均以1头/瓶最高,随着幼虫密度的增加而显著下降。雌雄蛾寿命均以10头/瓶最长,与1和5头/瓶没有显著性差异。生命表分析显示:二点委夜蛾的种群增长指数以5头/瓶最高,幼虫密度过低或者过高均不利于种群增长。【结论】幼虫密度是影响二点委夜蛾种群增长的重要因子之一。     

幼虫密度对马铃薯块茎蛾生殖的影响

[目的]为了研究马铃薯块茎蛾Phthorimaea operculella(Zeller)幼虫的饲养密度对生殖的影响。[方法]本实验研究并比较了两种幼虫密度(15头/130 g块茎、45头/130 g块茎)的马铃薯块茎蛾成虫按照1:5和1:1比例交配后代的产卵量、畸形卵率、孵化率、化蛹率、羽化率、性比等生物学参数。[结果]高幼虫密度饲养的马铃薯块茎蛾化蛹率、羽化率、存活率、性比均显著较低,而幼虫~蛹的历期显著短于正常幼虫密度的。两种密度成虫按1:5头配对产卵,若雄性亲本为高幼虫密度饲养则卵的孵化率显著较低,若雌性亲本为高幼虫密度饲养则产卵量较低,畸形卵率显著较高。两种密度雌雄虫均为5头进行配对时,正常幼虫密度雌虫其所产卵的畸形率显著较低,产卵量、卵孵化率均显著较高,后代幼虫历期、化蛹率显著较高。而高幼虫密度雌虫其所产卵则受雄虫影响,亲代为高密度雄虫则畸形率较低,孵化率较高。[结论]高幼虫密度饲养的雄、雌虫生殖活力均降低。高幼虫密度雌虫可受高幼虫密度雄虫的诱导提高生殖能力,并影响其后代性比从而调节其种群动态。     

幼虫密度对草地螟生长发育及繁殖的影响

为了明确幼虫密度对草地螟Loxostege sticticalis种群增长的影响, 对室内条件下（温度22±1℃, RH 70%±5%, 光周期16L∶ 8D）不同幼虫密度[1, 10, 20, 30和40头/瓶（650 mL）］饲养的草地螟生长发育及繁殖进行了研究。结果表明: 幼虫密度对草地螟幼虫体色、 发育历期和存活率, 以及蛹重和成虫生殖等有显著影响。随着幼虫密度的增加, 幼虫体色黑化程度呈增强趋势, 幼虫密度大于10头/瓶时的体色黑化值均显著大于幼虫密度为1头/瓶时的体色黑化值（P<0.05）。20头/瓶的幼虫和蛹历期最短, 且随幼虫密度的增加而显著延长（P<0.05）。幼虫存活率以10头/瓶最高, 其他幼虫密度的幼虫存活率显著较低（P<0.05）。蛹重以1头/瓶的最重, 并随幼虫密度增加而显著下降（P<0.05）。成虫产卵量和交配率分别以1和20头/瓶的幼虫密度最高, 幼虫密度升高则产卵量、 交配率逐渐降低。成虫产卵历期随着幼虫密度的增加逐渐缩短。雌、 雄蛾寿命分别以10和20头/瓶幼虫密度时最长, 幼虫密度过高时雌雄蛾寿命又显著缩短（P<0.05）。生命表分析表明, 幼虫密度对草地螟种群增长指数有显著影响, 以10头/瓶幼虫密度的种群增长指数最高, 幼虫密度过高或过低时种群增长指数下降。据此认为, 幼虫密度是影响草地螟种群增长的重要因子之一。     

食用菌厉眼蕈蚊Lycoriella ingenua在温度逆境下的存活率

以食用菌重要害虫-厉眼蕈蚊属的Lycoriella ingenua为研究对象,研究了不同逆境温度下各虫态存活率的差异。结果表明温度对不同虫态存活率的影响存在显著性差异。成虫和蛹对高温具有一定适应性,卵对高温的适应性最低但具有一定的低温耐受力。在35-40℃高温下,相同暴露时间,各虫态的存活率随温度的升高而降低,但成虫的存活率均高于其它虫态。38℃下全部死亡的暴露时间分别为:成虫48 h,蛹24 h,幼虫12 h,卵2h。在40℃达到全部死亡的暴露时间分别为:成虫24 h、蛹12 h、卵和幼虫0.5 h。低温处理下,各虫态随着暴露时间的延长存活率逐渐降低。5℃低温下,相同暴露时间,成虫存活率均高于其它虫态,但在0℃低温下暴露24 h后全部死亡,显著高于其它虫态;幼虫在低温下取食活动减弱,5℃下暴露24 h后停止取食,相同暴露时间下随着温度的降低存活率下降;蛹对0℃的耐受力高于成虫和幼虫,暴露4 h后可以正常羽化,48 h后全部死亡;卵对短时间的低温具有一定耐受力,但随着暴露时间的延长存活率降低幅度大。     

幼虫密度对桑螟生长发育和繁殖的影响

【目的】本研究旨在了解桑螟Diaphania pyloalis幼虫不同饲养密度对其生长发育和繁殖的影响。【方法】本研究测定了室内同一条件下5个幼虫密度(130, 650, 1 300, 1 950和2 600头/m²)下桑螟生长发育和繁殖指标,包括发育历期、幼虫存活率、化蛹率、成虫羽化率、蛹重、产卵期、单雌产卵量等。【结果】幼虫密度对桑螟的生长发育和繁殖均产生不同程度影响,幼虫密度偏低或偏高都不利于桑螟生长发育和繁殖。其中以1 300和1 950头/m² 2种幼虫密度下的桑螟幼虫生长发育和成虫繁殖状态均最佳且两密度下各项指标无明显差异,1 300头/m²密度下,桑螟的幼虫历期、蛹历期和成虫历期分别为11.32, 6.33和5.31 d; 1 950头/m²密度下,桑螟的幼虫历期、蛹历期和成虫历期分别为11.50, 6.00和5.47 d。1 300头/m²幼虫密度下,桑螟化蛹率、成虫羽化率和幼虫存活率分别为86.67%, 100%和86.67%, 1 950头/m^2<...     

棉铃虫室内饲养技术的改进

在传统人工饲料饲养技术的基础上 ,对棉铃虫的卵、幼虫、蛹和成虫的饲养器材和操作方法进行了简化和改进。将产于纱布上的卵经消毒晾干后 ,直接放于塑料保鲜袋中孵化。初孵幼虫用毛笔移入特制的带盖 1 0孔饲养盒 ,每孔 1头 ,孔径和高度为 2 5cm× 1 8cm ,接虫前每孔加人工饲料 4～ 5g ,接虫后加盖 ,直至化蛹。幼虫化蛹后用培养皿收集 ,直接放于成虫饲养笼中 ,任其羽化、交配和产卵。采用这一改进饲养技术 ,幼虫存活率、化蛹率、羽化率等均有显著提高 ,棉铃虫的病害明显减少 ,同时节约饲养成本约 5 0 %。     

虫酰肼对甜菜夜蛾汰选种群生长发育及生殖的影响

研究虫酰肼对甜菜夜蛾汰选种群生长发育及生殖的影响。结果显示:经虫酰肼处理后,甜菜夜蛾SS种群和RR种群卵的孵化抑制中浓度分别为179.38和160.71mg/kg,孵化幼虫的存活抑制中浓度分别为18.64和30.53mg/kg,虫酰肼对甜菜夜蛾卵的孵化率影响较小,而对孵化后幼虫的存活率影响较大。处理初孵幼虫6d后,2种群幼虫存活率及化蛹率随处理浓度的增加而降低,幼虫历期最高饲毒浓度与最低饲毒浓度相比分别延长了2.71d和6.19d,同一浓度下,RR种群幼虫历期比SS种群缩短了0.94～2.59d。处理甜菜夜蛾3龄幼虫12h后,随虫酰肼浓度的增加,2种群化蛹率逐渐降低,雌雄蛹重均有递减的趋势,雌蛹比例随浓度的增加变化较小,但SS种群雌蛹比例≤50.00%,而RR种群雌蛹比例≥50.00%,雌雄成虫羽化率总体上依次递减,处理浓度大于1.00mg/kg时虫酰肼对甜菜夜蛾成虫羽化的影响较大。     

黄曲条跳甲室内饲养方法的改进

介绍一种饲养黄曲条跳甲Phyllotreta striolata(Fabricius)的改进新方法,采用分隔式养虫笼饲养成虫和萝卜"凹"型孔饲养幼虫,结果表明,使用该方法进行饲养,卵的成活率可达89.3%,1~3龄幼虫的存活率为65.0%~70.0%,蛹的存活率达80.0%,可以有效实现黄曲条跳甲的室内饲养。     

温度对大菜粉蝶生长发育的影响

为明确温度对大菜粉蝶生长发育的影响,在16、20、22、25、28和31℃共6个恒温条件下以白菜为寄主进行饲养,测定了温度对大菜粉蝶各虫态的发育历期、发育速率、存活率及成虫寿命等的影响,并采用直接最优法计算其各虫态的发育起点温度和有效积温。结果表明：在16～28℃温度范围内,大菜粉蝶的卵、幼虫、蛹及全世代平均发育速率具有随温度升高而加快的趋势,存活率则随着温度的升高而降低;卵、幼虫、蛹和成虫的发育起点温度分别为11.76℃、6.87℃、5.30℃和14.91℃,有效积温分别为38.14、213.90、169.68和43.01 d·℃。在28℃时大菜粉蝶卵的孵化率、各龄幼虫存活率、化蛹率、蛹重及羽化率均显著低于其他温度,31℃条件下不能完成个体发育。由此可见,高温环境不利于大菜粉蝶的存活和生长发育。研究结果可为大菜粉蝶田间发生期预测及综合防治提供科学依据。     

幼虫密度对甜菜夜蛾生长发育与繁殖的影响

为了研究甜菜夜蛾Spodoptera exigua(Hübner)幼虫的密度对其发育及繁殖的影响,本实验观察了5种幼虫密度下（1,5,10,20,30头/瓶）,幼虫发育和成虫繁殖情况。结果表明：幼虫和蛹历期、存活率和蛹重均差异显著。幼虫和蛹历期均以20头/瓶的最短,1头/瓶的最长,其余随幼虫密度增加而延长;幼虫至蛹存活率以10头/瓶的最高,其余随幼虫密度增加而降低;1头/瓶的蛹最重,显著高于其他密度的,其余随幼虫密度增加而下降。尽管密度间成虫羽化率和产卵前期均无显著差异,但成虫产卵量、寿命和畸形率差异显著。1头/瓶的产卵量最多,其次为10头/瓶的,其余随幼虫密度增加而减少,30头/瓶的产卵量显著少于其他密度的; 密度在1～20头/瓶范围内,雌蛾寿命均较短,显著短于30头/瓶的,而雄蛾寿命以5头/瓶的最短,显著短于其他密度的（10头/瓶除外）,10头/瓶的次之,其余密度间差异不显著;不同幼虫密度下羽化的成虫畸形率差异显著,10头/瓶的最低,其余随幼虫密度增加而升高; 生命表结果表明甜菜夜蛾在10头/瓶下世代存活率和种群增长指数均最高,幼虫密度过低或过高均不利于种群增长;世代存活率（S）和种群增长指数（I）与幼虫密度之间的关系均呈抛物线关系：S =－0.2087x²+2.5694x+211.52 (R²=0.88),I=－0.0552x²+0.9166x+54.168 (R²=0.95)。结果提示幼虫密度影响甜菜夜蛾种群动态的重要生态因子之一。     

密度对大树蛙蝌蚪生长发育和存活率的影响

种群密度效应主要表现在影响和调节种群的死亡率、发育速率、繁殖率以及扩散、迁移等反应种群数量动态的重要参数。分析密度对大树蛙蝌蚪生长发育和存活率的影响,有助于探究外界环境因子导致大树蛙种群密度迅速下降的作用机制。设置了15、20、25只/L和30只/L 4个密度组,测量大树蛙蝌蚪的尾长、体长、发育时间和存活率。结果表明,在15—30只/L范围内,密度升高显著降低了大树蛙蝌蚪尾长和体长的生长速率,减小其变态期的尾长和体长大小,其中与15只/L相比,20、25只/L和30只/L 3组蝌蚪的尾长分别降低了11.6%、11.8%和13.9%,体长分别降低了11.1%、9.5%和12.9%;随着密度的升高,大树蛙蝌蚪发育至跗蹠部伸长期和前肢伸出期的所需时间显著延长;大树蛙蝌蚪生长后期的存活率随密度升高显著降低,但密度对蝌蚪生长早期的存活率影响不显著。因此,密度升高可显著减小大树蛙蝌蚪的尾长和体长、延长发育时间和降低其生长后期的存活率,可能影响大树蛙蝌蚪变态后的适合度。     

Studies on Aedes albopictus larval mass-rearing optimization

To set up a sterile male technique program to control Aedes albopictus (Skuse) in areas in northern Italy, a pilot mass-rearing facility is under development. For this purpose, experiments were carried out to find the optimal larval density for the optimization of the rearing parameters, i.e., to obtain the fastest larval development, the highest larval and pupal survival rate, and large-sized pupae. Several different larval densities, from 40 to 2874 larvae per liter, were tested. For densities from 40 to 600 larvae per liter significant size differences were found among pupae obtained under different larval densities. The larvae raised at the lowest density tended to be smaller and to develop most slowly, i.e., longer pupation time. Also, increasing water volume and depth seemed to negatively affect the pupation success. Compared with the other larval densities tested, the larvae reared at a density of 2874 larvae per liter developed slightly faster and showed higher survival rates, indicating this density as appropriate for the development of a mass rearing, at least using the current larval diet.     

粘虫幼虫密度对成虫飞行与生殖的影响

本文报道了不同幼虫密度下(1、10、20、30、40头/瓶-850m1)粘虫蛾飞行能力与产卵量的变化情况。对未取食1日龄成虫12h飞行能力的测定结果表明,不同幼虫密度羽化的成虫飞行力差异显著(P<0.05),其中以10头/瓶羽化的成虫飞行时间最长(平均225.4分),飞行距离最远(平均17.5km),飞行超过120min的个体为61.1%,超过10 km的为55%。其它处理的各项参数随幼虫密度的增加而下降。粘虫蛾的翅长、翅宽、翅面积和翅负荷随幼虫密度的增加而下降。除翊负荷外,其余各项参数在处理间的差异显著(P<0.05)。成虫飞行能力与蛹重或翅负荷不呈直线相关,但与蛹重具有一定的关系：当蛹重为300-400mg时, 强飞行个体均超过50%, 当小于300mg或大于400mg时,强飞行个体比例下降,当小于225mg时,强飞行个体为零。处理间的成虫产卵量差异显著(P<0.05),且随幼虫密度的增加而下降。密度内的蛹重与成虫产卵量的关系不明显,但密度间的蛹重与产卵量的关系高度相关(r=0.78,P<0.01)。这些结果表明,当粘虫幼虫密度达到一定的阈值时,便可能促使成虫迁飞,而不是等到种群密度很高时才进行迁飞。     

Stocking density‐dependent growth and survival of Asian sun catfish,Horabagrus brachysoma (Gunther 1861) larvae

The aim of the experiment was to evaluate the growth and survival of Horabagrus brachysoma larvae at different stocking densities (3, 7, 13, 20, 27 and 33 larvae L^?1) during their hatchery phase. Total length and wet weight of the larvae consistently decreased (P < 0.05) at the end of 14 and 28 days of rearing as the density increased. The specific growth rate was significantly (P < 0.05) highest at three larvae L^?1 compared to the other five densities. The percent weight gain and survival of larvae was also highest at lowest density. The observation corroborates that catfish larvae can be reared at low densities in stagnant water conditions. Considering the value of larval growth, survival and overall weight gain, the stocking density of seven larvae L^?1 has been identified as the maximum for larval rearing of H.  brachysoma under hatchery conditions.     

幼虫密度对斜纹夜蛾抗病能力的影响

为了阐明斜纹夜蛾Spodoptera litura Fabricius幼虫密度对其抗病能力的影响,在室内条件下(温度23℃±1℃,相对湿度75%)对不同幼虫密度(1、2、5、10、15头/皿(直径为12cm))饲养的斜纹夜蛾幼虫抵抗斜纹夜蛾核型多角体病毒侵染的能力及其免疫指标进行了研究。结果表明:幼虫密度对斜纹夜蛾幼虫接种核型多角体病毒后的存活率、存活时间及血淋巴酚氧化酶活性影响显著。随着幼虫密度的增加,接种核型多角体病毒后幼虫的存活率降低,存活时间缩短。当幼虫密度达到15头/皿时,幼虫存活率显著低于其它幼虫密度。不同幼虫密度幼虫的存活时间以1头/皿的最高,15头/皿的最低,且二者之间差异显著。幼虫血淋巴中酚氧化酶活性随幼虫密度的增加而明显降低,当幼虫密度达到5头/皿时,幼虫酚氧化酶活性显著低于1头/皿的。另外,幼虫溶菌酶活性和血细胞总数受幼虫密度影响不显著。不同密度幼虫抗病性的变化与其血淋巴中酚氧化酶活性的变化趋势较为一致。所以斜纹夜蛾幼虫抗病能力的降低可能与幼虫酚氧化酶活性的下降有关。因此,幼虫密度是影响斜纹夜蛾幼虫抗病性变化的重要因子。     

Microbiota of Atlantic cod (Gadus morhua L.) rearing systems at pre‐ and posthatch stages and the effect of different treatments

Aims: To study the effect of ova disinfection, antibiotic and microbial treatments on the dominant cultivable cod rearing microbiota at pre‐ and posthatch stages, determining some virulence‐related phenotypic traits among bacterial isolates and their relation to larval survival. Methods and Results: Sampling of rearing systems (rearing water, ova, larvae, feeds and supplement) for analysis of cultivable microbiota took place at early stages in 2004 and 2005. Cultivation, phenotypic and genotypic (16S rRNA gene) analyses were performed. The production of putative virulence factors (PVFs), including haemolysin, siderophores and quorum‐sensing signals, by bacterial isolates was investigated and related to larval survival. The study was performed during two spawning seasons, evaluating current hatchery practices (ova disinfection and antibiotic treatment of unhealthy larvae) and specific putative probiotics applied to ova and larvae or rotifers. A diversified microbiota (75 operational taxonomic units, OTUs) was observed in cod rearing systems influenced by the feeds and treatments, with prevailing γ‐Proteobacteria prior to hatching towards a multiphyla microbiota posthatch. Phenotypic tests demonstrated the heterogeneity within some OTUs. Multivariate analysis of survival data in larval silos and the corresponding larval microbiota was used to divide the genotypic groups into beneficial/harmless and detrimental/opportunistic clusters. PVFs were common among the proposed detrimental/opportunistic OTUs. Conclusions: The results clearly demonstrate the influence of exogeneous feeding and treatments on larval gastrointestinal microbiota and the role of bacteria in larval survival. Significance and Impact of the Study: Increased understanding of the microbiota in rearing systems may contribute to successful implementation of microbial management in cod aquaculture.     

Rearing Costelytra zealandica (Coleoptera: Scarabaeidae)

Interaction between larvae can be a cause of mortality when scarabaeid larvae are concentrated in a confined volume of soil. Larvae of Costelytra zealandica (White), the New Zealand grass grub, were held for 30 days at population densities between 1 and 50 larvae per 200 ml of medium, and the effect of crowding on their survival and weight change was assessed. Larval density had no effect on survival in soil plus chopped sheep dung (3 :1), with up to 10 2nd‐instar larvae or 5 3rd‐instar larvae per 200 ml of medium. Larval survival and weight gain were increased by adding germinating ryegrass seed (Grasslands Ruanui) to the medium base, but the effect of density did not diminish. Weight gain of 3rd‐instar larvae decreased as their density increased. When the amount of germinating ryegrass seed in the medium was varied, there was no significant difference between the survival of larvae held in treatments with 5, 25, and 50 g of seed per litre of medium. Survival was significantly lower with 0 and 100 g of seed per litre of medium. It is concluded that, in rearing conditions, the final density of fully grown 3rd‐instar larvae should be a maximum of about 20 per litre of medium to prevent mortality caused by larval interaction—provided that adequate food is available.