棉铃虫蛹期土壤水分对其种群发生的影响

1999-2000年在室内通过模拟试验研究了棉铃虫蛹期的不同阶段土壤水分状况对其入土化蛹和羽化出土的影响,以及对出土成虫的后效应。结果表明不同的土壤相对含水量和不同时间土壤浸水对棉铃虫的入土和化蛹无影响,但却能显著影响其羽化和出土。此期土壤干燥（土壤相对含水量≤20％）对棉铃虫的羽化出土十分有利,大于40％的土壤相对含水量对其羽化出土不利,饱和的土壤相对含水量对棉铃虫的影响则是毁灭性的（羽化出土率≤10％）;而棉铃虫入土后的第2天、第3天和第10天土壤浸水对其羽化出土的影响也很大,羽化出土率分别为16.33％、9.28％和21.05％。此外,土壤水分状况通过影响棉铃虫的土中生态而间接影响出土成虫的存活、卵巢发育、交配和产卵,乃至下代卵的孵化,进而影响下代种群的发生。     

土壤湿度对粘虫入土化蛹和羽化出土的影响

【目的】研究不同土壤湿度对粘虫Mythimna separata (Walker)入土化蛹和羽化出土的影响,并结合当地冬季地表温度分析,以期为粘虫越冬种群预测及其防控提供指导。【方法】在山东德州地区,通过设置室内和室外不同土壤相对含水量(梯度分别为0、10%、20%、40%、60%、80%和100%),并结合当地地表温度,观察并分析粘虫入土化蛹和羽化出土情况。【结果】土壤不同相对含水量对粘虫入土化蛹、羽化出土及土中历期的影响差异显著。2016-2017年,土壤相对含水量为0、10%、20%、40%、60%、80%和100%的粘虫平均入土化蛹率分别为75.0%、82.5%、92.5%、90.0%、77.5%、65.0%和60.0%;2017-2018年,粘虫平均入士化蛹率分别为70.0%、75.0%、90.0%、87.5%、77.5%、60.0%和57.5%。粘虫化蛹的最适土壤相对含水量在20%-40%,0%和100%土壤相对含水量都不利于粘虫入土化蛹。2016-2017年,土壤相对含水量为0、10%、20%、40%、60%、80%和100%的粘虫平均羽化出土率分别为12.5%、47.5%、42.5%、47.5%、77.5%、45.0%和7.5%;2017-2018年粘虫羽化出土率分别为20.0%、27.5%、40.0%、57.5%、67.5%、52.5%和25.0%。粘虫羽化为成虫的最适土壤相对含水量为60%,0%和100%土壤相对含水量都不利于粘虫正常的羽化出土。2016年11月和2017年11月份在室外大田埋蛹,发现相同土壤相对含水量处理下,第二年春天均未见有粘虫成虫羽化出土。【结论】研究结果表明,山东德州地区粘虫入土化蛹的适宜土壤相对含水量为20%-40%,而羽化出土的适宜土壤相对含水量为60%。可见,土壤相对含水量影响粘虫的入土化蛹和羽化出土,过高或过低的土壤相对含水量导致粘虫土中蛹大量死亡而不能羽化出土。结合当地冬季地表温度分析,山东德州宁津地区粘虫无法越冬存活。     

空气和土壤湿度对美洲斑潜蝇发育与存活的影响

美洲斑潜蝇 L iriomyza sativae在相对含水量 0 %～ 10 0 % (W/W)的土壤中均可化蛹 ,但以含水量为 40 %的土壤化蛹量最高 ,占总蛹数的 3 0 .0 %。以相对含水量为 10 0 %的土壤化蛹量最低 ,占总蛹数的 4.2 %。不同土壤含水量对该蝇的羽化具有明显的影响 ,在 3 0℃时 ,以相对含水量为 60 %的土壤最适于蛹的发育 ,其蛹期最短 (7.50 d) ,羽化率最高 (93 .3 % )。反之 ,淫湿 (相对含水量为 10 0 % )和干涸 (相对含水量为 0 % )的土壤均不利于蛹的发育 ,其蛹期延长 (依次为 8.17d和 8.0 d) ,羽化率明显降低(依次为 13 .3 %和 10 .0 % )。在空气相对湿度 (RH )为 0 %、52 %、76%和 10 0 % ,室温为 3 0℃的处理中 ,蛹的失水率随其日龄的增高而增加。在蛹羽化的前 1d,高湿 (RH10 0 % )处理的失水率为 10 .1% ,低湿处理 (RH0 % )为 41.6% ,对照 (RH76% )为 18.2 %。在各 RH 下 ,蛹 1日龄后的逐日累计失水率都与它们的日龄呈明显的线性关系。在 3 0℃ ,蛹在 8h内测定的表皮渗透力最大为2 .59μg/(cm2 · h· mm Hg)     

球孢白僵菌两种施用方式对侵染桔小实蝇的影响及田间的防治效果

室内研究了球孢白僵菌Beauveria bassiana不同施用方式对侵染桔小实蝇Bactrocera dorsalis的影响,以及田间喷施球孢白僵菌防治桔小实蝇的效果。结果表明,两种诱集感染方式桔小实蝇成虫存活率分别为40%、41.7%,差异不显著;添加性引诱剂在白僵菌侵染桔小实蝇的过程中没有起到明显地促进感病的作用,只是缩短了病程,IIPC为0.41-0.44,说明两种诱集感染方式对桔实蝇成虫有一定的控制作用。三种施菌方式的桔小实蝇羽化率、成虫死亡率与对照差异均显著;以IIPC为评价指标,施菌方式对桔小实蝇各因子的影响大小顺序为：成虫存活率 >羽化率>化蛹率,其中以对成虫存活率的影响最大。应用化学防治和球孢白僵菌田间防治桔小实蝇的效果表明,施用2500倍40%毒死蜱效果最好,控制作用达到71.9%,其次是喷施2.0×108孢子/mL球孢白僵菌孢子悬浮液,防效达46.9%,施用2500倍4.5%高效氯氰菊酯防治效果达最差, 防效仅37.5%。     

低含水量饲料对黑水虻生长发育的影响

【目的】了解低含水量饲料对黑水虻Hermetia illucens生长发育的影响。【方法】在27℃、RH 80%、光周期14L∶10D的饲养条件下,以含水量70%人工饲料饲养黑水虻为对照,比较饲料含水量降为30%和50%时黑水虻幼虫的存活率、幼虫体重、雌雄成虫体长、羽化率以及不同发育阶段持续时间等生物学参数与对照组的差异。【结果】30%和50%含水量饲料饲养幼虫平均体重与对照幼虫相比显著降低（P<0.05）,30%和50%含水量两个处理间体重亦有显著差异（P<0.05）。黑水虻幼虫不能在含水量30％的人工饲料中发育至预蛹,大部分幼虫至13 d时死亡。50%含水量饲料饲养幼虫比对照延迟5 d出现预蛹,滞后14 d结束预蛹,预蛹过程耗时18 d,比对照延长8 d;50%含水量饲料饲养雌雄虫比对照成虫体长显著缩短（P<0.05）,雌雄成虫羽化时间亦比对照延后5 d,雌雄成虫羽化历期均为18 d,比对照增加5 d;50%含水量饲料饲养黑水虻自卵孵化至蛹全部羽化为成虫所需时间比对照延长10.67 d,所需时间为55.67 d,而对照仅需45.00 d;但是50%含水量饲料饲养幼虫存活率和成虫羽化率与对照相比差异均不显著（P>0.05）。【结论】含水量低于70%的人工饲料不利于黑水虻的生长发育。     

土壤含水量和土壤类型对豆大蓟马蛹期发育和羽化的影响

豆大蓟马Megalurothrips usitatus(Bagrall)是近年来严重制约海南豇豆生产的重要害虫。针对该蓟马在土壤中化蛹的习性,本文研究了在室内条件下不同土壤含水量和土壤类型对豆大蓟马化蛹的影响。结果表明,土壤含水量和土壤类型显著影响豆大蓟马蛹的发育历期和羽化率,土壤含水量为15%且土壤类型为砂壤土时,豆大蓟马的发育历期最短为3.62±0.15 d,羽化率最高为52.08%±0.07%,低含水量(5%)和高含水量(25%)均不利于豆大蓟马化蛹。土壤类型以砂壤土最适宜豆大蓟马化蛹,粘土最不适合豆大蓟马化蛹,其羽化率最低为19.17%±0.02%。     

南美斑潜蝇蛹期的生物学特性

南美斑潜蝇Liriomyzahuidobrensis在 1 5 ,2 0 ,2 5 ,30 ,35℃时 ,其蛹的历期分别为 34 5 ,1 5 8,1 0 1 ,7 2d ,而在 35℃时则不能正常羽化。土壤相对含水量为 30 %～ 90 %均比较适合南美斑潜蝇蛹的发育 ,就死亡率而言 ,它们之间没有显著差异。浸水处理表明 ,南美斑潜蝇的预蛹及蛹的初期和末期对浸水比较敏感 ,死亡率均达到 90 %以上 ,而处于中间期的蛹对浸水相对不敏感。田间调查和室内饲养均发现 ,南美斑潜蝇在 1 2时以前的化蛹个数占 1d总化蛹个数的 90 %以上 ,而 1 4时以前的羽化数占 1d总羽化数的 99%以上。南美斑潜蝇化蛹的场所在不同时期不同的蔬菜上有所不同 ,越冬时主要是以蛹在越冬寄主田的土壤中越冬 ,在生长季节 ,除了在菜豆的叶片反面化蛹外 ,其它蔬菜上则是在土壤和下部叶鞘上化蛹。     

不同日龄七星瓢虫成虫和蛹的低温储存研究

为明确七星瓢虫Coccinella septempunctata Linnaeus不同日龄的虫体经低温储存后的存活差异并获取最佳的储存虫龄和时间。分别选择羽化后0、3、7、14、21和28 d的成虫和化蛹1、2、3和4 d的蛹在8℃进行低温储存试验,确定不同储存时间（7、14、21、28、35和45 d）后虫体的存活率或羽化率。结果显示：不同日龄（0~21 d）的瓢虫成虫,存活率与储存期呈显著负相关关系。日龄＞7 d的瓢虫成虫,经低温储存21 d后,存活率为80%左右,储存28 d后,存活率仍大于70%。日龄＞14 d的瓢虫成虫储存45 d后还有60%以上存活。不同日龄的蛹最终羽化率不同,1~2 d蛹在储存21 d后羽化率为70%左右,高于3~4 d蛹的50.00%和13.33%。结果表明,七星瓢虫成虫羽化14 d后在低温下储存期最长可达45 d,可在长期储存时使用。储存期不高于28 d时,可选用羽化7 d的成虫。储存期低于21 d时,可选用羽化7 d的成虫或1~2 d蛹,其中1~2 d蛹最为经济。     

湿度对梨小食心虫存活和繁殖的影响

【目的】本研究旨在明确湿度变化对梨小食心虫Grapholitha molesta(Busck)在果实外各阶段存活率和蛀果率的影响及湿度对害虫最终存活率产生影响的关键阶段。【方法】在室内相对湿度25%,40%,55%,70%和85%条件下,记录和分析梨小食心虫的产卵量、卵孵化率、幼虫蛀果率、老熟幼虫化蛹率、蛹羽化率以及产卵、化蛹和羽化时间。【结果】湿度高低对化蛹率没有影响,供试的5种相对湿度下,化蛹率均为100%;但湿度对产卵量、卵孵化率、幼虫蛀果率、蛹羽化率和世代存活率均有显著影响,湿度越高,各阶段存活率、幼虫蛀果率和世代存活率也越高。不同虫态存活对湿度要求从高到低依次为:幼虫蛀果期成虫期卵期蛹期老熟幼虫期。湿度对害虫世代存活率产生显著影响主要发生在幼虫蛀果期、成虫期和卵孵化期。同时,湿度提高利于成虫产卵、化蛹和羽化,反之发育延缓。【结论】湿度会显著影响梨小食心虫各阶段的存活率、幼虫蛀果率和繁殖,成虫盛发期、卵期和蛀果期的湿度影响害虫种群数量和蛀果率的关键阶段。     

寄主对桔小实蝇耐寒性的影响

为了研究寄主营养对桔小实蝇耐寒性的作用,测定了以15种果蔬饲养的桔小实蝇1日龄蛹的过冷却点(supercooling points,SCP); 再选取南瓜、西红柿、柑桔、番石榴和杨桃等5种果蔬,测定了桔小实蝇3龄老熟幼虫、1日龄蛹、3日龄蛹、5日龄蛹、7日龄蛹和雌雄成虫的过冷却点,并观察了1日龄蛹的低温存活力。结果表明：（1）15种果蔬饲养所得的桔小实蝇1日龄蛹SCP均值在-11.03℃～-13.17℃,不同寄主发育的桔小实蝇SCP值存在显著性差异,其中以取食蒲桃的最高,为-11.03℃,取食苦瓜的最低,为-13.17℃。（2）5种果蔬饲养所得的桔小实蝇各虫态的SCP均值存在极显著差异(F_(4,863)＝35.6,P<0.01); 同一寄主上的桔小实蝇不同虫态之间SCP均值也达到极显著性差异(F_(6,863)＝392.9,P<0.01); 且寄主和发育龄期之间存在着极显著的交互作用(F_(24,863)＝9.4,P<0.01)。（3）桔小实蝇各发育阶段,SCP值表现一定变化： 老熟幼虫发育至1日龄蛹,SCP值变化不大; 蛹发育至3、5和7天过冷却能力明显增强,降至-20℃左右,但他们之间没有明显区别; 羽化后3～5天的成虫SCP值又升高至-10℃左右。老熟幼虫、1日龄蛹和2～3日龄成虫与3日龄、5日龄和7日龄蛹的SCP值之间有显著性差异。（4）将5种果蔬饲养所得的桔小实蝇1日龄蛹置于6℃和-3℃下进行较长时间(1～8天)和较短时间(1～8 h)的低温处理,发现番石榴、杨桃和南瓜发育的蛹经低温处理后的校正羽化率较西红柿和柑桔发育的蛹高; 同样在0℃、3℃、6℃和9℃处理(2天)的实验中,得出相似的结果。因此,本实验结果表明桔小实蝇幼虫由于生活寄主的不同使得其下一代蛹的耐寒性产生了差异,引起其差异的原因值得进一步研究。     

吉林省中部玉米出苗率和产量对播种-出苗期水分胁迫的反应及其气象评估

2010-2011年春季,在吉林省中部玉米主产区开展春玉米水分胁迫和分期播种双处理试验,分析玉米出苗率和产量对土壤水分胁迫的反应,建立基于气象条件的玉米出苗率和干旱减产评估模式.结果表明： 研究期间,研究区春玉米出苗率和单产与0～20 cm土壤湿度和土壤有效水含量的关系均呈显著的二次函数关系,耕层土壤水分越充足,玉米出苗率和产量越高,干旱明显降低玉米出苗率和产量.土壤湿度在22%～24%或土壤有效水量在50～65 mm,玉米出苗率和产量较高;土壤湿度<19%或土壤有效水量<35 mm,玉米出苗率和产量明显下降.土壤湿度每下降1%,出苗率下降约6%,产量降低约7%;耕层有效水量每减少10 mm,玉米出苗率降低约13%,减产约14%.本文所设指标和模式可用于玉米出苗率和干旱减产的评估与预测.     

Influence of warming on soil water potential controls seedling mortality in perennial but not annual species in a temperate grassland

In a water-limited system, the following hypotheses are proposed: warming will increase seedling mortality; elevated atmospheric CO2 will reduce seedling mortality by reducing transpiration, thereby increasing soil water availability; and longevity (i.e. whether a species is annual or perennial) will affect the response of a species to global changes. Here, these three hypotheses are tested by assessing the impact of elevated CO2 (550 micromol mol(-1) and warming (+2 degrees C) on seedling emergence, survivorship and establishment in an Australian temperate grassland from autumn 2004 to autumn 2007. Warming impacts on seedling survivorship were dependent upon species longevity. Warming reduced seedling survivorship of perennials through its effects on soil water potential but the seedling survivorship of annuals was reduced to a greater extent than could be accounted for by treatment effects on soil water potential. Elevated CO2 did not significantly affect seedling survivorship in annuals or perennials. These results show that warming will alter recruitment of perennial species by changing soil water potential but will reduce recruitment of annual species independent of any effects on soil moisture. The results also show that exposure to elevated CO2 does not make seedlings more resistant to dry soils.     

水热因子对退化草原羊草恢复演替群落土壤呼吸的影响

 对内蒙古锡林郭勒白音锡勒牧场退化恢复羊草（Leymus chinensis）草原生态系统土壤呼吸作用的主要影响因子分析表明,环境因子对土壤呼吸作用的影响程度依次表现为：土壤水分>温度;水分对土壤呼吸作用的影响可分成3段,即<7.5%、7.5%～18.4%和>18.4%。当0～10cm土壤含水量＜7.5%时,土壤温度是土壤呼吸作用的主导控制因子,土壤呼吸作用与5cm土壤温度呈幂函数关系;而当0～10cm土壤含水量＞7.5%时,土壤呼吸作用受土壤水分和土壤温度的共同作用。研究还表明：在植物生长季内,当土壤水分接近羊草草原土壤萎蔫系数6.0%时所测得土壤呼吸作用为植被在干旱胁迫下的土壤呼吸作用,而当土壤水分大于羊草草原土壤萎蔫系数6.0%时,土壤呼吸作用的增加主要是由于植物生长及其引起的根系活动和微生物数量、组成及其活性共同影响的,进而可以解释不同水分条件下土壤及植物根系在土壤呼吸作用中的不同贡献,为建立土壤呼吸作用模型及正确地理解陆地碳收支及其固碳潜力提供依据。     

不同饲养温度对橘小实蝇蛹色伴性遗传品系的影响

分别在19℃,22℃,25℃,28＇t2,31℃下饲养橘小实蝇蛹色伴性遗传品系,统计各温度下卵到蛹的的获得率、蛹重、羽化率、存活率及飞出率。结果表明卵到蛹的获得率28℃最大,为62．12％,19℃最小,为43．12％;蛹重25℃最重为1．3854g／100粒,19℃最轻,为1．2610g／100粒;羽化率25℃最高,为93％,31℃最低,仅82．67％;存活率31℃最高,为66％,19℃最低,仅为4．67％;飞出率25℃最高,为65％,31℃最低,为16％。综合不同温度下的卵到蛹的的获得率、蛹重、羽化率、存活率及飞出率得出25℃-28℃是大量饲养橘小实蝇蛹色伴性遗传品系的最佳温度。     

温度和水分对草甸草原土壤氧化亚氮产生速率的调控

通过试验室模拟试验,研究了调控草甸草原黑钙土N₂O产生速率的因素.结果表明,土壤水分对草甸草原土壤N₂O产生速率有重要影响(F=6.149,P＜0.01).但相关性分析表明,草甸草原土壤含水量与N₂O的产生速率间线性相关不显著.就土壤N₂O的产生速率而言,温度的影响远低于土壤水分的影响(F=2.275,P=0.106).土壤水分和温度对不同生长阶段的草甸草原土壤N₂O产生速率的调控作用主要表现为阶段性的多阶多项式关系：y=ax³+bx²+cx+d,其中a、b、c、d是常数.     

Importance of internal hydraulic redistribution for prolonging the lifespan of roots in dry soil

Redistribution of water within plants could mitigate drought stress of roots in zones of low soil moisture. Plant internal redistribution of water from regions of high soil moisture to roots in dry soil occurs during periods of low evaporative demand. Using minirhizotrons, we observed similar lifespans of roots in wet and dry soil for the grapevine 'Merlot' (Vitis vinifera) on the rootstock 101-14 Millardet de Gramanet (Vitis riparia x Vitis rupestris) in a Napa County, California vineyard. We hypothesized that hydraulic redistribution would prevent an appreciable reduction in root water potential and would contribute to prolonged root survivorship in dry soil zones. In a greenhouse study that tested this hypothesis, grapevine root systems were divided using split pots and were grown for 6 months. With thermocouple psychrometers, we measured water potentials of roots of the same plant in both wet and dry soil under three treatments: control (C), 24 h light + supplemental water (LW) and 24 h light only (L). Similar to the field results, roots in the dry side of split pots had similar survivorship as roots in the wet side of the split pots (P = 0.136) in the C treatment. In contrast, reduced root survivorship was directly associated with plants in which hydraulic redistribution was experimentally reduced by 24 h light. Dry-side roots of plants in the LW treatment lived half as long as the roots in the wet soil despite being provided with supplemental water (P < 0.0004). Additionally, pre-dawn water potentials of roots in dry soil under 24 h of illumination (L and LW) exhibited values nearly twice as negative as those of C plants (P = 0.034). Estimates of root membrane integrity using electrolyte leakage were consistent with patterns of root survivorship. Plants in which nocturnal hydraulic redistribution was reduced exhibited more than twice the amount of electrolyte leakage in dry roots compared to those in wet soil of the same plant. Our study demonstrates that besides a number of ecological advantages to protecting tissues against desiccation, internal hydraulic redistribution of water is a mechanism consistent with extended root survivorship in dry soils.     

Development of a technique to study seedling emergence in response to moisture deficit in the field —The seed bed environment*

The ability of crops of sorghum (Sorghum bicolor (L.) Moench) to establish in farmers' fields depends largely on its capacity to germinate and emerge under limited soil moisture conditions. Studies on germination under moisture stress have been previously conducted using osmotic media which do not wholly reproduce the conditions of the seed bed in the field. Hence the need for a field screening technique. A line source irrigation system was used to provide five moisture regimes ranging from -0.08 MPa to -0.92 MPa. The drying rate of the soil and the soil temperature depended largely on incident radiation, and the relationship between the moisture content and daily soil temperature and daily radiation was consistant. Total porosity of the seed bed, derived from bulk density measurements and particle density ranged from 43.8% to 45.3%, which would allow sufficient aeration when as in the experiments conducted here, water content was low (> 0.14 g/g). Under these seed bed conditions the pattern of response of emergence to the moisture gradient was linear or curvilinear. Genotypic differences existed for emergence and its response to water level. The field method developed is useful for identifying genotypes able to germinate and emerge under conditions of low seed bed moisture.     

拟孔蜂巨柄啮小蜂对家蝇的寄生作用

拟孔蜂巨柄啮小蜂Melittobia acasta Walker是一种可以寄生家蝇Musca domestica L.的寄生蜂。首次报道食物对该蜂寿命的影响,以及该蜂日龄、家蝇蛹龄、寄生蜂密度和蝇蛹密度与寄生率的关系。以15%糖水饲养该小蜂寿命最长;单只啮小蜂最多可以寄生8只蝇蛹,最大出蜂总量达58只;单个蝇蛹最多出蜂22只;随着寄生蜂的日龄和蝇蛹日龄增加,该蜂对蝇蛹的寄生个数有下降的趋势,寄生率和寄生蜂日龄符合y=3.36-0.062x-0.045x2,寄生率和蝇蛹日龄符合y=2.50+0.91x-0.34x2;蝇蛹的密度对小蜂的寄生率的影响拟合Holling功能反应模型:Na=0.6165TrN0(1+0.6165×0.499N0);寄生蜂自身密度对寄生率的影响符合方程:a=0.4943P-0.306。     

Delayed density dependence and oscillatory population dynamics in overlapping-generation systems of a seed beetle Callosobruchus chinensis: matrix population model

Long-term experimental systems with overlapping generations using a seed beetle, Callosobruchus chinensis, were maintained by providing 5 g of azuki beans (Vigna angularis) in two different renewal intervals: either 7 days or 10 days. The 7-day-renewal system (system 1) showed oscillatory dynamics with a constant periodic cycle of ca. 7 weeks. More stable population dynamics were seen in the 10-day-interval system (system 2). Short-term experiments showed that survivorship of adults increased with higher adult density, and that the survival rate of adults up to the age of 7 days was much higher than up to 10 days of age. In addition, the per capita production of hatched eggs by females which had survived for 7 days increased with increasing density experienced by the females. Females aged 10 days rarely laid eggs which hatched. We constructed a matrix population model based on either 1 week for system 1 or 10 days for system 2. The model included five stages in system 1: the hatched egg, the final instar larva, the pupa, the young adult and the old adult. Four stages were incorporated in the model for system 2: the young instar larva, the pupa, the young adult, and the old adult. Logistic-difference equations were applied to formulate both overcompensatory density dependence in the hatched-egg production by adults and undercompensatory response in the larval development up to the pupa. The survivorship of young adults to the old stage and the per capita hatched-egg productivity of the old females followed a linear regression against the young adult density. Inside-bean processes were adjusted to be equivalent in the two models, irrespective of the resource renewal intervals. The model predicted that system 1 would oscillate for a long time but that system 2 would rapidly converge to the equilibrium point. Multiplicative effects of both the delayed density dependence through interstage restraint effects and the overcompensatory density dependence in hatched-egg production generated various dynamic patterns ranging from a quickly disappearing damped oscillation to stable limit cycles in system 1. The relationship between resource renewal cycles and delayed density dependence was discussed based on these simulations.