空心莲子草叶甲室内大量繁殖研究

为了大量繁殖供环境释放的空心莲子草叶甲Agasicles hygrophila以实现空心莲子草区域减灾, 我们探索出室内大量饲养与繁殖空心莲子草叶甲的方法与流程, 包括用叶片法或苗水培法孵化卵粒、用盒养法饲养各龄幼虫与成虫并供成虫产卵、用栽培活苗笼养法化蛹羽化。在室内成虫终日均能取食、交配、产卵, 产卵前期约4～5 d, 产卵高峰期在羽化后第7～24 天, 每雌平均产卵21.08块, 约570粒。盒养法叶片平均可着卵4.28块, 叶背与叶面着卵量相近; 笼养法叶片平均着卵为1.46块, 卵主要产于叶背。盒养法与笼养法得到的卵孵化率分别为94.02%与92.50%。空心莲子草叶甲除化蛹需在栽培活苗上完成外, 各龄幼虫与成虫均可用离体新鲜苗盒养法密集饲养。初孵1龄幼虫转株（叶）期、3龄老熟幼虫转化蛹苗期是室内大量饲养与繁殖空心莲子草叶甲的关键时期, 高密度成功饲养与繁殖空心莲子草叶甲的最适化蛹接虫量是每株8头, 产卵期雌虫的最适密度是每株5头。     

捕食者对空心莲子草叶甲种群的生物胁迫

广食性捕食者广泛捕食植食性昆虫,常被用于有害生物的生物防治,也因此影响植食性昆虫对杂草的生物效果。空心莲子草叶甲(Agasicles hygrophila)(鞘翅目:叶甲科Chrysomelidae)作为入侵恶性杂草空心莲子草(Alternanthera philoxeroides)(苋科:莲子草属Alternanthera)的专性天敌,从美国的弗罗里达州引入中国,在释放地防治空心莲子草取得了较好的防治效果。虽然空心莲子草叶甲在引入地均已建立田间种群并有一定程度的自然扩散,但丰富的食物资源,并未使空心莲子草叶甲的自然种群数量变得繁荣,因此其未能有效抑制空心莲子草的扩散蔓延。在野外调查时发现空心莲子草生境中存在大量广食性捕食者。这些广食性捕食者是抑制空心莲子草叶甲种群数量扩张的生物胁迫因子吗?为此,选择捕食性昆虫龟纹瓢虫(Propylaea japonica)(鞘翅目:瓢虫科Coccinellidae)、蜘蛛类捕食者拟水狼蛛(Pirata subpiraticus)(蜘蛛目:狼蛛科Lycosidae)与斜纹猫蛛(Oxyopes sertatus)(蜘蛛目:猫蛛科Oxyopidae)为捕食者,分别以空心莲子草叶甲各虫态为猎物,构建简单的捕食者-猎物系统,在室内检测了上述3种捕食者对空心莲子草叶甲各虫态在不同密度下的日捕食量,以期了解捕食者对空心莲子草叶甲的捕食作用,客观评估空心莲子草叶甲的生物防治效能。研究结果表明:捕食者龟纹瓢虫、斜纹猫蛛与拟水狼蛛均捕食空心莲子草叶甲的卵粒及1龄、2龄幼虫,斜纹猫蛛与拟水狼蛛捕食3龄幼虫,捕食者的捕食量均随着猎物密度的升高而增加,寻找效应降低。三者均不捕食成虫。除拟水狼蛛对3龄幼虫的捕食用Holling II模型拟合不呈显著相关关系外,其余捕食反应均拟合Holling II模型并显著相关。通过拟合方程得出捕食者对空心莲子草叶甲卵粒的理论日最大捕食量为:斜纹猫蛛10.9粒,拟水狼蛛为6.2粒,龟纹瓢虫为5.6粒;对1龄幼虫的理论日最大捕食量为:斜纹猫蛛为17.1头;拟水狼蛛为35.8头,龟纹瓢虫为10.4头;对2龄幼虫的理论日最大捕食量为:斜纹猫蛛为6.6头,拟水狼蛛为11.2头,龟纹瓢虫为2.9头;对3龄幼虫的理论日最大捕食量为:斜纹猫蛛捕食12.3头,拟水狼蛛为1.1头。研究结果证实了捕食者可通过捕食作用降低空心莲子草叶甲种群密度,削弱空心莲子草叶甲对空心莲子草的控害效能,是空心莲子草叶甲种群存活的生物胁迫因子。建议在提高空心莲子草叶甲田间种群数量,达到对空心莲子有效的持续控制效果方面开展进一步研究。     

空心莲子草叶甲对越冬保护的响应与控害效能

空心莲子草叶甲Agasicles hygrophila是入侵杂草空心莲子草Alternan thera philoxeroide的重要天敌,冬春季低温冰冻是影响其安全越冬的关键胁迫因子。为了探明采取保护措施是否能提高越冬后的种群基数问题,在低温冰冻天气来临前,用塑料膜覆盖网室构建空心莲子草与空心莲子草叶甲保护生境(PH),分低温期(2009年1月21日至4月9日)、升温期(4月15日至5月1日)与自然生境(NH)中叶甲成虫初现期(从6月1日至29日)3个阶段,调查比较PH与NH两类生境中空心莲子草叶甲种群数量、结构、空间生态位分布特征及控害效能。结果表明:在保护生境中,低温期空心莲子草叶甲不休眠,且能安全越冬,当晴天温度较高时,成虫主要在直立茎或嫩枝上活动取食、补充营养,而在阴雨低温天气则停留在匍匐草层或土壤表层、缝隙中,少活动。随着气温回升,成虫转移到直立茎生态位上活动取食,并于4月上旬开始产卵繁殖,种群数量迅速增加,对空心莲子草的地上部分有较好的控制效果。在自然生境中,直到6月初才见少量成虫活动,此时草生长茂密,较低的空心莲子草叶甲种群难以发挥生防因子的作用。比较两种生境中6月1日与6月15日的控草效果显示,空心莲子草株高增长率分别为:PH-13.91%,NH-2.94%,NH中空心莲子草株高极显著高于PH,且单株生物量的控制率为PH(47.56%)极显著高于NH(4.89%)。在6月15日与29日的调查表明,单株叶片控制效果PH极显著优于NH,PH中的空心莲子草茎上均无叶,叶片或被取食殆尽、或被害后干枯脱落。茎被害率、茎蛀孔数与蛀茎率均为PH极显著高于NH。结果说明覆膜保护能显著提高叶甲越冬种群基数,使其提前进入繁殖期,从而能更有效地控制生境中的空心莲子草。     

除草剂胁迫对空心莲子草叶甲种群的影响及应对策略

为探讨除草剂胁迫对空心莲子草叶甲种群的影响,寻求合理施用除草剂,有效保护叶甲,提高其控草效果的应对策略,利用叶片残留法测试了在草甘膦、农达、水花生净与35%苄·丁可湿粉等除草剂胁迫下空心莲子草叶甲卵孵化率,幼虫、成虫存活率以及蛹羽化率。结果表明被测试的4种除草剂均不同程度地降低空心莲子草叶甲卵孵化率,幼虫与成虫存活率及蛹羽化率,特别是水花生净28.0、35.0 g/L两种浓度处理,35%苄·丁可湿粉4.0 g/L浓度处理显著降低卵孵化率;农达13.4 g/L浓度处理显著降低1龄前期幼虫存活率,农达40.1 g/L与 53.4 g/L两种浓度处理显著降低2龄前期幼虫存活率;水花生净28.0 g/L浓度处理显著降低3龄前期幼虫存活率;草甘膦97.6 g/L与 122.0 g/L浓度处理、农达26.7 g/L与66.8 g/L浓度处理、35%苄·丁可湿粉2.0 g/L浓度处理显著降低后期蛹的羽化率;35%苄·丁可湿粉1.0 g/L浓度处理显著降低羽化后3 d雌虫的存活率。除草剂除直接杀死空心莲子草叶甲,降低其种群数量外,使叶甲失去食物与避护所,快速地引起叶甲种群崩溃。建议合理施药,并在施药时,随机留若干小斑块不施药,保护叶甲,可望提高其田间控草效果。     

福寿螺取食对空心莲子草生长和繁殖的影响

福寿螺(Pomacea canaliculata)和空心莲子草(Alternanthera philoxeroides)是我国南方淡水生态系统中常见的两种入侵生物, 空心莲子草是福寿螺的植物性食物之一。以福寿螺和空心莲子草为研究对象, 研究了不同福寿螺取食强度对空心莲子草生长和繁殖的影响, 探讨了两者之间的相互关系。结果表明: 与对照相比, 福寿螺取食抑制了空心莲子草的生物量积累, 但不同取食强度的影响存在差异。在每盆1、3 只取食强度下, 空心莲子草鲜重先下降然后上升, 而在每盆5、7 只取食强度下, 其鲜重一直保持下降的趋势。与处理前相比, 福寿螺取食下空心莲子草的节数和分枝数均增加(每盆7 只除外), 而叶片数一直保持下降的趋势。每盆7 只福寿螺的取食强度下, 空心莲子草的花数显著高于对照(P<0.05), 为对照的10.5 倍(处理20 天时)。可见, 福寿螺取食在一定程度上抑制了空心莲子草的生长, 但空心莲子草对不同的取食强度产生不同的生长响应。低取食强度可能促进了空心莲子草的营养生长, 高取食强度抑制了空心莲子草的营养生长, 却促进了其有性繁殖。同时, 福寿螺对空心莲子草叶片的取食偏好性优于其茎秆。     

空心莲子草叶斑病菌及代谢产物除草活性研究

从空心莲子草叶斑病叶或茎分离的镰刀菌及代谢产物对空心莲子草具有杀灭作用。代谢产物主要作用于空心莲子草叶片,使叶片组织变黄,最后枯萎死亡,发病死亡较快。用病菌分生孢子接种时致使植株叶片组织失水、发黄、脱落或从节间处折断枯死。开始时局部发病,有病斑形成,最后全株发病枯死。     

空心莲子草叶甲成虫取食量和耐饥饿能力的研究

空心莲子草叶甲是空心莲子草重要的专食性天敌昆虫。本文研究了在室温条件下,空心莲子草叶甲成虫对空心莲子草的取食量以及耐饥饿能力。结果表明：雌虫日取食量为47．0～104．0mm^2（12．2-27．0mg）,雄虫日取食量为14．0～48．0mm^2（3．6～12．5mg）。雌虫日平均取食量为72．1mm^2（18．7mg）,是雄虫的日平均取食量27．6mm^2（7．2mg）的2．61倍。雌虫耐饥饿能力比雄虫强。     

9种植物水浸提液对空心莲子草的化感作用

【背景】空心莲子草是难以防除的恶性入侵杂草,因此,探索高效无毒的化感防治方法具有重要意义。【方法】利用水浸提法研究了博落回、苦瓜、樟树、柳杉、凤尾蕨、柑橘、夹竹桃、洋葱及大蒜9种植物不同器官对空心莲子草的化感作用。【结果】与对照相比,博落回叶、苦瓜果肉与种子、凤尾蕨、樟树叶和柳杉叶的水浸提液对空心莲子草具有较强的化感作用,主要表现为空心莲子草叶片数和茎节数减少,株高与生物量的增长受到抑制。【结论与意义】不同植物水浸提液对空心莲子草的化感作用有所差异。本研究为利用植物的化感作用控制空心莲子草提供了依据。     

两种生态型空心莲子草对莲草直胸跳甲发育和繁殖的影响

【目的】评价空心莲子草Alternanthera philoxeroides 2种生态型食物对莲草直胸跳甲Agasicles hygrophila生长发育和繁殖的影响。【方法】建立莲草直胸跳甲在水生型和旱生型空心莲子草上的实验种群两性生命表。【结果】2种生态型空心莲子草对莲草直胸跳甲2龄和3龄幼虫的历期、产卵前期、产卵期、雌虫寿命、雄成虫寿命和繁殖力的影响无显著差异,但取食水生型空心莲子草的莲草直胸跳甲具有较短的蛹历期（6.28 d）、较高的幼虫期存活率（99.00%）和较高的成虫前期存活率（95.00%）;取食旱生型空心莲子草的莲草直胸跳甲在内禀增长率和周限增长率都显著低于水生型食物,但莲草直胸跳甲的净增殖率（R_0）和平均世代周期（T）在旱生型和水生型食物间并无显著差异。【结论】与旱生型空习莲子草相比,水生型空心莲子草是莲草直胸跳甲的较适宜食物,但旱生型空心莲子草并不显著影响莲草直胸跳甲的发育和繁殖。     

莲草直胸跳甲的空间选择与性别分化

【背景】莲草直胸跳甲是空心莲子草的专一性天敌,成功地大量繁殖是其大规模应用于空心莲子草生物防治的必要条件,为了更好地开展莲草直胸跳甲的室内大量繁殖,明确其不同虫态对空心莲子草空间的选择性具有重要意义。【方法】本研究调查了莲草直胸跳甲成虫取食与产卵、幼虫取食、老熟幼虫化蛹的空间选择性,并分析了空心莲子草茎秆直径对幼虫化蛹空间选择、蛹羽化率和羽化成虫性别分化的影响。【结果】雌雄成虫均嗜好栖息于空心莲子草幼嫩的顶叶,位于顶叶的雌、雄成虫数量分别占整株的62.9%和63.3%;成虫偏好将卵产在第2节叶片上,比例高达41.2%;幼虫主要集中于上部3节的叶片上取食,占84.8%;老熟幼虫化蛹前在茎秆上蛀孔后钻入茎秆中化蛹,其不在第1节茎秆内化蛹,化蛹主要选择在3～5节,其中在第4节茎秆内化蛹量最高,达1.0头.节-1;老熟幼虫在1～5节茎秆内的化蛹量与空心莲子草茎秆直径具有显著相关性（y=-19.209x2＋16.66x＋2.6737,R2=0.841）;羽化成虫的雌雄性比则与茎秆直径呈显著正相关（y=5.5704x-1.1718,R2=0.914）。【结论与意义】莲草直胸跳甲成虫和幼虫均偏好在空心莲子草上部的叶片取食,老熟幼虫化蛹则偏好中部较粗壮的茎节,因此,培育茎秆较粗且老化程度较低的空心莲子草是实现莲草直胸跳甲大量饲养的重要途径。本研究可为优化人工大量饲养繁殖莲草直胸跳甲的条件提供数据支持。     

除草剂对莲草直胸跳甲存活与繁殖的影响

【背景】除草剂应用是目前防治空心莲子草的主要措施之一,但其可能对空心莲子草的重要天敌昆虫莲草直胸跳甲的存活、发育和繁殖产生不利影响;为了协调应用化学除草剂和莲草直胸跳甲联合控制空心莲子草的防治措施,本研究探明了除草剂对莲草直胸跳甲的安全性。【方法】采用空心莲子草叶片喷施除草剂后饲喂莲草直胸跳甲的方法,测定了使它隆、农达和稻杰3种除草剂对莲草直胸跳甲成虫和3龄幼虫的取食和存活、幼虫化蛹和成虫产卵的影响。【结果】使它隆对莲草直胸跳甲成虫产卵量的影响较小,喷施农达则显著降低莲草直胸跳甲的产卵量,稻杰的影响居中。连续取食除草剂处理的叶片5d,莲草直胸跳甲成虫取食量均显著降低,3种除草剂的影响为使它隆〉农达〉稻杰。农达对莲草直胸跳甲幼虫的取食量影响较大,取食高浓度农达处理的叶片3d后,其幼虫停止取食;稻杰影响较小。除草剂对莲草直胸跳甲雌虫影响较小,存活率较高。【结论与意义】3种供试除草剂中,稻杰对莲草直胸跳甲最安全,以0.9L.ha-1浓度最佳,在空心莲子草的综合治理中可与莲草直胸跳甲协同应用。     

黄玛草蛉对两种蚜虫的捕食效能

实验室条件下研究了黄玛草蛉2龄与3龄幼虫对甘蓝蚜以及玉米蚜成虫的捕食功能反应。结果表明:黄玛草蛉2龄与3龄幼虫对2种蚜虫的捕食量均随着猎物密度的增加而增加,寻找效应随着猎物密度的增加而减小。不同龄期幼虫对2种蚜虫的捕食功能反应均符合HollingⅡ模型,黄玛草蛉2龄与3龄幼虫对玉米蚜最大理论日捕食量分别为120.48头、185.18头;黄玛草蛉2龄与3龄幼虫对甘蓝蚜最大理论日捕食量分别为60.60头、86.95头。在相同猎物种类下,黄玛草蛉3龄幼虫对2种蚜虫的捕食量均高于黄玛草蛉2龄幼虫;在相同猎物密度下,黄玛草蛉2龄幼虫与3龄幼虫对玉米蚜的捕食量均高于甘蓝蚜。     

Monitoring Tribolium castaneum (Coleoptera: Tenebrionidae) in pilot-scale warehouses treated with residual applications of (S)-hydroprene and cyfluthrin

Pilot-scale warehouses, artificially infested with all life stages of Tribolium castaneum (Herbst), were used to evaluate the efficacy of two contact insecticides, (S)-hydroprene and cyfluthrin, and to determine the effect of insecticide treatments on insect captures in food- and pheromone-baited pitfall traps. Two application strategies were compared; insecticides were applied at the labeled rate either around the inside perimeter of the warehouse or in a band around the base of shelf units containing discrete food patches (10 g of wheat flour) infested with T. castaneum. Insect populations were assessed weekly for 6 wk by recording number of dead adults on the warehouse floor; number of larvae and adults captured in pitfall traps; and number of larvae, pupae, and adults recovered from food patch samples. There were significantly more dead adults in warehouses treated with cyfluthrin than with (S)-hydroprene or water (control treatment). However, food patch samples showed no detectable differences in quantity of larvae, pupae, or adults among any treatments. Pitfall traps detected fewer larvae starting the fourth week of the study in the warehouses treated with cyfluthrin around the shelf perimeter. Rate of larval capture in traps increased overall with increasing larval populations, but it was more pronounced in traps located closer to the food patches. Number of adults captured in pitfall traps reflected adult mortality in cyfluthrin-treated warehouses. Capture of larvae and adults was greater near the source of the infestation than elsewhere in the warehouse, suggesting that trapping data should be considered when precision targeting insecticide applications in the field.     

Life cycle of Hysterothylacium haze (Nematoda: Anisakidae: Raphidascaridinae)

Natural infections with Hysterothylacium haze in the Japanese common goby, Acanthogobius flavimanus, were observed in detail. In gobies in which no worm eggs were deposited, second-stage larvae were found in the digestive tract wall, and third-stage larvae occurred in the digestive tract wall, mesentery, and body cavity, whereas fourth-stage larvae and adults were found in the body cavity. This stage-habitat relationship demonstrates the infectivity of second-stage larvae to the goby and the larval migration. In heavily infected gobies, eggs and all worm stages, from hatched second-stage larvae to adults, often were found together in the body cavity of one individual host, suggesting that hatched second-stage larvae can develop in the body cavity. It was shown experimentally that H. haze develops to the second stage in the egg and does not hatch spontaneously. When a goby was fed the viscera of heavily infected gobies containing eggs and various stages of worms or artificially incubated eggs containing second-stage larvae, second- and third-stage larvae were recovered from the digestive tract wall, and fourth-stage larvae and adults were found in the body cavity. When polychaetes or crustaceans were placed in contact with infected goby viscera or incubated eggs, only second-stage larvae were recovered from the body cavity of the invertebrates. The experimental results were consistent with observations on natural infections and indicate that the direct life cycle of H. haze may involve invertebrates as transport hosts.     

蓝蝽对马铃薯甲虫低龄幼虫的捕食潜能初探

室内研究了蓝蝽Zicrona caerula(Linnaeus)对马铃薯甲虫Leptinotarsa decemlineata(Say)低龄幼虫的捕食功能反应和选择效应。HollingII型圆盘方程和HollingⅢ型新模型拟合结果共同显示,蓝蝽若虫对马铃薯甲虫1龄幼虫的捕食量随着龄期的增加而增大;4、5龄若虫及成虫的捕食量均在17头以上。由HollingII模型获得蓝蝽对马铃薯甲虫1龄幼虫的控制能力为2龄<3龄<4龄<5龄<成虫;随着食物密度的增加,蓝蝽各虫态的寻找效应逐渐下降。田间防治马铃薯甲虫1龄幼虫时,2～5龄蓝蝽若虫及成虫的最佳益害比应该分别为1∶2、1∶4、1∶13、1∶14、1∶13,然而,食物选择效应显示蓝蝽原生境中猎物-兰叶甲可能会对防治产生影响。     

不同虫态及虫龄大草蛉与七星瓢虫之间的集团内互作

【目的】为明确新疆棉田棉蚜 Aphis gossypii 捕食性天敌之间的集团内捕食效应及其对蚜虫数量的控制作用。【方法】本研究以优势天敌昆虫大草蛉 Chrysopa pallens 和七星瓢虫 Coccinella septempunctata 为对象,以棉蚜为猎物,在温室中利用盆栽棉花,首先观察了2种天敌昆虫之间各虫态及虫龄配对的19个处理在无蚜植株上共存24 h后的存活数,然后观察了2种天敌昆虫配对处理下棉苗上棉蚜数量随时间的变化趋势。【结果】在无蚜棉株上2种捕食性天敌昆虫共存24 h后的存活结果表明：（1）在发育阶段相同的配对组合中,若是成虫则均存活,若是１龄幼虫则大草蛉存活较多,若是末龄幼虫则七星瓢虫存活较多;（2）在有卵的组配中,除七星瓢虫卵不被大草蛉成虫所捕食外,其他5个组配处理中卵均被捕食;（3）在有蛹的配对组合中,除七星瓢虫蛹被大草蛉末龄幼虫捕食外,其他处理下蛹均不被捕食;（4）在成虫与幼虫的配对组合中,七星瓢虫成虫捕食较多的大草蛉1龄幼虫,但不捕食大草蛉末龄幼虫,而大草蛉成虫与七星瓢虫1龄或末龄幼虫之间不发生捕食;(5）在不同龄期幼虫的配对组合中,大草蛉末龄幼虫捕食七星瓢虫1龄幼虫,而七星瓢虫末龄幼虫捕食大草蛉1龄幼虫。在有蚜植株上2种捕食性天敌共存对棉蚜数量具有不同的控制作用：（1）2种捕食昆虫的幼虫各自单独存在（对照）下,蚜虫密度随时间而降低;（2）大草蛉幼虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而增大;（3）大草蛉成虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而减小。【结论】研究结果说明,大草蛉与七星瓢虫之间存在集团内捕食,但２种天敌共存对棉蚜的控制作用取决于大草蛉虫态, 若大草蛉为幼虫,可使蚜虫密度增大,若为成虫,则使蚜虫密度减小。     

Biological and biochemical characteristics for quality control of Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae) reared on a liver-based diet

Biological and biochemical parameters of a flightless strain of Harmonia axyridis, fed on a pork liver-based artificial diet and on Ephestia kuehniella eggs as controls, were compared. The diet-grown larvae showed a significantly longer developmental time and a lower adult emergence rate compared to control larvae. The weights of the newly emerged adults were significantly higher for adults fed E. kuehniella eggs during their larval stages than fed the artificial diet. In contrast, larval food source had no effect on the duration of the pre-oviposition period or adult longevity. For adults fed on E. kuehniella eggs as larvae, a significantly longer pre-oviposition period, lower daily weight gain and fecundity were found for the diet-fed females compared to those fed on E. kuehniella eggs throughout the life span. The adult food source had no significant effect on longevity and fertility. Lower amino acid and fatty acid contents (in particular C16:1 and C18:3n-3) were found for the prepupae and newly emerged females obtained from diet-reared larvae compared to controls. Deficiencies in fatty acids C16:1 and C18:3n-3 were also observed in females obtained from E. kuehniella egg-reared larvae and fed on diet from adult emergence. The analyses of the foods showed deficiencies in artificial diet, especially for some amino and fatty acids. The results suggest a non-optimal composition of the artificial diet and some possibilities for its improvement. However, this polyphagous predator could be reared from first instar larvae to fully reproductive adults on a pork liver-based artificial diet.     

Number of Malpighian Tubules in Larvae and Adults of Stingless Bees (Hymenoptera: Apidae) from Amazonia

The number of Malpighian tubules in larvae and adults of bees is variable. Larvae of Apis mellifera L. have four Malpighian tubules, while adults have 100 tubules. In stingless bees, this number varies from four to eight. The objectives of this study were to provide characteristics of the Malpighian tubules as well as to quantify their number in larvae and adults of six species of Meliponinae, Melipona seminigra merrillae Cockerell, Melipona compressipes manaosensis Schwarz, Melipona rufiventris Lepeletier, Scaptotrigona Moure, Frieseomelitta Ihering, and Trigona williana Friese. Malpighian tubules were dissected from larvae and adults, measured, quantified, and maintained in microtubes with Dietrich??s solution. The numbers of Malpighian tubules were constant only for larvae of M. rufiventris (four and eight) and Scaptotrigona sp. (four). The most frequent number of tubules in the Melipona group was seven and eight in larvae, and 70 and 90 in adults. In the Trigona group were four and 20 to 40, for larvae and adults, respectively. The results showed differences in the number of Malpighian tubules among the species analyzed and also between the larvae and adults of the same species. Despite the variation observed, species of the group Melipona always have a larger number and longer Malpighian tubules in both larvae and adults as compared to the Trigona group, which may indicate an evolutionary trend of differentiation between these groups.     

Respiratory metabolism of Hydromedion sparsutum and Perimylops antarcticus (Col., Perimylopidae) from South Georgia

Summary Metabolic rates were studied in adults and larvae of the two phytophagous beetles Hydromedion sparsutum and Perimylops antarcticus (Col., Perimylopidae) indigenous to the Sub-Antarctic island of South Georgia. From the regression lines for log₁₀ metabolic rate on temperature no difference in oxygen consumption was found between adults and larvae of Hydromedion or adults of Perimylops from lower sites near sea level and upper sites at about 200 m. Elevated rates of metabolism, however, was found in larvae of Perimylops from upper sites. The slopes of the regression lines of corresponding upper and lower sites adults or larvae were similar in all cases. The metabolic rates were of the same level in adults of both species and in the larvae, but generally higher in adults than in larvae. The activation energies, calculated from Arrhenius plots, varied from 6.7 to 13.6 kcal.mol^–1 in larvae and from 10.7 to 11.3 kcal.mol^–1 in adults. The low values may be interpreted as an expression of cold adapted metabolism. Compared with published data on phytophagous beetles, the metabolic rates of the two species from South Georgia are comparable to two alpine species, but lower than the rates of an Arctic species.