截头堆砂白蚁在恒温恒湿条件的分飞活动

截头堆砂白蚁Cryptotermes domesticus(Haviland)是世界性的重要蛀木害虫,原始繁殖蚁分飞是该种白蚁的重要扩散传播途径之一。为了解截头堆砂白蚁的分飞活动规律,本文研究了其成熟群体在恒温恒湿条件下的分飞期。结果表明,在恒温27℃和相对湿度80%的条件下,经历持续10年零3个月的观察,有7年内全年每个月均有原始繁殖蚁分飞,只有3年内每年均缺少2个月无原始繁殖蚁分飞。试验结果揭示了截头堆砂白蚁成熟群体在形成有分飞能力原始繁殖蚁的基础上,只要温、湿度条件适宜,全年中不分季节和日期,都有可能进行分飞活动。     

截头堆砂白蚁性比的研究

为了解截头堆砂白蚁Cryptotermes domesticus（Haviland）群体中不同品级、不同虫态的雌雄性比,本文研究了该种白蚁自行配对室温条件下饲养4年巢龄的实验群体与采集的自然群体的各个品级和不同虫态的雌雄性比。结果表明：自行配对室温饲养4年巢龄群体与自然环境群体中原始繁殖蚁、幼蚁、若蚁、兵蚁都有雌雄之分,其中自行配对室温饲养群体的原始繁殖蚁雌雄比例为1：1,兵蚁雌雄比例为1：1．24,幼蚁和若蚁雌雄比例为1：1．46;自然环境群体原始繁殖蚁雌雄比例为1：1,兵蚁雌雄比例为1：1．15,幼蚁和若蚁雌雄比例为1：1．43。     

Sex ratios of the dryword termite Cryptotermes domesticus

为了解截头堆砂白蚁Cryptotermes domesticus(Haviland)群体中不同品级、不同虫态的雌雄性比,本文研究了该种白蚁自行配对室温条件下饲养4年巢龄的实验群体与采集的自然群体的各个品级和不同虫态的雌雄性比.结果表明:自行配对室温饲养4年巢龄群体与自然环境群体中原始繁殖蚁、幼蚁、若蚁、兵蚁都有雌雄之分,其中自行配对室温饲养群体的原始繁殖蚁雌雄比例为1:1,兵蚁雌雄比例为1:1.24,幼蚁和若蚁雌雄比例为1:1.46;自然环境群体原始繁殖蚁雌雄比例为1:1,兵蚁雌雄比例为1:1.15,幼蚁和若蚁雌雄比例为1:1.43.     

不同树种木材对截头堆砂白蚁初建群体的影响

收集了62种从东南亚进口的不同树种的木材,并作为截头堆砂白蚁Cryptotermesdomestictis(Haviland)的食料,让其原始繁殖蚁自行配对钻入这些木料中取食,建立新群体.观察该种白蚁对不同树种木材的取食状况,了解不同树种木材对该种白蚁初建群体的影响.结果表明,该种白蚁食性广泛,能取食多种在分类上差异很大的木材,除坤甸外,均被其取食.试验用的全部木材对该种白蚁原始繁殖蚁配对没有影响,均有原始繁殖蚁配对钻入洞内.在配对3个月后解剖群体发现,除坤甸、樟木、硬榄仁、柚木、子京、虫眼木、暗罗、硬椴、轻胭脂、胭脂、番龙眼外,其余树种的初建群体,雌雄繁殖蚁存活,子代发育正常.     

截头堆砂白蚁新群体的形成及发展

本文主要论述在广州室温及恒温27℃、相对湿度80%条件下,截头堆砂白蚁Cryptotermes domesticus(Haviland)新群体的形成、繁殖特性及其群体的发展、发育状况.(1)在广州6～7月室温下,截头堆砂白蚁原始繁殖蚁自行配对后,产卵前期7～16天,平均10.33±2.32天,卵期46～71天,平均55.13±6.42天,巢龄为1年、2年的新建群体,子代个体分别为3～8头、10～16头;3年巢龄群体,子代个体12～35头;4年巢龄群体,兵蚁开始出现,子代个体23～57头,其中兵蚁1～3头.该种白蚁新建群体经历7年才发育成熟,此时群体子代个体36～115头,其中兵蚁1～4头.(2)在恒温27℃、相对湿度80%条件下,截头堆砂白蚁原始繁殖蚁配对后产卵前期8～18天,平均11.6±2.66天,卵期50～73天,平均57.8±5.79天.1年巢龄群体,子代个体6～10头;2年巢龄群体,兵蚁出现,子代个体16～34头,其中兵蚁1～2头.新建群体经历2～3年发育成熟,此时群体内的子代个体18～44头,其中兵蚁1～2头.     

截头堆砂白蚁原始繁殖蚁形成的周期

采用马尾松(Pinusmassonianalamb)、东北松(PinusSpp.)、北美黄杉(花旗松)(Pseudotsugamenziesii)、青岗(CyclobalanopsisSpp.)、荷木(SchimaSpp.)作为截头堆砂白蚁Cryptotermesdomesticus(Haviland)的食料,研究其原始繁殖蚁配对后新建群体的形成和发展,从饲养的新建群体中培养产生了下一代的原始繁殖蚁,完成了1个世代的生活周期观察。试验证实,截头堆砂白蚁在广州市室温下,产生下一代原始繁殖蚁(完成1个生活周期)为7年;在湛江市室温下6、7年;而在恒温27℃,相对湿度80%的条件下只需2～3年。     

截头堆砂白蚁原始繁殖蚁行为特点研究

本文主要论述截头堆砂白蚁Coptotermes domestictis(Haviland)原始繁殖蚁行为特点以及利用其特点判断木材及木制品有该蚁存在的方法.原始繁殖蚁行为特点:1、刚分飞时有趋光性.2、雌雄蚁没有明显的追逐行为.3、脱翅后的原始繁殖蚁喜欢找隐蔽的场所营站.4、钻洞后的原始繁殖蚁封闭洞口,抗外界干扰.5、在洞内活动、取食、排泄、繁殖子代.6、原始繁殖蚁形成群体后把排泄物推出洞外.7、原始繁殖蚁形成群体后容易蔓延.判断有该蚁存在的方法:1、木材及木制品表面有0.3mm-1.5mm圆形封闭或未封闭洞口.2、洞口外有细砂粒状及不易碎的排泄物.     

截头堆砂白蚁的分飞期研究

对不同群体、不同年份截头堆砂白蚁Cryptotermesdomesticus(Haviland)的分飞期进行了 3年的观察研究。结果表明 :该种白蚁的分飞期长 ,且 3年的分飞期基本相同。在广州 ,该种白蚁的分飞期一般在每年的 4月中旬至 8月下旬 ,分飞始期的第 1次分飞日最早为 4月 1 5日 ,分飞末期的最后 1次分飞日在 9月 1 6日。 1年中该种白蚁的分飞日数为 5 5～ 80日。其中 ,分飞日数较多的月份为 5～ 7月。其飞出时间一般在傍晚 1 8:3 0～ 1 9:3 0 ,以 1 9:0 0～ 1 9:3 0分飞次数最多 ,占分飞总数的 66 66%。     

温度、湿度、气压对截头堆砂白蚁原始繁殖蚁分飞的影响

经三年的室内试验观察,探讨了截头堆砂白蚁Cryptotermes domesticus(Haviland)原始繁殖蚁的分飞与温度、湿度、气压的关系.结果表明,该种白蚁分飞时适应的温度、湿度、气压范围较广,分飞时温度一般在25℃～30℃,相对湿度介于70%～90%,气压幅度在999百帕(hPa)～1006百帕(hPa)之间.温度在27℃～30℃之间较适宜,该种白蚁分飞次数较多,其中,28℃～29℃分飞次数最多,占总分飞次数的48.89%.相对湿度在70%～85%范围内分飞次数较多,其中相对湿度在75%～80%范围内分飞次数最多,占总分飞次数的35.35%.气压在1003百帕(hPa)～1005百帕(hPa)之间分飞次数较多,其中气压在1004百帕(hPa)～1005百帕(hPa)之间分飞次数最多,占总分飞次数的35.59%.     

类雄激素受体在尖唇散白蚁繁殖蚁和工蚁精子发生中的免疫细胞化学定位

为了比较和探讨类雄激素受体 (androgen receptor-like,AR-like)在白蚁生殖品级和非生殖品级精子发生过程中的作用,运用免疫细胞化学方法对尖唇散白蚁Reticulitermes aculabialis繁殖蚁和工蚁精子发生中的AR-like的定位进行了研究。结果显示：在繁殖蚁和工蚁精子发生过程中都有AR-like免疫阳性细胞的分布,均分布于初级精母细胞的细胞质和细胞核中;与繁殖蚁相比,AR-like在工蚁中的表达较弱。结果提示,AR-like的表达与精子发生过程中初级精母细胞的减数分裂有关,雄激素及其受体通过调控精母细胞的第一次减数分裂来影响白蚁精子的发生。虽然工蚁的精巢发育受抑制,但其精子发生和维持具有与繁殖蚁相同的激素调节机制,能形成精子。本研究为工蚁性腺退化不育而根据群体的变化又可以发育为补充繁殖蚁这一特殊的生理功能提供了组织学依据。     

白蚁跟踪信息素及其类似物的活性比较试验初报

自从1967年Smythe等发现某些真菌寄生过的木材中含有一种活性物质,与白蚁腹腺分泌的跟踪信息素有相似的效用以后,引起了人们探讨白蚁踪迹物质的浓厚兴趣。白蚁是一种社会性昆虫。群体间的觅食、防卫、筑巢、交哺等行为都是通过信息物质的调节来进行的。所以开展白蚁跟踪信息素及其类似物的研究,有可能为我们找出一条新的防治途径。     

合成黑翅土白蚁踪迹信息素类似物的生物活性

合成了黑翅土白蚁踪迹信息素类似物(Z,Z)-3,6-十二碳二烯醇-1（DDE-OH）,该类似物对黑翅土白蚁工蚁具有和信息素提取物类似的行为反应。活性反应阈值为10^-3～10 ng/cm,大于10 ng/cm时产生较强的驱避作用。最佳活性浓度DDE-OH与信息素提取物的活性反应之间没有显著差别。     

Characterization of the complete mitochondrial genome of Cryptotermes domesticus (Blattodea: Kalotermitidae): Genome description and phylogenetic implications

The complete mitochondrial genome of Cryptotermes domesticus (Haviland) was sequenced and annotated to study its characteristics and the phylogenetic relationship of C. domesticus to other termite species. The mitogenome of C. domesticus is a circular, close, and double-stranded molecule with a length of 15,655 bp. The sequenced mitogenome contains 37 typical genes, which are highly conserved in gene size, organization, and codon usage. Transfer RNA genes (tRNAs) also have typical secondary structures. All of the 13 protein-coding genes (PCGs) start with an ATN codon, except for nad4, which starts with GTG and terminates with the terminal codon TAA and TAG or the incomplete form T-- (cox2 and nad5). Most tRNAs have a typical cloverleaf structure, except for trnS1, in which this form is replaced by a simple loop and lacks the dihydrouridine (DHU) arm. The nucleotide diversity (Pi) and nonsynonymous (Ka)/synonymous (Ks) mutation rate ratios indicate that nad1, cox1, and cox3 are the most conserved genes, and that cox1 has the lowest rate of evolution. In addition, an 89 bp repeated sequence was found in the A + T-rich region. Phylogenetic analysis was performed using Bayesian inference (BI) and maximum likelihood (ML) methods based on 13 PCGs, and the monophyly of Kalotermitidae was supported.     

Termite damage to maize grown in agroforestry systems, traditional fallows and monoculture on nitrogen-limited soils in eastern Zambia

Abstract 1 Termites cause significant damage to maize and other crops in southern Africa. Several studies were conducted with the objective of determining the difference in termite damage to maize in various land use systems between monoculture maize, maize grown using traditional fallows and improved fallows. 2 In an experiment conducted at four sites on noncoppicing fallows, maize planted after Tephrosia candida 02971 fallows had lower termite damage compared with fully fertilized monoculture maize. However, the termite suppression was not low enough to warrant rotation of noncoppicing fallows for termite management.. 3 In four experiments comparing termite damage to maize grown in monoculture and in coppicing fallows, fully fertilized monoculture maize had a higher percentage of lodged plants compared with maize grown in pure Leucaena leucocephala, Gliricidia sepium and Acacia anguistissima fallows or in a mixture of A. anguistissima + Sesbania sesban or Tephrosia vogelii + S. sesban. 4 More than 50–75% of the variance in maize yield was explained by preseason inorganic nitrogen and termite damage. However, termite damage to maize was not influenced by inorganic nitrogen, which represents nitrogen readily available to maize. The decomposition rate of biomass (related to lignin + polyphenol to nitrogen ratio) and water retention under fallows also appeared to influence termite damage. 5 It is concluded that maize grown in L. leucocephala, G. sepium, A. anguistissima and S. sesban fallows suffers less termite damage and produces maize yields comparable with conventionally tilled and fully fertilized monoculture maize.     

Meristems under Continuous Irradiation

Root tips of Vicia faba and Zea mays have been subjected tocontinuous irradiation from radium or cobalt-60 for long periodsat various dose rates. The rates of mitosis and the damage tothe chromosomes (assessed as percentages of cells with micronulei)have been measured in four regions of the meristems. In Zearates of mitosis are reduced under chronic irradiation, exceptin the quiescent centre, and the cap initials are particularlysensitive. In Vicia the main change in mitosis is that the quiescentcentre increases its rate, but at 12°C there is a slightstimulation of division all over the meristem. In Vicia increasingthe dose rate or lowering the temperature increases the nucleardamage. At 19° C there is an increase in damage with accumulateddose percell cycle, but the data at 12°C do not fall onthe 19°C curve, suggesting that there may be a temperatureeffect on damage other than that caused by changing the durationof the cell cycle. The differences in radiosensitivity betweenthe different regions of the meristem are due solely to differencesin the rates of mitosis of the cells.     

Genotype Affects the Morphogenic Response in vitro of Epicotyl Segments of Citrus Rootstocks

The influence of light, hormones and explant orientation onin vitro regeneration in epicotyl cuttings was compared in fourCitrus species (C. aurantium, C. macrophylla, C. reshni andC.sinensis ) and the hybrid Troyer citrange (C. sinensis x Poncirustrifoliata). In all cases, explants planted vertically regeneratedshoots at the apical end by a process of direct organogenesiswithout callus formation. When the Troyer citrange explantswere incubated horizontally, regeneration at the apical endoccurred by an indirect organogenic pathway after callus formation.This change in the pathway of regeneration did not occur inany of the Citrus species, and incubation horizontally resultedin a reduction in the number of buds and shoots formed throughthe direct organogenic pathway. Shoot formation through thedirect organogenic pathway was inhibited by darkness, and thisinhibitory effect was counteracted by the cytokinin benzyladeninein Troyer citrange and, partly, in C. sinensis, but not in C.macrophylla. A non-organogenic callus formed at the basal endof most of the cuttings of C. reshni. InC. sinensis and C. aurantium,a non-organogenic callus formed only in a low proportion ofexplants. Troyer citrange formed an organogenic callus in whichbuds or roots differentiated depending on the auxin/cytokininbalance. C. macrophylla formed callus in the dark but not inthe light. Root formation occurred both in the presence of theauxin naphthaleneacetic acid or low concentrations (2.2 to 4.4µM) of the cytokinin benzyladenine, but no buds were formed.These qualitative and quantitative differences in the organogenicresponse indicate that the conditions for regeneration mustbe optimized for each genotype. Copyright 2000 Annals of BotanyCompany Benzyladenine, citrus, Citrus aurantium, Citrus macrophylla, Citrus sinensis, Citrus sinensis x Poncirus trifoliata, naphthaleneacetic acid, organogenesis, rooting, shoot regeneration, Troyer citrange     

Predation risk, host immune response, and parasitism

Predation risk may affect the allocation priorities of limitingresources by potential prey. Investment in immune function shouldreceive reduced priority, when hosts are exposed to predatorsbecause of the costs of immune function. We tested this hypothesisby randomly exposing adult house sparrows, Passer domesticus,to either a cat, Felis catus, or a rabbit, Oryctolagus cuniculus,for 6 h while assessing their ability to raise a T-cell–mediatedimmune response to a challenge with phytohemagglutinin. Sparrowsexposed to a cat had a significant reduction of, on average,18% and 36% in T-cell response in two different experimentscompared with sparrows that were exposed to a rabbit. In a fieldexperiment with a barn owl, Tyto alba, or a rock dove, Columbalivia, placed next to a nest-box during laying, we found a meanreduction in T-cell–mediated immune response of 20%. Inmales, the reduction in cell-mediated immune response owingto cat exposure increased with increasing size of the badge,which is a secondary sexual character, but only during the breedingseason. In a third experiment, house sparrows were either exposedto a barn own, T. alba, or a rock dove, C. livia, and developmentof malarial infections was recorded during the following 6 weeks.Individual sparrows exposed to a predator had a higher prevalenceand intensity of Haemoproteus malarial infection than did controlindividuals. Therefore, exposure to predators reduced theirability of hosts to cope with parasitism mediated through effectson immune function.     

Deleterious effect of Chattonella marina on short-necked clam (Ruditapes philippinarum); possible involvement of reactive oxygen species

In laboratory exposure experiments, Chattonella marina showeda deleterious effect on short-necked clams (Ruditapes philippinarum).Accumulated C. marina cells were observed in gill tissues ofthe clams exposed to C. marina. Immunohistochemical analysisusing antiserum against the crude glycocalyx of C. marina suggestedthat the glycocalyx was present on the gill surface. Mucus substancesprepared from gill tissue of the clams stimulated C. marinato generate increased amounts of O₂^– in a concentration-dependentmanner. These results suggest that reactive oxygen species (ROS)-mediatedgill tissue damage is one of the causative factors responsiblefor the harmful effect of C. marina on shellfish.     

Reactive oxygen species as causative agents in the ichthyotoxicity of the red tide dinoflagellate Cochlodinium polykrikoides

The underlying toxic mechanisms of the red tide dinoflagellate,Cochlodinium polykrikoides, were studied with respect to thereactive oxygen species-mediated toxic effect. Cochlodiniumpolykrikoides generates superoxide anion (O₂^–) and hydrogenperoxide (H₂O₂), as measured by the cytochrome c reduction methodand scopoletin–peroxidase method, respectively. The capabilityof C.polykrikoides to generate these oxygen radicals was relatedto the growth phase: the highest rate in the exponential phaseand a gradual decrease in the stationary phase. Other phytoplankton,such as Eutreptiella gymnastica, Heterosigma akashiwo, Prorocentrummicans, Gymnodinium sanguineum and Alexandrium tamarense, alsoproduce H₂O₂; the rate of H₂O₂ generation by these species waslower than that of C.polykrikoides. The exposure of liposomalsamples to intact or ruptured individuals of C.polykrikoidesresulted in severe membrane damage, such as liposomal lipidperoxidation. Cochlodinium polykrikoides-induced lipid peroxidationwas significantly reduced by oxygen radical scavengers, superoxidedismutase, benzoquinone, catalase and mannitol. In addition,lipid peroxidation of gill tissue of flatfish exposed to C.polykrikoidesincreased with increasing algal cell density. These resultssuggest that reactive oxygen species generated from C.polykrikoidesare responsible for oxidative damage leading to fish kills.     

Feeding experience and relative size modify the begging strategies of nestlings

The offspring of birds and mammals use a combination of movementsand vocalizations, known as begging, to solicit food from theirparents. A widespread interpretation of begging is that itconstitutes an honest signal of offspring need. But we knowthat in the house sparrow (Passer domesticus) the intensityof begging calls reflects the past experience of offspringin addition to their need. Here we show that this result generalizesto other species. An experiment with hand-reared magpies (Pica pica) and great spotted cuckoos (Clamator glandarius) indicates that the begging strategies depend on the past experience ofchicks and the composition of their brood. In asynchronoustwo-magpie broods, both chicks begged at the same intensitywhen the large chick obtained food more easily than its sibling,but the large chick begged at higher intensity when it was easier for the smaller chick to obtain food. Cuckoo chicks beggedat higher intensity than magpies.