小翅稻蝗的精子竞争及交配行为的适应意义

许多昆虫有多次交配行为 ,因多次交配而引起不同雄虫的精子竞争 ,提供雌虫一种有效的性选择方式。小翅稻蝗 (Oxyayezoensis Shiraki)具多次交配行为 ,雌雄交配时间长 ,且交配后常伴有长时间的抱对行为。利用近缘种的种间交配 ,对小翅稻蝗的精子竞争、交配后抱对行为的适应意义进行了探讨。结果表明 ,小翅稻蝗的 P2 值 (最后交配雄虫子代的比例 )达 94 .3%±5 .3% ,说明最后交配雄虫的精子优先用于卵子的受精 ,交配时存在着精子置换。长时间的交配后抱对行为是为了阻止雌虫与不同雄虫个体的再交配 ,保护精子免被置换。     

东亚飞蝗行为和形态型变的判定指标

通过田间、室外罩笼、室内行为测试等一系列实验,研究了东亚飞蝗群居型和散居型之间的行为和形态差异。确立了东亚飞蝗不同生态型个体的形态和行为指标．结果表明,雌雄散居型蝗蝻每分钟的跳跃次数均在1．4以下,转向次数分别在1．3和1．4以下;雌雄群居型蝗蝻每分钟的跳跃次数均在1．6以上,转向次数分别在1．6和1．5以上．群居型蝗虫的跳跃次数、转向次数显著高于散居型蝗虫。所以跳跃次数、转向次数可作为东亚飞蝗行为型变判定指标．在同型不同性别的蝗虫之间行为型变指标没有显著差异．F／C值可作为4龄以上东亚飞蝗的形态型变判定指标。而E／F值可作为东亚飞蝗成虫的形态型变判定指标．两型的F／C值都随龄期的增长而增加,且同龄期雄虫F／C均大于雌虫F／C．F／C、E／F值在不同型态和同型不同性别间均存在极显著差异．因此,确定两型形态型变标准时应将雌、雄虫分开,即雌性和雄性散居型第4、5龄及成虫的F／C值分别大于2．5、2．8、3．3和2．6、2．9、3．5;雌性和雄性群居型第4、5龄及成虫的F／C值分别小于2．5、2．7、3．1和2．5、2．8、3．3．成虫的E／F值也可以作为成蝗形态型变的判断指标．     

飞蝗变型及体色多型的内分泌控制机理

飞蝗具变型现象,散居型和群居型在形态特征、生理机能、行为及体色等方面存在明显差异。保幼激素已被证实能诱导飞蝗散居型绿色的出现。近年,从飞蝗心侧体成功地分离了一种神经肽——黑化诱导激素([His^7]-corazonin),并用白化型进行检测,证实了其对体色黑化作用的活性。不同时间对飞蝗若虫注射不同剂量的[His^7]-corazonin,能诱导出现除绿色以外的散居型体色,如浅褐色、褐色、赤褐色、黑色等;也能诱导出现群居型的体色,即黑色配以橘黄色的底色。而且,对散居型若虫注射[His^7]-corazonin能诱导其形态向群居型转换。这些研究证实[His^7]-corazonin对飞蝗的变型有着重要的控制作用,但又不是唯一的。     

群居型和散居型东亚飞蝗雌成虫飞行肌的超微结构

应用电子显微镜对群居型和散居型东亚飞蝗Locusta migratoria manilensis（Meyen）雌成虫背纵肌进行了比较观察。结果表明：群居型和散居型成虫背纵肌具有类似的亚细胞结构,飞行肌的肌原纤维具有1∶3粗细丝比例,每根粗丝由6根细丝环绕排列成六角形结构。飞行肌的发育和线粒体的形成均是渐进的过程,在不同日龄成虫间存在差异。肌节长度为2.1～3.4 μm;7和10日龄时群居型成虫肌节长度小于散居型;7日龄群居型肌原纤维直径显著大于散居型。背纵肌内线粒体含量约占肌纤维的20%～43%,两型飞蝗之间存在着显著的差异,7日龄时群居型线粒体占肌原纤维的比例高达42.96%,而散居型的只有22.45%;10日龄群居型线粒体含量为41.32%,散居型线粒体29.98%。上述差异可能是东亚飞蝗群居型成虫飞行能力显著强于散居型成虫的重要原因之一。     

东亚飞蝗Locusta migratoria manilensis(Meyen)二型生物学特性的初步研究

本文是研究东亚飞蝗二型生物学特性的一部分报导,目的在于通过二型生物学特性的比较,阐明二型在种群数量变动上的某些特点。实验结果指出:1.散居型飞蝗的发育速度大于群居型。低密度虫群的成活率亦高于高密度虫群。2.散居型成虫产卵量高于群居型,其卵小管数目也比后者稍多。3.若以食物吸收量与取食量的干重比例为指标,则散居型食物利用系数低于群居型。4.群居型体内水分含量比散居型低,但脂肪含量则比散居型高,实测结果前者的耐寒性比后者略强。此外,本文还简单讨论了二型的上述特性差异在飞蝗猖獗学上的意义。     

长足大竹象交配行为

【目的】探索长足大竹象Cyrtotrachelus buqueti Guerin-Meneville成虫的交配行为规律。【方法】通过室内饲养和野外观察相结合的方法,记录了完整的交配过程,比较了不同寄主及虫体大小间交配行为的差异。【结果】长足大竹象一次完整的交配包括示爱、抱对、插入输精和配后保护4个阶段,雌雄都有多次交配行为。室内试验证明,长足大足象完整交配时间为21.71±1.84 min,其中示爱时间为0.46±0.05 min,抱对时间为6.18±0.38 min,插入输精时间为8.36±0.62 min,配后保护时间为6.71±0.79 min。雄虫初次交配时,在示爱、抱对和插入输精时间上均显著长于有交配经历的雄虫(P0.05)。长足大竹象在不同寄主植物上的交配时间存在差异,在慈竹上的示爱时间(0.46±0.05 min)和插入输精时间(8.36±0.62 min)显著长于在唐竹、撑×绿杂交竹、孝顺竹和芦竹上的时间(P0.05);在孝顺竹上的配后保护时间显著长于在其他植物上的时间(P0.05)。长足大竹象成虫会选择最适体长的配偶进行交配,当雌虫体长≥3.3 cm和3.0~3.2 cm时,与不同体长的雄虫在示爱、抱对、插入输精和配后保护时间上都显著长于其他体长的雌虫(P0.05)。林间长足大竹象的交配行为与室内观察结果基本一致。【结论】研究结果有助于了解长足大竹象交配过程,也对研究该虫的繁殖行为学及行为控制技术提供了依据。     

繁殖盛期雄性普通东方小蛙的个体大小不影响交配成功率

通过比较抱对和非抱对普通东方小蛙(Crinia signifera) 的吻尾干骨长(体长) 和检测个体较大或状态较好的雄体是否为成功繁殖个体, 检测雌蛙体长与交配成功的雄蛙的体长和相对状态(体重/体长) 之间是否存在线形关系, 评估交配与个体大小之间的关系。在实验室内, 令未交配雌体选择随机选出的雄体, 观测雌体是否与最大的雄体交配; 将抱对的蛙暴露于其它雄蛙, 观测其它较大或较小的雄蛙是否取代已抱对的雄蛙。结果表明: 抱对雄蛙和雌蛙的个体大小无显著的关系, 成功交配的雄蛙并不比未交配的雄蛙大, 其它雄蛙不能取代已抱对的雄蛙。在这一C. signifera种群中, 繁殖盛期雄性个体的大小似乎不影响交配成功率, 在此期间即便存在配偶选择, 亦决定于与雄性个体大小无关的其它因素。在更长的繁殖期内, 雄性个体大小则与交配成功率有关, 这是该种的典型特征。     

意大利蝗交配行为观察

通过昆虫行为观测仪与室外饲养观察,分析意大利蝗Calliptamus italicus的交配行为,阐明交配经历和温度对意大利蝗交配持续时间的影响。结果发现:(1)意大利蝗的交配行为包括相遇和交配两个阶段。相遇行为包括避让、打斗和交配3种类型,其中打斗多发生在雄雄相遇、雄虫与一对正在交配成虫相遇情况。避让和交配则多发生在雌雌相遇、雌雄相遇、雌虫与一对正在交配成虫相遇情况。雄虫在交配过程中占据主动。意大利蝗的交配行为包括曲腹、爬背、抱对和交配4个过程,平均时间为11.25±1.40 min。(2)雌雄虫初次交配的持续时间(12.88±0.67 min)显著长于雌雄虫均有交配经历的时间(10.47±0.39 min)(P0.05);初次交配雌虫和有交配经历雄虫的交配持续时间(11.00±0.75 min),与初次交配雄虫和有交配经历雌虫的时间(12.12±0.67 min)无显著差异(P0.05)。(3)随温度升高意大利蝗的交配持续时间缩短,27℃时交配持续时间最长(15.93±2.25 min),且与36℃、42℃时的时间差异显著(P0.05),42℃时的交配持续时间最短,为6.01±0.43 min,与36℃时的时间(7.47±0.52 min)差异不显著(P0.05)。     

飞蝗型变相关基因表达的大规模分析

飞蝗是世界上最具破坏性的农业害虫之一。在特定的环境条件下,它可以从“散居型”转变成“群居型”,从而获得集群和迁飞的能力。为了阐释飞蝗型变的分子机理,中国科学院动物研究所康乐研究员领导的研究组与其合作通过大规模的测序分析,得到70000多条飞蝗的表达序列标签(ESTs),并发现了532个与型变相关的基因。总体分析表明,     

白边痂蝗在青藏高原上的地理变异

蝗虫的种类很多,是为害农作物和牧草的重要害虫。有些种类的形态在不同地点或不同时间有很大的差异,这些差异给分类工作者带来了很大的麻烦,并且往往由于标本数量少或工作粗糙而鉴定错误,甚至错订成新种或新亚种。就飞蝗(Locusta migratoria L.)而言,Uvarov(1921)发表了变型学说,揭示了飞蝗的群居型、散居型、中间型之间后代可以互变的秘密。而在此学说发表之前,人们都把群居型和散居型飞蝗当作二个种。这种种内变异现象引起了分类工作者和生态工作者的重视。近来国内外学者对种下分类工作研究颇多,(1972)对雏蝗[Chorthippus macrocerus (F.-W.)]的种内变异进行了研究,利用t值来区分亚种。     

Phase-specific responses to different qualities of food in the desert locust, Schistocerca gregaria: developmental, morphological and reproductive characteristics

Solitarious female adults are known to produce smaller hatchlings than those produced by gregarious adults of the desert locust, Schistocerca gregaria. This study investigated developmental, morphological and reproductive responses to different qualities of food in hatchlings of different phases. Mortality was higher, the duration of nymphal development longer and adult body weight lighter with a low-quality food than a high-quality food. Gregarious hatchlings showed better survivorship, grew faster and became larger adults than did solitarious ones. The incidence of locusts exhibiting extra molting, which was typically observed in the solitarious phase, was dramatically increased when a low-quality food was given to the solitarious hatchlings. Low-quality food caused locusts to shift morphometric ratios toward the values typical of gregarious forms; smaller F/C (hind femur length/maximum head width) and larger E/F (elytra length/hind femur length). Solitarious hatchlings grown at either high- or low-quality foods and then given high-quality food after adult emergence revealed that food qualities during the nymphal stage influence their progeny quality and quantity via adult body size that influenced reproductive performance. Female adults showed an overshooting response to a shift from low- to high-quality food by increasing egg production that was specific to body size. This study may suggest that gregarious hatchlings are better adapted to adverse food conditions than solitarious counterparts and extra molting is induced even among gregarious hatchlings under poor food conditions.     

Phase-independent responses to phase-specific aggregation pheromone in adult desert locusts, Schistocerca gregaria (Orthoptera: Acrididae)

Abstract. Volatiles from solitary-reared (solitarious) and crowd-reared (gregarious) adult male desert locusts, Schistocerca gregaria (Forskal) (Orthoptera: Acrididae), were quantitatively and qualitatively different.In particular, solitarious males did not emit phenylacetonitrile, a key component of the aggregation pheromone produced by gregarious adult males.In laboratory bioassays, solitarious and gregarious adults of both sexes responded similarly to the natural aggregation pheromone blend, the major pheromone component phenylacetonitrile, and a synthetic pheromone blend comprising benzaldehyde, guaiacol, phenylacetonitrile and phenol.EAG measurements showed significant differences in the responsiveness of adults of the two phases to the four synthetic components at high doses; however, the general response patterns were similar.These results suggest that the gregarious adult male aggregation pheromone may play a role in the arrestment and subsequent recruitment of solitarious individuals into gregarious or gregarizing groups during the early stages of a locust outbreak.     

Phase polymorphism in Schistocerca gregaria: Assessment of juvenile hormone synthesis in relation to vitellogenesis

Juvenile hormone (JH) synthesis by the corpora allata of gregarious and solitarious phase females of Schistocerca gregaria was determined in vitro during the penultimate and last stadia as well as during the first gonotrophic period of adults. Generally, the corpora allata of solitarious females showed higher rates of JH synthetic activity. In addition, in adult females there was a temporal difference between the corpora allata activities of gregarious and solitarious locusts, the latter exhibiting relatively higher rates of JH synthesis early in the first gonotrophic period. The corpus allatum volumes of solitarious females were also generally larger than those of their gregarious counterparts; there was no synchrony between fluctuations in JH synthetic activity and changes in corpus allatum volume in either phase.The early onset of relatively high JH synthetic rates in solitarious females was correlated with the early detection, by rocket immunoelectrophoresis, of vitellogenin in the haemolymph and vitellin in the oöcytes. Vitellogenin appeared in the haemolymph on day 4 in solitarious females and on day 6 in gregarious females and vitellin appeared in the oöcytes on days 6 and 8 respectively. Oöcyte length at which vitellogenesis was first detected was 1.8 mm for gregarious and 1.3 mm for solitarious females. However, despite the accelerated onset of both vitellogenin synthesis and uptake, oöcyte maturation time of solitarious females was longer. In both gregarious and solitarious females, vitellogenin titres increased until oöcytes reached a length of about 4 mm and declined thereafter. Vitellin content of ovaries increased proportionately to oöcyte growth until they attained a length of 5.0 mm. The subsequent increase in length of oöcytes to maturity is attributed to postvitellogenic growth, possibly by hydration.     

Role of Olfactory and Visual Cues in the Attraction/Repulsion Responses to Conspecifics by Gregarious and Solitarious Desert Locusts

Desert locusts [Schistocerca gregaria Forskål (Orthoptera, Acrididae)] change phase in response to population density: solitarious insects avoid one another, but when crowded they change to the gregarious phase and aggregate. The attraction/repulsion responses of gregarious and solitarious locusts maintain phase differences in locust populations. Despite considerable research, the cues for aggregation are poorly understood; moreover, the repulsion response of solitarious locusts has not previously been investigated. This study analyzes the role of visual and olfactory stimuli in triggering these different responses to conspecifics. Isolation-reared insects were repelled by both olfactory and visual stimuli from other locusts. Crowd-reared insects were attracted by the combination of olfactory and visual cues. In addition, olfactory stimuli affected other behaviors in both phases, and behavioral differences between isolation- and crowd-reared locusts were clear even in the absence of conspecifics. The sensory and neurological mechanisms underlying these responses are not well understood and will form the basis for neurobiological investigations of locust phase.     

Is there an intraspecific role for density-dependent colour change in the desert locust?

Attempts to uncover the adaptive significance of density-dependent colour polyphenism in the desert locust, Schistocerca gregaria (Orthoptera: Acrididae), have been unsuccessful. Desert locust juveniles can change colour as part of a phenotypically plastic response to changes in local population density known as phase polyphenism. They are typically cryptic in colour at low rearing density (solitarious phase), but become conspicuous at high density (gregarious phase). Recent evidence indicates that this colour change functions interspecifically as an aposematic signal. Other recent evidence, however, suggests that previous attempts to demonstrate an intraspecific function of gregarious coloration in mediating group interactions among locusts may have been confounded by the effects of multiple sensory cues. We reinvestigated the intraspecific function of density-dependent colour polyphenism and specifically controlled for potentially confounding olfactory and tactile cues. We found no effect of gregarious phase (yellow and black) coloration as either a gregarizing stimulus to behaviourally solitarious locusts or as a visual aggregation stimulus behaviourally to gregarious locusts. We did, however, find that nonmoving solitarious phase (green) coloration significantly increased the activity levels of behaviourally gregarious locusts. We cannot explain this result and its biological relevance remains unknown. In the absence of support for the intraspecific visual cue hypothesis, we favour an aposematic perspective on the function of density-dependent colour polyphenism in the desert locust. The aposematic perspective parsimoniously accounts for density-dependent changes in both colour and behaviour. Copyright 2000 The Association for the Study of Animal Behaviour.     

Innate phase behavior in the desert locust,Schistocerca gregaria

Abstract Detailed aspects of the transition from the solitarious to the gregarious phase in the framework of locust ecology are undoubtedly most important for understanding locust phase polyphenism. Nevertheless, due to obvious difficulties in studying the solitarious phase in nature, such information is limited and mostly available from research carried out under laboratory conditions. In the current study, we examined the dispersal patterns of newly hatched locust nymphs in a laboratory setup that simulated seminatural conditions. This was carried out with no previous manipulation of the nymphs other than controlling their parental density. We comparatively tested the spatial distribution of newly hatched nymphs on perches located at different ranges within an emergence arena, and the expected Poisson (random) distribution. Hatchlings were found to disperse among the perches in a pattern significantly different from that expected by random. Irrespective of their parents’ phase, the observed distributions of all nymphs were clearly clumped, similar or close to those expected for gregarious locusts. It seems that rather than emerging with a parentally derived and predetermined phase, hatchlings have an independent default or innate behavioral state, which reflects at least tolerance if not attraction to conspecifics. The typical phase behavior may later become dominant under the appropriate environmental conditions. These results imply novel perspectives on locust phase transformation, which contribute to our understanding of the formation of locust crowds under field conditions. These should be considered in any rationale for developing a preventative management strategy of locust populations.     

Morphological and behavioural characteristics of a gynandromorph of the desert locust, Schistocerca gregaria

Abstract.  Morphological and behavioural characteristics are investigated for a gynandromorph of the desert locust, Schistocerca gregaria , appearing under isolated rearing conditions in the laboratory. It has both male and female external reproductive organs bilaterally. The body size and dimensions are similar to a normal male. Morphometric traits (fore wing length/maximum head width ratio and fore wing length/hind femur length ratio) of the gynandromorph are typical for the values of solitarious locusts. When the gynandromorph is placed into an arena holding ten sexually mature gregarious females, it shows a distinct male behaviour: it jumps on a female and tries to mate with her. When kept together with males, males recognize this gynandromorph as a female because some of them try to mount, although no successful copulation is observed. The results suggest that the gynandromorph might have had a female-specific pheromone. Dissection reveals that the gynandromorph has no testis but abnormal ovaries containing vitellogenic oocytes. These observations indicate that the gynandromorph obtained has a mixture of male and female morphological characteristics and behaves like a male but is recognized as a female by conspecific males.     

Fever and phenotype: transgenerational effect of disease on desert locust phase state

Natural enemy attack can cause transgenerational shifts in phenotype such that offspring are less vulnerable to future attack. Desert locusts (Schistocerca gregaria) show density‐dependent variation in their resistance to pathogens, such that they are less vulnerable to pathogens when in the high‐density gregarious phase state (when they would probably be more exposed to pathogens) than when in the solitarious phase state. We therefore hypothesized that infected gregarious parents would maintain this phenotype in their offspring. We infected gregarious desert locust nymphs with the fungal pathogen Metarhizium anisopliae var. acridum, and allowed them to survive to reproduction by means of behavioural fever. The phase state of the locust offspring was assessed by their colouration and behavioural assays. Contrary to our hypothesis, we found an increase in solitarization in the infected population (14.6% solitarious offspring from infected parents, vs. <2% from uninfected counterparts at equivalent density). In a second experiment, we simulated behavioural fever temperatures and obtained a similar result (13.6% solitarious offspring vs. 4.4% from controls), implying that the phenomenon is probably a side‐effect of the hosts’ fever response. Identification of this novel environmental factor affecting locust phase state could have important implications for the biological control of these major pests.