大肠杆菌改变果蝇产卵偏嗜性

【目的】用大肠杆菌Escherichia coli和黑腹果蝇Drosophila melanogaster分别作为微生物和宿主模型,研究微生物对宿主产卵行为的影响,并探讨大肠杆菌对果蝇存活率的影响。【方法】本研究首先利用野生型果蝇在双选择食物装置分别检测果蝇对大肠杆菌发酵食物的产卵偏嗜性和位置效应;利用大肠杆菌细胞和上清液解析诱导这种行为的原因;利用视觉、味觉和嗅觉突变体果蝇检测作用的感觉系统;通过蛹和成虫存活率检验果蝇对大肠杆菌发酵食物的产卵选择后果。【结果】黑腹果蝇产卵对大肠杆菌发酵的食物具有极显著趋避行为,产卵指数为-0.89。黑腹果蝇产卵对大肠杆菌代谢产物的产卵指数为-0.52,对大肠杆菌菌体的产卵指数为0.02。Orco2突变体果蝇产卵对大肠杆菌发酵的食物趋避行为严重受损,对应的产卵指数为-0.25。大肠杆菌在食物上生长,黑腹果蝇后代的存活率不足5%,而划破食物表面可以显著地降低大肠杆菌引起的黑腹果蝇死亡,将其存活率恢复到正常水平。【结论】大肠杆菌会改变黑腹果蝇产卵行为,使黑腹果蝇避开在其发酵食物上产卵;大肠杆菌代谢产物引起黑腹果蝇产卵的趋避性,果蝇主要通过嗅觉并联合其他感觉系统感知大肠杆菌代谢产物;黑腹果蝇对大肠杆菌产卵趋避行为可提高后代存活率,因为大肠杆菌形成一层菌膜,会引起果蝇缺氧死亡。     

不同成熟度杨梅果实上果蝇的动态变化

【目的】果蝇类害虫是杨梅果实的主要害虫,本文旨在探讨果蝇对不同成熟度果实的选择倾向以及杨梅园果蝇动态变化规律。【方法】通过饲养获得黑腹果蝇Drosophila melanogaster种群,探讨果蝇在不同成熟度杨梅果实上的繁殖量,通过果园调查统计杨梅成熟过程中落果数量、落果和树上挂果中果蝇数量。【结果】杨梅成熟过程中,果色经历绿色、粉红色、红色和紫红色变化过程;果蝇分别在各种成熟度果实上繁殖时,绿色果实上果蝇后代数量最少,但接近成熟的粉红色、红色和紫红色果实上果蝇后代数量无显著差异;同时提供各种成熟度的果实时,随着果实成熟度增加,黑腹果蝇的后代繁殖数量增多。在果实成熟前后对果园果蝇数量的调查表明,在果实成熟前,落果中果蝇数量显著高于树上挂果,落果是果园果蝇的主要繁殖地;但当果园果实大量成熟时,挂果中果蝇数量显著多于落果,挂果成为果蝇主要繁殖场所。【结论】在杨梅园,果蝇存在从地面落果转移至树上挂果的动态变化,果蝇对不同成熟度果实的选择性差异可能是这种动态变化的主要原因。     

边闻边看记得牢——科学家首次发现视嗅觉协同功效

看到汽车闻到汽油味,可以加深你对汽车的印象;而看到汽车闻到奶酪味,则不会有同样的效果。中国科学家对果蝇的最新实验证实,当果蝇同时使用嗅觉和视觉时,学习记忆的效果明显强于单一使用嗅觉或视觉。这一发现不仅朝果蝇的"认知世界"又迈近了一步,同时也可能为指导人类的学习和记忆提供新的科学依据。该成果发表在7月8日出版的《科学》杂志上。     

贮食动物的盗食与反盗食行为策略

食物贮藏是许多动物应对食物短缺、保障其生存和繁衍的一种适应性行为。保护好贮藏食物以供食物短缺期利用,是食物贮藏成功的标志和进化动力。同种或异种动物盗食是贮藏食物损失的重要原因。嗅觉、视觉与空间记忆、随机搜寻等是动物搜寻和盗取食物的重要手段;避免盗食、阻止盗食和容忍盗食是动物反盗食的重要策略。动物通常采用多种行为策略进行盗食和反盗食,分配食物资源,形成相对稳定的种内、种间关系。盗食与反盗食互作及其对贮食行为进化的意义已成为行为生态学的研究热点和前沿之一,针对鸟类和哺乳类动物的研究尤为丰富。本文总结了贮食动物常见的盗食和反盗食行为策略及其相互作用的研究进展,主要内容涉及贮食动物利用嗅觉、视觉与空间记忆、随机搜寻等盗取其他个体食物的盗食策略,以及通过隐藏、转移、保卫、容忍等方式减少被盗食,保护贮藏食物的行为策略。针对现有研究状况,从种间盗食与反盗食及其与物种共存的关系,种间非对称盗食关系及其适应意义,盗食与反盗食最适行为策略及其与贮食动物适合度的关系等方面对今后研究提出了建议。     

果蝇视觉学习记忆能力与脑部cAMP水平的相关性

利用闭环飞行模拟系统研究果蝇视觉飞行定向行为的操作式条件化 ,证明正常果蝇视觉学习记忆能力与日龄有关 ,即 3～ 4d龄果蝇的学习记忆能力明显优于1～ 2d龄果蝇 ,蝇脑内的cAMP含量也呈现随果蝇日龄增加而增加的趋势 .同时对学习记忆缺陷型果蝇进行检测 ,其脑内cAMP含量高于正常对照组果蝇 .通过喂食PDEase抑制剂咖啡因扰乱cAMP代谢 ,使果蝇cAMP水平异常提高 ,导致果蝇学习记忆能力显著下降 ,表明果蝇视觉学习记忆需要脑内cAMP水平处于一适当范围 ,过高或过低的cAMP水平都将影响果蝇的视觉学习记忆能力     

信息与动态

醣脂作为苏芸金芽孢杆菌晶体毒素的受体,配偶选择导致新物种的形成,视觉和嗅觉帮助果蝇的学习记忆,转基因植物调动天敌来抵御害虫,雪蚤的抗冻蛋白     

嗅觉缩短了果蝇的寿命

一项研究指出,食物的嗅觉特征也许是调节寿命的一个关键,食物的味道可能是潜在的可得到的营养信号。过去的研究显示,包括啮齿类以及灵长类的大多数动物,它们摄入的热量被严格限制时,寿命会更长。酵母是果蝇食物的主要成分。Sergiy Libert和同事让被严格限制热量的果蝇Drosophil     

拟果蝇对不同寄主水果的产卵选择与适应性研究

【目的】探明拟果蝇Drosophilasimulans对不同寄主水果的行为选择及适应性。【方法】利用四臂嗅觉仪等测定了拟果蝇对5种水果（苹果、红提、香梨、香蕉和杨梅）的趋性与产卵选择性,并比较不同水果饲喂对拟果蝇生殖和适合度指标的影响。【结果】拟果蝇对不同水果的气味喜好为：杨梅>香蕉>香梨>苹果,产卵选择喜好表现为：香蕉>红提>杨梅>香梨>苹果;与苹果饲养相比,拟果蝇在香蕉和杨梅上的产卵量较高、发育历期较短,而其孵化率、化蛹率和羽化率在5种寄主水果上无显著差异（P>0.05）。【结论】该研究初步明确了拟果蝇对5种水果的行为偏好及适应性,拟果蝇对不同水果的气味与产卵的偏好差异可能是其行为选择性与后代适应性权衡的结果,研究结果为该虫的综合防控提供理论依据。     

影响稻褐飞虱声诱集的若干因素(同翅目：飞虱科)

稻褐飞虱Nilaparvata lugens(stal)雌、雄成虫均能发出由固体介质(寄主植株)传递的鸣声(振动)信号,用于交尾前的个体间通讯。雄虫对雌虫鸣声或重放鸣声录音具有强趋性。由此研制的声诱集器有可能首先用于改进褐飞虱测报的田间采样技术。 声诱集效果受若干因素的影响。实验室试验结果表明,声诱集具有种的选择性;诱集率随雄虫虫龄变化,对羽化后4一5日龄雄虫的诱集率最高;异性干扰对诱集效果有明显影响;一天中,中午前后诱集率最高,9：00-18：00的诱集量占总诱集量的54.0%±10.8%;诱集率随气温变化,26℃-28℃诱集效果最好;而室外晴、阴、雨等天气差异对诱集串无显著影响;另外,随诱集信号播放时间的延续,诱集率下降;间断信号的诱集效果高于连续信号。     

蜜蜂对复合气味中特征因素的选择性记忆巩固的研究

目的 蜜蜂天生具有丰富的嗅觉辨识能力,觅食、交配、导航以及社交活动均依赖其嗅觉系统,是研究嗅觉感知和学习记忆的行为及神经机制的理想模型。蜜蜂既能够将某个复合气味作为一个整体也可以将复合气味的各组成成分进行辨别和区分,但是在特征依赖的联合记忆中依据何种原则进行加工并存储到长期记忆还不清楚。方法 本文利用特征阳性（feature positive：AB+,B-）和特征阴性（feature negative：AB-,B+）的奖赏性嗅觉条件化,训练蜜蜂对复合气味和成分气味的辨别,并检测蜜蜂对复合气味（AB）、成分气味（B）以及特征气味（A）的中长时记忆（3 h）和长时记忆（24 h）。结果 在特征阳性的奖赏性嗅觉条件化中,蜜蜂对训练过的气味可以形成稳定的中长时和长时记忆,并且对复合气味中的特征气味的记忆与复合气味的记忆呈现高度相似。但在特征阴性的奖赏性嗅觉条件化中,蜜蜂虽能够在3 h和24 h对训练过的两种气味具有显著的伸喙反应差异,且对特征阴性的气味无显著反应,但对复合气味的反应随时间的推移而增加。结论 实验结果表明,蜜蜂选择性地将与奖赏信息联合出现的气味巩固到长时记忆中,但并未依据特征成分加工储存到长时记忆中。奖赏信息预示着食物源,与生存息息相关,表明对环境信息进行选择性的记忆巩固加工并储存可能是低等动物高效地编码生存相关信息的重要策略。     

Influence of habitat pattern on orientation during host fruit location in the tomato fruit fly, Neoceratitis cyanescens

Fruit flies have evolved mechanisms using olfactory and visual signals to find and recognize suitable host plants. The objective of the present study was to determine how habitat patterns may assist fruit flies in locating host plants and fruit. The tomato fruit fly, Neoceratitis cyanescens (Bezzi), was chosen as an example of a specialized fruit fly, attacking plants of the Solanaceae family. A series of experiments was conducted in an outdoor field cage wherein flies were released and captured on sticky orange and yellow spheres displayed in pairs within or above potted host or non-host plants. Bright orange spheres mimicking host fruit were significantly more attractive than yellow spheres only when placed within the canopy of host plants and not when either within non-host plants or above both types of plants. Additional experiments combining sets of host and non-host plants in the same cage, or spraying leaf extract of host plant (bug weed) on non-host plants showed that volatile cues emitted by the foliage of host plants may influence the visual response of flies in attracting mature females engaged in a searching behaviour for a laying site and in assisting them to find the host fruit. Moreover, the response was specific to mature females with a high oviposition drive because starved mature females, immature females and males showed no significant preference for orange spheres. Olfactory signals emitted by the host foliage could be an indicator of an appropriate habitat, leading flies to engage in searching for a visual image.     

Volatile host fruit odors as attractants for the oriental fruit fly (Diptera: Tephritidae)

We examined the responses of oriental fruit flies, Bactrocera dorsalis Hendel, to the odors of different stages and types of fruit presented on potted trees in a field cage. Females were most attracted to odors of soft, ripe fruit. Odors of common guava were more attractive to females than papaya and starfruit, and equally as attractive as strawberry guava, orange, and mango. In field tests, McPhail traps baited with mango, common guava, and orange captured equal numbers of females. Traps baited with mango were compared with 2 commercially available fruit fly traps. McPhail traps baited with mango captured more females than visual fruit-mimicking sticky traps (Ladd traps) and equal numbers of females as McPhail traps baited with protein odors. Results from this study indicate that host fruit volatiles could be used as lures for capturing oriental fruit flies in orchards.     

Visual and olfactory stimuli and fruit maturity affect trap captures of Oriental fruit flies (Diptera: Tephritidae)

An effective lure-and-kill trap is a potentially important instrument in monitoring and controlling oriental fruit flies, Bactrocera dorsalis (Hendel). A number of experiments were performed in an orchard of commercial guava, Psydium guajava L., to determine how fly captures are affected by combining visual and olfactory stimuli, and by the timing of trap deployment relative to host phenology. Baiting sticky Ladd traps with hydrolyzed liquid protein significantly increased the number of captured flies. Mostly male flies were caught in the absence of mature guava fruit, whereas mostly female flies were caught when ripe fruit was abundant. These results suggest that an effective oriental fruit fly trap should include both visual and olfactory lures, and that proper timing of trap deployment can be an important factor in monitoring female abundance in oriental fruit fly populations.     

Identification of active components from volatiles of Chinese bayberry, <Emphasis Type="Italic">Myrica rubra</Emphasis> attractive to <Emphasis Type="Italic">Drosophila suzukii</Emphasis>

Drosophila suzukii (Diptera: Drosophilidae) is native to Southeast Asia and now has become a severe pest of several soft fruits in Europe and the Americas. It causes considerable damage to Chinese bayberry, Myrica rubra, in China. In the present study, we employed gas chromatograph–electroantennographic detection (GC–EAD) together with behavioural bioassays and trapping experiments to identify volatile semiochemicals emitted by Chinese bayberry attracting D. suzukii. Electrophysiological experiments revealed the presence of six EAD-active compounds from ripe bayberry fruits, including methyl (E)-3-hexenoate, methyl (E)-2-hexenoate, ethyl (E)-2-hexenoate, α-ylangene, α-humulene and an unidentified compound that elicited consistent antennal response. In two-choice bioassays, bayberry fruits attracted all responding flies, and significantly more flies responded to the volatile extract of bayberry fruits. Four EAD-active compounds were attractive to mated female D. suzukii at lower doses (0.01 and 0.1 µg), but showed repellency at higher doses (10 and 100 µg). Mixtures of these four compounds at different ratios attracted D. suzukii flies at all test doses (0.1, 1 and 10 µg). Both male and female flies were trapped by a mixture of synthetic methyl (E)-3-hexenoate, methyl (E)-2-hexenoate, ethyl (E)-2-hexenoate and α-humulene in a ratio of 1:1.3:1:6.4 in the field trapping experiment. Significantly more males than females were captured in the trap baited with the synthetic blend, and the percentages of D. suzukii captured out of all flies by the traps baited with lure were higher than that baited with blank control. Our findings may provide insights into the olfactory responses of D. suzukii to specific host plant volatiles, and contribute to further development of an effective lure for monitoring D. suzukii in the field.     

Field evaluation of three-component solid food-based dispenser versus torula yeast for capturing Mediterranean and oriental fruit flies (Diptera: Tephritidae)

Certain species of true fruit flies (Diptera: Tephritidae) are worldwide pests of fruits and vegetables, and many countries operate trapping programs to detect and monitor invasions. Torula yeast-borax (TYB) solution is a widely used food bait, although its effective field longevity is relatively short (1–2 weeks). This led to the development of a synthetic cone-shaped food dispenser that contains ammonium acetate, putrescine, and trimethylamine. The food cone has received limited testing, and the objective of this study was to compare captures of the Mediterranean fruit fly (Ceratitis capitata (Wiedemann)) and the oriental fruit fly (Bactrocera dorsalis (Hendel)) in traps baited with the fresh TYB solution versus traps baited with fresh or weathered food cones. Captures showed a female bias for both baits and both species. For C. capitata, fresh food cones generally attracted more individuals than fresh TYB. Weathered food cones attracted similar or greater numbers of medflies than TYB for the initial two weeks, but food cones weathered for 4 or 6 weeks attracted fewer flies than TYB. For B. dorsalis, TYB-baited traps captured more females than fresh or weathered food cone-baited traps in each of six weekly sampling periods, and the differences were statistically significant in weeks 1–4. In a release-recapture experiment, both C. capitata and B. dorsalis were captured in higher numbers in traps baited with fresh TYB than those baited with food cones weathered for 0 (fresh) to 6 weeks. The implications of these results for fruit fly surveillance are discussed.     

Broadcasts of wing-fanning vibrations recorded from calling male Ceratitis capitata (Diptera: Tephritidae) increase captures of females in traps

Female Mediterranean fruit flies, Ceratitis capitata (Wiedemann), from the sterile-male rearing facility in El Pino, Guatemala, were exposed to broadcasts of wing-fanning vibrations recorded from males engaged in calling behavior to investigate the feasibility of developing a female-selective acoustic trap. The recorded signals had frequent amplitude fluctuations and peak frequencies approximately 350 Hz, typical of signals observed in previous studies of Mediterranean fruit fly acoustic behavior. Females did not exhibit long-distance phonotaxis, but remained near a speaker significantly longer when the sounds were broadcast at 103-107 dB than when the speaker was silent. In addition, significantly higher percentages of females were captured by yellow adhesive traps next to a broadcasting speaker than by traps next to a silent mimic. Additional bioassays were conducted with synthetic, 350-Hz tones produced by a thermoacoustic tube as well as with silent mimics of the different sound sources to examine the relative responsiveness of female Mediterranean fruit flies to traps with different acoustic and visual features. The visual attributes of the different sound source assemblies significantly affected capture rates. The range over which the broadcast significantly increased the percentage of female captures was <0.5 m, which may limit the utility of these acoustic cues in large-scale trapping programs. However, the findings of this study do justify further testing of whether optimized short-range acoustic signals could be used to augment longer range pheromonal and visual cues to improve the efficacy of female-selective traps.     

Attraction of Drosophila melanogaster males to food-related and fly odours

The fruit fly Drosophila melanogaster has become a model for olfaction and odour-mediated behaviour. In the wild, Drosophila flies aggregate on decaying fruit where they mate and oviposit and a strategy to find mates would be to locate fruit which has already been colonized by other flies. We therefore developed a bioassay to investigate attraction of males to food and fly odours. We showed that upwind flights are initiated by food odours. At shorter distances, males are attracted by volatiles produced by conspecifics. However, only odours produced by copulating flies attract males. This suggests either a synergistic effect of both male and female odours or changes in pheromone release during mating, that indicate the presence of sexually receptive females. Our findings demonstrate the essential role of food odours and pheromones for mate location in D. melanogaster.     

Associative learning and memory in Drosophila: beyond olfactory conditioning

The associative learning abilities of the fruit fly, Drosophila melanogaster, have been demonstrated in both classical and operant conditioning paradigms. Efforts to identify the neural pathways and cellular mechanisms of learning have focused largely on olfactory classical conditioning. Results derived from various genetic and molecular manipulations provide considerable evidence that this form of associative learning depends critically on neural activity and cAMP signaling in brain neuropil structures called mushroom bodies. Three other behavioral learning paradigms in Drosophila serve as the main subject of this review. These are (1) visual and motor learning of flies tethered in a flight simulator, (2) a form of spatial learning that is independent of visual and olfactory cues, and (3) experience-dependent changes in male courtship behavior. The present evidence suggests that at least some of these modes of learning are independent of mushroom bodies. Applying targeted genetic manipulations to these behavioral paradigms should allow for a more comprehensive understanding of neural mechanisms responsible for diverse forms of associative learning and memory.     

Effect of the entomopathogenic fungus,Entomophthora muscae (Zygomycetes: Entomophthoraceae), on sex pheromone and other cuticular hydrocarbons of the house fly,Musca domestica

House fly (Musca domestica) males are highly attracted to dead female flies infected with the entomopathogenic fungus Entomophthora muscae. Because males orient to the larger abdomen of infected flies, both visual and chemical cues may be responsible for the heightened attraction to infected flies. Our behavioral assays demonstrated that the attraction is sex-specific-males were attracted more to infected females than to infected males, regardless of cadaver size. We examined the effect of E. muscae on the main component of the house fly sex pheromone, (Z)-9-tricosene, and other cuticular hydrocarbons including n-tricosane, n-pentacosane, (Z)-9-heptacosene, and total hydrocarbons of young (7 days old) and old (18 days old) virgin females. Young E. muscae-infected female flies accumulated significantly less sex pheromone and other hydrocarbons on their cuticular surface than uninfected females, whereas the cuticular hydrocarbons of older flies were unaffected by fungus infection. These results suggest that chemical cues other than (Z)-9-tricosene, visual cues other than abdomen size, or a combination of both sets of cues might be responsible for attraction of house fly males to E. muscae-infected females.     

Drosophila rely on learning while foraging under semi‐natural conditions

Learning is predicted to affect manifold ecological and evolutionary processes, but the extent to which animals rely on learning in nature remains poorly known, especially for short‐lived non‐social invertebrates. This is in particular the case for Drosophila, a favourite laboratory system to study molecular mechanisms of learning. Here we tested whether Drosophila melanogaster use learned information to choose food while free‐flying in a large greenhouse emulating the natural environment. In a series of experiments flies were first given an opportunity to learn which of two food odours was associated with good versus unpalatable taste; subsequently, their preference for the two odours was assessed with olfactory traps set up in the greenhouse. Flies that had experienced palatable apple‐flavoured food and unpalatable orange‐flavoured food were more likely to be attracted to the odour of apple than flies with the opposite experience. This was true both when the flies first learned in the laboratory and were then released and recaptured in the greenhouse, and when the learning occurred under free‐flying conditions in the greenhouse. Furthermore, flies retained the memory of their experience while exploring the greenhouse overnight in the absence of focal odours, pointing to the involvement of consolidated memory. These results support the notion that even small, short lived insects which are not central‐place foragers make use of learned cues in their natural environments.