视觉和嗅觉信号对果蝇食物搜寻行为的协同作用

为了探索视觉和嗅觉信号在昆虫食物搜寻过程中的作用, 本研究利用杨梅和橘子为引诱物, 在实验室条件下测定了嗅觉和视觉信号诱集到的黑腹果蝇Drosophila melanogaster数量, 分析了嗅觉经历对果蝇嗅觉和视觉食物搜寻的影响。发现同源性嗅觉和视觉信号存在的杨梅诱集到的果蝇数量显著大于单一的视觉信号和嗅觉信号, 但异源性嗅觉和视觉信号组合诱集到的果蝇数量和单独的嗅觉信号相似。嗅觉信号预处理不仅能够显著增加嗅觉信号诱集到的果蝇数量, 其中杨梅嗅觉信号对杨梅预处理果蝇的吸引能力与视觉和嗅觉信号存在的杨梅相似, 而且异源性嗅觉和视觉信号组合诱集到的预处理果蝇数量也不低于视觉和嗅觉信号存在的杨梅。另外杨梅嗅觉信号预处理也能够显著增强杨梅视觉信号诱集到的果蝇数量。但嗅觉预处理并不会改变同源性视觉和嗅觉信号组合诱集到的果蝇数量。本研究表明, 果蝇同时利用视觉和嗅觉信号进行食物搜寻, 因此同源性视觉和嗅觉信号在果蝇诱集过程中具有协同作用。另外果蝇具有较强的记忆和学习能力, 能够将记忆中的嗅觉信号应用于食物搜寻。本研究结果不仅有利于我们了解果蝇在自然状态下的食物搜寻机制, 而且有利于开发更有效的果蝇新型诱捕器。     

Sex-specific differences in the chasing behaviour of houseflies (Musca)

Flies were filmed simultaneously from above and from the side. Their flight tracks were analyzed frame by frame. Male and female flies were found to chase other flies. But female chases are brief and poorly controlled as compared to male chases. Female flies use the lower frontal part of their visual field for tracking other flies. Male flies use the upper frontal part of their visual field for that purpose. Male flies are capable of controlling their forward velocity roughly proportional to the distance to their target. Implications for the function of recently found sexdimorph visual interneurones are discussed.     

The use of visual information by house flies,Musca domestica (Diptera: Muscidae), foraging in resource patches

Summary House flies, Musca domestica, respond to visual contrasts on the substrate if a resource is associated with the contrasting patterns. Visible resource patch boundaries serve as a signal to flies that they are about to leave a rewarding patch. Searching flies respond to such visual information by walking along the resource patch boundary and turning back into the patch at its edge. This edge detection and response serve as a mechanism for flies with visual cues to stay in a rewarding patch and locate more resources within it. The intensity of their response correlates with the quality of the resource. In the absence of visual cues, patch shape affects foraging success; flies find more resources in circular than in linear resource distributions. The effects of visual cues, however, render patch shape unimportant. Various substrate contrasts are effective as resource information for flies: dark (e.g., green) figures on bright (e.g., white) backgrounds or bright figures on dark backgrounds. Responses to substrate contrasts measured in this study indicate that, over the short term, house flies can learn a visual cue associated with a food source.     

Visual and olfactory cue interaction in resource-location by the blowfly, Lucilia sericata

Abstract. The interactions between olfactory and visual cues in the landing responses of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae) were examined in a laboratory wind tunnel. The odour of liver and sodium sulphide solution released at 1 L/min, resulted in a greater number of landings, closer to, but downwind of, the central odour release point, than when odour was absent. Three-day-old protein-deprived females landed in greater numbers than protein-fed female flies of the same age; no difference existed between 6-day-old protein-fed or protein-deprived females. Six-day-old, protein-fed flies landed closer to the odour source than did 3-day-old, protein-fed flies. In the presence of odour, flies landed closer to the central release point when it was accompanied by a visual cue. No such effect of the visual cue was evident in the absence of odour. When a plain white sticky-surface (25 × 25 cm) was paired with an identical white surface plus odour, approximately equal numbers of flies landed when the surfaces were placed together; increasingly higher numbers of flies landed on the surface with the odour cue when the distance between the surfaces was increased. When a white surface with a visual cue was presented with the plain white surface plus odour, more flies landed on the white surface with the visual cue than on the plain white surface with odour when they were close together. However, as these two surfaces were moved apart, flies landed increasingly more on the surface with the odour than the surface with the visual cue. The results show that while odour cues may enhance the induction of landing by female L. sericata , visual cues are important when selecting a final landing site.     

苯甲醛对果蝇视觉联想记忆的阻断

采用飞行模拟系统,以视觉模式为线索、热惩罚为负强化因子,对于在不同发育时期经受苯甲醛处理过的果蝇的视觉飞行定向条件化进行了检验。苯甲醛气味分别作用于果蝇幼虫和成虫阶段,将阻断果蝇成虫建立视觉联想记忆的能力;雌性果蝇在处女期对苯甲醛气味的接触,会阻断其子代建立视觉联想记忆,这种视觉联想记忆的能力可以通过对其子代连续３代的正常饲养而逐渐得到恢复。     

Structural organization of male-specific visual neurons in calliphorid optic lobes

Summary The superiority of male flies over female flies in locating and intercepting small rapidly moving targets has been ascribed to differences in their visual systems. In males, this sexual dimorphism is externally expressed by an area of high visual acuity called the acute zone. Selective cobalt uptake reveals 12 types of male-specific visual interneurons in the male lobula, the axons of which terminate in neuropil supplying premotor descending neurons to neck and flight motor circuits. The dendritic fields of the individual male-specific neurons can be extrapolated out into visual space to demonstrate that each is assigned a discrete area of the visual panorama. The dendritic fields of 10 of the 12 male-specific neurons subtend areas of the retina associated with the male acute zone. The functional significance of male-specific neurons is discussed with respect to their putative receptive field and a model circuit for target location by male flies.     

Fixation-sensitive areas in the eyes of the walking fly,Calliphora erythrocephala

In Calliphora erythrocephala the visual fixation behaviour in one-eyed flies and partial blinded flies has been investigated. One-eyed flies show approximately the same stripe and edge fixation response as intact flies. Elimination of the frontal eye parts including the binocular field of vision does not effect the visual stripe fixation. On the other hand, if only the frontal areas of both eyes including the binocular field of vision are left open, no preferential direction can be observed (Fig. 1–3). The results imply the existence of a fixation-sensitive area of the eye located outside the binocular field of vision.     

Attention-like processes underlying optomotor performance in a Drosophila choice maze

The authors present a novel paradigm for studying visual responses in Drosophila. An eight-level choice maze was found to reliably segregate fly populations according to their responses to moving stripes displayed on a computer screen. Visual responsiveness was robust in wild-type flies, and performance depended on salience effects such as stimulus color and speed. Analysis of individual fly choices in the maze revealed that stereotypy, or choice persistence, contributed significantly to a strain's performance. On the basis of these observations, the authors bred wild-type flies for divergent visual phenotypes by selecting individual flies displaying extreme stereotypy. Selected flies alternated less often in the sequential choice maze than unselected flies, showing that stereotypy could evolve across generations. The authors found that selection for increased stereotypy impaired flies' responsiveness to competing stimuli in tests for attention-like behavior in the maze. Visual selective attention was further investigated by electrophysiology, and it was found that increased stereotypy also impaired responsiveness to competing stimuli at the level of brain activity. Combined results present a comprehensive approach to studying visual responses in Drosophila, and show that behavioral performance involves attention-like processes that are variable among individuals and thus sensitive to artificial selection.     

Relationship between visual learning/memory ability and brain cAMP level in Drosophila

Ｄｒｏｓｏｐｈｉｌａｈａｓｂｅｃｏｍｅａｎｉｍｐｏｒｔａｎｔｅｘｐｅｒｉｍｅｎｔａｌａｎｉｍａｌｍｏｄｅｌｂｅｃａｕｓｅｏｆｉｔｓｔｗｏａｄｖａｎｔａｇｅｓ,ｉ.ｅ.ｉｔｓｒｅｌａｔｉｖｅｌｙｃｌｅａｒｇｅｎｅｔｉｃｂａｃｋｇｒｏｕｎｄａｎｄａｖａｒｉｅｔｙｏｆａｓｓｏｃｉａｔｉｖｅｌｅａｒｎｉｎｇａｂｉｌｉｔｉｅｓ.Ｓｉｎｇｌｅｇｅｎｅｏｌｆａｃｔｏｒｙｌｅａｒｎｉｎｇｍｕｔａｎｔｓｈａｖｅｂｅｅｎｉｓｏｌａｔｅｄ.ＳｏｍｅｏｆｔｈｅｍａｒｅｒｅｌａｔｅｄｔｏｔｈｅｃＡＭＰｓｉｇｎａｌｔｒａｎｓｄ…     

Visual signals in the courtship of Drosophila melanogaster: Mutant analysis

Visual cues are necessary for optimal mating success in Drosophila melanogaster. The male's most important visually guided behaviour is tracking. It is shown here that tracking requires intact visual receptor cells R1–6 and the presence of screening pigments in the eye. Thus flies carrying the mutation ebony as well as wild type flies affected in receptor cell R1–6 are unable to use visual cues when they track females. A similar defect was obseved in white-eyed flies lacking screening pigments. Female receptivity depends on visual signals provided by the male flies. Most important cues are the light reflection from and the shape of the male's eyes. No influence of the light reflected from the thorax could be seen. Absence of eyes in the male, however, does not depress female receptivity as much as white eyes. Some evidence is provided that male courtship behaviour is evaluated visually by the female.     

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.     

Host-foraging stable flies,Stomoxys calcitrans,are preferentially attracted to objects with both visual and thermal host-like characteristics

Many haematophagous insects use the heat emitted by warm-blooded animals as a cue for locating suitable hosts. Blood-feeding stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), are known to respond to visual and olfactory host cues. However, the effects of thermal host cues on the foraging behaviour of these flies remain largely unknown. Here we tested the hypothesis that host-foraging stable flies preferentially land on objects with host-like temperature, and on objects with both visual and thermal host-like cues. In laboratory bioassays, stable flies were offered a choice between paired temperature-controlled copper discs. Flies preferentially landed on the disc with a host-like temperature (40 °C), discriminating against discs that were cooler (26 or 35 °C) or warmer (50 or 60 °C) than vertebrate hosts. Flies that were well fed and thus not in foraging mode, or host-foraging flies that were offered infrared radiation but not the conductive and convective heat of different temperature discs, failed to discriminate between the stimuli. In greenhouse experiments, when flies were offered a choice between paired barrels as surrogate hosts, flies preferentially landed on barrels that were both thermally and visually appealing (38–39 °C, black), discriminating against barrels that were cold (10 °C), white, or both cold and white. Thermal cues augmented the overall landing responses of flies but their initial (mid-range) attraction to barrels was mediated by visual cues. Overall, the data suggest that thermal host cues affect the host-foraging behaviour of stable flies primarily at close range, prompting landing on a host.     

Relationship between visual learning/memory ability and brain cAMP level inDrosophila

Using the flight simulator system, the operant conditioned visual flight orientation behavior inDrosophila was studied. It was demonstrated that the visual learning performance is associated with age; flies learn more reliably at 3–4 days than at 1–2 days of age; the cAMP level of brain is also increasing with age; the brain cAMP content of nonlearner flies of wild type is much higher than that of normal flies; the cAMP level of brain increased abnormally after being fed with caffeine, and the learning performance decred. These results imply that a moderate range of cAMP level is necessary for the visual learning and memory pmess. Abnody high or low level of cAMP causes defects of leaming and memory ability.     

Three‐dimensional flight tracking shows how a visual target alters tsetse fly responses to human breath in a wind tunnel

Tsetse flies Glossina spp. (Diptera; Glossinidae) are blood‐feeding vectors of disease that are attracted to vertebrate hosts by odours and visual cues. Studies on how tsetse flies approach visual devices are of fundamental interest because they can help in the development of more efficient control tools. The responses of a forest tsetse fly species Glossina brevipalpis (Newstead) to human breath are tested in a wind tunnel in the presence or absence of a blue sphere as a visual target. The flight responses are video recorded with two motion‐sensitive cameras and characterized in three dimensions. Although flies make meandering upwind flights predominantly in the horizontal plane in the plume of breath alone, upwind flights are highly directed at the visual target presented in the plume of breath. Flies responding to the visual target fly from take‐off within stricter flight limits at lower ground speeds and with a significantly lower variance in flight trajectories in the horizontal plane. Once at the target, flies fly in loops principally in the horizontal plane within 40 cm of the blue sphere before descending in spirals beneath it. Successful field traps designed for G. brevipalpis take into account the strong horizontal component in local search behaviour by this species at objects. The results suggest that trapping devices should also take into account the propensity of G. brevipalpis to descend to the lower parts of visual targets.     

Dissociation of visual associative and motor learning in Drosophila at the flight simulator

Ever since operant conditioning was studied experimentally, the relationship between associative learning and possible motor learning has become controversial. Although motor learning and its underlying neural substrates have been extensively studied in mammals, it is still poorly understood in invertebrates. The visual discriminative avoidance paradigm of Drosophila at the flight simulator has been widely used to study the flies' visual associative learning and related functions, but it has not been used to study the motor learning process. In this study, newly-designed data analysis was employed to examine the flies' solitary behavioural variable that was recorded at the flight simulator-yaw torque. Analysis was conducted to explore torque distributions of both wild-type and mutant flies in conditioning, with the following results: (1) Wild-type Canton-S flies had motor learning performance in conditioning, which was proved by modifications of the animal's behavioural mode in conditioning. (2) Repetition of training improved the motor learning performance of wild-type Canton-S flies. (3) Although mutant dunce(1) flies were defective in visual associative learning, they showed essentially normal motor learning performance in terms of yaw torque distribution in conditioning. Finally, we tentatively proposed that both visual associative learning and motor learning were involved in the visual operant conditioning of Drosophila at the flight simulator, that the two learning forms could be dissociated and they might have different neural bases.     

Comparisons of sampling methods and seasonal abundance of Drosophila repleta in caged-layer poultry houses

Abstract. Four sampling methods were compared to determine their practicality and suitability for detecting population fluctuations of adult Drosophila repleta, a pest in caged-layer poultry houses. Five caged-layer poultry houses with gutter-flush manure removal systems in Franklin County, North Carolina, U.S.A., were sampled once every 2 weeks over 15 months, from June 1991 to August 1992. The flies were most abundant during the spring and early summer. Visual counts of adult flies resting on the feed troughs in front of cages in the aisles and counts of flies caught on a sticky ribbon lowered into the gutter used for manure removal by flushing were more satisfactory sampling methods than using counts of flies caught on sticky ribbons carried along the aisles or aspirator collections from the gutters. For the visual count method, the effects of location in the house, within each aisle, and feed trough height were determined; two counts on feed troughs in each of two inside rows of cages were sufficient to measure population changes. For routine monitoring of D. repleta populations, visual counts of flies resting on the feed troughs in the front area of two aisles and catching flies on sticky ribbons inserted into the rear gutter area are recommended.     

Animal behavior: flying back to front

To avoid collisions, flies steer away from expanding visual scenes generated during straight flight: so how do they fly forward when no collision is imminent? A new study shows that wind compensates for this aversion, allowing flies to forge ahead.     

NMDA receptors‐dependent plasticity in the phototaxis preference behavior induced by visual deprivation in young and adult flies

Adult mammals have experience‐dependent plasticity in visual system, but it is unclear whether adult insects also have this plasticity after the critical period of visual development. Here, we have established a modified Y‐maze apparatus for investigating experience‐dependent plasticity in Drosophila. Using this setup we demonstrate that flies after the critical period have bidirectional modifications of the phototaxis preference behavior (PPB) induced by visual deprivation and experience: Visual deprivation decreases the preference of flies for visible light, while visual experience exerts the opposite effect. We also found an age‐dependent PPB plasticity induced by visual deprivation. Molecular and cellular studies suggest that the N‐methyl‐ d ‐aspartate receptors (NMDARs) mediate ocular dominance plasticity in visual cortex in mammals, but direct behavioral evidence is lacking. Here, we used the genetic approaches to demonstrate that NMDAR1, which is NMDARs subunit in Drosophila, can mediate PPB plasticity in young and adult flies. These findings provide direct behavioral evidence that NMDAR1 mediates PPB plasticity in Drosophila. Our results suggest that mammals and insects have analogous mechanisms for experience‐dependent plasticity and its regulation by NMDAR signaling.     

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.     

Relationship between visual learning/memory ability and brain cAMP level in Drosophila

Using the flight simulator system, the operant conditioned visual flight orientation behavior inDrosophila was studied. It was demonstrated that the visual learning performance is associated with age; flies learn more reliably at 3–4 days than at 1–2 days of age; the cAMP level of brain is also increasing with age; the brain cAMP content of nonlearner flies of wild type is much higher than that of normal flies; the cAMP level of brain increased abnormally after being fed with caffeine, and the learning performance decred. These results imply that a moderate range of cAMP level is necessary for the visual learning and memory pmess. Abnody high or low level of cAMP causes defects of leaming and memory ability. Project supported by the National Natural Science Foundation of China rant No. 69435013) and the National Fundarnental Research Programme in China