昆虫定向机制研究进展

许多昆虫具有定向运动的行为。对部分社会性昆虫和迁飞性昆虫定向行为的大量研究已经初步阐明太阳、地磁场、天体、风及地面标志物等都可能成为昆虫返巢和迁飞定向的线索。社会性昆虫具有对不同定向线索进行整合而实现精确导航的能力。日间迁飞性昆虫利用时间补偿太阳罗盘进行定向的机制亦已明确,但夜间迁飞昆虫的定向机制尚需深入研究。迁飞性害虫定向机制的明确将有助于判断害虫迁飞路径及降落区域,为迁飞害虫的准确预测提供科学依据。本文对昆虫的定向机制研究进展进行了综述。     

Landmark orientation during the approach to the nest in the stingless beeTrigona (Tetragonisca) angustula (Apidae,Meliponinae)

Summary We displaced a small nest box containing stingless bees (Trigona (Tetragonisca)angustula) over distances of up to 1.6 meters in different directions and counted the numbers of returning foragers to measure the effects of this manipulation on the homing ability of bees. Bees find it hard to locate the nest box when it was displaced more than about 1 m backwards, forwards or sideways relative to the direction into which the nest entrance pointed. They do not find the nest when its height above ground is changed. The bees use landmarks in the vicinity of the nest to locate it: When the nest box is displaced and landmark positions are changed so that their angular position at the new nest site is the same as at the normal nest position their homing ability is less impaired than it is without changes in landmark positions. Our results show that the bees do not use the nest box itself as a landmark until they have approached the nest position to within about 1 meter with the aid of surrounding landmarks.     

Ant opsins: Sequences from the Saharan silver ant and the carpenter ant

cDNA clones encoding opsins from compound eyes of carpenter ant,Camponotus abdominalis, and Saharan silver ant,Cataglyphis bombycina, were isolated from cDNA libraries. The opsin cDNAs from each species code for deduced proteins with 378 amino acids which are 92% identical. Of the 30 amino acid differences between the two proteins, 13 are non-conservative. Eight of these non-conservative substitutions are within the membrane spanning domain. The presence of a potential Schiff-base counterion in helix III in both species suggests that these opsins are the protein moiety of the visible range pigments. When compared to all known opsins, these opsins are most similar to the opsin from preying mantis (76% identity at the amino acid level). Phyletic comparisons group the two ant opsins with the other arthropod long wavelength opsins.     

Scototaxis and shape discrimination in the female cricket Acheta domesticus in an arena and on a compensatory treadmill

ABSTRACT. The scototactic responses of adult female Acheta domesticus L. were tested toward various shaped targets in an orientation arena and on a compensatory treadmill. In an arena, crickets oriented toward dark targets (positive scototaxis) if they had horizontal visual angles ≥30, and if the vertical dimensions of the target was ≤ its horizontal dimension. Unattractive targets did not result in negative scototaxis but caused crickets to orient randomly with no net directionality. When complex targets were composed of two or more simple rectangular targets which had been previously defined as attractive or unattractive, intermediate responses were obtained. Crickets oriented less toward complex targets than toward simple attractive targets, but oriented more than toward simple unattractive targets. The responses of a female cricket toward an attractive target can be modified by the presence of a chemical signal emitted by previously tested females. When the signal is present females are less likely to orient toward a target that would otherwise be very attractive. This effect was not as great when the females being tested were taken directly from densely populated colonies.
When running on a compensatory treadmill, female crickets exhibit scototactic tendencies similar to those displayed in the arena. When tested on the treadmill over long periods, the amount of time spent orienting toward an attractive target increased.     

Olfactory clues play a critical role in the estuarine migration of silver-phase American eels

Estuarine migration of anosmic and control silver-phase American eels was examined during the fall spawning migration. Ultrasonic telemetry was used to track seventeen control and eight anosmic silver eels through 32 km of the Penobscot Estuary, Maine, U.S.A.. Twelve of seventeen control eels migrated out of the estuary in 97 h (approximately 4 d) on average. Only two of eight anosmic eels migrated out of the estuary. On average these two anosmic eels migrated out of the estuary within 180 h (approximately 7.5 d) of release and the other six had not left within 9 d. Most control eels progressed rapidly to the mouth of the estuary within a few days. Anosmic eels spent more time in the estuary and demonstrated different behavior from control eels due to their lack of olfaction. Some control eels moved with the appropriate tide, the ebb tide for transport out of the estuary, within one tidal cycle of being released into tidal freshwater. However, anosmic eels either did not move with the appropriate tide or took significantly longer to do so. Olfaction was probably used for orientation by control eels sensing chemical clues (organic and inorganic), which change throughout the tidal cycle. Increased migration times and errors in orientation were likely related to the inability of anosmic eels to use selective tidal stream transport for movement out of the estuary. Chemical clues seem to be one of the most important environmental clues used to guide estuarine migration of silver eels. However, a hierarchy of sensory mechanisms and environmental clues are most likely used for estuarine orientation.     

Short wavelength-sensitive opsins from the Saharan silver and carpenter Ants

We have previously cloned the opsins coding for the long-wavelength visual pigments from the Saharan silver ant and carpenter ant. Here we report two new cDNA clones isolated from cDNA libraries which also code for opsin proteins. These cDNAs code for deduced proteins with 369 amino acids which are 91% identical to each other, but only 38% identical to the previously cloned opsins. Phyletic comparisons suggest that these opsins are likely the ultraviolet sensitive visual pigments, a conclusion that is supported by the presence of a phenylalanine at the counterion position in the third transmembrane segment.     

Orientation responses of the grasshopper, Melanoplus sanguinipes, to visual, olfactory and wind stimuli and their combinations

Prereproductive adults of the grasshopper, Melanoplus sanguinipes (F.) (Orthoptera, Acrididae), demonstrated orientation and movement towards both visual and olfactory stimulus sources in a still-air chamber. Visual stimuli (wheat and lima bean foliage, vertical black or yellow-green stripes, and a yellow-green broad leaf pattern) were approached more frequently than the control white background surface. Olfactory stimuli (chopped wheat foliage and a four-component, synthetic, grass odor blend of volatiles) elicited an even greater positive response than the visual stimuli. Changing the proportions of the four volatiles in the blend significantly reduced positive orientation responses to the stimulus source. Visual cues of wheat foliage and olfactory cues of either chopped wheat odor or the grass odor blend gave greater responses when combined than when presented separately.In flowing air or wind, nearly all insects demonstrated a rapid positive response to odors of chopped wheat and the grass odor blend, significantly greater than the response to the same stimuli in still air. However, positive responses to visual cues were not significantly greater in wind than in still air. When combined with the olfactory stimuli in flowing air, visual cues did not increase the incidence of response. Grasshoppers responding to grass odors in wind moved more rapidly and directly toward the source, and stopped less often and for shorter durations than insects responding to odor in still air or to visual cues.We conclude from these studies that M. sanguinipes adults show orientation behavior to both visual and olfactory stimuli from food plant sources, although leaf odors elicit a stronger positive response particularly when carried by wind.     

Homing movements of displaced stream-dwelling brown trout

In April and May of 1993, 12 of 14 brown trout (202–288 mm), tagged with radio transmitters and displaced over 800–3600 m in a natural river system, returned to the areas from which they were captured. Homing was generally directed and rapid (up to 1·22 body lengths s⁻¹ against the flow). Homing commenced within 65 min of displacement for four of five trout displaced downstream, and within 4 days for those displaced above the confluence of a home tributary burn with the main stem of the river.     

Host Location by Apterous Aphids After Escape Dropping from the Plant

In response to approaching enemies aphids may drop from their host plant to the ground. The risk of predation on the ground, desiccation and host loss, create the need for efficient host location by the dropping aphids. Most studies have focused on the factors that influence dropping behavior; only a few have addressed host location after dropping from the plant. We assessed post-dropping behavior in apterous Macrosiphoniella artemisiae (Boyer de Fonscolombe) (Aphididae), which feed on Artemisia arborescens L. Vibration of the apical bud induced dropping in 36% of the colony members. Dropping rates were highest in mature aphids (63%). In the experimental arena (without ground predators), nearly all mature aphids that were dropped 13 cm from the plant, found their way back in ca. 40 s. The location process may be based on visual cues, as M. artemisiae is capable of visually discriminating between host and non-host targets and apparently does not react to volatiles emitted from the plant.     

Flight manoeuvers used by a parasitic wasp to locate host-infested plant

Cotesia rubecula Marshall (Hymenoptera: Braconidae) is a specialist larval parasitoid of the butterfly Pieris rapae L. which itself feeds almost exclusively upon cruciferous plants. Female wasps are attracted to the odour of host-infested plant (plant-host complex: PHC) and the probability of flights in a wind tunnel depends on females' prior oviposition experience with the PHC and on the concentration of the PHC odour. This study considers the effect of both factors on characteristics of oriented flight upwind towards the PHC. The flight track parameters that we measured and calculated were not significantly affected by these factors. C. rubecula females exhibited high average flight velocity and relatively straight flight tracks. There was a considerable variability between individuals, however, in their odour-modulated upwind flight tracks. Some females generated a zigzagging upwind flight track similar to those commonly observed from male moths responding to female sex pheromone. Other females flew along a straight track directly upwind. The flight tracks of most female wasps were intermediate between these extremes. The full range of these flight performances was observed to all experimental treatments.     

Visual-Olfactory Integration in the Human Disease Vector Mosquito Aedes aegypti

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