單眼與複眼在蟑螂運動行為上的調控功能

蔡任圃

指導教授 ： 林金盾

國立臺灣師範大學/理學院/生物學系/碩士(2001年)

摘要

美洲蟑螂(Periplaneta americana)同時具有單眼與複眼，在「生物經濟原則」的觀點上，其生理角色必定有所不同。本研究利用攝影連續紀錄蟑螂在光區與暗區的時間比率，比較單眼與複眼在光趨向行為(phototaxis)中的生理角色。此外，利用攝影配合電腦影像分析，記錄並測量蟑螂附肢的運動行為與個體的行進速度，探討運動行為的光活動(photokinesis)特性，以比較單眼與複眼在調節運動行為上的生理角色。
在光趨向行為方面，證明蟑螂具有避光行為，而單眼與複眼對避光反應具有相同程度的調節能力。當單眼與複眼同時照光時，對於光趨向行為具加成的作用。在光活動行為方面，觸角、步足的運動行為與個體的行進速度具有光活動行為的特性；照光適應與刺激尾毛引發逃亡，對附肢運動與個體行進速度具有一樣的效應，但照光適應的調節作用較逃亡時運動狀態的改變微弱。此外，在觸角的擺動角度、步足的步行頻率與個體的行進速度等參數上，照光與刺激尾毛同時作用時，具有加成的效果。
在附肢運動行為與附肢EMG階層的參數上，單眼與複眼皆具調節能力，並且同時具有角色重疊與分工合作的特性。蟑螂的視覺訊息對運動行為的調控，可因照光處理的方式不同而有所改變。在檢視單眼與複眼對各項參數的調節作用後，發現在蟑螂逃亡時複眼調節附肢運動的程度(如跨步距離)，進而影響其他參數的表現(如伸腳跨步速度與平均行進速度)；而單眼與複眼在停止逃亡後，能調節附肢運動的時程(如觸角的擺動時距、行走期的比率)，進而影響其他參數的表現(如觸角內擺的角速度、平均的行進速度)；其中單眼對於附肢運動的調節，在照光適應或照光刺激作用一致，而複眼則較具變化。
比較單眼與複眼對各項附肢運動行為參數的調節作用後，可發現單眼與複眼對蟑螂運動行為的調節角色不盡相同，而具有複雜的互動關係。兩種視覺器官在不同的參數上具有不同的合作調節型態，並且可因視覺訊息輸入的時間與強度、個體的運動狀態與其他感覺輸入(如臉部的觸覺刺激)等因子的影響，而對運動行為具有不同的調節作用。

關鍵字

單眼 ； 複眼 ； 蟑螂 ； 運動行為 ； 附肢 ； EMG

並列摘要

Cockroaches, Periplaneta americana, are equipped with ocelli and compound eyes. According to the principles of biological economy, the physiological role of ocelli and compound eyes should be different. Using computer-based image analysis the present study has compared the functional differences between ocelli and compound eyes by determining the ratio of light-avoiding reaction for phototaxis and by measuring the movement of antennae and legs, the velocity of insect locomotion for photokinesis.
Results from the phototaxic experiments showed that American cockroach behave with light-avoiding responses and the light-avoiding response is regulated by both ocelli and compound eyes. The effects of simultaneous illumination to ocelli and compound eyes on the light-avoiding response are synergetic. In photokinetic experiments, it is proved that both the movement of antennae and legs, and the velocity of insect locomotion conformed to the photokinetic characteristics. The effects of light-adaptation and cerci-stimulation on the movement of antennae and legs, and the velocity of insect locomotion are in a similar manner, however, the effects of the former is weaker than those of the latter. In addition, the effects of the simultaneous light-adaptation and cerci-stimulation on the swing degree of antennae, the stepping frequency of legs and the velocity of insect locomotion are synergetic.
Upon the regulation of the movement of antennae and legs, and the EMG recorded from antennae and legs during movement, ocelli and compound eyes perform simultaneously in the role of visual organs, but differently in some parameters. The regulatory effects of visual signals on the movement of antennae and legs depends on the different intensity of illumination. During insects’ escape induced by cerci-stimulation, the strength of legs’ movement(e.g. stepping distance) is regulated by the visual signals from compound eyes, then the other parameters (e.g. stepping velocity of retraction and the mean velocity of insect locomotion) was followed by the effects of stimulating compound eyes. After ceasing cerci-stimulation, the duration of movement of antennae and legs (e.g. swing duration of antennae and ratio of walking phase) is regulated by the visual signals from both ocelli and compound eyes, then the other parameters of movement (e.g. inward swing angular velocity of antennae and the mean velocity of insect locomotion) was followed by the effects of stimulating both ocelli and compound eyes. However, the effects of ocelli-illumination only on the parameters of movement during light-adaptation and light-stimulation are more consistent than those of compound eyes-illumination only.
In conclusion, results evidence that the regulatory functions of ocelli and compound eyes on the locomotion behavior are different. There are a complex interaction between ocelli and compound eyes with different co-regulation type among parameters. Furthermore, their regulatory effects vary according to the intensity and the timing of visual signals input, the locomotion condition of insect and whether other sensory inputs (e.g. tactile sensation from insect’s face) or not, they showed differently functional regulations.

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