| Summary: | 碩士 === 國立臺灣師範大學 === 生物研究所 === 90 === 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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