A comparative study on muscle and leg properties of male and female stick insects and their impact on the insects behaviour

Abstract

The physiological, mechanical and morphological properties of the specialized metathoracic leg and flexor muscle of the male and those homologous but unspecialized ones of the female stick insects, Eurycantha calcarata were examined, to find the correlation between the properties of the muscles and legs with the animal behavior. The intact insects, isotonic and isometric transducer, pen recorder and oscilloscope were used. The initial contraction of the muscle was a rapid contraction with the duration of 70 to 130 msec. Its delayed contraction was much longer remaining in contraction, more than 30 sec. The muscle of the male was much more developed, faster, produced more force and did more initial and delayed work than the muscle of the female. Also the produced power output and work output by the muscle of the male were higher than those of the female, due to its greater size. The muscle produced the highest tension at the femur-tibia joint angle of 1.22 rad. The muscles, as compared with other insect muscles, produced relatively high power and were considered to be relatively fast.