The Jumping Performance And Leg's Functional Morphology Of Flea Beetles

As one of the most important jumping insects in Coleoptera,the metafemora of flea beetles are swollen and with a chitinized spring,which is good at jumping and flexible in locomotion.In recent years,with the development of functional morphology and bionics,the functional morphology,locomotion performance and bionic applications of insect's legs have becoming important than before.However,jumping performance of flea beetles is still insufficient.In this disseration,the jumping performance,external and internal structures of thorax and legs of Altica cirsicola Ohno,Altica viridicyanea(Baly),Altica fragariae(Nakane)and Ophrida xanthospilota(Baly)were addressed by conducting high-speed photography,micro CT and three-dimensional reconstruction.The main results are as follows:(1)Jumping performance: there are three take-off modes in the Altica cirsicola Ohno,Altica viridicyanea(Baly),Altica fragariae(Nakane)and Ophrida xanthospilota(Baly).Wingless mode(mode1): the flea beetles take off without wings,the body spin continuously during the jump,wings always fold,finally landing;Semi-winged mode(mode2): the flea beetles take off and spin,then deploy its wings in mid-air and the body stop spin,land finally;Winged mode(mode3): the flea beetles take off with wings assisted,do not spin,fly and land directly.All four species of flea beetles prefer to take off with mode1,followed by mode2 and mode3.In mode1,the proportion of A.cirsicola is greater than that of other three species,and in mode2,the proportion of O.xanthospilota is greater than that of other three species.In the platform with fixed inclination angle,the proportion of land with their ventral body side in the four species is obviously greater than that of on their dorsal body side.While in the movable platform,the ratio is close to 1:1.The take-off velocity of O.xanthospilota is significantly higher than that of other three species,take-off time among four species does not present significant difference.When the flea beetles take off,the fore-and mid-legs leave ground first than the hind legs,and there is no significant difference in the time of the two hind legs leaving the ground.In A.fragariae,the range of the angle between the body and the horizontal plane is the smallest in the process of taking off.(2)Morphological structures of thorax and legs: The flea beetle's thorax is the center of locomotion,with 51 muscles in in O.xanthospilota totally.The internal structures of the metafemora are composed of metafemoral spring,triangular plate,elastic plate,tibial flexor,primary tibial extensor,secondary tibial extensor,primary tibial ligament and secondary tibial ligament.The metafemoral spring of A.cirsicola,A.viridicyanea and A.fragariae are all composed of dorsal lobe,extended arm,ventral lobe,reverse flange and central furrow.The extended arm is shorter and without reverse flange in O.xanthospilota.The structure of different stages of the hind legs during the take-off process of O.xanthospilotas are analyzed by conducting three-dimensional reconstruction,three muscles connecting the coxa and trochanter are present,and these three muscles interact to pull the trochanter to rotate.The simulation results of three-dimensional reconstruction in different stages of hindleg during the take-off of A.cirsicola showed that the trochanter can rotate 125° relative to the coxa.This study deeply analyzed the jumping structure and performance of flea beetels,analyzed the jumping mechanism,and provided theoretical reference and technical support for the design of jumping robot.