Meeting Abstract

P1.123  Tuesday, Jan. 4  The Behavioral Correlates of Directed Aerial Descent in Larval Stick Insects ZENG, Y; CHANG, S*; NGUYEN, N; KAZI, C; DUDLEY, R; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley dreavoniz@berkeley.edu

The behavior of directed aerial descent, the controlled gliding performed without wings, has been documented in many arboreal arthropod clades. However, the behavioral factors that associated with the evolution of directed aerial descent remain unclear. In newly hatched instars of an Australian stick insect Extatosoma tiaratum , the ability of directed aerial descent has been found in previous research, showing the best gliding capability is in the youngest instars. On the other hand, the newly hatched instars exhibit strong tendency of moving towards canopy space in the daytime, shown as negative geotaxis, phototaxis and endurance of upward travel. This active travel stage may typically last for three days, during which several other defensive traits, including ant-mimicry and voluntary dropping, are also expressed. Here we quantitatively studied how these behavioral traits change through ontogeny and their relevance to the functioning of directed aerial descent. The levels of activities and expression of these behavioral traits are temporarily associated with the developmental stage when the larval stick insects perform the best glide. Our results indicate active diurnal travel in canopy environment as the behavioral context associated with directed aerial descent in larval E. tiaratum , and that directed aerial descent benefits survivorship and conserves energy expenditure in these larval insects. The adaptive significance of directed aerial descent within this behavioral context may help to understand the evolution of diverse aerial behaviors.