Revista Chilena de Historia Natural (Mar 2000)
Locomotor activity of Phalerisida maculata Kulzer (Coleoptera, Tenebrionidae) on Chilean sandy beaches Actividad locomotora de Phalerisida maculata Kulzer (Coleoptera, enebrionidae) en playas arenosas chilenas
Abstract
The locomotor activity of the beetle Phalerisida maculata Kulzer (Coleoptera Tenebrionidae) was studied on the surface of the substrate in two sandy beaches of the Chilean coast: one in north central (ca. 29ºS) and the other in south central Chile (ca.39ºS). During the summer period of 1991 the circadian locomotor activity was studied in the southern beach, while during that of 1997 in both beaches. To analyze the activity, pitfall traps were used which were ordered along two transects extended between the upper beach and the resurgence zone. The traps were checked (i.e. collection of captured insects) every two hours for a total period of 26 hours. The results showed that the adults of P. maculata were mostly active during the night hours, whereas the larvae were active during both, the day and night. Studies carried out in the beach located in south central Chile show that differences in the tidal range (neap vs. spring tides) do not affect the activity patterns. During the locomotor activity, adult and larvae move to lower intertidal levels than those usually occupied while buried. Results of laboratory experiments using actographs under conditions of darkness and constant temperature, suggest that adults and larvae of P. maculata presented a circadian rhythm similar to that observed in the field experiments. It is concluded that P. maculata presents a behaviour that appear to be under control of an endogenous rhythm, without showing differences in the circadian rhythm of activity when beaches located at different latitudes are comparedSe estudió la actividad locomotriz del escarabajo Phalerisida maculata Kulzer (Coleoptera, Tenebrionidae) sobre la superficie del sustrato de dos playas arenosas de la costa de Chile: una en el centro norte (ca. 29ºS) y otra en el centro sur (ca. 39ºS). Durante el período estival de 1991 se estudió la actividad locomotriz circadiana en la playa del centro sur y durante el de 1997 en ambas playas. Para analizar dicha actividad, se usaron trampas ordenadas a lo largo de dos transectos extendidos entre el borde superior de la playa y la zona de resurgencia. Las trampas se revisaron (i.e. recolección de insectos capturados) cada dos horas por un período total de 26 horas. Los resultados mostraron que los adultos de P. maculata fueron activos mayoritariamente durante las horas de oscuridad, mientras que las larvas fueron activas durante el día y la noche. Estudios llevados a cabo en la playa localizada en el centro sur de Chile, mostraron que las diferencias en el rango mareal (período de sicigia vs. cuadratura) no afectan los patrones de actividad. Durante la actividad locomotriz, adultos y larvas se desplazan a niveles ms bajos de los que ocupan habitualmente cuando están enterrados. Los resultados de experimentos de laboratorio realizados con actógrafos bajo condiciones de oscuridad y temperatura constante, sugieren que adultos y larvas de P. maculata presentan un ritmo circadiano similar al observado en los experimentos de terreno. Se concluye entonces que P. maculata presenta un comportamiento de actividad que pareciera estar bajo control endógeno, no presentando diferencias en el ritmo circadiano de actividad cuando se comparan playas ubicadas en diferentes latitudes
