IP Respiration

Respirometric studies of Cornops aquaticum (Orthoptera: Acrididae) in the surroundings of Rio Claro, Brazil

M. G. Lhano 1 , C. H. S. Penteado 2 & J. Adis 3

1 Dept.of Biology and Zoology, Univ. Federal of Mato Grosso, Ave. Fernando Correa da Costa s/n, 78060-900, Cuiabá, MT, Brazil; 2 Center of Environmental Studies – University of São Paulo State, Ave. 24 A, 1515, 13500-000, Rio Claro, SP, Brazil; 3 Max-Planck-Institute for Limnology, Tropical Ecology Working Group, Postfach 165, D-24302 Plön, Germany

Cornops aquaticum (Bruner, 1906) is a semi-aquatic acridid (Orthoptera, Tetraeniini) with a wide geographical distribution, ranging from the South of Mexico (23°N) to Uruguay and the Northeast of Argentine (35°S). These grasshoppers can be found on leaves of the aquatic macrophyte Eichhornia spp., where they pass their life cycle. The study site “Sítio das Acácias”, was located between the subdistricts of Ferraz and Ajapi (22°16’S, 47°34’W) near Rio Claro-SP, Brazil. Adult specimens were collected during daylight with the help of an entomological net in a flooded area affected by cattle, about 20m from the Corumbataí River. Experiments about the respiratory metabolism of males and females were carried out with a Warburg respirometer, testing correlations with a possible cycle of daily activity. Bottles of about 35ml were used in the respirometer and temperature during measurements was 25°C. Each experiment lasted one hour with readings made every 15 mins. The respirometric data obtained from adults (32 males and 12 females), showed that the respiratory rate in females did not differ from that in males (P>0,05), although the female’s corporal size was bigger and heavier (average weight: female = 0,27 + 0,04g, male = 0,17 + 0,015; P<0,05). The average values of the respiratory rates found were: VO2 (female)= 314,80 + 114,05 ?lO2.g -1 .h -1 and VO2 (male)= 309,64 + 140,42 ?lO2.g -1 .h -1 in the morning and VO2 (female)= 276,95 + 82,91 ?lO2.g -1 .h -1 and VO2 (male)= 284,14 + 78,49 ?lO2.g -1 .h -1 in the afternoon. Due to the high standard deviation of data, a “size-rule” could not be established. Also, no difference found in the respiratory rates of C. aquaticum measured during the morning and afternoon indicate the lack of a daily rhythm, at least with the metodology applied.

Index terms: grasshopper, sex, metabolism, respiration

Copyright: The copyrights of this abstract belong to the author (see right-most box of title table). This document also appears in Session 13 – INSECT PHISIOLOGY, NEUROSCIENCES, IMMUNITY AND CELL BIOLOGY Symposium and Poster Session, ABSTRACT BOOK II – XXI-International Congress of Entomology, Brazil, August 20-26, 2000.