Effects of life history on oxygen delivery in the grasshopper jumping leg (879.22)

Abstract

Although the insect tracheal system is extremely efficient, oxygen delivery is reduced during the intermolt period. Intermolt growth results in compressed tracheae, reduced tracheal volume, and reduced femoral air sac ventilation rates. Gravidity reduces tracheal volume in adult female grasshoppers; however, it is unknown whether gravid grasshoppers also have lower ventilation rates. Using micro‐dissections and video analysis, we examined the tracheal system of the abdomen and femur of ten (5 females; 5 males) American locust grasshoppers (Schistocerca americana). We found that abdominal compression rates correlated with the inflation of proximal and distal femoral air sacs. Females (1.99 to 2.95 g) had higher compression rates in both their abdomens (36.2 ± 3.62 min‐1; mean ± s.e.m.) and femoral air sacs (36.8 ± 3.73 min‐1) than male grasshoppers (1.07 to 1.27 g; abdomen 28.6 ± 2.04 min‐1 and femoral air sacs 26.8 ± 1.85 min‐1). The most gravid females showed the highest abdominal and femoral air sac compression rates. These findings suggest that gravid females will compensate for reduced tracheal volumes by increasing tracheal ventilation rates. Current research is examining how gravidity affects tibial and tarsal air sac compression rates.Grant Funding Source: Supported by Union College Undergraduate Research Grants