Rates of Water Loss and Absorption in Stick Insect Eggs

Garret Jolma, Dr. Art Woods, Division of Biological Sciences, University of Montana, 32 Campus Drive, Missoula, MT 59812

The thorny devil stick insect (Eurycantha calcarata) of New Guinea has eggs that take four months or more to develop—incredibly long for an insect.  Long development times can be a challenge for eggs because of their finite resources, including nutrients, energy to support development, and water.  I investigated the physiological mechanisms underlying long development times in stick insect eggs.  The first experiment examined rates of water loss and survival of eggs held in different experimental humidities (0, 75, or 100% RH).  Eggs dried quickly in the 0% humidity “dry” container and more slowly in the 75% humidity “intermediate” container.  The eggs did not dry out in the 100% “saturated” container and maintained their original mass throughout the experiment.  While none of the dry treatment eggs hatched, one of the intermediate treatment eggs did, and nearly all of the saturated eggs hatched.  To see if the eggs could reabsorb water, a fresh batch of eggs were dried until they reached 90% of their original mass.  Then they were transferred into a 100% humidity or wet cotton treatment.   In both cases, the eggs gained some mass, but never returned to their original mass.  These experiments show that the eggs require a high humidity to survive, and that they cannot absorb water from their environment.  For thorny devil stick insect eggs, conserving water is of the utmost importance.

Additional Abstract Information

Presenter: Garret Jolma

Institution: University of Montana

Type: Poster

Subject: Ecology

Status: Approved

Time and Location

Session: Poster 5
Date/Time: Tue 12:30pm-1:30pm
Session Number: 4094