SOME EFFECTS OF OXYGEN UPON THE WHITE PUPAE OF HABROBRACON

Abstract

1. Habrobracon were exposed as white pupae to oxygen and studied for effects upon development, oxygen consumption and pigmentation. 2. A marked decrease in the incidence of pupae that complete development occurs after exposure to oxygen within the range from air to 20 pounds. The greatest decrease in the rate of oxygen uptake and pigmentation occurs after exposure within the range from 20 to 30 pounds. 3. The decrease in oxygen uptake following treatment is immediate. No subsequent recovery of oxygen uptake was observed 24 hours after treatment. 4. There is no modification of the respiratory quotient following treatment with oxygen. With increasing pressures of oxygen both the oxygen consumption and carbon dioxide liberation decrease at the same rate. 5. The sensitivity of white pupae to oxygen is modified by temperature. Pupae treated when cold are more resistant than pupae treated when warm. Thus, lowering the metabolic state of the pupae increases their resistance to oxygen. 6. The inability of the oxygen-treated pupae to acquire pigmentation has been explained on the basis of insufficient oxygen to allow for the oxidation of tyrosine to melanin. The effect of the oxygen treatment upon oxygen consumption and on development is unexplained and at present obscure.