STARVATION STUDIES WITH THE PARASITIC WASP HABROBRACON

¹ Department of Zoology and Entomology, N. C. State College of Agriculture and Engineering of the University of North Carolina, Raleigh, N. C.

1. In conditions of complete starvation, Habrobracon females live longer than males. This fact is more obvious at lower temperatures of storage.

2. There is a distinct positive correlation between size of a wasp and longevity. This is interpreted to have a basis in a lower metabolic rate in the larger organisms.

3. Weight loss is chiefly from the abdominal region which in the ultimate condition is extremely flattened dorsoventrally.

4. Histologically the greatest loss of material from both males and females is in number and size of the "fat" cells of the fat body. In females an additional loss occurs from the ovary, especially during the last stages of starvation. In wasps starved to the point of death the loss includes all the developing, as well as the mature eggs. Thus identified for the female seem to be two sources of reserve food supply. This point and attendant features are discussed from the standpoint of sex differences in structure, function and longevity.

5. Provided examination is made within the first two days. internal tissue other than the fat body should be in adequate quantitative state regardless of conditions of culture during the adult stage. It is also indicated that investigations employing ova should be started before two days after emergence from cocoons have elapsed.