Relationship of aging, food reserves, and infectivity of larvae of Ascaridia galli

Abstract

1. 1. A physiological study was made of the effects of age on the infectivity of eggs of the fowl nematode, Ascaridia galli. 2. 2. Experiments with susceptible chicks were conducted to determine the infectivity of different-aged A. galli eggs. The average number of A. galli recovered per chick was larger from younger cultures than from older cultures. 3. 3. A. galli egg cultures maintained under laboratory conditions demonstrated high infectivity until approximately 200 days of age. 4. 4. A rapid decline in the infectivity of A. galli egg cultures occurred between the ages of 200 and 290 days. Results from repeated tests showed but slight infectivity of A. galli egg cultures one year (365 days) or more old. 5. 5. Measurements of the fat-containing areas in the bodies of different aged A. galli larvae demonstrated a diminution of fat (reserve food substance) with increase of age. 6. 6. The decrease of fat content occurs more rapidly in the younger larvae than in the older ones. 7. 7. The initial decline in the fat content was greater than was the initial fall in infectivity. 8. 8. Exhaustion of fat from the larvae liberated from older egg cultures and loss of infectivity appeared to be correlated. 9. 9. The occasional worms recovered from infections produced by cultures over one year (365 days) of age may be explained in part by their retention of fat in spite of their chronological age. 10. 10. Maintenance of embryonated egg cultures of the fowl nematode, A. galli, at a temperature of 28 °C for periods of more than 200 days results in the loss of a large portion of the fat reserves and of most of the infectivity of the larvae.