Boll weevil: experimental sterilization of large numbers by fractionated irradiation

Boll weevils, Anthonomus grandis grandis Boheman, 9 days after egg implantation in the larval diet were transported from the Boll Weevil Research Laboratory, Mississippi State, MS, to the Comparative Animal Research Laboratory, Oak Ridge, TN, and irradiated with 6.9 krad (test 1) or 7.2 krad (test 2) of 60Co gamma rays delivered in 25 equal doses over 100 h. In test 1, from 600 individual pairs of T (treated) males x N (normal) females, only 114 eggs hatched from a sample of 950 eggs, and 47 adults emerged from a sample of 1042 eggs. Also, from 600 pairs of T females x N males, 6 eggs hatched of a sample of 6 eggs and 12 adults emerged from a sample of 20 eggs. In test 2, from 700 individual pairs of T males x N females, 54 eggs hatched from a sample of 1510, and 10 adults emerged from a sample of 1703 eggs. Also, in T females x N males matings, 1 egg hatched of a sample of 3, and no adults emerged from a sample of 4. Transportation and handling in the 2nd test reduced adult emergence an avg of 49%. Thus the 2 replicates in test 2 resulted in 3.4 x 105 and 4.3 x 105 irradiated weevils emerging/day for 7 days. Bacterial contamination of weevils was low