Figure 7.

Mating competitiveness of LL #67 in field cage tests. To test the competitiveness of the embryonic LL #67, 20 non-irradiated and 20 irradiated males from LL #67 (120 Gy) competed with 20 non-irradiated wildtype (WT) Argentinean (Arg) males for mating with 20 WT Arg females in a field cage [17]. The males were marked with different colored water-based paints. Mating couples were taken out of the cage and the type of mating couple was recorded. Twelve replications were carried out. (A) The proportion of matings of each mating type was calculated by dividing the number of the occurred matings by the number of total possible matings (limited by the number of Arg females, n = 20). The proportion of matings was 18 ± 11% for non-irradiated LL #67 males, 13 ± 9% for irradiated LL #67 males, and 12 ± 12% for non-irradiated Arg males. The proportion of total matings over all 12 replications was 43 ± 5%, indicating an acceptable degree of sexual activity during the test period. Running a conventional ANOVA, no statistical differences (F = 1.62; P = 0.171) can be found between the different matings that occurred. The tests thus showed that non-irradiated and irradiated LL #67 males were at least as, if not more, competitive as WT non-irradiated Arg males. (B) Eggs and hatched larvae from each mating type were recorded and the egg hatch is shown. All matings of LL #67 males (regardless of whether non-irradiated or irradiated) to WT Arg females led to complete embryonic lethality. In comparison with the complete lethality of LL #67 (descending from EgII) with or without irradiation, previous sterility tests with irradiated WT EgII males (100 Gy) showed an egg hatch of 1.2% [35]. In addition, radiation-induced sterility has been shown to be indirectly correlated to the competitiveness of the flies [4].