According to our observations, all of the successful courtships were composed of the following sequence of behaviors in males-calling, wing fanning, wing buzzing, peaceful attempt and copulation. Although the proportion of successful male did not differ significantly between strain, some differences have been observed when the times used for each activity were compared both between strains and between successful and unsuccessful males (Table 1). Unsuccessful males used significantly more time than successful males in several activities, particularly in stationary calling in both strains. However, successful males used more time in peaceful mating attempts, which quickly led to copulation. Some differences between successful and unsuccessful males also were observed between strains. For example, successful mass-reared males spent less time in mobile calling and fanning. In contrast, no significant difference was detected for these activities in the wild strain. There were marginally significant differences between strains (pooling successful and unsuccessful males) for some of the behavioral variables. Wild males spent more time in mobile, stationary and fighting activities than did mass-reared males, although these differences were not significant using a table wide P value of 0.05. Hence, copulation tends to be reached earlier by the mass-reared males. Almost all successful mass-reared males completed copulation within 20 min (Fig 1), while -GO% of the successful wild males had completed mating by this time.
Overall, these results suggest that the mass-reared males tended to use less time in activities which, under our experimental conditions, do not contribute to mating quickly. The results of the analysis using the number of occurrences of each activity are shown in (Fig 2). In general, wild males seem to be less sexually motivated, as they were busier in nonreproductive activities. For example, when a meeting was observed, wild males were less active in calling than mass-reared males. Adverse reactions during the meeting were more frequent in courtships involving wild males. Moreover, wild males were more likely to perform wing displays (signaling) during meetings. Differences between strains also were observed for the courtship steps (Fig 3). For example, wing fanning per meeting was less frequent in wild than in mass-reared males. The same pattern of between strain variations also was observed for the buzzing behaviour (Fig 4).
The results of the first cage showed that there is no significant difference between the strains (Fig 1). The ration of this data was always at the minimum required (0.20) of data analysis. The wild males were successfully competing for the female that presented on Table (1). However, the mass reared flies showed the lower sexual success in the lab. The males in the experiments were against all females. The mass reared males were performed better when compete with wild females, while not compete for the female from their own strain. In overall, the data showed that there is no significant difference between wild strains. The number of hatched were different depends on the weather conditions (water, temperature, humidity and light), the hatch start with 81.81% (F1) and the (F30) was 70.90 (Table 1).
The data obtained in this study show the normal lower competitiveness of sterilized mass-reared males, but clearly no significant isolation in terms of mating compatibility among all the strains of flies tested. These results were expected in accordance with the compatibility studies of by
Cayol et al., (2002), for several medfly strains from many regions of the world, including Madeira Island. Important results were obtained when recently domesticated male medflies were tested in the field cages. These semi-wild males performed significantly worse compared to the best wild male treatment in each of the experiments (
Cáceres et al., 2002). However, the semi-wild males performed better than sterilized mass-reared males.
The phenomenon of rapid decrease in mating sexual performance soon after strains of flies are adapted to mass-rearing conditions is well documented (
Economopoulos, 1992;
Orozco and Lopez, 1993). The loss of sexual competitiveness of recently domesticated flies (only 7 to 10 generations from the wild) even under low stress conditions, i.e., low adult fly and larval density, respectively, in adult cages and in larval diet, is likely a result of high selection pressure that laboratory conditions impose on the insects (
Fisher and Caceres, 1998;
Al-khshemawee et al., 2019).
The phenomenon of rapid strain deterioration after colonization is likely more evident when under the high stress of mass-rearing conditions as is common in the medfly factories around the world (
Caceres, 2002;
San Andrés et al., 2007). For this reason, the development of a filter rearing system to manage mother colonies under rearing conditions (fly density, sex-ratio and physical features) more similar to conditions found in nature, as described by (
Rendón et al., 2004;
Franz, 2005), is recommended. In conclusion, our data indicate no mating incompatibility among strains tested and support the need to improve sterile male competitiveness by instituting in medfly mass rearing facilities filter rearing systems to manage adult colonies under less stressful conditions
(Arredondo et al., 2016).
