Application of Orange Oil to Pre-Release Holding Boxes Increases the Mating Success of Sterile Males of the Mediterranean Fruit Fly in Field Cage Trials (Diptera: Tephritidae)

Previous research showed that exposure to the aroma of orange oil (Citrus sinensis L.) increased the mating success of male Mediterranean fruit flies (medfly), Ceratitis capitata (Wiedemann). This work, however, involved the exposure of small groups of males (n = 25) in small containers (volume 400 ml). In implementing the Sterile Insect Technique (SIT), several programs use plastic adult rearing containers (PARC boxes, 0.48 by 0.60 by 0.33 m) to hold newly emerged males before release (≈ 36,000 males per box). The objective of this study was to determine whether the application of orange oil to individual PARC boxes increases the mating competitiveness of sterile C. capitata males. Orange oil was applied to paper placed on the screened opening on the top of PARC boxes. Two doses (0.25 and 1.0 ml) were tested, and the paper was either covered by a Petri dish lid (to reduce volatilization) or was left uncovered. Using field cages, we ran mating trials in which oil-exposed (treated) or non-exposed (control) sterile males competed against males from a recently established (from wild flies) colony for females from the same colony. In all trials, the wild-derived males obtained significantly more matings than the sterile males. In those trials involving uncovered, oil-laden paper, there was no difference in mating success between treated and control sterile males. However, when the paper was covered, the treated males obtained significantly more matings than the control males at both doses. These results are compared with similar, previously conducted experiments involving ginger root oil, and the potential use of orange oil in medfly SIT is discussed.