Supermarket ginger powder increases the mating success of mass-reared males of the Mediterranean fruit fly

A series of studies has shown that exposure to the aroma of ginger root oil (Zingiber officinale, GRO hereafter) enhances the mating success of mass-reared, sterile males of the Mediterranean fruit fly (medfly), Ceratitis capitata. The use of GRO to enhance male mating competitiveness appears to represent a simple means to increase the efficacy of the Sterile Insect Technique (SIT) against this pest. However, the relatively high cost of GRO, along with its restricted commercial availability, may preclude its use in SIT programs with limited budgets and/or no domestic supply of the oil. Consequently, we assessed the effectiveness of supermarket-brand ginger powder, as a potentially less expensive and more widely available substitute for GRO, by comparing the mating success of powder-exposed (treated) and non-exposed (control) sterile males in competition against males from a recently established colony for matings with females from this same colony. In one set of experiments, sterile males were exposed to 2 or 10 g of the ginger powder placed inside storage boxes. In a second set, 1 or 2 g of powder was added to the sugar-agar food block placed on the storage boxes, and the food block was applied on the same day as pupal placement or on the day of peak adult emergence (2 d later). Treated sterile males achieved a significantly greater proportion of total matings than control sterile males at both doses of ginger powder in both sets of experiments, except that ginger powder had no detectable effect (at either dose) when added to food blocks placed on boxes on the same day as pupal placement. The cost of applying GRO to individual storage boxes is compared with that of ginger powder

Exposure to ginger root oil decreases capture of male Mediterranean fruit flies (Diptera: Tephritidae) in Trimedlure-baited traps

Detection programs for pestiferous tephritid fruit flies rely on traps baited with either natural or synthetic food substances, or so-called male lures. While studies on several tephritid species have demonstrated that protein feeding reduces subsequent attraction to protein food baits, comparable data for male lures are scant and largely restricted to the genus Bactrocera. Ginger root oil (GRO) is attractive to males of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and males exposed to this oil’s scent exhibit heightened mating competitiveness. Because of this increased mating success, several sterile male release programs against C. capitata now include pre-release, GRO exposure as part of their standard operating procedures. However, the impact of such exposure on subsequent trap capture has received little study. The purpose of the present study was to measure the effect of GRO exposure on subsequent capture of sterile male medflies in trimedlure-baited traps in two fruit orchards in Hawaii. At each study site, 600 control (non-exposed) and 600 treated (GRO-exposed) males from a mass-reared, genetic sexing strain were released per replicate from a central release point, and trap captures were scored 2 d post-release for eight trimedlure- baited Jackson traps placed in a circular array around the release point. At both orchards, control males were, on average, captured in significantly greater numbers than treated males. This result did not appear to reflect differential mortality between the male types: mortality in screen cages under field conditions was similar over a 48 h period for control and treated males. Implications of these findings for sterile release programs are discussed

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