SEARCH

SEARCH BY CITATION

Keywords:

  • longevity;
  • mating competitiveness;
  • methyl eugenol;
  • sexual maturity;
  • sterile male;
  • yeast hydrolysate

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Enhancement of the sterile male performance in Bactrocera philippinensis through access to protein (yeast hydrolysate) and/or exposure to methyl eugenol (ME) was investigated in this study. The temporal occurrence of sexual maturity of B. philippinensis was determined for both laboratory sterile and wild flies. Laboratory tests were also conducted to determine the peak age of ME feeding in relation to male fly age and sexual maturity and effect of protein on the longevity of sterile males. Field cage mating tests were performed to examine the effect of adult diet (P+ vs. P−) and ME exposure (ME+ vs. ME) on the mating competitiveness of the sterile male B. philippinensis. P+ME+ sterile male flies achieved significantly more matings with wild females than P+ME or PEME sterile males. Based on the relative sterile index, P+ sterile male flies were significantly more sexually competitive when competing for wild females than P flies. The results confirm that the pre-release diet can be significantly improved to increase the effectiveness of the application of the sterile technique against B. philippinensis.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Bactrocera philippinensis Drew and Hancock is a destructive pest of mango, Mangifera indica L., and other important fruits in the Philippines. To suppress the population of this insect pest, a feasibility study on an integrated fruit fly management programme with a sterile insect technique (SIT) component was initiated in 1997 on Guimaras Island, a major mango producing area in the Western Visayan region (Covacha et al. 2000). Improvement of the mating competitiveness of the released sterile males is of paramount importance to reduce the cost and increase the effectiveness of future programmes that integrate the SIT with other fruit fly suppression techniques.

Exposing sterile males to male lures or parapheromones before release has been shown to increase mating competitiveness in several Bactrocera species (Shelly and Dewire 1994; Shelly and Villalobos 1995; Wee and Tan 2007). Methyl eugenol (ME) (4-allyl-1,2-dimethoxy benzene) is one of the natural attractants of some Bactrocera, which when ingested by male flies, produces more potent sex pheromone components such as trans-coniferyl alcohol, 2-allyl-4,5dimethoxyphenol and cis-3,4-dimethoxycinnamyl alcohol; the metabolites are stored in the rectal gland and released during fanning and courtship (Nishida et al. 1988a,b; Tan and Nishida 1996). The role of ME in relation to pheromone production and mating behaviour has been studied intensively in Bactrocera dorsalis (Hendel) (Shelly 1994; Shelly and Dewire 1994; Shelly et al. 2005; Wee and Tan 2007). However, the role of ME in improving sexual performance and competitiveness in B. philippinensis is not fully understood. Shelly et al. (1996) reported that irradiated male B. philippinensis that fed on ME have a mating advantage over wild males that were not given access to the lure.

Feeding emerged adults with yeast hydrolysate prior to release may also serve to increase the mating success of sterile males of B. philippinensis. Experiments with a young laboratory colony of B. dorsalis males showed that males fed yeast hydrolysate in addition to sugar achieved more copulations than males fed sugar exclusively (Shelly et al. 2005). In the closely related tephritid Bactrocera tryoni (Froggatt), incorporation of such protein into the post-teneral diet improved the mating performance of the sterile males (Pérez-Staples et al. 2009). Several studies in Ceratitis capitata (Wiedemann) have also shown the importance of protein feeding on the sexual performance of male flies both wild and laboratory reared (Blay and Yuval 1997; Yuval et al. 1998; Kaspi and Yuval 2000; Shelly et al. 2002; Yuval et al. 2007).

This article assesses whether protein (yeast hydrolysate) feeding and ME exposure enhance the mating competitiveness of sterile male B. philippinensis in relation to males and females of the wild population. It also assesses ME feeding in relation to age, the longevity and sexual maturation of B. philippinensis.

Materials and Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Biological material

Laboratory flies were obtained from stock culture of B. philippinensis at the Philippine Nuclear Research Institute (PNRI) Fruit Fly Rearing Facility. The colony has been reared in the laboratory since 1996 and backcrossed with wild flies on an irregular basis. Pupae were marked with fluorescent dye (3 g/l) and irradiated with 65 Gy using a 60Co Gammacell 220 Irradiator (Nordion, Ottawa, ON, Canada) to render the flies sterile.

Wild flies were obtained from several collections of infested mango fruits on Guimaras Island. The larvae were placed in coir dust to develop into the pupal stage. The pupae were placed in small cubicle Plexiglass cages (30 × 30 × 40 cm) provided with sugar (sucrose) and enzymatic yeast hydrolysate (3:1, wt:wt; P+ diet) and water for emergence. The resulting colony of wild flies was provided papayas (Carica papaya L.) for oviposition.

Flies were held at 24–32°C (room temperature) and 65–83% RH. The flies were separated by sex within 24 h of adult emergence for the laboratory flies and within 48 h for the wild flies. Sexed flies were placed in small cubicle Plexiglass cages. Wild flies used in the experiments were all 1–3 generations removed from the wild.

Sexual maturation

Twenty-five pairs of newly emerged virgin wild or laboratory-sterile flies were confined in separate cylindrical mylar cages (30 cm length; 18 cm diam.) and provided with P+ diet and water for comparison of sexual maturity. As the aim of this experiment was merely to determine the age of sexual maturation of the wild and laboratory sterile males before further testing, the data for protein-deprived (sugar-fed) laboratory sterile and wild males were not presented. Observations of matings were carried out daily until flies reached the age of 34–40 days and were made from 17:00 to 22:00 h since mating occurs at dusk. Mating pairs were removed from the cages and recorded. They were not returned to their cages after the end of mating. The whole procedure was repeated three times for laboratory and wild flies.

Male ME feeding

Sterile males from the laboratory strain fed the P+ diet and ranging from 0 to 12 days old were placed individually in small screen cages along with a cotton ball suspended in an ampoule bottle into which 1.5 ml ME (SYMRISE GmbH & Co., Holzminden, Germany; Purity = 98%) was added. A total of 50 males per age were used in the study. The length of time the individual males spent feeding on the cotton ball were recorded for. If the male was still on the cotton ball (probably feeding) after 1 h, it was allowed to continue feeding until it stopped feeding and flew out from the ME source. This was performed to determine the duration of feeding and the percentage of males feeding in relation to fly age and sexual maturity. The feeding of individual males was observed from 08:00 to 15:30 h because it is within this time that male Bactrocera spp. respond to ME under natural conditions (Tan et al. 2002).

Longevity of sterile flies on protein and sugar diets

Ten pairs of males and females of newly emerged sterile B. philippinensis were placed in a cylindrical cage (30.5 × 19.0 cm) and provided either with the P+ diet or sugar exclusively. The flies were also given water ad libitum. Ten replications totalling 200 flies were used for both treatments. Daily observations and data collection on the number of dead adults (male/female) were performed until all flies were dead. Dead flies were removed during daily checks. Although these were sterile flies, each cage was provided with small egging cups to allow oviposition by adult females to check for presence of eggs.

Field cage mating experiments

The B. philippinensis strain used is a bisexual strain in which sterile fly releases include both sexes. Hence, newly emerged virgin laboratory sterile male and female flies were fed either the P+ or the P diet. Furthermore, males fed the P+ or P diets were either exposed or unexposed to ME (ME+ or ME). Ten-day-old sterile flies were exposed to ME (1.5 ml) applied in a cotton ball in a bottle ampoule for 2 h, after which they were held for 2 days before use in the field cage experiment. Wild flies were collected, fed a P+ diet and handled as previously described. Nineteen- to 30-day-old wild flies were used in the test. For each field cage trial with either P+ME+, P+ME, PME+ or PME males, we released 50 sterile flies of each sex and 50 wild flies of each sex (i.e. 200 total flies) in a nylon screen cage (361 cm L × 180 cm W × 201 cm H).

Field cages enclosed 4–5 2-year-old, potted, grafted mango seedlings that is about 2 m high with 80–100 leaves located at the grounds of the PNRI Fruit Fly Rearing Facility. The flies were released between 16:00 and 16:30 h. Adult males were released 15–20 min earlier than the females to give the males time to disperse and establish on the foliage. Mated pairs were collected in bottle ampoules at 15-min interval until none of the flies were mating. Individual pairs were kept in a freezer and identified on the following day using an ultraviolet (UV) lamp. As sterile flies were marked with fluorescent dye (3 g/l pupa), the sterile flies fluoresced under the UV lamp. Eight replicates of this field cage test were performed. The relative sterile index (RSI), an overall index of the mating competitiveness of sterile males (FAO/IAEA/USDA, 2003), was used. It is represented by the formula:

  • image

where: SW, sterile male × wild female matings; WW, wild male × wild female matings

The RSI indicates the proportion of wild females mating with sterile males (FAO/IAEA/USDA 2003). Values range between 0 and +1. Zero indicates that wild females mate only with wild males, and +1 means that wild females mate only with sterile males; a value of +0.5 indicates that wild females mate indiscriminately equally with wild or sterile males.

Statistical analysis

The data were tested for normality using Kolmogorov–Smirnov normality test and for equal variance using Bartlett’s test. Sexual maturity data were analyzed using Student-t test for percentage mating and Kruskal–Wallis (non-parametric) test for mean mating age, because the latter did not meet assumptions of normality. One-way anova was used to analyze the ME feeding. Two-way anova was used to analyze the longevity (sex and diet) and also the RSI (strain and ME) data. One-way anova was used to analyze data on the percentage mating in the field cage mating tests. Arc-sine transformation of all percentage data was performed prior to anova. Most analyses were performed using the anova General Linear Model of Minitab statistical software (Minitab 2000). Tukey’s test was used to compare treatment means, when differences were found.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Sexual maturation

For sterile flies, a mean of 89% (SE ±5.33%) of all the individuals had mated within 7 days post-eclosion, whereas a mean of only 48% (SE ±6.11%) of wild flies had mated by 14 days of age (t = 4.387, P = 0.0126). Under these small-cage conditions, mass-reared sterile flies have a median mating age of about 3.85 (±0.18) days after emergence and wild flies about 10.5 (±0.36) days. The median days to sexual maturity of sterile flies was significantly different from that of wild flies (H = 12.79, P < 0.001).

Male ME feeding

In sterile laboratory flies, we observed no feeding on ME in 0- and 1-day-old males, and only about 2% of 2-day-old males fed on ME for a period of only about 0.02 min (fig. 1). As the sterile males become sexually mature, the percentage of adult males feeding on ME as well as the duration of feeding increased. Results show that 50% of the 5-day-old males fed on ME, and peak feeding occurred among 10-day-old males (94%). Also feeding duration increased with age, and the highest average maximum feeding time was 59.45 min (SE ±4.01) for 10-day-old males (fig. 2).

image

Figure 1.  Relationship between age and feeding on methyl eugenol (ME) in sterile laboratory Bactrocera philippinensis with access to a P+ (sugar–yeast hydrolysate) diet. Values on y-axis represent the proportion of males of a given age (N = 50) observed feeding on ME.

Download figure to PowerPoint

image

Figure 2.  Relationship between age and mean feeding duration in minutes (±SE) on methyl eugenol by sterile laboratory Bactrocera philippinensis males with access to a P+ (sugar–yeast hydrolysate) diet. The figure represents the step-wise separation of means (lower case letters) using Tukey’s test. Means followed by the same letter are not significantly different at α = 0.05.

Download figure to PowerPoint

Longevity of sterile flies on protein and sugar diets

The mean longevity of laboratory sterile B. philippinensis flies obtained in our study is shown in fig. 3. Flies fed the P+ diet lived longer than flies fed only sugar (Pdiet) (F1,27 = 72.01, P < 0.001). Regardless of diet type, females lived longer than males (F1,27 = 17.27, P < 0.001). Based on the results, inclusion of protein in the adult diet increased the longevity of both male and female flies (F1,27 = 10.08, P < 0.001).

image

Figure 3.  Mean longevity (±SE) of sterile laboratory sterile Bactrocera philippinensis adult males and females fed with a sugar–protein (P+) or and only sugar (P) diets. The figure represents the step-wise separation of means (lower case letters) using Tukey’s test. Means followed by the same letter are not significantly different at α = 0.05.

Download figure to PowerPoint

Field cage mating experiments

Similar to most of the Bactrocera species, mating of B. philippinensis occurs during dusk (Shelly and Dewire 1994; Shelly et al. 1996; Fletcher 1987). The start of mating was observed as early as 17:00–18:00 h. More than 95% of the matings were achieved 1 h after the onset of mating. P+ ME+ males achieved significantly more matings with wild females than PME+ and PME males (F3,28 = 81.00, P < 0.003) (fig. 4), while there was no significant difference between P+ME+ and P+ME males.

image

Figure 4.  Field cage mating competitiveness for sterile laboratory Bactrocera philippinensis flies when competing with wild flies. Sterile flies were treated with either P+ME [sugar–yeast hydrolysate diet and no methyl eugenol (ME) exposure]; P+ME+ (sugar–yeast hydrolysate diet and ME exposure); PME (only sugar diet and no ME exposure) or PME+ (only sugar diet and ME exposure). Values represent percentages of mating (±SE) between sterile male and wild female flies (L-W). The figure represents the results of eight replicates per treatment with the step-wise separation of means (lower case letters) based on arc sine transformed means using Tukey’s test. Means followed by the same letter are not significantly different at α = 0.05.

Download figure to PowerPoint

P+ME and P+ME+ males obtained RSI values above 0.5, reflecting the higher number of protein-fed sterile males mating with wild females as compared with wild males (fig. 5). In contrast, the RSI values below 0.5 for PME and PME+ indicated a lower number of protein-fed sterile males mating with wild females as compared with wild males (fig. 5). There was a significant RSI difference between males fed P+ and P diets (F1,28 = 24.7, P < 0.001), but no significant RSI difference between males fed ME+ and ME males (F1,28 = 11.85, P = 0.185), nor between type of diet and ME exposure (F1,28 = 0.34, P = 0.562).

image

Figure 5.  Relative Sterile Index (RSI) values (±SE) obtained in field cage studies (eight replicates) for sterile laboratory sterile Bactrocera philippinensis adults when competing with wild flies. Sterile flies were treated with either P+ME [sugar–yeast hydrolysate diet and no methyl eugenol (ME) exposure]; P+ME+ (sugar–yeast hydrolysate diet and ME exposure); PME (only sugar diet and no ME exposure) or PME+ (only sugar diet and ME exposure). Values represent mean RSIs (±SE). The figure represents the results of eight replicates per treatment with the step-wise separation of means (lower case letters) using Tukey’s test. Means followed by the same letter are not significantly different at α = 0.05.

Download figure to PowerPoint

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

As in related Bactrocera species, our results show that the small-cage conditions encouraged earlier age of mating in B. philippinensis when compared with open-field or semi-field conditions where only lekking and courting males succeed in mating (Miyatake and Haraguchi 1996). Also in mass-reared Bactrocera cucurbitae Coquillett and B. dorsalis, the initiation of sexual activity took place earlier than in the wild strain (Suzuki and Koyama 1980; Kuba and Koyama 1982 and Wong et al. 1982). For B. cucurbitae, 50% of individuals of a mass-reared strain copulated at an age at which copulation only started in the wild strain (Koyama 1982). The inadvertent selection for precociousness is inherent to most insect mass-rearing systems (Calkins and Parker 2005).

Several studies have shown that male attraction to ME is related to sexual maturity (Shelly and Dewire 1994; Hee and Tan 1998; Shelly et al. 1996; Wee and Tan 2000). Our results confirm that male maturation and response to ME in species of Bactrocera that respond to this lure is closely linked and reaches a peak when they are sexually mature (Metcalf 1990). Methyl eugenol consumption and rates of sexual maturity were observed to vary with species. Bdorsalis has a higher consumption and responded earlier to ME compared with B. papayae Drew and Hancock and B. carambolae Drew and Hancock, which are closely related species within the B. dorsalis complex (Wee and Tan 2000; Wee et al. 2002).

Male annihilation treatment (MAT) works well when wild males respond to ME baits at a younger age or before they are able to mate and produce offsprings (Wee et al. 2002). The low incidence of repeat feeding on ME in previously fed males (Shelly 1994) allows the simultaneous application of MAT and the release of ME fed males, thereby enhancing the effectiveness of the SIT as a result of the replacement of wild males by sterile males (Robinson and Hendrichs 2005). The release of sterile B. philippinensis males previously exposed to ME may increase the number of matings with wild females over wild males (Shelly et al. 1996). However, based on the results of ME feeding, there is a need to hold the flies for at least 5 days before exposure to the lure and another 2–5 days before release in the field. This is not possible using the paper bag release method used in Guimaras Island (Covacha et al. 2000), as it may affect the quality of sterile males for release. Other holding methods for sterile B. philippinensis should, therefore, be investigated. Our results agree with the findings of Müller et al. (1997) in laboratory C. capitata where the females lived longer than males when both were fed on diet that included protein. For flies fed with sugar exclusively, there was no significant difference in longevity of P females and P males. Our results also support those obtained by Plácido-Silva et al. (2006) in C. capitata where protein intake increased adult longevity of a laboratory population and affected the longevity of both males and females. However, results of Kaspi and Yuval (2000) showed reduced longevity in sterile male Mediterranean fruit flies when fed with a pre-release diet including protein during 4 days after emergence and starved for 24 h thereafter. After this starving period, males fed the P+ died significantly faster in the laboratory than males fed with the P diet. Nevertheless, this differential mortality did not occur in the field during the week immediately after sterile male release during which most sterile males die in nature because of predation and other causes.

Based on these results, feeding of sterile B. philippinensis males before release with protein-enriched diet and exposure to ME appears valuable to enhance their mating performance. Feeding of adult B. philippinensis to ME has been found to increase the male signalling activity (wing fanning) and male attractiveness to females (Shelly et al. 1996).

In C. capitata, Shelly et al. (2002) found that protein-fed laboratory males had a significant advantage in mating competition over protein-deprived males. In a very young laboratory colony of B. dorsalis, field cage mating tests have shown that protein-fed males achieved significantly higher matings than protein-deprived males (Shelly et al. 2005).

Based on the RSI values, the inclusion of protein in the adult diet increased the mating competitiveness of the sterile males. Furthermore, exposure of P+ sterile males to ME+ increased the percentage of laboratory male matings with wild females in B. philippinensis. Exposure of P males to ME also increased the percentage of L-W matings, but the RSI values showed that the males were not sexually competitive with wild males.

Our study indicates that the pre-release diet can be significantly improved to increase the effectiveness of the application of the SIT against B. philippinensis. In this study, access to protein (yeast hydrolysate) immediately after adult emergence is a promising way to enhance the competitiveness by improving mating performance and longevity of sterile male B. philippinensis. Field experiments are therefore needed to confirm results obtained in laboratory and field cage tests.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

The authors wish to thank the UN-FAO International Atomic Energy Agency for partial funding of this project under Research Contract No. 12862. Special thanks to Helen Bignayan and Nenita Zamora of the National Mango Research and Development Center for facilitating the collection of wild flies. We would also like to thank Dolores Lazo, Ricky Garcia, Flora Isip, Zenaida Reyes and John Faustus Vidal of the PNRI for the assistance during the conduct of the experiments and to the staff of the PNRI Multipurpose Irradiation Facility for the irradiation of fruit fly pupae. Finally, our heartfelt thanks to Dr. Todd Shelly of USDA-APHIS, Hawaii, USA for a review of an earlier version of this article.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  • Blay S, Yuval B, 1997. Nutritional correlates to reproductive success of male Mediterranean fruit flies. Anim. Behav.54, 5966.
  • Calkins CO, Parker AG, 2005. Sterile insect quality. In: Sterile insect technique, principles and practice in area-wide integrated pest management. Ed. by Dyck VA, Hendrichs J, Robinson AS, Springer, Dordrecht, The Netherlands, 269296.
  • Covacha SA, Bignayan HG, Gaitan EG, Zamora NF, Maranon RP, Manoto EC, Obra GB, Resilva SS, Reyes MR, 2000. Status report on the integrated fruit fly management based on sterile insect technique in Guimaras Island, Philippines. In: Area-wide control of fruit flies and other insect pests. Ed. by Tan KH, Penerbit Universiti Sains Malaysia, Penang, Malaysia, 401408.
  • FAO/IAEA/USDA, 2003. Manual for product quality control and shipping procedures for sterile-mass-reared tephritid fruit flies, version 5.0. International Atomic Energy Agency, Vienna, Austria, 85pp.
  • Fletcher BS, 1987. The biology of Dacine fruit flies. Ann. Rev. Entomol.32, 115144.
  • Hee AK-W, Tan KH, 1998. Attraction of female and male Bactrocera papayae to conspecific males fed with methyl eugenol and attraction of females to male sex pheromone components. J. Chem. Ecol.24, 753764.
  • Kaspi R, Yuval B, 2000. Post-teneral protein feeding improves sexual competitiveness but reduces longevity of mass-reared sterile male Mediterranean fruit flies. Ann. Entomol. Soc. Am.93, 949955.
  • Koyama J, 1982. Quarterly problems in the mass-rearing for the melon fly, Dacus cucurbitae. JARQ16, 181187.
  • Kuba H, Koyama J, 1982. Mating behavior of the melon fly, Dacus cucurbitae Coquillett (Diptera: Tephritidae): comparative studies of one wild and two laboratory strains. Appl. Ent. Zool.17, 559568.
  • Metcalf RL, 1990. Chemical ecology of Dacine fruit flies (Diptera: Tephritidae). Ann. Entomol. Soc. Am.83, 10171030.
  • Minitab2000. Minitab reference manual release 13.20. Minitab Inc., State College, PA.
  • Miyatake T, Haraguchi D, 1996. Mating success in Bactrocera cucurbitae (Diptera: Tephritidae) under different rearing densities. Ann. Entomol. Soc. Am.89, 284289.
  • Müller HG, Wang JL, Capra WB, Liedo P, Carey JR, 1997. Early mortality surge in protein-deprived females causes reversal of sex differential of life expectancy in Mediterranean fruit flies. PNAS94, 27622765.
  • Nishida R, Tan KH, Serit M, Lajis NH, Sukari AM, Takahashi S, Fukami H, 1988a. Accumulation of phenylpropanoids in the rectal glands of male Oriental fruit fly, Dacus dorsalis. Experientia44, 534536.
  • Nishida R, Tan KH, Fukami H, 1988b. Cis-3,4-dimethoxycinnamyl alcohol from the rectal glands of male Oriental fruit fly, Dacus dorsalis. Chem. Express3, 207210.
  • Pérez-Staples D, Weldon CW, Smallridge C, Taylor PW, 2009. Pre-release feeding on yeast hydrolysate enhances sexual competitiveness of sterile male Queensland fruit flies in field cages. Ent. Exp. Appl.131, 159166.
  • Plácido-Silva MC, Neto AMS, Zocoloto FS, Joachim-Bravo IS, 2006. Effects of different protein concentrations on longevity and feeding behavior of two adult populations of Ceratitis capitata Wiedemann (Diptera: Tephritidae). Neotrop. Entomol.35, 747752.
  • Robinson AS, Hendrichs J, 2005. Prospects for the future develoment and application of the sterile insect technique. In: Sterile insect technique, principles and practice in area-wide integrated pest management. Ed. by Dyck VA, Hendrichs J, Robinson AS, Springer, Dordrecht, The Netherlands, 727760.
  • Shelly TE, 1994. Consumption of methyl eugenol by male Bactrocera dorsalis (Diptera: Tephritidae): low incidence of repeat feeding. Fla. Entomol.77, 201208.
  • Shelly TE, Dewire AM, 1994. Chemically mediated mating success in male Oriental fruit flies, Bactrocera dorsalis (Diptera: Tephritidae). Ann. Entomol. Soc. Am.88, 883886.
  • Shelly TE, Villalobos EM, 1995. Cue lure and the mating behavior of melon flies (Diptera: Tephritidae). Fla. Entomol.78, 473482.
  • Shelly TE, Resilva SS, Reyes MR, Bignayan HG, 1996. Methyl eugenol and mating competitiveness of irradiated male Bactrocera philippinensis (Diptera: Tephritidae). Fla. Entomol.79, 481488.
  • Shelly TE, Kennelly SS, McInnis DO, 2002. Effect of adult diet on signaling activity, male attraction and mating success in male Mediterranean fruit flies (Diptera: Tephritidae). Fla. Entomol.85, 150155.
  • Shelly TE, Edu J, Pahio E, 2005. Influence of diet and methyl eugenol on the mating success of males of the Oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae). Fla. Entomol.88, 307313.
  • Suzuki Y, Koyama J, 1980. Courtship behavior of the melon fly, Dacus cucurbitae Coquillett (Diptera: Tephritidae). Appl. Ent. Zool.16, 164166.
  • Tan KH, Nishida R, 1996. Sex pheromone and mating competition after methyl eugenol consumption in the Bactrocera dorsalis complex. In: Fruit fly pests: a world assessment of their biology and management. Ed. by McPheron BA, Steck GJ, St Lucie Press, Delray Beach, FL, 147153.
  • Tan KH, Nishida R, Toong YC, 2002. Floral Synomone of wild orchid, Bulbophyllum cheiri, lures Bactrocera fruit flies for pollination. J. Chem. Ecol.28, 11611172.
  • Wee SL, Tan KH, 2000. Sexual maturity and intraspecific mating success of two sibling species of the Bactrocera dorsalis complex. Ent. Exp. Appl.94, 133139.
  • Wee SL, Tan KH, 2007. Temporal accumulation of phenylpropanoids in male fruit flies, Bactrocera dorsalis and B. carambolae (Diptera Tephritidae) following methyl eugenol consumption. Chemoecology17, 8185.
  • Wee SL, Hee AK-W, Tan KH, 2002. Comparative sensitivity to and consumption of methyl eugenol in three Bactrocera dorsalis (Diptera: Tephritidae) complex sibling species. Chemoecology12, 193197.
  • Wong TTY, Couey HM, Nishimoto JI, 1982. Oriental fruit fly: sexual development and mating response of laboratory-reared and wild flies. Ann. Entomol. Soc. Am.75, 191194.
  • Yuval B, Kaspi R, Shloush S, Warburg MS, 1998. Nutritional reserves regulate male participation in Mediterranean fruit fly leks. Ecol. Entomol.23, 211215.
  • Yuval B, Maor M, Levy K, Kaspi R, Yaylor P, Shelly TE, 2007. Breakfast of champions or kiss of death? Survival and sexual performance of protein-fed, sterile Mediterranean fruit flies (Diptera: Tephritidae)Fla. Entomol.90, 115122.