Male Mediterranean Fruit Flies Research Articles

Microbial Biotransformation of Male Specific Pheromone α-Copaene with Cunninghamella elegans and Antibacterial Activity of Its Transformed Products

Pharmaceutical industries are increasingly turning to microbial transformation instead of chemical methods. This is because microbial biotransformation is a more effective way to produce pharmacologically active molecules with high specificity and efficient yield. Additionally, it is a step towards eco-friendly synthesis. α-Copaene (1), a tricyclic sesquiterpene, is a potent attractant of the male Mediterranean fruit fly Ceratitis capitata. This paper presents the utilization of the filamentous fungus Cunninghamella elegans TSY 0865 for large-scale biotransformation of 1. α-Copaene (1) has been incubated with Cunninghamella elegans for 11 days and extracted with CH2Cl2. Four new hydroxylated metabolites 10,13-dihydroxycopaene (2); 11,13-dihydroxycopaene (3); 11-hydroxycopaen-5-one (4); and 11-hydroxy-13-copaenic acid (5) were afforded. The structures of the new metabolites were elucidated by 1D (1H, 13C) and 2D NMR (COSY, HMBC, HMQC, and NOESY) techniques and MS analyses. Metabolite 5 exhibited significant antibacterial activity against Bacillus subtilis and Pseudomonas aeruginosa.

Male Mediterranean fruit flies prefer warmer temperatures that improve sexual performance

Females and males have divergent strategies of energy investment, so the thermal preference of each sex in insects may differ because energetic conversion of metabolic reserves is dependent on temperature. We determined the thermal preference of virgin, sexually mature Mediterranean fruit flies, Ceratitis capitata, and found that males preferred a significantly higher temperature (23.8 ± 0.3 °C) than that of females (22.1 ± 0.3 °C). We then tested predictions for the difference in thermal preference related to the energetic demands of reproduction over a range of temperatures. The frequency and duration of calling bouts by male C. capitata were optimal at 26 °C. Mating propensity and latency, and copula duration, were optimal over the range of 22–28 °C. When mating occurred, temperature had little effect on the incidence of sperm storage by females, but there was a notable decline in the number stored at 28 °C. Female lifespan was highest at 18 °C, but lifetime egg production was optimal at 24 °C. These results illustrate temperature-related differences in the reproductive fitness of the sexes in C. capitata, although the optima for male traits align best with their thermal preference. They also support the theoretical prediction that insect thermal preference should be lower than the optimum for fitness.

Chemical Composition of Essential Oils from Leaves and Fruits of Juniperus foetidissima and Their Attractancy and Toxicity to Two Economically Important Tephritid Fruit Fly Species, Ceratitis capitata and Anastrepha suspensa.

The present study analyzed the chemical composition of Juniperus foetidissima Willd. essential oils (EOs) and evaluated their attractancy and toxicity to two agriculturally important tephritid fruit flies. The composition of hydrodistilled EOs obtained from leaves (JFLEO) and fruits (JFFEO) of J. foetidissima was analyzed by GC–FID and GC–MS. The main compounds were α-pinene (45%) and cedrol (18%) in the JFLEO and α-pinene (42%), α-thujone (12%), and β-thujone (25%) in the JFFEO. In behavioral bioassays of the male Mediterranean fruit fly, Ceratitis capitata (Wiedemann), both JFLEO and JFFEO showed strong attraction comparable to that observed with two positive controls, Melaleuca alternifolia and Tetradenia riparia EOs. In topical bioassays of the female Caribbean fruit fly, Anastrepha suspensa (Loew), the toxicity of JFFEO was two-fold higher than that of JFLEO, with the LD50 values being 10.46 and 22.07 µg/µL, respectively. This could be due to differences in chemical components between JFLEO and JFFEO. The JFFEO was dominated by 48% monoterpene hydrocarbons (MH) and 46% oxygenated monoterpenes (OM), while JFLEO consisted of 57% MH, 18% OM, and 20% oxygenated sesquiterpenes (OS). This is the first study to evaluate the attractancy and toxicity of J. foetidissima EOs to tephritid fruit flies. Our results indicate that JFFEO has the potential for application to the management of pest tephritid species, and further investigation is warranted.

Field Capture of Male Mediterranean Fruit Flies (Diptera: Tephritidae) in Traps Baited with Varying Amounts of Trimedlure

Detection of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), relies heavily on traps baited with the male attractant trimedlure. This lure is dispensed from solid polymeric plugs (2 g a.i.) that are changed out every 6 wk, because beyond this interval their attractiveness drops significantly below that of fresh lure. Existing data suggest that plugs loaded with 4 g of trimedlure may have longer attractancy, which would allow for longer servicing intervals with associated reductions in material and labor costs. The objective of the present study was to gather additional data on the effectiveness of plugs having trimedlure loadings greater than 2 g. In 4 field experiments conducted in Hawaii, the capture of male medflies was compared over 10 or 12 wk periods between control traps baited with 2 mL fresh liquid trimedlure on a cotton wick and treatment traps baited with aged plugs containing 2 to 4 g of the lure. In all experiments, 6-wk-aged plugs, regardless of the specific loading, attracted similar numbers of males as the fresh liquid lure. Conversely, in 3 of the 4 experiments, plugs aged for 10 or 12 wk attracted significantly fewer males than the fresh lure. The performance of plugs aged 8 wk was inconsistent, showing similar attractiveness as fresh lure in certain cases but not others. Based on these findings, we conclude that, counter to our expectations, the use of 4 g trimedlure plugs would not allow effective trapping over longer inter-servicing intervals. Key Words: Ceratitis capitata; detection; trapping program; invasive species; male lure Resumen La deteccion de la mosca mediterranea de la fruta (moscamed), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), depende en gran medida de trampas cebadas con trimedlure, un senuelo de machos. Este senuelo se dispensa de tapones polimericos solidos (2 g a.i.) que se cambian cada 6 semanas, porque despues de este intervalo su atractivo baja significativamente con respecto a un senuelo fresco. Los datos existentes sugieren que los tapones cargados con 4 g de senuelo trimedlure pueden tener una atraccion mas larga, lo que permitiria intervalos de servicio mas largos con reducciones asociadas en los costos de material y mano de obra. El objetivo del presente estudio fue reunir datos adicionales sobre la efectividad de los tapones que tienen la cantidad de senuelo trimedlure mayor de 2 g. En 4 experimentos de campo realizados en Hawai, se comparo la captura de moscas moscas macho durante 10 o 12 semanas entre trampas de control cebadas con 2 ml de trimedlure liquido fresco en una mecha de algodon y trampas de tratamiento cebadas con tapones viejos que contienen de 2 a 4 g de senuelo. En todos los experimentos, los tapones de 6 semanas de edad, independientemente de la cantidad de trimedlure especifica, atrajeron un numero similar de machos como las trampas con senuelo de liquido fresco. Por el contrario, en 3 de los 4 experimentos, los tapones usados para 10 o 12 semanas atrajeron significativamente menos machos que el senuelo fresco. El rendimiento de los tapones de 8 semanas de edad fue inconsistente, mostrando un atractivo similar al senuelo fresco en ciertos casos, pero no en otros. Con base en estos hallazgos, llegamos a la conclusion de que, en contra de nuestras expectativas, el uso de tapones trimedlure de 4 g no permitiria la captura efectiva durante intervalos mas largos entre servicios. Palabras Clave: Ceratitis capitata; deteccion; programa de trampeo; especies invasivas; senuelo de machos View this article in BioOne

Laboratory Evaluation of Natural and Synthetic Aromatic Compounds as Potential Attractants for Male Mediterranean fruit Fly, Ceratitis capitata.

Ceratitis capitata, the Mediterranean fruit fly, is one of the most serious agricultural pests worldwide responsible for significant reduction in fruit and vegetable yields. Eradication is expensive and often not feasible. Current control methods include the application of conventional insecticides, leading to pesticide resistance and unwanted environmental effects. The aim of this study was to identify potential new attractants for incorporation into more environmentally sound management programs for C. capitata. In initial binary choice bioassays against control, a series of naturally occurring plant and fungal aromatic compounds and their related analogs were screened, identifying phenyllactic acid (7), estragole (24), o-eugenol (21), and 2-allylphenol (23) as promising attractants for male C. capitata. Subsequent binary choice tests evaluated five semisynthetic derivatives prepared from 2-allylphenol, but none of these were as attractive as 2-allylphenol. In binary choice bioassays with the four most attractive compounds, males were more attracted to o-eugenol (21) than to estragole (24), 2-allylphenol (23), or phenyllactic acid (7). In addition, electroantennography (EAG) was used to quantify antennal olfactory responses to the individual compounds (1–29), and the strongest EAG responses were elicited by 1-allyl-4-(trifluoromethyl)benzene (11), estragole (24), 4-allyltoluene (14), trans-anethole (9), o-eugenol (21), and 2-allylphenol (23). The compounds evaluated in the current investigation provide insight into chemical structure–function relationships and help direct future efforts in the development of improved attractants for the detection and control of invasive C. capitata.

Attraction of Ceratitis capitata (Diptera: Tephritidae) Sterile Males to Essential Oils: The Importance of Linalool.

Small cage and wind tunnel bioassays were used to understand the role of volatile chemicals found in ginger root oil and other essential oils in the attraction of sterile male Mediterranean fruit flies, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Small cage bioassays found that both a 10 component blend (geraniol, linalool, β-myrcene, limonene, α-pinene, β-pinene, β-caryophyllene, terpinen-4-ol, α-terpineol, and α-humulene) and a 4 component subset of that blend (geraniol, linalool, β-myrcene and limonene) were more attractive than paired mineral oil controls. Both blends were equally attractive as ginger root oil and each other. Deletion studies, which tested all 3 component blends, found decreased attraction when linalool was deleted from the 4 component blend. Linalool alone attracted an equal percentage of flies as the 4 component blend, confirming that this chemical was responsible primarily for attraction to ginger root oil. Wind tunnel bioassays confirmed previous studies that panel traps baited with ginger root oil captured more flies than traps baited with manuka oil. Addition of linalool to manuka oil resulted in capture equal to ginger root oil, and addition of linalool to ginger root oil resulted in capture of more flies than ginger root alone. The results of this study will allow a better understanding of the role of individual plant-based chemicals in the attraction of male C. capitata.

Occurrence of Fruit-Decaying Fungi on Adult Male Mediterranean Fruit Flies (Ceratitis capitata) Captured in Orchards and Adjacent Vineyards

The occurrence of adult male Ceratitis fruit flies and their potential to transmit fungi associated with pre- and postharvest decay of fruit in natura were investigated. Sensus fruit-fly traps were installed in orchards each bordering on a vineyard on farms in the Stellenbosch region, South Africa. Ceratitis fruit flies were collected weekly, identified and counted to determine the fluctuations in fruit-fly population levels. Captured fruit flies were plated on a semi-selective medium and the number of flies yielding the fungi was recorded. Both the Mediterranean fruit fly (C. capitata), and the Natal fruit fly (C. rosa) were trapped. C. rosa seldom occurred and comprised only 1 % of the total number of flies captured. Fruit-fly patterns showed that early infestation of orchards may contribute to the infestation of adjacent vineyards later in the season. At localities where flies were not trapped in the early season, infestation usually occurred in the orchards and adjacent vineyards in the late season, and well after fruits were harvested. Fruit flies from all localities yielded species of Alternaria, Penicillium, Aspergillus, Rhiwpus, Mucor and Botrytis cinerea on the medium. Of the different fungi, Alternaria and Penicillium spp. were most commonly carried by the flies at the various localities. The organisms occurred in a specific pattern on flies captured at a specific locality, and in a given orchard or vineyard. The pattern of fruit-fly infestation and their fungal contamination suggest that the Mediterranean Fruit-fly has the potential to transfer fungi associated with post-harvest decay in natura from early-season to mid- and late-season peach and plum orchards, and to neighbouring mid- and late-season wine and table grape vineyards. This highlights the importance of fruit-fly management in order to control disease epidemics in orchards and vineyards.

Exposure to Tea Tree Oil Enhances the Mating Success of Male Mediterranean Fruit Flies (Diptera: Tephritidae)

The aroma of various plant essential oils has been shown to enhance the mating competitiveness of males of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Laboratory observations revealed that male medflies show strong short-range (<10 cm) attraction to tea tree oil (TTO hereafter) derived from leaves of the Australian plant Melaleuca alternifolia (Maiden & Betch) Cheel (Myrtales: Melastomataceae). The present study was undertaken to i) compare the attractiveness of TTO with that of trimedlure (the male lure routinely used in detection surveys) in field and field cage tests and ii) assess the influence of TTO exposure on male mating success under conditions of varying dose, duration of post-exposure (i.e., pre-test) interval, and access (contact possible or not) to the TTO source. Results showed that TTO-baited traps captured 50% as many males as trimedlure-baited traps in field cages but only 8% as many males as trimedlure-baited traps in the open field. Males exposed to pure TTO or dilutions of 50% and 5% TTO in hexane had higher mating success than non-exposed control males in tests conducted 1 d after exposure. TTO-exposed males also had a mating advantage when tested 3 d after exposure and when physical contact with the TTO source was prevented. In an additional experiment, TTO exposure was found to enhance the mating competitiveness of mass-reared, sterile males in competition against wild males for copulations with wild females in tests conducted 1 or 3 d after exposure.

Exposure to the Plant Compound -Humulene Reduces Mating Success in Male Mediterranean Fruit Flies (Diptera: Tephritidae)

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), displays lek mating, where searching females actively choose among aggregated males that produce visual, acoustic, and olfactory signals within the tree canopy. Recent studies demonstrated that treated males exposed to the aroma of particular plant compounds (α-copaene) or oils (orange, manuka, and ginger) gain a mating advantage over control, nonexposed males. The goal of this study was to assess the impact of another plant compound, α-humulene, on the mating success of male C . capitata . Prior work showed that α-humulene was not attractive to either sex but elicited a strong electroantennal response in males. Field cage tests showed that males exposed to the aroma of α-humulene obtained significantly fewer matings than control (nonexposed) males as long as 3 d after exposure. Exposed males exhibited lower signaling (pheromone calling) activity than control males, which presumably contributed to their reduced mating success. Despite this lessened activity, the mortality of treated males after chemical exposure was similar to that observed for control, nonexposed males, suggesting that α-humulene was not a toxic or severely debilitating agent.

Distance-dependent capture probability of male Mediterranean fruit flies in trimedlure-baited traps in Hawaii

Many countries operate regional trapping programs for the detection of exotic tephritid fruit flies, which because of their polyphagous habits pose a serious threat to fruit and vegetable crops. Detection of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), relies primarily on trimedlure (TML), a synthetic male-specific lure, yet few studies have measured the relationship between distance from TML-baited traps and the probability of male capture, and consequently the detection sensitivity of medfly trapping programs is largely unknown. The present study measured distance-dependent capture probabilities for male C. capitata in TML-baited traps using mark–release–recapture procedures. Releases were performed at distances of 25, 50, 100, and 200m at 4 sites in Hawaii, and the resulting capture rates were used to estimate the minimum detectable population size (detection probability>99.9%) for a trapping density of 5 TML traps per 2.59km2 (=1mi2, the density used in California, USA). Capture rates were similar for 3 of the sites (6.5%, 3.8%, 1.1%, and 0.1% for the 4 distances, respectively) and yielded an estimated minimum detectable population of ≈2300 males, a value similar to that obtained in a comparable study conducted in California. For unknown reasons, capture rates were significantly lower at the remaining site (1.8%, 0.6%, 0.1%, 0.04%) and the estimated minimum detectable population was correspondingly much larger (≈10,000 males). Implications of these results for medfly detection programs are discussed.

Sterile males of Ceratitis capitata (Diptera: Tephritidae) as disseminators of Beauveria bassiana conidia for IPM strategies

Sterile Mediterranean fruit fly, Ceratitis capitata (Wied.), males were evaluated as vectors to spread Beauveria bassiana (Bals) conidia to wild C. capitata populations under field conditions. The inoculated sterile males were released by air, using the chilled adult technique over 7000 ha of coffee growing in Chimaltenango, Guatemala, Central America. The impact of releases was determined using dry traps baited with a food attractant. The effects of these releases on Apis mellifera, Linnaeus (honey bee), Hypothenemus hampei, Ferrari (coffee berry borer) and the parasitic mite Varroa destructor (Oudeman) were also evaluated. Inoculated sterile males were able to transmit fungal spores to 44% of the wild C. capitata flies captured in traps, which likely were infected through intra- and intersexual interactions during leks, mating or mating attempts. There was no transmission of the fungal spores to non-target insect species such as coffee berry borer, honey bees or varroa. We conclude that sterile males of Mediterranean fruit fly inoculated with B. bassiana can act as effective vectors of conidia to wild populations, constituting a safe, environmentally friendly and selective alternative for suppressing the medfly under a Sterile Insect Technique-based IPM approach.

Capture ofAnastrepha suspensaand Sterile MaleCeratitis capitata(Diptera: Tephritidae) in Multilure Traps Versus Phase 4 Traps

Field trials were conducted in south Florida to compare capture of wild Caribbean fruit flies, Anastrepha suspensa (Loew), and sterile male Mediterranean fruit flies, Ceratitis capitata (Wiedemann), in Multilure traps, which are McPhail-type traps that use an aqueous solution to retain attracted flies, and Phase 4 traps, which are open-bottom dry traps that use a sticky insert to retain attracted flies. One study was conducted in a guava orchard and compared capture of A. suspensa in both trap types baited with ammonium acetate plus putrescine alone (two-component BioLure) or in combination with trimethylamine (three-component BioLure). A second study compared captures of A. suspensa and sterile male C. capitata in traps baited with three-component BioLure in an urban area near the end of the eradication program for a C. capitata outbreak. In both studies, captures were higher in the Multilure traps than the Phase 4 traps baited with the same lure, with catches ranging from 5:1 for sterile C. capitata, and ∼10:1 to ∼100:1 for wild A. suspensa. Large scale area-wide deployment of fruit fly detection traps is costly in both materials and in the time and effort required in routine servicing. Although a simpler and cheaper trap such as the Phase 4 trap would be a welcome relief to any large scale area-wide detection programs, it must perform effectively. This is the first report of tests of fruit fly capture in Phase 4 traps conducted under of south Florida conditions.

Chilling and flight ability and mating competitiveness of sterile males of the Mediterranean fruit fly

AbstractThe Sterile Insect Technique (SIT) is widely used to suppress or eradicate infestations of the Mediterranean fruit fly, Ceratitis capitata (Wied.). In large‐scale programs, sterile males are chilled (4°C) to allow their transfer and storage in the aircraft used for the releases. Sterile males may remain chilled for as long as 3 h prior to release. Here, we describe the results of experiments that assessed the effect of chilling on flight ability and mating competitiveness of sterile male Mediterranean fruit flies held under conditions of low (plastic buckets) or high (emergence tower trays) density. Males from both densities were subject to 0 (no chill), 1, or 3 h of chilling at 3 days of age. Chill treatment had no effect on flight ability for males held at low density. However, for males held at high density, chilling for 1 or 3 h significantly reduced flight ability below that observed for the no chill treatment. Consistent with the flight data, chill treatment had no effect on the mating success of males held at low density. However, among males held at high density, 3 h of chilling significantly reduced mating success below levels observed for unchilled males or males chilled for 1 h only in trials conducted 1 day after the cold treatment. An auxiliary experiment revealed that this reduction in mating performance was temporary: in mating trials conducted 3 days after 3 h of chilling, sterile males derived from tower trays had similar mating success as unchilled males. Implications of these findings for Mediterranean fruit fly SIT are discussed.

Leg impairment magnifies reproductive costs in male Mediterranean fruit flies, Ceratitis capitata

Injuries frequently accumulate with age in nature. Despite the commonality of injury and the resulting impairment, there are limited experimental data for the effects of impairment on life history trade-offs between reproduction and survival in insects. We tested the effects of artificial injury and the resulting impairment on the reproductive costs and behavior of male medflies, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Treatment flies were impaired by amputating tarsomere segments 2-5 from the right foreleg at either eclosion or age 22 days. The effect of impairment and age on the cost of reproduction was tested by varying the timing of female availability among the treatments. Courtship behavior and copulation rates were observed hourly from age 2-5 days to determine the effects of impairment on reproductive behavior. Female access combined with the impairment reduced the life expectancy of males more than the impairment alone, whereas the health effect of amputation was influenced by age. Conversely, the risk of death due to impairment was not influenced by the males' mating status prior to amputation. The males' copulation success was reduced due to impairment, whereas courtship behavior was not affected. Impairment does not reduce the males' impulse to mate but decreases the females' receptivity to copulation, while also increasing the cost of each successful mating. Overall, minor impairment lowers the reproductive success of males and reduces longevity.

Attraction and Electroantennogram Responses of Male Mediterranean Fruit Fly to Volatile Chemicals from Persea, Litchi and Ficus Wood

Trimedlure is the most effective male-targeted lure for the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). A similar response is elicited by plant substances that contain α-copaene, a naturally-occurring sesquiterpene. α-Copaene is a complex, highly-volatile, widely-distributed plant compound, and male C. capitata respond to material from both hosts (e.g., Litchi chinensis) and non-hosts (e.g., Ficus benjamina) that contain α-copaene. Avocado, Persea americana, recently was found to contain varying amounts of α-copaene in the bark and underlying cambial tissue. Short-range attraction bioassays and electroantennography (EAG) were used to quantify responses of sterile male C. capitata to samples of rasped wood from four avocado genotypes, L. chinensis, and F. benjamina. Gas chromatography-mass spectral (GC-MS) analysis was used to identify and quantify the major sesquiterpenes. Attraction and EAG amplitude were correlated, with L. chinensis eliciting the highest and F. benjamina the lowest responses. Responses to the avocado genotypes were intermediate, but varied among the four types. GC-MS identified 13 sesquiterpenes, including α-copaene, from all samples. Amounts of α-copaene in volatile collections from samples (3 g) ranged from 11.8 μg in L. chinensis to 0.09 μg in F. benjamina, which correlated with short-range attraction and EAG response. α-Copaene ranged from 8.0 to 0.8 μg in the avocado genotypes, but attraction and EAG responses were not correlated with the amount of α-copaene. Differences in enantiomeric structure of the α-copaene in the different genotypes and/or presence of additional sesquiterpenes may be responsible for the variation in male response. EAG responses were correlated with the amount of several other sesquiterpenes including α-humulene, and this compound elicited a strong antennal response when tested alone.

Ginger root oil increases mating competitiveness of sterile Mediterranean fruit fly (Diptera:Tephritidae) in Western Australia

AbstractThe exposure of sterile male Mediterranean fruit fly, Ceratitis capitata (Wiedemann) to the aroma of essential oil derived from ginger root Zingiber officinale Roscoe (GRO) has been shown in field cage trials to increase their mating success. This field cage study compared the mating performance of mass reared sterile Mediterranean fruit fly males prepared for ground release programmes under four different post‐irradiation systems, two of which involved exposure of the flies to GRO aroma. In the first system, irradiated pupae were placed into non‐vented 5‐L paper tubs, individually aromatized by 20 μl of GRO (4 ml/m3) for 96–120 h until the adults were 2–3 days old. In the second system, irradiated pupae were placed in vented 5‐L paper tubs, exposed for 24 h in a GRO aromatized room (0.5 ml/m3) when the adults were 3 days old and contained until required for mating tests at 5 days old. The third and fourth systems were the same as the first two systems respectively, except that the flies were not exposed to GRO aroma. Significant differences in mating success were found among treatments. The exposure of 2 to 3‐day old flies to GRO aroma improved mating performance slightly compared with equivalent non‐exposed flies, but it was still below the minimum value accepted under international standards, while 27% of unexposed 5‐day‐old sterile males mated and had competitiveness (Fried value 0.38) slightly above this minimum level. GRO exposed 5‐day‐old flies had the highest mating percentage (67%) and a level of competitiveness (Fried value 1.81) based on induced sterility above that of wild flies (Fried value 1). The results indicate that the effectiveness of sterile male ground release programmes can be increased significantly by releasing 5‐day‐old sterile males that have been exposed to GRO in an entirely aromatized adult fly holding room.

Bacterially enriched diet improves sexual performance of sterile male Mediterranean fruit flies

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), (medfly) is a polyphagous and cosmopolitan agricultural pest, targeted in many areas for control by the Sterile Insect Technique (SIT). Our objective in the present study was to test the hypothesis that a bacterially enriched diet provided to sterile males will improve their sexual performance in competitive settings that emulate natural condi- tions. Specifically we determined how feeding on diets enriched with Klebsiella oxytoca affected the ability of sterile males to compete for wild females against wild males, their ability to inhibit female receptivity, and their survival. We found that enriching the sterile male diet with K.oxytoca significantly improved mating competitiveness in the labora- tory and in field cages. In addition, bacterially enriched sterile males inhibited female receptivity more efficiently than sugar fed males and survived longer duration of starvation. We conclude that inoculating mass reared sterile flies with bacteria prior to their release is a valid approach to improve the efficacy of SIT.

Field Response of Mediterranean Fruit Flies to Ceralure B1 Relative to Most Active Isomer and Commercial Formulation of Trimedlure

In a field test to examine attractancy of Mediterranean fruit fly, Ceratitis capitata (Wiedemann), relative to release rates, equal moles of racemic ceralure B1 and trimedlure isomer C were compared on cotton wicks. Data were collected at 2, 4, and 7 d. The substrates were analyzed for longevity and overall persistence in the field. Ceralure B1 was equally attractive as trimedlure C for the first 2 d and significantly more so at 4 and 7 d based on trap counts of captured male Mediterranean fruit flies. Residue analysis of weathered wicks showed that the trimedlure C lasted for just 2 d in our field evaluations, whereas ceralure B1 had measurable material present after 7 d. Thus, based on the amounts of chemicals released, ceralure B1 was more active even in the first 2 d. Ceralure B1 also was formulated in a plastic matrix (ceralure coin) at three different dosages and tested for attractancy in the field against a 2-g trimedlure plug. A 150-mg ceralure B1 coin was equally attractive as a commercial 2-g trimedlure plug, whereas a 300-mg coin was significantly more attractive during a 6-8-wk deployment. Although our results clearly show that ceralure B1 is a superior attractant to trimedlure, costs of synthesis need to be considered as part of an overall program management strategy.

Survival of sterile male Mediterranean fruit flies in large field cages after release at different ages

AbstractIn Mediterranean fruit fly (Ceratitis capitata) sterile insect technique (SIT) programs worldwide, sterile flies are usually released at 2–3 days of age. However, they usually do not reach full sexual maturity until ca. 5 days of age. We tested whether holding sterile males longer at a fly emergence and release facility, until they were 5 days old, might result in significantly more flies surviving to reach sexual maturity in the field. In large field cages in Hawaii, we released sterile Mediterranean fruit fly males 2 or 5 days old under conditions where food and water were provided, or not provided. Flies were released 2 days after peak emergence in one field cage, while they were released 5 days after peak emergence in a second field cage. The numbers of flies flying out and remaining (dead, dying or non‐flying) in the holding boxes were recorded on the day of fly release. At 5 and 8 days of fly age, the size of the male fly populations were estimated using trimedlure‐baited traps placed into each of the two field cages for a 30‐min period when the numbers of flies trapped were compared. Following six tests (three replications each with and without water and sugar provided), the differences in fly captures (i.e. survival) between 2 days vs. 5 days old releases were highly significant. With food and water provided, several times as many flies from the 5‐day‐old release field cage were captured at 5 and 8 days of age compared to the 2‐day‐old release field cage. These differences were magnified under conditions of no food and water provided. Holding Mediterranean fruit flies longer prior to release, requires more holding space and food, but will lead to significantly greater numbers of sexually mature flies in the field.

Effect of diet on survival, in the laboratory and the field, of sterile male Mediterranean fruit flies

To improve the effectiveness of the sterile insect technique against the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), our objectives in this study were two-fold. First, to evaluate the ability of sterile males of the Vienna-8 strain to survive starvation, we compared them to wild males under laboratory conditions. The second objective was to determine the effect of protein-rich nutrition on sterile male fly survival, under starvation conditions in the laboratory, under semi-natural conditions in a field enclosure, and under natural conditions in the open field. Therefore, we released marked sterile flies of the two diet regimes, protein-fed or protein-deprived, and monitored their survival by recapturing them after 4, 6, and 7 days. In the laboratory, wild males endured starvation significantly better than sterile ones and protein addition to sterile fly diet resulted in even greater reduced capability to endure starvation. On the other hand, the addition of protein to sterile-male diet did not affect their ability to survive in a field enclosure or in the open field. We conclude that under natural conditions, where food is available, sterile male fly survival is unaffected by protein-rich pre-release diet.