Effects of essential oil formulations on Ceratitis capitata Wied. (Dipt., Tephritidae) adult flies

The effects on adult Ceratitis capitata of the ingestion of formulations containing different concentrations of some essential oils were examined. The bioassays were carried out using groups of C. capitata adults fed for 3 days with formulations containing a known concentration (0.25%, 0.5%, 1.0%) of essential oils. The oils, of different chemical composition, were obtained by steam distillation from aromatic plants collected during the balmy period. The essential oils of Rosmarinus officinalis and Salvia officinalis , which are rich in monoterpenic hydrocarbons and monoterpenic ketones, respectively, showed poor activity, whereas the oils of Cinnamomum zeylanicum and Thymus sp. showed a marked toxic effects (over 90% mortality after 72 h). This could be explained by the activity of cinnamic aldehyde (about 80% of the Cinnamomum oil) and carvacrol (68% of Th. capitatus oil and about 45% of Th. herba barona oil). The first consequence of ingesting even small quantities of essential oils was a depressive effect on the nervous system. Dissection of dead flies showed marked differences compared with the controls and microscopic examination revealed anomalies in the gut region.     

Function of multiple sperm storage organs in female Mediterranean fruit flies (Ceratitis capitata, Diptera: Tephritidae)

Sperm storage organs allow females to temporally separate insemination from fertilization, manipulate ejaculates and control fertilization. In the reproductive tract of female fruit flies (Diptera: Tephritidae), sperm are found in two different organs--a pair or triplet of spermathecae, and a "fertilization chamber". In order to understand the specific function of each of these organs, we tested the following hypotheses: (1) Sperm are distributed equally amongst the various sperm storage organs; (2) Both organ types maintain sperm viability; and (3) Sperm used in fertilization come from the fertilization chamber. We counted sperm in spermathecae and fertilization chamber of Mediterranean fruit flies (Ceratitis capitata) every 3 days for 18 days following insemination, and used a live/dead staining technique to determine the viability of sperm in these organs. Finally, by extirpating spermathecae from inseminated females and allowing them to oviposit, we were able to identify the fertilization chamber as the source of fertilizing sperm. Numbers of sperm in the spermathecae declined from an average of 3575 on the day of copulation to 649, 18 days later. Conversely, the fertilization chamber maintained a fairly constant level of sperms, ranging between an average of 207 cells on day 3 to 115 sperms on day 18. Throughout the period we monitored, we found high levels of sperm viability in both organs (> 80%). Sperm viability was similarly high in the fertilization chambers of females without spermathecae. However, fertility of eggs laid by these females declined rapidly, as did the number of sperm in the fertilization chamber. We conclude that both the spermathecae and the fertilization chamber are active sperm storage organs, with separate functions: the spermathecae for long-term storage and the fertilization chamber, periodically filled by the spermathecae, a staging point for fertilizing sperm. We suggest that the use of both organs by females results in sperm economy, which adaptively prolongs the intervals between copulations.     

Uptake of adhesive powders from lure stations by Mediterranean fruit fly (Dipt., Tephritidae)

Powders that are capable of adhering to insect cuticles can act as carrier particles when combined with insecticides, entomopathogens, or pheromones, for targeted insect control. One potential method of delivering the powder to an insect is to lure the insects to stations containing powder using a species‐specific attractant. Here, we report on the uptake of two different powders from lure stations (henceforth called ‘dispensers’) by the Mediterranean fruit fly, Ceratitis capitata, and the transfer of the powders to conspecifics during field studies in Portugal, as part of a research programme to develop lure‐and‐kill technologies based on adhesive powder. Uptake of an electrostatic wax powder, Entostat?, from dispensers was greater than uptake of a proprietary metallic powder, Entomag?, for both wild male C. capitata visiting field‐placed dispensers and laboratory‐reared males confined with dispensers in field cages. In agreement with field data, C. capitata also took up more Entostat than Entomag when artificially dosed on dispenser trays containing powder in the laboratory, and the quantities taken up were shown to be greater than that calculated from field experiments. Increasing the amount of Entostat powder in field‐placed dispensers resulted in greater uptake of powder by visiting male C. capitata. Laboratory‐reared male and female C. capitata were released in field cages in which were hung dispensers containing adhesive powder that were baited with the male attractant trimedlure. After 24 h, the powder was successfully extracted from all males and nearly all females collected, indicating that males probably transferred powder to conspecific females after visiting dispensers. The results underscore that a lure‐and‐kill system based on adhesive powder might have potential for controlling Mediterranean fruit fly and other flying insects.     

Interference between male‐targeted and female‐targeted lures of the Mediterranean fruit fly Ceratitis capitata (Dipt., Tephritidae) in Italy

The efficacy of male‐targeted and female‐targeted baits was compared when lures were presented together or singly in traps for capturing the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). For male‐targeted baits, either trimedlure or ceralure presented singly attracted large numbers of flies, supporting data from many previous reports. The present results are the first published data on the attractiveness of ceralure to a European population of C. capitata. The quaternary female bait consisting of ammonium carbonate, putrescine, trimethylamine and acetic acid was a potent attractant for female flies (and also showed some activity for males). Replacing acetic acid with ammonium acetate in the quaternary female bait did not influence activity. Traps with female‐targeted and male‐targeted baits together always showed a tendency of catching fewer flies than traps with only one type of bait. The decrease was significant in females, regardless of whether ceralure or trimedlure was the male‐targeted bait. In males, the tendency was the same for traps with trimedlure or ceralure alone, catching higher numbers than those with both male and female baits. Our present results suggest that both types of baits mutually decrease the numbers of the non‐target sex in the trap. In conclusion, it is advisable to use both male‐ and female‐targeted baits in separate and distant traps and not jointly in the same trap, lest the efficacy of detection or monitoring trials be compromised.     

Evaluation of synthetic food-based attractants for female Mediterranean fruit flies (Dipt., Tephritidae) in McPhail type traps

During summer 1997 field experiments were conducted on the island of Chios, Greece, to compare captures of female Mediterranean fruit flies (medflies), Ceratitis capitata (Wiedemann), in traps baited with either synthetic female-targeted lures or a standard protein bait (NuLure and borax). The synthetic lures contained ammonium acetate,1,4 diaminobutane (putrescine), and trimethylamine. Two trap types (International Pheromone's McPhail Trap (IPMT) and the Tephri trap) were tested as either wet or dry. Wet IPMT traps baited with the synthetic attractants were the most attractive of all trap combinations tested and captured 2.1 times more female medflies and 1.8 times more total medflies than traps baited with NuLure and borax. Traps containing the synthetic attractant captured approximately 4.6 times fewer nontarget insects than NuLure baited traps. Vapona used in IPMT traps was repellent to medflies and dry traps with lower concentrations of Vapona were approximately 1.5 times less attractive to female medflies than traps containing water. Even with a decrease in attractiveness, the dry traps were significantly more effective for females and more practical for mass trapping and monitoring than the currently used traps baited with protein solutions.     

Short- and long-range dispersal of medfly, Ceratitis capitata (Dipt., Tephritidae), and its invasive potential

Abstract:  Data were obtained from mark recapture trials pertaining to the dispersal of medfly, Ceratitis capitata (Dipt., Tephritidae), over both short (10–160 m) and very long distances (0.5–9.5 km) within the surveillance trapping array in Adelaide, Australia. They could be related to previously reported data sets by expressing the capture rates of each set in common terms that corrected for differences in recapture rate resulting from type of trap, season or climate. The mean capture rate at each distance from the point of release in each data set was expressed as a percentage of the real or inferred rate of that set at a distance of 100 m. The resulting distribution of dispersal distances conformed to both an inverse power model and a modified Cauchy model regardless of whether the present and previous data were combined or not. The modified Cauchy model inferred that the median distance flown was extremely short and 90% of flies displaced only 400–700 m despite the fact that a consistent trend in declining catch rates was obtained up to 9.5 km. The spread of invading propagules in quarantined zones in the first generation is likely to be limited by a decline to non-viable density within 1 km or less of the incursion point and the spread of larger infestations could be limited by the longevity of the dispersers. The results also have significance to the ability of surveillance trapping arrays to detect infestations and also to methods of distributing insects for the 'sterile insect technique'.     

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.     

Essential oils of citrus fruit stimulate oviposition in the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae)

Female Mediterranean fruit flies (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) perceive both qualitative and quantitative aspects of citrus fruit chemistry. However, the behavioural and biological adjustments of this response remain largely unknown. In the present study, the ovipositional responses of gravid female medflies to essential oils (i.e. the most critical resistance factor to medfly infestation) of various citrus fruits are investigated. In dual‐choice (treatment versus distilled water control) experiments, females lay significantly more eggs into pre‐punctured hollow oviposition hemispheres (domes) provided with 1 µL of citrus peel oil from sweet orange, satsuma mandarin, bitter orange, grapefruit and lemon compared with odourless domes. No‐choice tests show a weak effect of lemon essential oils in stimulating oviposition. The female ovipositional response to sweet orange oil (the most active in eliciting oviposition) is dose‐dependent. Additionally, limonene, the most abundant chemical in all citrus oils, stimulates oviposition, whereas linalool, a representative compound of immature citrus fruit associated with high toxicity against immature stages of fruit flies, has a significant deterrent effect. In further no‐choice tests, females lay approximately 23% fewer eggs in limonene (93%) (amount found in orange oil) and 60% fewer eggs in limonene 93% plus linalool 3% (approximately 10‐fold the amount found in orange oil) mixtures, relative to sweet orange oil. The results suggest that the limonene content accounts largely (but not completely) for the ovipositional responses observed in sweet orange oil, whereas high linalool proportions are capable of significantly masking and/or disrupting its stimulatory effects in citrus oils. The importance and practical implications of these findings with respect to understanding how citrus fruit chemistry influences the ovipositional responses of medfly is discussed.     

Life table assay of field-caught Mediterranean fruit flies, Ceratitis capitata, reveals age bias

Though traps are used widely to sample phytophagous insects for research or management purposes, and recently in aging research, possible bias stemming from differential response of individuals of various ages to traps has never been examined. In this paper, we tested the response of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) males and females of four ages (spanning from 1 to 40 days) to McPhail-type traps baited with a synthetic food attractant in field cages and found that the probability of trapping was significantly influenced by age. The type of food on which flies were maintained before testing (sugar or protein) also had a strong effect and interacted with age. In another experiment, we collected wild C. capitata adults of unknown age using 1–3 methods and then reared them in the laboratory until death. The survival schedules of these flies were subsequently used in a life table assay to infer their age at the time of capture. Results showed that on a single sampling date, males captured in traps baited with a food attractant were younger compared with males aspirated from fruiting host trees, or males captured in traps baited with a sex attractant. Likewise, females captured in food-baited traps were younger compared with aspirated females. In addition to providing the first evidence of age-dependent sampling bias for a phytophagous insect species, this paper also provides a novel approach to estimate the differences in the age composition of samples collected with different techniques. These findings are of utmost importance for several categories of insects, medically important groups notwithstanding.     

Oviposition deterrents for the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae) from fly faeces extracts

After oviposition, females of the Mediterranean fruit fly Ceratitis capitata Wiedemann deposit a host-marking pheromone on the fruit surface that deters oviposition by conspecifics. Methanolic extracts of fruit fly faeces elicit a similar deterrent effect. The results of laboratory and field experiments using raw methanolic extracts of C. capitata faeces as an oviposition deterrent are reported. Laboratory bioassays revealed a significant positive relationship between concentration of faeces and the inhibition of oviposition responses by C. capitata. Treatment of halves of coffee bushes with methanolic extracts containing 0.1, 1.0 and 10 mg faeces ml(-1) resulted in a significant reduction of infestation only at the highest concentration (P=0.03). Treatment of blocks of coffee bushes with an extract of 10 mg faeces ml(-1) resulted in an 84% reduction in infestation by C. capitata in sprayed plants and a 56% reduction in adjacent untreated coffee bushes surrounding treated plots, probably due to the deterrent effect of host-marking pheromone on fly oviposition. We conclude that faeces contain oviposition deterrent substances that effectively reduce fruit infestations by C. capitata, suggesting a clear potential for the use of this infochemical in integrated management programmes targeted at this pest.     

Attractiveness for Ceratitis capitata (Wiedemann) (Dipt., Tephritidae) of mango (Mangifera indica, cv. Tommy Atkins) airborne terpenes

The airborne volatiles of the Tommy Atkins cultivar of mango ( Mangifera indica L.), a fruit frequently damaged by Ceratitis capitata , were analysed by aeration of fresh fruits, adsorption and thermal desorption coupled to gas chromatography–mass spectrometry. Ethanol and acetic acid were identified as the major components, together with longifolene, which has not been described before in the mango aroma and other terpenes (α-pinene, 3-carene, p -cymene, limonene and α-terpinolene). The attractiveness of the identified terpenes for C. capitata was tested in laboratory cages and the results showed that p -cymene and limonene were the best terpene attractants for both males and females.     

Phloxine B effect on immature stages of the Mediterranean fruit fly,Ceratitis capitata (Diptera: Tephritidae) (Wiedemann)

A laboratory bioassay was developed to determine both the chemical toxicity and the phototoxicity of the xanthene dye, phloxine B (D&C Red No 28), to the immature stages of the Mediterranean fruit fly, Certitis capitata (Wiedemann). An additional goal was to find out which main tissues are affected first. A low, but significant, level of toxicity was observed when the insects were maintained in the dark: at the point of adult ecdysis, the LC50 was 11.03 mM. As expected, after 8-h exposure of late larva III to light, a high level of mortality was produced (LC50 at ecdysis: 0.45 mM) as a dose-dependent function of dye concentration. At sublethal concentrations of the dye, the surviving insects showed a number of physiological abnormalities. Phloxine B appeared to mainly affect the larval longitudinal muscles as well as the abdominal muscles of ecdysing adults, giving rise to abnormal puparia and failed adult ecdysis, respectively. Moreover, a significant phloxine B-dependent delay in the jumping of surviving larvae for dispersal was documented. This could be attributed to a delay in attaining a threshold weight for jumping and/or to abnormalities in neuromuscular coordination, thus reinforcing the idea of pleiotropic effects of the dye.     

Acrosome formation in Ceratitis capitata (Diptera, Tephritidae)

The stages of morphogenesis of the acrosome of Ceratitis capitata are well defined. This organelle is formed by the Golgi complex and, as it matures, takes up a position laterally in relation to the anterior region of the sperm nucleus. An interstitial membrane marks the area of contact between nucleus and acrosome in the spermatid, and is found even in mature sperm cells. The acrosome contains hydrolytic enzymes, as detected by acid phosphatase reaction.     

地中海实蝇地理种群遗传分化研究

以mtDNA的CO Ⅰ基因的部分序列作为分子标记,研究了来自安哥拉、黎巴嫩、刚果共和国、尼日利亚、贝宁、多哥、加纳、科特迪瓦、南非、埃及、法国、约旦、秘鲁、智利、美国佛罗里达和美国夏威夷等16个国家和地区共75个个体的地中海实蝇Ceratitis capitaza地理种群序列特征和单倍型特征,并分析了各种群间的遗传分化水平和进化关系,结果表明,在供试的样品中发现单倍型的数目是29,其中有5种为共享倍型.地中海实蝇各地理种群的遗传多态性水平差异较大,总体遗传距离D等于0.007.非洲南撒哈拉区(安哥拉、刚果、尼日利亚、贝宁、多哥、加纳、科特迪瓦)的种群的单倍型数、单倍型百分比和群内遗传距离等遗传多态性参数值都高于其它供试地区,多样性明显较其他地区丰富.     

Development of a diagnostic DNA probe for the fruit flies Ceratitis capitata and Ceratitis rosa (Diptera: Tephritidae) using amplified fragment-length polymorphism

The AFLP technique (amplified fragment-length polymorphism) was employed to identify and isolate species specific markers in tephritids. We have found that the technique has good potential for this purpose, with the only difficult part being the reamplification of AFLP fragments from silver stained gels. Cloning of putative species-specific markers and genomic dot blot hybridizations resulted in the development of diagnostic probes for tephritid identification. A repetitive DNA sequence from the genome of Ceratitis capitata (Wiedemann) was isolated. This sequence rapidly and reliably identified C. capitata and C. rosa Karsch in a collection of closely related and outgroup species tested in this study. Although this probe has been developed for C. capitata and C. rosa, the proposed methodology can be applied to any group of organisms.     

Scent Marking by Males of the Mediterranean Fruit Fly, Ceratitis capitata (Diptera: Tephritidae)

Males of the Mediterranean fruit fly, Ceratitis capitata (medfly), defend individual leaves as mating territories. While perching, males release an air-borne pheromone (known to attract females) from everted rectal epithelium at the tip of the abdomen. Males also occasionally touch the substrate with the tip of their abdomen. The main objective of the present study was to determine whether such abdomen dipping was a form of intersexual signaling, i.e., whether this action resulted in increased female visitation to the territory. Following observations on the frequency of pheromone calling and abdomen dipping of individually marked males, I ran a standard set of experiments using leaves from four different plant species. Leaves were exposed to varying numbers of (mature) males and females, respectively, for varying durations, and female settlement was compared on exposed versus nonexposed leaves in laboratory cages. Exposing leaves to females had no, or little, influence on female distribution for any of the four plant species. Exposing leaves to males had little influence on subsequent female settlement for orange, coffee, or macadamia trees. However, leaves of the fig tree Ficus bejamina that were exposed to males were much more attractive to females than nonexposed leaves. I then conducted a series of additional tests using fig leaves and found that i) leaf exposure to immature males had no effect on female distribution, ii) leaf exposure to mature males for as little as 90 min increased leaf attractiveness to females, iii) prohibiting males direct contact with the leaf during exposure eliminated any effect on female settlement, and iv) females discriminated between exposed and nonexposed leaves even in physically complex environments (i.e., potted plants). The possible role of abdomen dipping in sexual advertisement of male medflies is discussed.     

Phenotypic plasticity of thermal tolerance contributes to the invasion potential of Mediterranean fruit flies (Ceratitis capitata)

1. The invasion success of Ceratitis capitata probably stems from physiological, morphological, and behavioural adaptations that enable them to survive in different habitats. However, it is generally poorly understood if variation in acute thermal tolerance and its phenotypic plasticity might be important in facilitating survival of C. capitata upon introduction to novel environments. 2. Here, by comparison of widely distributed C. capitata with a narrowly distributed congener, C. rosa, we show that both species have similar levels of survival to acute high and low temperature exposures under common rearing conditions. However, these species differ dramatically in the time‐course of plastic responses to acute low temperature treatments. 3. The range of temperatures that induce rapid cold hardening (RCH) are similar for both species. However, C. capitata has two distinct advantages over C. rosa. First, at 5°C C. capitata develops RCH significantly faster than C. rosa. Second, C. capitata maintains a RCH response longer than C. rosa (8 vs. 0.5 h). 4. A simple population survival model, based on the estimated time‐course of RCH responses determined for both species, was undertaken to simulate time to extinction for both species introduced into a similar thermally variable environment. The model showed that time to extinction is greater for C. capitata than for C. rosa, especially in habitats where temperatures frequently drop below 10°C. 5. Thus, variation in RCH responses may translate into significant variation in survival upon introduction to novel thermal habitats for C. capitata, particularly in cooler and more thermally variable geographic regions, and may contribute to their ongoing invasion success relative to other, more geographically constrained Ceratitis species.     

Determination of host status of citrus fruits against the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)

Abstract  The Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann) is a pest of citrus in parts of Western Australia. Three citrus cultivars: Valencia oranges, Eureka lemons and Imperial mandarins, as well as non-citrus control fruits, were examined for attractiveness and suitability to Medfly in the field and in the laboratory using choice and no-choice experiments. Oranges were more susceptible to Medfly than mandarins and lemons. Punctures in the skin had a significant impact on the degree of infestation in both citrus and non-citrus control fruit. Artificial infestation and larval survivorship were used to investigate the suitability of each cultivar to Medfly under laboratory conditions. Oranges and mandarins were suitable for the development of Medfly, but lemons were a poor host. When each cultivar was in season, field cage trials demonstrated that infestation occurred in oranges and mandarins but not in lemons.