Adult Mediterranean Fruit Flies Research Articles

Age and mating status have complex but modest effects on the critical thermal limits of adult Mediterranean fruit flies from geographically divergent populations.

The highly invasive Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is currently expanding its geographic distribution into cooler temperate areas of the Northern Hemisphere. In marginal conditions, the invasion potential of medfly depends in part on innate tolerance to the novel environmental conditions. Physiological tolerances are potentially influenced by interactions among multiple factors, such as organism age or reproductive maturity, sex, and mating status. Furthermore, the relationships between the above factors and tolerances may differ among geographically distinct populations. Here, the effects of age and mating status on thermal tolerance of three geographically distinct medfly populations along a latitudinal gradient ranging from Greece (Crete & Volos) to Croatia (Dubrovnik) were examined. The upper and lower critical thermal limits (scored as loss of neuromuscular function during controlled cooling or heating) of adult males and females (a) at 1-, 6-, 15-, and 35 days old and of (b) both mated and virgin flies were assessed. Results showed that estimates of lower and upper thermal limits (CTmin and CTmax) were both population- and age-dependent. In most age classes tested, CTmin values were lower for the adults obtained from Crete and higher for those from Dubrovnik. CTmax values were lower for the females from Dubrovnik compared to the females from any other population on day one after emergence but not on days 6, 15 and 35. Differences among populations were observed across different age classes both for cold and heat tolerance but mostly in CTmin estimates. Mating status had a little effect on cold and heat tolerance. Complex patterns of thermal limit variation within and among populations suggest a suite of factors determine population-level mortality from thermal extremes under field conditions in medfly. These results contribute towards understanding the invasion dynamics of medfly and its range expansion to northern, more temperate regions of Europe.

Evaluation of insecticidal activity of Lavandula coronopifolia essential oil against the Mediterranean fruit fly Ceratitis capitata Wiedemann (Diptera: Tephritidae)

The present investigation was aimed to assess the toxicity of Lavandula coronopifolia (Lamiaceae) essential oil (EO) against adult Mediterranean fruit fly. Ceratitis capitata (Wiedemann) (Diptera Tephritidae) is one of the most destructive fruit pests in Morocco.Essential oil was extracted from leaves of lavender (L. coronopifolia) by hydrodistillation and analyzed by GC and GC/MS. The main compound is carvacrol (48.9%) followed by E-caryophyllene (10.8%) and caryophyllene oxide (7.7%).The EO was examined in the laboratory for 7 days to assess their activity against Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) adults by ingestion toxicity. We also conducted oviposition bioassay in the laboratory, testing the oviposition deterrence of essential oils.The oil showed 75% mortality of adults at the concentration of 150 µl/g after 24 h of exposure. Great differences in insect mortality were observed depending on the sex of the insects, oil concentrations and exposure time.The ingestion toxicity potential of L. coronopifolia on adults was higher (LC 50 = 86.34 µl/g, LC 95 = 236.07 µl/g) and also, deterred significantly the oviposition by C. capitata, reducing the number of eggs laid by about 94% compared with the controls for the concentration of 55µl/g.Results suggested that L. coronopifolia EOs may have potential as a control agent against this major stored product insect.

The Survival of Mediterranean Fruit Fly (Diptera: Tephritidae) Over Winter in Western Australia.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is one of the most economically important pest insects of fruit crops worldwide. Mediterranean fruit fly can cause up to 100% crop loss in susceptible fruit. In order to formulate best management practices, it is critical to understand how Mediterranean fruit fly overwinters in a given geographical location and bridge the gap between autumn and spring populations. In this study, we evaluated the overwintering potential of Mediterranean fruit fly immature and adult stages in two locations in Perth Hills, Western Australia. We also monitored wild adult Mediterranean fruit fly populations for 2 yr. Adults were present year-round with captures very low in winter to early spring relative to summer and autumn. Field experiments revealed that immature stages in apples (eggs/first instar) and soil (pupae) remained viable in winter, emerging as adults at the onset of warmer weather in spring. In field cages, adults survived 72-110 d, and female laid viable eggs when offered citrus fruit, though only 1-6% eggs survived to emerge as adults. Adults survived longer in field cages when offered live citrus branch. The findings suggest that all Mediterranean fruit fly life stages can survive through mild winter, and surviving adults, eggs in the fruit and/or pupae in the soil are the sources of new population that affect the deciduous fruit crops in Perth. We recommend that Mediterranean fruit fly monitoring is required year-round and control strategies be deployed in spring. Furthermore, we recommend removal of fallen fruit particularly apple and other winter fruit such as citrus.

Toxic and hormetic-like effects of three components of citrus essential oils on adult Mediterranean fruit flies (Ceratitis capitata).

Plant essential oils (EOs) and a wide range of their individual components are involved in a variety of biological interactions with insect pests including stimulatory, deterrent, toxic and even hormetic effects. Both the beneficial and toxic properties of citrus EOs on the Mediterranean fruit fly (medfly) have been experimentally evidenced over the last years. However, no information is available regarding the toxic or beneficial effects of the major components of citrus EOs via contact with the adults of the Mediterranean fruit fly. In the present study, we explored the toxicity of limonene, linalool and α-pinene (3 of the main compounds of citrus EOs) against adult medflies and identified the effects of sub-lethal doses of limonene on fitness traits in a relaxed [full diet (yeast and sugar)] and in a stressful (sugar only) feeding environment. Our results demonstrate that all three compounds inferred high toxicity to adult medflies regardless of the diet, with males being more sensitive than females. Sub-lethal doses of limonene (LD20) enhanced the lifespan of adult medflies when they were deprived of protein. Fecundity was positively affected when females were exposed to limonene sub-lethal doses. Therefore, limonene, a major constituent of citrus EOs, induces high mortality at increased doses and positive effects on life history traits of medfly adults through contact at low sub-lethal doses. A hormetic-like effect of limonene to adult medflies and its possible underlying mechanisms are discussed.

Culture conditions affect virulence and production of insect toxic proteins in the entomopathogenic fungus Metarhizium anisopliae

Conidial spores are often used as the infectious agent during insect biocontrol applications of entomopathogenic fungi. Here we show differential virulence of conidia derived from Metarhizium anisopliae strain EAMa 01/58-Su depending upon the solid substrata used for cultivation, where LC50 values differed by up to ~10-fold (5.3×106−4.5×105 conidia/ml) and LT50 values by ~40% (9.8−7.1 d). This fungal strain is also known to secrete proteins that are toxic towards adult Mediterranean fruit flies, Ceratitis capitata, and the Greater wax moth, Galleria mellonella, larvae. In vitro production and intrahemoceol injection using G. mellonella as the host was used to test fractions during purification of the protein toxins, demonstrating that they elicited defence-related responses including melanisation and tissue necrosis. Production of these proteins/peptides along with a number of potential cuticle degrading enzymes was confirmed both in vitro and during the infection process (in vivo). Two-dimensional gel electrophoresis, followed by gel elution and bioassay, was used to identify at least three proteins or peptides (molecular mass=11, 15 and 15 kDa) as mediating the observed insect toxicity. These data demonstrate that in vitro screening for insect toxins can mimic in vivo (i.e. during the infection process) secretion and applies the use of proteomics to invertebrate pathology.

Susceptibility of kiwifruit (Actinidia spp.) cultivars to Ceratitis capitata (Diptera: Tephritidae) infestation

AbstractLaboratory no‐choice tests were conducted to determine whether the kiwifruit cultivars Hayward, Tsechelidis (Actinidia deliciosa) and Soreli (A. chinensis) are hosts of the Mediterranean fruit fly, Ceratitis capitata. Kiwifruits were exposed to gravid females for 24 h, and the number of eggs laid as well as larval developmental rates and survival rates of immatures' was determined. Moreover, oviposition and survival rates were recorded for adults obtained from the above three cultivars. Similar experimental procedures were followed using nectarines (Prunus persica), a favourable host for C. capitata. Furthermore, using McPhail‐type traps loaded with food attractants, we compared adult population densities in four kiwifruits and adjacent citrus orchards. Infestation rates were also determined in kiwifruits collected from the above kiwifruit orchards. The results demonstrate that C. capitata, under laboratory conditions, oviposit on all three kiwifruit cultivars tested. The numbers of eggs laid and survival rates of immatures were significantly lower for the two cultivars of A. deliciosa compared with nectarines. On the other hand, oviposition rates were much higher in the cultivar Soreli (A. chinensis) compared with nectarines; however, none of the immatures reached adulthood. Adults obtained from the Hayward and Tsechelidis cultivars had shorter longevity and females were less fecund than those obtained from nectarines. Adult Mediterranean fruit flies were captured in all four kiwifruit orchards, but at significantly lower numbers compared with citrus orchards. Fruit sampling from the Hayward and Tsechelidis cultivars indicated a minimal infestation of the Hayward fruits only (0.41%), which, however, resulted in no adult emergence. Removal of the fruit surface hairs of Hayward cultivar increased dramatically the oviposition rates of C. capitata in laboratory conditions, suggesting significant oviposition‐deterrent properties. The importance of our findings for determining a non‐host status for kiwifruits is discussed.

Toxicity of some essential oil formulations against the Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera Tephritidae)

Essential oils (EOs) extracted from fresh leaves of rosemary (Rosmarinus officinalis L.), lavender (Lavandula angustifolia Miller), chan (Hyptis suaveolens (L.) Poiteau (Lamiaceae) and arborvitae (Thuja occidentalis L. – Cupressaceae) were evaluated for their toxicity against adult Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera Tephritidae), a worldwide fruit pest. The chemical composition of the EOs was also investigated. T. occidentalis and H. suaveolens EOs were dominated by monoterpene hydrocarbons, followed by sesquiterpene hydrocarbons in H. suaveolens and oxygenated sesquiterpenes in T. occidentalis. Oxygenated monoterpenes were the main chemical class in R. officinalis and L. angustifolia EOs. In ingestion toxicity assays, T. occidentalis was the most toxic oil, with an LC50 of 5371 ppm. At the highest dose (2.5% w/v), no differences between the four EOs were observed in the ingestion toxicity assay. Topical applications revealed that all the EOs had a good insecticidal activity at 24 h. At 0.1 μL/fly, R. officinalis, L. angustifolia and T. occidentalis caused mortality rates higher than 70%. In fumigation trials, the essential oils of L. angustifolia and R. officinalis were the most toxic at 24 h, with CL50 of 9.09 and 16.73 μg/L air, respectively. Generally, all the EOs showed remarkable toxic effects against medfly adults, regardless of the bioassay used. The development of a technology that allows the incorporation of the EO in a food bait could provide an alternative method of C. capitata attract and kill field applications.

Spatio-temporal distribution of Ceratitis capitata population in a heterogeneous landscape in Central Italy

The spatio-temporal dynamics of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), was investigated to evaluate the effect of the landscape elements and host plants on pest distribution, in an agricultural landscape of 500 ha located in Central Italy. Two farms (farm 1 and farm 2) are located in the experimental area, composing mixed fruit orchards and surrounded by hedgerows, small woodlots, private gardens and cereal fields. Ceratitis capitata population fluctuation was monitored, from 2006 to 2008, using traps baited with trimedlure. Geostatistical methods such as Inverse distance squared weighted were used to obtain distributional maps of adults, mainly males. Results showed that the adult Mediterranean fruit flies were primarily distributed inside farm 1, with the maximum density found in the months of September and October. Away from the principal host plants, particularly in cereal fields, the number of trapped individuals was always low or zero. In both farms, flies were caught sequentially in traps located on host plants (i.e. peach, apple, pear, oriental persimmon and prickly pear) at varying times of maturation, especially when fruits remained on the trees. Distributional maps provided evidence that allowed to identify habitats in which the fly developed early in the season (mixed peach orchards) and afterwards during the periodic flights.

Within-generation variation of critical thermal limits in adult Mediterranean and Natal fruit flies Ceratitis capitata and Ceratitis rosa: thermal history affects short-term responses to temperature

Insect thermal tolerance shows a range of responses to thermal history depending on the duration and severity of exposure. However, few studies have investigated these effects under relatively modest temperature variation or the interactions between short- and longer-term exposures. In the present study, using a full-factorial design, 1 week-long acclimation responses of critical thermal minimum (CTmin) and critical thermal maximum (CTmax) to temperatures of 20, 25 and 30 °C are investigated, as well as their interactions with short-term (2 h) sub-lethal temperature exposures to these same conditions (20, 25 and 30 °C), in two fruit fly species Ceratitis capitata (Wiedemann) and Ceratitis rosa Karsch from South Africa. Flies generally improve heat tolerance with high temperature acclimation and resist low temperatures better after acclimation to cooler conditions. However, in several cases, significant interaction effects are evident for CTmax and CTmin between short- and long-term temperature treatments. Furthermore, to better comprehend the flies' responses to natural microclimate conditions, the effects of variation in heating and cooling rates on CTmax and CTmin are explored. Slower heating rates result in higher CTmax, whereas slower cooling rates elicit lower CTmin, although more variation is detected in CTmin than in CTmax (approximately 1.2 versus 0.5 °C). Critical thermal limits estimated under conditions that most closely approximate natural diurnal temperature fluctuations (rate: 0.06 °C min−1) indicate a CTmax of approximately 42 °C and a CTmin of approximately 6 °C for these species in the wild, although some variation between these species has been found previously in CTmax. In conclusion, the results suggest critical thermal limits of adult fruit flies are moderated by temperature variation at both short and long time scales and may comprise both reversible and irreversible components.

Thermal tolerance in adult Mediterranean and Natal fruit flies ( Ceratitis capitata and Ceratitis rosa): Effects of age, gender and feeding status

1. Determining the critical thermal limits to activity is a first step towards clarifying how temperature affects population dynamics and geographic distribution of ectothermic insects. However, thermal tolerance may be influenced by a number of factors at the species or population level, including age, gender and feeding status. 2. Here, we report the results of experiments investigating the effects of age, gender and feeding status on adult Mediterranean fruit fly ( Ceratis capitata) and Natal fruit fly ( Ceratitis rosa) thermal tolerance. We measured critical thermal maximum (CT max) and critical thermal minimum (CT min) using a dynamic method on different ages (2, 5, 9, 14, 28 days old) and feeding states (recently fed vs. fasted for 48 h) in both genders of adult C. rosa and C. capitata. 3. Results show that for the adult life-stage of C. rosa and C. capitata CT max significantly increases with age up to 14 days. Generally, CT min also varied with age and 14-day-old flies were the most low temperature tolerant. However, 28-day-old flies in both species generally had poorer thermal tolerance (i.e. narrower thermal range) than younger flies. Feeding significantly improved both CT max and CT min while gender had little influence. 4. Preliminary comparisons of C. capitata and C. rosa thermal tolerance suggests that both species have similar CT min (5.4–6.6 °C) but C. capitata have significantly higher CT max (42.4–43.0 °C) than C. rosa (41.8–42.4 °C). These results support observations that C. capitata inhabits warmer geographic areas than C. rosa. Furthermore, these data are significant for understanding population dynamics under agro-ecosystem conditions and the potential geographic distribution of these species.

Are citrus species favorable hosts for the Mediterranean fruit fly? A demographic perspective

AbstractWe studied, under laboratory conditions, demographic parameters of adult Mediterranean fruit flies,Ceratitis capitata(Wiedemann) (Diptera: Tephritidae) (medfly), obtained from three sweet orange varieties, lemon, and bitter oranges. These data were combined with immature developmental rates and survival on the same hosts to estimate host‐specific population parameters. Pairs of newly emerged adults from each citrus variety were held individually in transparent plastic cages, and females were allowed to oviposit in either red domes (artificial, pre‐punctured plastic oviposition devices), or intact, whole citrus fruits. We found strong effects of larval host (citrus fruits) on adult longevity and fecundity. In all five citrus varieties, females did not manage to deposit eggs into fruit pulp. The proportion of eggs laid in either the flavedo or albedo area of the fruit peel differed depending on the citrus variety. In all cases except bitter oranges, females oviposited fewer eggs in citrus fruits than in the artificial oviposition substrates, suggesting that most citrus fruits cause a significant reduction in the reproductive potential of medflies. Negative correlations were found between fecundity and (a) the density of oil glands, and (b) the amount of essential oils in the flavedo area of citrus fruits. There was no correlation between fecundity and other fruit physical characteristics, such as resistance of fruit peel to pressure and thickness of the flavedo. Apparently, resistance of citrus fruits to medfly infestation is directly related to citrus essential oils. The intrinsic rate of increase (r) was higher in bitter oranges than in the three sweet orange varieties tested. A negative r was estimated for flies that developed and oviposited in lemons, indicating a tendency for population decrease in this host. The suitability of citrus fruits for medfly development and the practical implications of our findings for management of medflies in citrus orchards are discussed.

Establishment and Vertical Passage of Enterobacter (Pantoea) Agglomerans and Klebsiella pneumoniae through All Life Stages of the Mediterranean Fruit Fly (Diptera: Tephritidae)

Abstract We investigated the fate of ingested Enterobacter (Pantoea) agglomerans and Klebsiella pneumoniae within adult Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), in a mass rearing facility. This examination revealed the establishment of both bacterial strains as biofilms within the adult intestines, on the apical end of developing and developed eggs, and throughout all subsequent life stages. The bacteria were detected in adults through two generations. Irradiation treatment for the sterile insect technique did not disrupt the vertical transmission of E. (P.) agglomerans or K. pneumoniae. This is the first demonstration of maternal spread of Enterobacter/ Pantoea spp. and Klebsiella spp. through populations of C. capitata. A mixed pattern of vertical and horizontal transmission of symbionts associated with tephritids may be one explanation for the difficulty in defining the symbiotic associations of tephritids.

Chemosterilants as control agents of Ceratitis capitata (Diptera: Tephritidae) in field trials

Lufenuron is a chitin synthesis inhibitor, which is able to impede Mediterranean fruit fly, Ceratitis capitata (Wiedemann), reproduction. In laboratory trials, following ingestion of lufenuron, the eggs laid by female Ceratitis capitata were prevented from hatching. In field trials in Valencia, Spain, lufenuron showed its effectiveness by reducing C. capitata wild populations and its continuous application to several generations of fruit fly resulted in increased pest control. This field trial was conducted in an isolated valley some 80 ha in size, over a continuous four-year period. In order to maintain the sterilizing effect in the field throughout the whole year, a new lufenuron bait gel was developed. This bait gel was introduced in to delta traps suspended in trees at a density of 24 traps ha-1, and these traps were replaced once a year during the field trial. Monitoring of the adult C. capitata population was conducted to assess the effects of the chemosterilant treatment. In the first year of treatment with sterilizing traps, a reduction of the C. capitata population was observed, indicating that the traps reduce the population right from the first generation. In the second, third and fourth years, a continuous and progressive reduction of the adult Mediterranean fruit fly population was observed. Therefore, the successive application of chemosterilization treatment has a cumulative effect on reducing the fly population year after year. Aerial treatment using malathion does not produce this cumulative effect, and consequently every year it is necessary to start again with the same number of flies as the year before. The possibility of using the chemosterilant method alone or combined with the sterile insect technique is discussed.

Mediterranean fruit fly as a potential vector of bacterial pathogens.

The Mediterranean fruit fly (Ceratitis capitata) is a cosmopolitan pest of hundreds of species of commercial and wild fruits. It is considered a major economic pest of commercial fruits in the world. Adult Mediterranean fruit flies feed on all sorts of protein sources, including animal excreta, in order to develop eggs. After reaching sexual maturity and copulating, female flies lay eggs in fruit by puncturing the skin with their ovipositors and injecting batches of eggs into the wounds. In view of the increase in food-borne illnesses associated with consumption of fresh produce and unpasteurized fruit juices, we investigated the potential of Mediterranean fruit fly to serve as a vector for transmission of human pathogens to fruits. Addition of green fluorescent protein (GFP)-tagged Escherichia coli to a Mediterranean fruit fly feeding solution resulted in a dose-dependent increase in the fly's bacterial load. Flies exposed to fecal material enriched with GFP-tagged E. coli were similarly contaminated and were capable of transmitting E. coli to intact apples in a cage model system. Washing contaminated apples with tap water did not eliminate the E. coli. Flies inoculated with E. coli harbored the bacteria for up to 7 days following contamination. Fluorescence microscopy demonstrated that the majority of fluorescent bacteria were confined along the pseudotrachea in the labelum edge of the fly proboscis. Wild flies captured at various geographic locations were found to carry coliforms, and in some cases presumptive identification of E. coli was made. These findings support the hypothesis that the common Mediterranean fruit fly is a potential vector of human pathogens to fruits.

Infection ofCeratitis capitata by two species of theEntomophthora muscae species complex (Zygomycetes: Entomophthorales) in the field

Adult Mediterranean fruit flies (Ceratitis capitata), collected in the field, were infected with entomophthoralean fungi. The fungi sporulated poorly on the cadavers, and resting spores, rhizoids and cystidia were not observed. Measurements of conidia and nuclei and counts of nuclei per conidium from different specimens suggest that the causative agents wereEntomophthora muscae sensu stricto andEntomophthora schizophorae, species recently separated from theEntomophthora muscae species complex. This is the first report ofC. capitata as a host for entomopathogenic fungi.

Population Fluctuations of Adult Mediterranean Fruit Flies (Diptera: Tephritidae) in a Mediterranean Heterogeneous Agricultural Region

We investigated the regional population fluctuations of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in a Mediterranean setting located in the hills (700 m above sea level) of central Israel. The region is composed of commercial orchards, residential mixed-fruit gardens, and Mediterranean shrubs and forests. Adult C. capitata population in the studied region was sampled weekly for 2 years (1994–1995) with Trimedlure traps spread as grids of different scales (between 74–130 traps). No flies were trapped during the winter and early spring months. During the summer and fall, flies were caught sequentially in traps located on host trees (i.e., apple, fig, and mixed fruit-gardens with apricot, plum, and others) at varying times of maturation. Flies first appeared in 'Granny Smith' apple orchards (May–June), which are also the same places where the last adult flies were trapped during December. This fact points at the possibility that C. capitata overwinters as larvae in these orchards on nondecaying apple fruits. Small numbers of flies were caught in traps located on nonhost trees—with the exception of English walnut, which showed large trapping numbers between May and August and which seems to be related to the availability of large amounts of aphid honeydew that probably served to replenish energy reserves of the overwintering populations. Traps on abandoned fig trees, which have the apparent role for the expansion of the population in the summer, caught large numbers of flies between August and November. We conclude that the perpetuation of C. capitata in this Mediterranean setting reflects the ability of an overwintering population to realize its reproductive potential by exploiting the continuous succession of oviposition hosts during the warmer months.

Effects of diet and activity on lipid levels of adult Mediterranean fruit flies

Abstract. The objectives of this study were to determine whether adult Mediterranean fruit flies, Ceratitis capitata Wiedeman (Diptera: Tephritidae), are capable of synthesizing lipids, and whether adult diet affects this ability.Lipid levels in females fed protein and carbohydrate or carbohydrate alone declined significantly from emergence to the fourth day of life and then rose back to teneral levels on the fifth day, before oviposition took place on the sixth day.In males fed protein and carbohydrate, lipid levels initially declined as males aged and then stabilized.In carbohydrate‐fed males lipid levels declined following emergence and recovered somewhat by the sixth day.Lipid levels declined significantly when flies underwent post‐emergence starvation, but after substantial feeding on the above‐mentioned diets they eventually (within 6–7 days) reached teneral levels in all experimental groups.Multivariate analysis of variance revealed that differences in lipid contents are primarily related to the flies' age, which corresponds to the various sex‐specific activities these flies exhibit.Average lipid investment in eggs was found to equal teneral lipid levels in females.Without lipogenic abilities, oviposition would completely deplete female lipid reserves.We conclude that adult medflies are capaple of lipid synthesis, and that this capability is modulated by individual and sex‐specific activity patterns.

Suppression of a Mediterranean Fruit Fly (Diptera: Tephritidae) Population with Concurrent Parasitoid and Sterile Fly Releases in Kula, Maui, Hawaii

Irradiated adult Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were released at an average rate of 3 million per week for 5 mo in a sterile insect technique (SIT) program to suppress a wild C.capitata population in the 13-km2 area of Kula, Maui, HI. Concurrent with sterile fly releases, the braconid larval parasitoid Diachasmimorpha tryoni (Cameron) was released at an average rate of 388,000 per week. The average weekly overflooding ratio was 76.0 ± 4.8 sterile/wild flies. Mean number (±SEM) of male C. capitata trapped per day was significantly reduced to 0.15 ± 0.05 in Kula compared with 1.30 ± 0.17 in a nearby control area. The mean percentage of C. capitata eggs hatching was significantly lower in Kula (22.9 ± 4.2%) than in the control area (90.2 ± 0.9%). The overall mean percentage parasitism of C. capitata in fruit samples was significantly higher in Kula (47.2 ± 2.7%) than in the control area (20.3 3.1%). After the first month of parasitoid releases, D. tryoni became the dominant parasitoid present in Kula, representing 61.6 ± 6.3% of the parasitoids recovered from C. capita’s in fruit samples. The mean number of adult C. capita’s recovered per kilogram of fruit was significantly lower in Kula (9.8 ± 1.3) compared with the control area (92.6 ± 22.7). This field experiment suggests that the concurrent release of parasitoids and sterile flies represents a valuable approach to eradication of established Mediterranean fruit fly populations.

Sex differences in movement between natural feeding and mating sites and tradeoffs between food consumption, mating success and predator evasion in Mediterranean fruit flies (Diptera: Tephritidae).

Systematic quantitative observations of the location and diel pattern of adult Mediterranean fruit fly, Ceratitis capitata (Wiedemann), activities were carried out in an orange grove and surroundings on the island of Chios in Greece. Natural fly foods were assessed for their contribution to fly longevity, fecundity and fertility. There were diel shifts in male and female location. Females required a substantial and varied diet to realize peak fecundity. This diet was acquired away from the primary host, orange. Foraging for food throughout most of the day on fig and non-host foliage (including feeding on bird droppings) as well as on fig fruit and grapes, females dispersed and fed more than males. A diet of grapes alone did not support any fecundity, contributing only to longevity. A diet of figs alone, on the other hand, sustained both longevity and egg production. Bird feces alone supported neither egg production nor longevity. However, when added to a diet of figs, bird feces significantly increased fly fecundity. Throughout most of the day, males aggregated in leks within the inner canopy of the primary host, orange. The arrival here during the warmest hours of the day of receptive females, followed by pair formation, reinforced the lek mating system on host foliage. In the afternoon, females shifted to orange fruit where they suffered from high predation mortality while ovipositing. Soon after, males also shifted to orange fruit, where they attempted matings with non-receptive ovipositing females. Male feeding on fig fruit occurred late in the day, a time when they were least likely to find a mate. Male survival did not differ between the natural diets. Tradeoffs between food consumption, mating success and predator evasion are discussed for each sex and related to fruit fly mating systems.

Mediterranean Fruit Fly (Diptera: Tephritidae) in Nature: Location and Diel Pattern of Feeding and Other Activities on Fruiting and Nonfruiting Hosts and Nonhosts

Systematic quantitative observations of locations and diel patterns of activities of adult Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were made in a semiisolated mixed orchard and surroundings in southern Egypt during 4 wk in early autumn 1984. Flies were regularly sighted on all fruiting and nonfruiting hosts, whereas on nonhost vegetation they were observed occasionally. At dawn, both sexes were at rest in upper sunlit parts of tree canopies, where females began primarily feeding and males released pheromone and began calling activities. With increasing temperature and light, flies moved progressively to lower, more shaded positions. Most feeding events occurred on juice oozing from ripe guava and wounds on orange fruit. Bird droppings and leaf surfaces (probably providing bacteria as nitrogen sources) were additional important feeding sites. Male feeding on fruit peaked in the late afternoon; most ovipositions (on orange and guava) also occurred then. The high level of predation on fruit is proposed as an explanation of the origin of lek behavior on foliage. We, as observers, could detect leks by the odor of the male pheromone. Preferred sites for lek formation were the illuminated areas of tree canopies that were on or near fruiting host trees and that were protected by dense foliage from intense predation by Odonata and wasps. The greatest number of calling males, bouts of male-male competition, leks, and mating pairs were found on fruiting citrus trees. Attraction of females to calling males and formation of mating pairs peaked in midmorning and again following hot midday temperatures.