Survival and development of different life stages of three Ceratitis spp. (Diptera: Tephritidae) reared at five constant temperatures

Fruit flies (Diptera: Tephritidae) are the most damaging pests on fruit crops on Réunion Island, near Madagascar. Survival and development of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), the Natal fruit fly, C. rosa Karsch and the Mascarenes fruit fly, C. catoirii Guérin-Mèneville were compared at five constant temperatures spanning 15 to 35 degrees C. Durations of the immature stages of C. capitata, C. rosa and C. catoirii ranged from 14.5-63.8, 18.8-65.7 and 16.8-65.8 days, respectively, at 30-15 degrees C. The lower developmental threshold and thermal constant were calculated using the temperature summation model. The thermal constant for total development of the immature stages of C. capitata, C. rosa and C. catoirii were 260, 405 and 356 DD, respectively. Species differed mainly during the larval stages and ovarian maturation period, with smaller differences in the egg stage. Ceratitis rosa appeared to be better adapted to low temperatures than the two other species as it showed a lower larval developmental threshold of 3.1 degrees C compared to 10.2 degrees C for C. capitata and 8.9 degrees C for C. catoirii. Overall, C. catoirii had a low survival rate within the range of temperatures studied. The different responses of the three Ceratitis species to various temperatures explain to some extent their distribution on the island. The results obtained will be used for optimizing laboratory rearing procedures and for constructing computer simulation models to predict fruit fly population dynamics.     

Climatic niche partitioning following successive invasions by fruit flies in La Réunion

1. Biological invasions have profound effects on community structure. The community composition following invasions can be influenced by the habitat diversity and the species' responses to abiotic factors. 2. We evaluated the tolerance to climatic factors and analysed the field distribution of four polyphagous fruit flies (Diptera: Tephritidae) of La Réunion Island (three exotic species that successively invaded the island and the endemic species Ceratitis catoirii) in order to evaluate the opportunities of coexistence by niche differentiation. 3. Atmospheric humidity and immersion in water in the laboratory greatly influence the survival of fruit fly pupae. While C. catoirii and C. rosa are very sensitive to desiccation, C. capitata and especially Bactrocera zonata are relatively tolerant. B. zonata also tolerated immersion in water much longer than did C. rosa and C. catoirii, that in turn were more resistant than C. capitata. Overall, field distributions agree with the predictions based on this study of humidity combined with previous data on the effects of temperature. 4. Climatic niche partitioning promotes coexistence between some but not all pairs of invasive species. Thus, C. rosa can coexist with both C. capitata and B. zonata at the regional scale, while climatic niches are not different enough to promote coexistence of the latter two species. The endemic species has no private climatic niche either and this now very rare species could be in the process of extinction. 5. By promoting coexistence or not, climatic diversity in invaded areas can directly affect the community composition following invasions.     

Can host‐range allow niche differentiation of invasive polyphagous fruit flies (Diptera: Tephritidae) in La Réunion?

Abstract.  1. Biological invasions bring together formerly isolated insect taxa and allow the study of ecological interactions between species with no coevolutionary history. Among polyphagous insects, such species may competitively exclude each other unless some form of niche partitioning allows them to coexist.
2. In the present study, we investigate whether the ability to exploit different fruits can increase the likelihood of coexistence of four species of polyphagous Tephritidae, one endemic and three successive invaders, in the island of La Réunion. In the laboratory, we studied the performances of all four species on the four most abundant fruit resources in the island, as well as the relative abundances of fly species on these four fruit species in the field. We observe no indication of niche partitioning for any of the four abundant fruits.
3. Analyses of an extensive field data series suggest that: (i) the four fly species largely overlap in fruit exploitation, once climatic effects are accounted for; (ii) however, one species ( Ceratitis capitata ) can exploit rare fruit species that are not exploited by others present in the same climatic niche; and (iii) the endemic species C. catoirii , now nearly extinct in La Réunion, has no private niche with respect to either climatic range or fruit use.
4. On the whole, with the possible exception of C. capitata , the results point to a limited role of fruit diversity in encouraging coexistence among polyphagous tephritids recently brought into contact by accidental introductions.     

Molecular phylogenetics of the genus Ceratitis (Diptera: Tephritidae)

The Afrotropical fruit fly genus Ceratitis MacLeay is an economically important group that comprises over 89 species, subdivided into six subgenera. Cladistic analyses of morphological and host use characters have produced several phylogenetic hypotheses for the genus. Only monophyly of the subgenera Pardalaspis and Ceratitis (sensu stricto) and polyphyly of the subgenus Ceratalaspis are common to all of these phylogenies. In this study, the hypotheses developed from morphological and host use characters are tested using gene trees produced from DNA sequence data of two mitochondrial genes (cytochrome oxidase I and NADH-dehydrogenase subunit 6) and a nuclear gene (period). Comparison of gene trees indicates the following relationships: the subgenus Pardalaspis is monophyletic, subsection A of the subgenus Pterandrus is monophyletic, the subgenus Pterandrus may be either paraphyletic or polyphyletic, the subgenus Ceratalaspis is polyphyletic, and the subgenus Ceratitis s. s. might not be monophyletic. In addition, the genera Ceratitis and Trirhithrum do not form reciprocally monophyletic clades in the gene trees. Although the data statistically reject monophyly for Trirhithrum under the Shimodaira-Hasegawa test, they do not reject monophyly of Ceratitis.     

Revision of the subgenus Ceratitis (Pardalaspis) Bezzi, 1918 (Diptera, Tephritidae, Ceratitini)

Abstract. The fruit fly genus Ceratitis (Diptera: Tephritidae) comprises several important pest species attacking a wide range of unrelated fruits. In this paper the subgenus Ceratitis ( Pardalaspis ) Bezzi is revised. Ten species are recognized of which five are described as new: C.(P.)hamata sp.n., C.(P.)munroi sp.n., C.(P.)serrata sp.n., C.(P.)semipunctata sp.n. and C.(P.)zairensis sp.n. A key to both sexes is provided. All species are restricted to the Afrotropical Region and distributional and known host plant data are given.     

Irradiation of mangoes as a postharvest quarantine treatment for fruit flies (Diptera: Tephritidae)

Mangoes infested with third instar larvae were irradiated using Co-60 gamma rays and a dose interval of 2-250 Gy to assess the irradiation dose required to prevent adult emergence of the Mexican fruit fly (Anastrepha ludens), the West Indies fruit fly (A. obliqua), the sapote fruit fly (A. serpentina), and the Mediterranean fruit fly (Ceratitis capitata). Doses of 76.9, 87.3, 91.4 and 112.7 Gy, were estimated to inhibit 99.9968% (probit 9) of adult emergence forA. obliqua, A. serpentina, A. ludens, and C. capitata, respectively. Using mangoes infested with a total of 100,000 larvae of each species, the results obtained in the laboratory were confirmed using a dose of 100 Gy for the Anastrepha species and 150 Gy for C. capitata. No adult emergence was observed for any of the four species compared with approximately 80% emergence in the controls. A dose of 150 Gy is recommended as a generic quarantine treatment against potential infestation of these species in exported mangoes. A minor decrease in the ascorbic acid content was the only adverse effects observed in irradiated mangoes.     

The complete nucleotide sequence of the mitochondrial genome of the oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae)

The complete mitochondrial genome of the oriental fruit fly Bactrocera dorsalis s.s. has been sequenced, and is here described and compared with the homologous sequences of Bactrocera oleae and Ceratitis capitata. The genome is a circular molecule of 15,915 bp, and encodes the set of 37 genes generally found in animal mitochondrial genomes. The structure and organization of the molecule is typical and similar to the two closely related species B. oleae and C. capitata, although it presents an interesting case of putative intra-molecular recombination. The relevance of the growing comparative dataset of tephritid complete mitochondrial genomes is discussed in relation to the possibility to develop robust assays for species discrimination in quarantine and agricultural monitoring practices, as well as basic phylogeography/population genetic studies.     

The fruit fly PUB: a phagostimulation unit bioassay system to quantitatively measure ingestion of baits by individual flies

Abstract:  A bioassay to investigate quantitative phagostimulation and ingestion physiology of baits on individual fruit flies is presented. The study was undertaken using two fruit fly species: the Mediterranean fruit fly ( Ceratitis capitata ), a cosmopolitan insect pest, and the Ethiopian fruit fly ( Dacus ciliatus ), a quarantine insect in Israel. Our model bait suspension included spinosad as the toxic agent, and 1% yeast hydrolysate with 10% sucrose as phagostimulant. A preliminary toxicology study showed that the two fruit flies are highly sensitive to low concentrations of spinosad baited with this phagostimulant. The maximum concentration needed to kill 90% of the female flies was 4.2 and 8.5 p.p.m. for C. capitata and D. ciliatus , respectively. The bioassay was able to detect the ingestion of low volumes (e.g. 1  μ l) of tested solutions. The bioassay was also able to detect differences in intake of different concentrations of spinosad solutions and relate ingestion to fruit fly mortality. Additionally, the bioassay was sensitive enough to highlight differences in intake related to the physiological status of the fruit fly and fly species. The bioassay can also be used to follow ingestion kinetics of baits. We expect that this bioassay will contribute in the exploration of more efficient bait systems for fruit flies.     

Ceratotoxins: female-specific X-linked genes from the medfly, Ceratitis capitata.

In this paper, we report the chromosomal localization of ceratotoxins, a gene family encoding antibacterial female-specific peptides from the mediterranean fruit fly Ceratitis capitata. The analysis of both polytene and mitotic chromosomes by in situ hybridization shows that ceratotoxins are the first case of female-specific X-linked genes from the medfly C. capitata. Southern blot analysis reveals that the ceratotoxin gene family is not specifically amplified in the female reproductive accessory glands of C. capitata.     

Population genetics of the potentially invasive African fruit fly species, Ceratitis rosa and Ceratitis fasciventris (Diptera: Tephritidae)

A set of 10 microsatellite markers was used to survey the levels of genetic variability and to analyse the genetic aspects of the population dynamics of two potentially invasive pest fruit fly species, Ceratitis rosa and C. fasciventris, in Africa. The loci were derived from the closely related species, C. capitata. The degree of microsatellite polymorphism in C. rosa and C. fasciventris was extensive and comparable to that of C. capitata. In C. rosa, the evolution of microsatellite polymorphism in its distribution area reflects the colonization history of this species. The mainland populations are more polymorphic than the island populations. Low levels of differentiation were found within the Africa mainland area, while greater levels of differentiation affect the islands. Ceratitis fasciventris is a central-east African species. The microsatellite data over the Uganda/Kenya spatial scale suggest a recent expansion and possibly continuing gene flow within this area. The microsatellite variability data from C. rosa and C. fasciventris, together with those of C. capitata, support the hypothesis of an east African origin of the Ceratitis spp.     

Native and introduced host plants of Anastrepha fraterculus and Ceratitis capitata (Diptera: Tephritidae) in northwestern Argentina

Wild or commercially grown, native and exotic fruit were collected in 30 localities in the Tucumán province (NW Argentina) from January 1990 to December 1995 to determine their status as hosts of Anastrepha fraterculus (Wiedemann) and/or Ceratitis capitata (Wiedemann), the only two fruit fly species of economic and quarantine importance in Argentina. A total of 84,094 fruit (3,466.1 kg) representing 33 species (7 native and 26 exotic) in 15 plant families were sampled. We determined the following 17 host plant associations: Annona cherimola Miller (Annonaceae), Citrus paradisi Macfadyn (Rutaceae), Diospyros kaki L. (Ebenaceae), Eugenia uniflora L., Psidium guajava L., Myrcianthes pungens (Berg) Legrand (Myrtaceae), Ficus carica L. (Moraceae), Juglans australis Grisebach (Juglandaceae), Mangifera indica L. (Anacardiaceae), Eriobotrya japonica (Thunb.) Lindl., Prunus armeniaca L., P. domestica L., and P. persica (L.) Batsch (Rosaceae) were infested by both A. fraterculus and C. capitata. Citrus aurantium L., Citrus reticulata Blanco, Citrus sinensis (L.) Osbeck (Rutaceae), and Passiflora caerulea L. (Passifloraceae) were only infested by Ceratitis capitata. Out of a total of 99,627 adults that emerged from pupae, 69,180 (approximately 69.5%) were Anastrepha fraterculus, 30,138 (approximately 30.2%) were C. capitata, and 309 (approximately 0.3%) were an unidentified Anastrepha species. Anastrepha fraterculus predominated in native plant species while C. capitata did so in introduced species. Infestation rates (number of larvae/kg of fruit) varied sharply from year to year and between host plant species (overall there was a significant negative correlation between fruit size and infestation level). We provide information on fruiting phenology of all the reported hosts and discuss our findings in light of their practical (e.g., management of A. fraterculus and C. capitata in citrus groves) implications.     

Host status of Vaccinium reticulatum (Ericaceae) to invasive tephritid fruit flies in Hawaii

Ohelo (Vaccicinium reticulatum Small) (Ericaceae) is a native Hawaiian plant that has commercial potential in Hawaii as a nursery crop to be transplanted for berry production or for sale as a potted ornamental. No-choice infestation studies were conducted to determine whether ohelo fruit are hosts for four invasive tephritid fruit fly species. Ohelo berries were exposed to gravid female flies ofBactrocera dorsalis Hendel (oriental fruit fly), Ceratitis capitata (Wiedemann) (Mediterranean fruit fly), Bactrocera cucurbitae Coquillet (melon fly),or Bactrocera latifrons (Hendel) in screen cages outdoors for 24 h and then held on sand in the laboratory for 2 wk for pupal development and adult emergence. Only B. dorsalis successfully attacked and developed in ohelo berries. In total, 1570 berries produced 10 puparia, all of which emerged as adults, for a fruit infestation rate of 0.0064% and an average of 0.0053 puparia per gram of fruit. By comparison, papaya fruit used as controls produced an average of 1.44 B. dorsalis puparia per g of fruit. Ohelo berry is a marginal host for B. dorsalis and apparently a nonhost for C. capitata, B. cucurbitae, and B. latifrons. Commercial plantings of ohelo will rarely be attacked by fruit flies in Hawaii.     

Comparison of the mitotic karyotypes of Ceratitis capitata, Ceratitis rosa, and Trirhithrum coffeae (Diptera: Tephritidae) by C-banding and FISH.

The sex chromosomes of the tephritid fruit fly Ceratitis capitata (Wiedemann) are heteromorphic. The male-determining region was located on the Y chromosome by deletion mapping using unbalanced offspring from several translocation strains. In addition, we showed that only 15% of the Y chromosome is required for male determination and male fertility. Based on this result, we expected to find Y-chromosomal length polymorphism in natural populations. Using fluorescence in situ hybridization with two repetitive DNA probes that label the Y chromosome, no obvious size differences were detected in seven wild-type strains and three mutant strains. As the medfly is probably of East African origin, we also analyzed two wild-type strains established recently from pupae sampled in Kenya. The Y chromosomes show a polymorphism in the hybridization pattern of a repetitive Y-specific medfly clone. However, the overall size of the Y chromosome is similar to that of the other strains. Besides C. capitata, the tephritid fruit flies Ceratitis (Pterandrus) rosa Karsch and Trirhithrum coffeae Bezzi also emerged from pupae sampled in Kenya. Their karyotype was analyzed by C-banding. Furthermore, the ribosomal genes were mapped to the sex chromosomes in these two species. Key words : Ceratitis capitata, Tephritidae, C-Banding, FISH, rDNA.     

Pathogenicity of Metarhizium anisopliae (Metsch.) Sorokin and Beauveria bassiana (Balsamo) Vuillemin,to three adult fruit fly species: Ceratitis capitata (Weidemann), C. rosa var. fasciventris Karsch and C. cosyra (Walker) (Diptera :Tephritidae)

The pathogenicity of two isolates of Beauveria bassiana and 12 of Metarhizium anisopliae towards adult fruit flies, Ceratitis capitata and Ceratitis rosa var. fasciventris was tested in the laboratory. Fruit flies were exposed to dry conidia evenly spread on velvet material covering the inner side of a cylindrical plastic tube. All isolates tested were pathogenic to both species of fruit flies. Mortality ranged from 7 to 100% in C. capitata and from 11.4 to 100% in C. rosa var. fasciventris at 4 days post-inoculation. Six isolates, M. anisopliae ICIPE 18, 20, 32, 40, 41 and 62, were highly pathogenic to both C. capitata and C. rosa var. fasciventris. The LT90 values of the most pathogenic isolates ranged between 3-4 days in both insects. Because of the difficulties in rearing C. cosyra, only the isolates that were highly pathogenic to both C. rosa var. fasciventris and C. capitata were tested against adult C. cosyra. They caused mortality of between 72-78% at 4 days post-inoculation. The LT90 values in all the isolates did not exceed 4 days. One of the most pathogenic isolates, M. anisopliae ICIPE 20, was evaluated against C. capitata and C. rosa var. fasciventris in cage experiments using three autoinoculators (maize cob, cheesecloth and Petri dish) in an autoinoculative device consisting of plastic mineral bottle. Mortality of between 70-93% was observed in flies of both species that were captured from the cages and held under laboratory conditions. These results indicate the possibility of fruit fly suppression with entomopathogenic fungi using an autoinoculative device.     

Comparative analysis of microsatellite loci in four fruit fly species of the genus Ceratitis (Diptera: Tephritidae)

The possibility to cross-species amplify microsatellites in fruit flies of the genus Ceratitis was tested with the polymerase chain reaction (PCR) by analysing 23 Ceratitis capitata (Wiedemann) microsatellite markers on the genomic DNA of three other economically important, congeneric species: C. rosa (Karsch), C. fasciventris (Bezzi) and C. cosyra (Walker). Twenty-two primer pairs produced amplification products in at least one of the three species tested. The majority of the products were similar, if not identical in size to those expected in C. capitata. The structures of the repeat motifs and their flanking sequences were examined for a total of 79 alleles from the three species. Sequence analysis revealed the same repeat type as the homologous C. capitata microsatellites in the majority of the loci, suggesting their utility for population analysis across the species range. A total of seven loci were differentially present/absent in C. capitata, C. rosa, C. fasciventris and C. cosyra, suggesting that it may be possible to differentiate these four species using a simple sequence repeat-based PCR assay. It is proposed that medfly-based microsatellite markers could be utilized in the identification and tracing of the geographical origins of colonist pest populations of the four tested species and in the assessment of their risk and invasive potentials; thereby assisting regulatory authorities in implementing quarantine restrictions and other pest control measures.     

Exceptional longevity in the tephritid, Ceratitis rosa, a close relative of the Mediterranean fruit fly

This study shows that the fruit fly, Ceratitis rosa (Karsch), has a significantly longer life span than the medfly, C. capitata (Wiedemann); the species used as a model organism for the demographics of insect aging. This was somewhat surprising given that both have similar distributions and overlapping niches. We postulate that the greater longevity of C. rosa is related to the fact that it can occupy colder habitats where the availability of suitable host plants may be very unpredictable in both time and space.     

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.     

Novel bait stations for attract-and-kill of pestiferous fruit flies

A novel, visually-attractive bait station was developed in Hawaii for application of insecticidal baits against oriental fruit fly, Bactrocera dorsalis (Hendel), melon fly, Bactrocera cucurbitae (Coquillett), and Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (all Diptera: Tephritidae). The bait station developed represents a supernormal visual stimulus of papaya foliage and takes advantage of the flies' strong response to the high light-reflecting properties of yellow color and of their need for shelter, while fully protecting the bait against rainfall. Field studies revealed that the behavioral response of female fruit flies, in particular C. capitata and B. cucurbitae , to yellow-painted bait stations sprayed with GF-120 NF Naturalyte Fruit Fly Bait was significantly enhanced compared with similarly sprayed bait stations that mimicked the green color of fully grown papaya leaves. Field studies conducted with B. cucurbitae indicated that the period of bait attractiveness can be extended for at least 1 week after bait application due to the rain-fastness properties of the bait stations and the use of a visually-attractive color. Our studies provide the behavioral basis for the development of improved attract-and-kill bait stations for fruit flies in Hawaii. These devices also provide a standardized way of evaluating bait spray formulations, thus allowing for proper comparisons over time, across species, and among geographical areas.     

Perimeter trapping strategy to reduce Mediterranean fruit fly (Diptera: Tephritidae) damage on different host species in Israel

To evaluate the perimeter trapping strategy as a control method, field tests were conducted in three different host species of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in Israel. Dry traps baited with a three component food-based synthetic attractant that were hung in the peripheral rows of a plum, a pear, and a persimmon orchard, caught female C. capitata (up to 20.1, 1.4, and 4.1 female C. capitata per trap per day, respectively). Fruit damage, estimated at harvest, indicated a negligible percentage for the plum orchard (< 1%), 3% for the persimmon orchard (compared with 9% at an untreated neighboring plot), and no damaged fruit in the pear orchard. Finally, dissections of female C. capitata caught in dry traps on different host plant species indicate that a high percentage (range, 84-100%) contained mature eggs. The attraction of mature females to the dry traps might explain the successful results. Future research, to determine precisely how many traps should be placed and how frequently they should be serviced, is necessary before applying this strategy on a commercial basis.     

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.