Susceptibility of the Mediterranean fruit fly (Ceratitis capitata) and the Natal fruit fly (Ceratitis rosa) to entomopathogenic nematodes

The potential of entomopathogenic nematodes, Heterorhabditis bacteriophora, Heterorhabditis zealandica and Steinernema khoisanae, to infect pupariating larvae, pupae and adults of Ceratitis capitata and Ceratitis rosa was investigated in laboratory bioassays. Pupariating larvae and adult flies were susceptible to nematode infection, with no infection recorded for the pupae. Pupariating larvae of C. capitata were generally more susceptible to infection than those of C. rosa. Significantly more larvae of C. capitata were infected by H. bacteriophora. For C. rosa, highest infectivity of larvae was obtained with H. zealandica. In contrast, adults of both species were highly infected by S. khoisanae.     

Host-specific demographic studies of the Mediterranean fruit fly Ceratitis capitata

Abstract. 1. This study was conducted in Greece using a wild strain of medflies ( Ceratitis capitata [Weidemann]) to assess age-specific vital rates in adults, and development and survival in pre-adults when reared on different host fruit. The results were used to construct life tables.
2. The demographic analyses suggested that there are basically four aspects of the medfly's life history which are of major importance: (i) multiple, highlyoverlapping generations; (ii) high net reproduction while young; (iii) high larval fitness in certain hosts; (iv) lack of diapause.
3. Reasons why these characteristics are felt to be important are briefly discussed.     

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.     

Molecular structure of yoyo, a gypsy-like retrotransposon from the Mediterranean fruit fly, Ceratitis capitata

We have isolated and characterized a new LTR-retrotransposon in the genome of the Mediterranean fruit fly (Medfly), Ceratitis capitata. This retrotransposon, which we named yoyo, appears to be a member of the gypsy/Ty3 class of elements. The yoyo element was originally discovered on the Y chromosome of the Medfly. Although the Y chromosome copy appears to be truncated, at least two other apparently complete copies of yoyo from other genomic locations have been isolated and characterized. The complete element is approximately 7.7 kb in size. In addition to fairly typical GAG and POL coding regions, the yoyo element contains a potential ENV gene. The presence of an ENV gene is a key feature distinguishing potential retroviral-like elements, such as gypsy (and possibly yoyo), from many other invertebrate retrotransposons previously described. In addition to the structural features of yoyo, evidence is provided to show that yoyo is capable of movement in the genome, including RFLPs showing variability in genomic localization of copies of yoyo between strains, and differences among individuals in the presence of yoyo at a specific site in the genome. This revised version was published online in July 2006 with corrections to the Cover Date.     

利用CLIMEX预测纳塔尔实蝇在中国的潜在地理分布

纳塔尔实蝇Ceratitis rosa Karsch属双翅目实蝇科腊实蝇属,为害30余种经济植物,被我国列为进境植物检疫性有害生物。本研究运用CLIMEX 3.0及ArcGIS 9.3对纳塔尔实蝇在我国目前及未来的潜在地理分布进行了预测。结果显示：在目前的气候条件下,纳塔尔实蝇在我国的潜在地理分布区为18.250°N-30.250°N,其中,华南和东南地区为高度潜在地理分布区,包括四川、重庆、云南、福建、广东、广西、海南以及台湾等地。在未来的气候条件下,2020和2050年潜在地理分布区的北界分别移至31.250°N和32.250°N,且中度潜在地理分布区北移明显;2100年潜在地理分布区的北界移至33.750°N,且高度适生区北移明显。因此建议目前应加强纳塔尔实蝇检疫措施,完善监测体系,监测网点主要设在我国的南方地区,尤其应对云南、广西、广东、福建和海南等地进行长期监测;同时,应对湖南、贵州、江西、湖北、江苏、安徽等省进行定期监测,严防该虫入侵。     

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.     

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.     

Changes of protein tyrosine phosphorylation in third instar larval integument of the Mediterranean fruit fly, Ceratitis capitata

Developmental analysis of the tyrosine protein phosphorylation levels in larval integument and partial characterization of the endogenous protein tyrosine kinase activity (PTK) in Ceratitis capitata are described in this study. Larval integument contains high levels of PTK activity at the early stages of the third instar, which progressively declines to low levels in the white pupal stage. An integumental 90-kDa polypeptide was identified to have prominent endogenous PTK activity and follow a similar developmental pattern. The major integumental phosphotyrosine-containing polypeptides have apparent molecular weights of 30, 41, 44, 46, and 54 kDa, respectively. Polypeptides with molecular weights of 62 and 73 kDa were identified as Ser/Thr-containing phosphoproteins and were shown to exhibit high levels of phosphorylation at the middle stage of larval development. These differences are likely to be due to the higher activation state of the protein tyrosine kinase(s) at the early stages of larval development.     

Response of Ceratitis capitata to citrus chemicals under semi-natural conditions

Responses of Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) adults to chemicals from citrus fruits were quantified in choice tests conducted in large field cages housing naturally planted orange trees, on the Greek island of Chios. Both sexes responded strongly to chemicals released from artificial cuts made in the pulp of peeled oranges and also to natural or commercial orange juice applied to the surface of yellow 7.0 cm diameter spheres. Males also responded strongly to chemicals released from cuts made in the oily region of the orange peel, or flavedo and less to sour orange and lemon. In contrast, females did not respond to flavedo chemicals. Male response to peel chemicals occurred throughout the day and increased as the number of cuts per fruit increased from 2 to 8. Contact of male mouthparts with sap from cuts, and mating attempts between males on or near the cuts were frequently observed. The males also responded to commercial essential orange oils applied to yellow spheres, but less to essential mandarin oils. The role of citrus chemicals in host finding behaviour of C. capitata and their potential use for the development of effective traps for monitoring and controlling the fly are discussed. The experimental method followed in this study can be used as a standard technique for evaluation of the quality of flies to be used in sterile insect technique programmes.     

Detection of novel mitochondrial haplotype variants in populations of the Mediterranean fruit fly,Ceratitis capitata,from Tunisia,Israel and Morocco

The direct analysis of DNA sequence‐based mitochondrial haplotypes in individuals from populations of the Mediterranean fruit fly, Ceratitis capitata, from Tunisia, Morocco and Israel has revealed levels of genetic diversity that far exceed those previously described. A total of 33 distinct haplotypes were identified from 117 individuals representing seven populations from these countries. A network of haplotypes was constructed showing that we have captured essentially all of the sequence variations present in these populations for this gene. These results have important implications for future studies of the genetic structure of this and other closely related pest species.     

Hosts of Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) from Broome and the Broome Peninsula, Western Australia

Abstract  In the Kimberley region of Western Australia, Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is only established at Broome. From 1998 to 2001 extensive fruit sampling was carried out at Broome during a trial investigating the eradication of medfly from the Kimberley using the sterile insect technique. Fruit was collected from 82 native and introduced plants growing in and surrounding the town of Broome and held for emergence of medfly. Eighteen plants, including the native tree Terminalia petiolaris , were found to be medfly hosts . On the basis of abundance, fruiting phenology and host suitability, eight species (kumquat Fortunella japonica , mango Magnifera indica , Barbados cherry Malpighia glabra , orange jessamine Murraya paniculata , guava Psidium guajava , Pacific almond Terminalia catapa , blackberry tree Terminalia petiolaris and yellow oleander Thevetia peruviana ) were the most important hosts ensuring medfly survival and population growth. Despite medfly being reared from T. petiolaris , it is likely that medfly can only maintain populations in areas close to human habitation, and eradication from these areas would lead to eradication from the whole Kimberley region.     

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.     

Rearing of the fruit fly parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae) on X-ray irradiated larvae of Ceratitis capitata (Diptera: Tephritidae)

We evaluated the effects of X-ray irradiation on larvae of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), with the aim of finding a treatment that prevented adult fly emergence, yet did not adversely affect larval quality as rearing hosts for the parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Ichneumonidae). Two experiments were carried out. In the first experiment, small numbers of larvae were held in Petri dishes with and without small amounts of rearing media and then irradiated with doses of X-rays ranging from 0 to 8333.6 R (equivalent to 80 Gy). In the second experiment, higher numbers of larvae were held in a manner resembling mass-rearing conditions, and were then irradiated with X-rays ranging from 0 to 10,417 R (equivalent to 100 Gy). In both experiments, the only factor that significantly affected fly emergence was irradiation of larvae. Fly emergence decreased markedly as the irradiation dose increased, and complete suppression of fly emergence was achieved at 6250.2 R (equivalent to 60 Gy) when larvae were irradiated in small batches with or without rearing media. Irradiation also affected the fertility of those flies that did emerge following treatment. In the second experiment, we found the parasitoids reared from irradiated larvae produced a higher parasitism rate and a higher number of female offspring than did parasitoids reared from control (non-irradiated) larvae. Mean fecundity of F1 parasitoids reared from irradiated larvae were affected positively by irradiation only at the 8333.6 R (80 Gy) dose. Our results show that X-ray irradiation can be used to inhibit fruit fly adult emergence and that irradiated larvae are at least as good a rearing substrate as non-irradiated larvae. Future studies should focus on the adjustment of our findings to a mass-rearing scale.     

Two-way selection for mating activity in the Mediterranean fruit fly, Ceratitis capitata

No significant variation in mating activity was observed among eight laboratory strains of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Two methods were used to select strains showing high and low mating activity: a single pair technique (SP) assessing time to mating and a mass technique (M) based on a mating index. Reciprocal pairings between fast and slow selected lines showed that the difference between the SP lines was female-determined whereas the difference between the M lines depended on the behaviour of both sexes. M selection, irrespective of its direction, affected two courtship parameters, vibration distance and vibration duration both of which tended to be shorter. M selection was also associated with a reduction in startle activity in females.

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Résumé Aucune variation significative n'a été observée dans les activités sexuelles de huit souches de laboratoire de la mouche méditerranéenne du fruit, Ceratitis capitata (Wiedemann) (Diptera Tephritidae).Deux méthodes ont été utilisées pour sélectionner des souches manifestant une activité sexuelle basse ou élevée: une technique utilisant un seul couple (SP), basée sur la durée de la période avant copulation, et une technique de masse (M), basée sur un index d'accouplement.Des appariements réciproques entre les lignées rapides et lentes ont montré que la différence entre les lignées SP était déterminée par les femelles, tandis que la différence entre les lignées M résultait du comportement des deux sexes. La sélection M, quelle que soit sa direction, affects deux paramètres, la distance entre partenaires lors de la vibration et la durée de la vibration qui tous deux tendent à se raccourcir. La sélection M est aussi associée à une réduction de la réaction des femelles à un brusque stimulus lumineux (Startle activity).

     

地中海实蝇及其近缘种基因芯片检测研究

本研究选择线粒体DNA (mtDNA) 细胞色素氧化酶Ⅰ基因（COⅠ）为分子标记基因,以双翅目实蝇科昆虫DNA序列为目标,建立了我国进境植物检疫害虫地中海实蝇Ceratitis capitata、芒果小条实蝇C. cosyra和纳塔尔小条实蝇C. rosa等生物芯片检测方法。地中海实蝇及其近缘种检测芯片由检测探针（实蝇科通用探针1条,小条实蝇属通用探针1条,地中海实蝇、芒果小条实蝇和纳塔尔小条实蝇近缘种探针2条和种特异探针4条）、质控探针（定位点探针、阳性质控、阴性质控和空白对照探针各1条）组成。芯片检测结果表明,检测探针特异性强,能实现上述3种实蝇的种类快速区分和准确鉴定; 检测方法稳定性好,地中海实蝇不同虫态（卵、幼虫、蛹和成虫）和不同地理种群检测结果完全一致。地中海实蝇生物芯片检测技术将为我国进口果蔬中检疫性实蝇快速筛查和种类鉴定提供检测方法,同时,还可应用到其他属的实蝇以及相关害虫的检疫中,为有害生物的快速鉴定提供了新方法。     

The ceratotoxin gene family in the medfly Ceratitis capitata and the Natal fruit fly Ceratitis rosa (Diptera: Tephritidae)

Ceratotoxins (Ctxs) are a family of antibacterial sex-specific peptides expressed in the female reproductive accessory glands of the Mediterranean fruit fly Ceratitis capitata. As a first step in the study of molecular evolution of Ctx genes in Ceratitis, partial genomic sequences encoding four distinct Ctx precursors have been determined. In addition, anti-Escherichia coli activity very similar to that of the accessory gland secretion from C. capitata was found in the accessory gland secretion from Ceratitis (Pterandrus) rosa. SDS-PAGE analysis of the female reproductive accessory glands from C. rosa showed a band with a molecular mass (3 kDa) compatible with that of Ctx peptides, also slightly reacting with an anti-Ctx serum. Four nucleotide sequences encoding Ctx-like precursors in C. rosa were determined. Sequence and phylogenetic analyses show that Ctxs from C. rosa fall into different groups as C. capitata Ctxs. Our results suggest that the evolution of the ceratotoxin gene family might be viewed as a combination of duplication events that occurred prior to and following the split between C. capitata and C. rosa. Genomic hybridization demonstrated the presence of multiple Ctx-like sequences in C. rosa, but low-stringency Southern blot analyses failed to recover members of this gene family in other tephritid flies.     

Mitochondrial DNA variation in Spanish populations of Ceratitis capitata (Wiedemann) (Tephritidae) and the colonization process

Abstract: Mitochondrial DNA variation in the Mediterranean fruit fly Ceratitis capitata (Wiedemann, Diptera: Tephritidae) was studied in three natural populations from southern, central and eastern Spain by means of restriction fragment length polymorphisms using 22 restriction endonucleases. Nine different haplotypes were found based upon the restriction patterns of the seven polymorphic endonucleases, providing a measure of discrimination between populations (N_ST = 0.2462, F_ST = 0.154). The observed distribution of haplotypes, corroborated by a parsimonious unrooted tree, suggests an ancient origin for haplotype VII, and a first step in the colonization of the Iberian Peninsula and subsequently the northern and eastern Mediterranean basin, through the Straits of Gibraltar. No relationship can be established between the colonization process for Europe and America.     

Performance of controlled-release formulations of trimedlure to attract the Mediterranean fruit fly, Ceratitis capitata

Mediterranean fruit flies (Ceratitis capitata Wied.) are detected by traps baited with the attractant, trimedlure (TML), deposited on the standard cotton dental roll dispenser. Since this dispenser is effective for only 2–4 weeks, controlled-release dispensers may extend the field life of TML-baited traps. A polymeric plug containing 70% by weight TML was highly effective for 8–12 weeks. Other formulations were less effective in the tests with released flies. A release rate of ca. 17 mg of standard TML/day or higher gave insect captures which were generally lower but statistically equivalent to those with the reference dispenser which released 61–63 mg/day. Normalized insect catches increased approximately as the square root of the release rate; the curvilinear regression equation suggested that TML release rates of ca. 52 and 15 mg/day give insect captures equal to ca. 100% and 50%, respectively, of the reference catches. The most attractive TML isomer (TML-C) was a highly effective attractant at a release rate of ca. 4 mg/day.

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Résumé C. capitata était attiré par des pièges alimentés avec de la trimedlure (TML), attractif déposé sur un distributeur commercial de coton dentaire en rouleau. Puisque ce distributeur ne fonctionne que 2 à 4 semaines, des distributeurs à libération contrôlée peuvent augmenter le temps de fonctionnement de pièges fournis en TML. Un bouchon en polymère contenant en poids 70% de TML a été très efficace pendant 8 à 12 semaines. D'autres formules ont été moins efficaces avec des mouches lâchées. Un taux de libération, de 17 mg ou plus de TML moyen par jour, capture moins, mais sans différence statistique significative, qu'un distributeur témoin qui libérait 61 à 63 mg/j. Les captures d'insectes ont augmenté à peu près comme le carré du taux de libération; l'équation de régression curviligne a conduit à penser que la libération de TML à des taux de 52 et 15 mg/j, provoque des captures égales à 100% et 50% des captures de référence. L'isomère le plus attractif (TML-C) a été un attractif très efficace au taux de libération de 4 mg/j.

     

Effects of egg load on finding and acceptance of host fruit in Ceratitis capitata flies

Abstract. In studies conducted on potted host trees in field cages and in the laboratory, we examined the influence of egg load on the finding and acceptance of high-ranking (kumquat) and lower-ranking (grapefruit) hosts for oviposition by wild-origin Mediterranean fruit fly females, Ceratitis capitata (Wiedemann). By prescribing the periods during which females had access to protein prior to testing, we generated four classes of females having progressively increasing egg loads but not differing in population origin, age, degree of protein hunger at testing, or amount of prior experience with host fruit (none). Egg load had no discernible effect on behaviour associated with finding either type of fruit but did have a significant effect on several behaviours associated with oviposition after alighting on fruit. Increasing egg load led to increasing propensity to engage in ovipositional-type behaviour on both kumquats and grapefruits. There was no evidence, however, to support a hypothesis that medflies would become less discriminating against grapefruits relative to kumquats as egg load increased. Relative to kumquats, grapefruits were accepted for oviposition by intermediate and high egg load females to a substantially greater degree in laboratory cages than on trees, suggesting that results of laboratory cage experiments on host discrimination by tephritid flies may poorly reflect differences in behavioural responses expressed under less constrained conditions.     

Intron size polymorphism of the Adh1 gene parallels the worldwide colonization history of the Mediterranean fruit fly, Ceratitis capitata

The exon-primed intron-crossing (EPIC) PCR technique was used to analyse the size variation at the first intron of the Ceratitis capitata Adh ₁ gene. A total of 27 samples from 16 natural populations was analysed from five geographical regions in the species range: Africa, Mediterranean Basin, Latin America, Hawaii and Australia. The Adh ₁ first intron varies extensively in length with at least 18 size variants ranging from 1400 bp to 3450 bp. These variants can be grouped into four distinct size categories: short, medium, long and very long. The majority of these variants are present only in the African populations. Only a subset of the ancestral variants appear to have succeeded in migrating from Africa during the medfly colonization process. The medfly population structure inferred from the intron size polymorphism is congruent with that observed from the analysis of allozyme variation. The geographical dispersal of the medfly from its source area is associated with a gradual and great reduction in intron variability which parallels the trend of decreasing variability evaluated at 26 biochemical loci. The intron phylogenetic tree is in agreement with allozyme data in portraying the dynamic population history of the medfly. Stochastic evolutionary forces such as drift, bottleneck effects and migration seem to have played the major roles in the dispersion pattern of Adh ₁ intron variation during the colonization of the medfly.