Significance of fruit flies in vegetable crops. Vegetable crops hold a key position in agricultural production in Reunion (Indian Ocean); however, many pests and diseases threaten the profitability of this agricultural sector. Fruit flies (Diptera: Tephritidae) figure among the main pests for solanaceous crops and cucurbits (cucumber, zucchini, melon, etc.). Losses of as much as 80% of tomato and 100% of cucurbit crop harvests have been frequently observed. Inventory and distribution. Four fruit fly species belonging to the Tephritidae family cause major damage to vegetable crops in Reunion: Bactrocera cucurbitae (Coquillet), Dacus ciliatus Loew and D. demmerezi (Bezzi) on Cucurbitaceae, and Neoceratitis cyanescens (Bezzi) on Solanaceae (primarily the tomato). Distribution of each of them is presented. Biology and behavior. A few studies on the biology and behavior of the four fruit flies were conducted in Reunion in the late 1990s. Their main biological characteristics are summarized. Population control methods used in Reunion. Various methods such as chemical control, preventive measures (sanitation), physical control, biotechnical control [colored traps, the Male Annihilation Technique (MAT) and the Bait Application Technique (BAT)], and biological control currently used in Reunion against fruit flies are reported. Other control methods such as Integrated Pest Management and the Sterile Insect Technique are not used in Reunion. Prospects for implementing agro-ecological management of vegetable fruit flies in Reunion. This part presents research actions implemented in fly bio-ecology, research actions into the genetic structure of populations and design of an agro-ecological management scheme for vegetable fruit flies. Conclusions. The control methods used independently have not been successful to effectively control tephritid populations. A more integrated approach is required, also taking into account the landscape scale and its mosaic of habitats, especially wild plants, whose role must be considered within a framework of agro-ecological management of these pest populations.

Introduction. After harvest, litchi fruits (Litchi chinensis Sonn.) rapidly lose their bright red skin color. Peel browning of harvested litchi fruit has largely been attributed to rapid degradation of red anthocyanin pigments associated with the oxidation of phenolic compounds by polyphenol oxidase (PPO) and/or peroxidase (POD). An anthocyanase has been also identified in litchi peel. Our work aimed at characterizing two specific litchi varieties that differ greatly in their color and browning behavior. Materials and methods. The anthocyanins, polyphenol oxidase (PPO), peroxidase (POD) and anthocyanase in the pericarp of two litchi cultivars, Kwai May and Wai Chee, grown in Reunion Island and Spain, respectively, were studied. Results and discussion. The qualitative composition of major anthocyanins (cyanidin-3-rutinoside and cyanidin-3-glucoside) was identical for the two cultivars studied, but, quantitatively, the variety Kwai May had a lower concentration than Wai Chee (64% less) of cyanidin-3-rutinoside. This component represented more than 90% of total anthocyanins in both cultivars. The activity of PPO was 6 times greater in the variety Kwai May than in Wai Chee and the activity of POD 30 times greater. The activity of POD was greater than that of PPO in both varieties. These differences help to explain the different behaviors of the cultivars during subsequent postharvest studies.

Introduction. Deux espèces de pitaya coexistent à la Réunion : Hylocereus undatus et H. costaricensis. Ces deux espèces, introduites, s'y reproduisent végétativement et, bien qu'elles fleurissent, ne produisent que rarement des fruits. Une étude a donc été menée pour vérifier les causes de l’improductivité de ces espèces et apprécier le rôle d’éventuels agents pollinisateurs. Matériel et méthodes. Deux modes de pollinisation libre (nocturne ou diurne) et deux modes de pollinisation contrôlée (croisement interspécifique manuel et autopollinisation) ont été comparés sur une parcelle plantée avec les deux espèces H. undatus et H. costaricensis intercalées. Les observations ont porté sur la viabilité du pollen, la nature des agents pollinisateurs, les conditions de pollinisation et la fructification. Résultats. Nous avons vérifié que l’absence de productivité des deux clones d’Hylocereus en conditions naturelles était due à leur auto-incompatibilité. En effet, aucune fécondation n’a été observée sur les 200 autopollinisations effectuées en 1999. Cette auto-incompatibilité n’est pas liée à une stérilité du pollen dont la viabilité in vitro s’est révélée satisfaisante. D'autre part, si les abeilles jouent un rôle dans la fécondation des deux clones, les fruits résultant de ces pollinisations libres sont significativement moins lourds que ceux issus d’une pollinisation manuelle croisée. Discussion et recommandations. Seule une pollinisation croisée et manuelle peut donc permettre aux deux clones d’Hylocereus présents sur l’île de la Réunion de produire des fruits de qualité. Un itinéraire technique de fécondation est proposé.

Introduction. In Algeria, the Mediterranean fruit fly Ceratitis capitata Wiedmann constitutes the main obstacle to production and exportation of many fruits. In studies of the genetic structure differences of medfly populations, certain authors, using molecular markers, observed the existence of different patterns among the pest Mediterranean populations. A clear understanding of the source and migration of the Mediterranean fruit fly would be useful for undertaking a successful eradication or control program. For this reason, preliminary work sought to compare the genetic structure of Algerian populations of C. capitata with that of other populations situated either in the western Indian ocean or on the northwestern Mediterranean coast. Materials and methods. The study of enzyme polymorphism allowed the comparison of the genetic structure of four Algerian populations of Ceratitis capitata with one from Reunion Island and five other populations collected from the northwestern Mediterranean coast (France and Spain). Enzyme analyses were performed on ground pest adults electrophoresed on a starch gel. Fifteen loci were analyzed for each population. Results and discussion. In spite of a wide geographic distribution of the analyzed populations (from a latitude of 24° to 44° N), no gradient of allelic frequencies was observed for any of the polymorphic loci. A higher genetic variability was observed in the population of Reunion Island than in the populations of Algeria or the northwestern Mediterranean coast. No genetic differentiation was observed among the populations of southern Algeria (Djanet and Ghardaïa) and northern Algeria (Boufarik and Oran).

Introduction. Beginning in 1994, vanilla vines grown under shade houses in Reunion Island have developed disorders mainly due to the cymbidium mosaic potexvirus (CymV) and potyviruses. To reduce damage and avoid viral epidemics, we considered developing a vanilla nursery to supply farmers with virus-free plant material and to provide prophylactic advice. Accordingly, we determined the relationship between symptoms on vanilla leaves and viral diagnosis. We also determined the temporal and spatial distribution patterns of viral diseases. Materials and methods. Symptom assessment and serological tests were carried out on vanilla leaves (Vanilla fragrans) at various times. The relationship between symptoms and viral infection data was analyzed with Statistica software. Spatial distribution patterns of infected plants were generated with two-dimensional distance class analysis (2DClass). Results and discussion. Results showed that symptoms do not correlate well with serological diagnosis. Plants in all shade houses in the survey were infected mainly by CymV which spreads in the row according to cultural practices. Potyviruses could be transmitted both by insect vectors and mechanically, but for the latter case less efficiently than CymV. Conclusion. Results from this study can be used to develop control measures, including the production of healthy planting materials to manage plant disease epidemics. Further studies will involve the characterization of vanilla potyviruses so that reliable serological techniques and better molecular tools can be developed.