The melon fruit fly, Bactrocera cucurbitae (Coquillett), is a serious agricultural pest which has defied the various control measures employed against it. Protease inhibitors present in plants which have the potential to inhibit the growth and development of associated insect pests can be a possible alternative which can be manipulated for developing resistance in plants to the pest. In the present study, winged bean (Psophocarpus tetragonolobus) protease inhibitor isolated through affinity chromatography was explored for its potential to disrupt the development of melon fruit fly, B. cucurbitae. Different concentrations (12.5, 25, 50, 100, 200, and 400 µg ml−1) of the winged bean protease inhibitor (WBPI) were incorporated into the artificial diet of the second instar (64–72 h old) larvae of B. cucurbitae. The WBPI significantly delayed the larval, pupal, and total development period. The percentage pupation and adult emergence of the treated larvae was reduced as compared with control. The activities of major digestive enzymes (trypsin, chymotrypsin, leucine aminopeptidase, and elastase) decreased significantly in the larvae treated with different concentrations (50, 100, 200, and 400 µg ml−1) of WBPI. The findings reveal that the inhibitor holds considerable promise for the management of the melon fruit fly.

Plant protease inhibitors (PI) constitute a major class of defence proteins being selected as an important strategy towards insect herbivory. With the objective of assessing the effect of PI towards larval growth and development, an artificial diet bioassay using partially purified PI obtained from peas was performed on the melon fruit fly Bactrocera cucurbitae (Coquillett). Larval growth and developmental parameters were assessed at different concentrations (namely 12.5, 25, 50, 100, 200 and 400 μg/ml) on the second-instar larvae of B. cucurbitae. Growth and survival responses determined the anti-insect potential of this PI even in its partially purified state. Larval and total development periods were found to be significantly prolonged for the larvae fed on an artificial diet incorporated with pea PI when compared with those fed with a control diet. Furthermore, when compared with the effect of the control diet (no inhibitor), the partially purified pea PI in the diet reduced larval weight gain, mean larval growth rate and food assimilated with respect to the control of the second-instar larvae tested at the same range of concentrations. The relative effectiveness of pea PI on these parameters is in agreement with the results obtained for percentage of pupation and percentage of adult emergence, as these parameters were significantly affected by the increase in the PI concentration in the artificial diet. Feeding the second-instar larvae a diet containing a range of concentrations (50, 100, 200 and 400 μg/ml) of partially purified pea PI significantly reduced the activities of digestive enzymes (trypsin, chymotrypsin, elastase and leucine aminopeptidase) and significantly affected the activities of other non-digestive enzymes (esterase, acid and alkaline phosphatases, glutathione S-transferase, superoxide dismutase and catalase).

Introduction. Knowledge of tephritid diversity in Senegal was poor before 2004, so PIP-COLEACP and CIRAD, in collaboration with Cérès-DPV, carried out, in 2004, trapping for preliminary detection of fruit flies in six orchards in the Niayes zone. Materials and methods. We selected three mixed mango orchards and three homogeneous mango orchards in this zone. In each orchard, we used three attractants: Terpinyl acetate (Ter), Trimedlure (Tri) and Torula (Tor). Traps were serviced weekly. Results. We captured 77 642 fruit flies in more than 4 months including mango season; they were represented by 18 identified fly species, including ten Ceratitis, six Dacus and two Bactrocera species. Two very serious pests were identified with the confirmation of Bactrocera cucurbitae (Coquillett) for cucurbit crops and the detection of B. invadens Drew Tsuruta & White for fruit crops. The two most abundant species of Ceratitis were C. cosyra and C. silvestrii. Discussion. We captured more fruit fly species in mixed mango orchards than in homogeneous mango orchards. Bactrocera invadens was also more abundant in mixed orchards, probably because of its polyphagous status. This new invasive species, B. invadens, can have many hosts in mixed mango orchards, enhancing its breeding potential. Conclusion. Effective management to deal with this alien species requires: (i) improvement of basic and applied research; (ii) an effective IPM package; (iii) an area-wide management approach; (iv) a sub-regional effort on the part of researchers, extension services, growers, exporters, farming associations and the different actors in fruit value chains (mainly mango).

Protease inhibitors (PIs) retard growth and development and cause mortality in a range of insect pests belonging to various orders. Some transgenic plants expressing PI genes have also been effective against insect pest attack. The effects of two purified soybean PIs, i.e. trypsin inhibitor (Kunitz type; SBTI) and trypsin–chymotrypsin inhibitor (Bowman-Birk type; SBBI), were investigated on first and third instar larvae of the melon fruit fly Bactrocera cucurbitae (Coquillett) in laboratory feeding bioassays. The larval period of both the first and third instar larvae was prolonged when the larvae were treated with various concentrations of SBTI and SBBI. The total development period prolonged significantly in both the instars of larvae treated with SBTI, but in SBBI-treated larvae, the development period was delayed significantly only in the third instar larvae. A decrease in percentage pupation and adult emergence was observed in the first and third instar larvae treated with different concentrations of both SBTI and SBBI. The present studies showed that SBTI and SBBI have a potential in inhibiting the growth and development of melon fruit fly, but further detailed and molecular level studies are required before their use in transgenics.

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. The data on Bactrocera cucurbitae collected over a large area of West Africa for around the past ten years enables us to make a synthesis, since this economically significant species is now widespread. Fruit samples were collected in the course of various trips to Africa; we focused on looking for the melon fly, B. cucurbitae (Coquillett). Equipment and methods. The Tephritidae were captured by means of trapping the adults and collecting holed fruit containing larvae. The fruit samples were taken from Cucurbitaceae found in the sub-region, and from other plant families hosting melon fly larvae. Fruit holed by flies were collected from untreated orchards and taken to the laboratory to be weighed, counted and classified by species, variety, date and location. The larvae collected metamorphosed into pupae. After hatching from the pupae, the adults were recovered. Results and discussion. The samples taken enabled us to determine the distribution of B. cucurbitae in West Africa; this species was found in Benin, Burkina Faso, Cameroon, Côte d’Ivoire, Guinea, Mali, Niger and Senegal. The fruit collected in these countries enabled us to draw up a list of B. cucurbitae host plants in these regions; besides Cucurbitaceae, there were two Anacardiaceae species, two Rutaceae species, one Annonaceae species, one Solanaceae species and one Oxalidaceae species. There were four economically important fruit species among them. Unlike Reunion, where the dietary pattern of the melon fly is oligophagous, in West Africa it appears to be polyphagous instead. Conclusion. The data collected from B. cucurbitae host plants is subsequently to be validated, and then refined by quantitative analyses for the different West African countries.

The attraction of the melon fly, Bactrocera cucurbitae (Coq.) (Diptera: Tephritidae) to soybean hydrolysate, fishmeal, beef extract, banana/grapes, bread and dog biscuit was evaluated in snakegourd (Trichosanthes anguina L.) gardens during 2000–2001. Vinegar and beer were added as the ‘bait components’ to the above ‘base baits’ to enhance their attractiveness. Edible oils, glycerine and petroleum jelly were tested as the ‘controlled releasers’ to sustain the attractiveness. The results indicated that banana and soybean hydrolysate were 85–95% more attractive to adult B. cucurbitae than fishmeal, beef extract, bread and dog biscuit. Among the fruit pulps, grapes and banana appeared to be more attractive than pineapple. The attractiveness of baits with palm oil lasted longer (up to 5 days) than that of baits without any controlled releaser (2–3 days). Grapes + beer + palm oil was found to be 37% more attractive than the other admixtures. The fruit flies were attracted towards the baits more intensively between 0600 and 0800 h and between 1600 and 1800 h.

Experiments were conducted to assess the effect of four plant growth regulators (PGRs), namely coumarin, kinetin, gibberellic acid (GA3) and indole-3-acetic acid (IAA), on the development of the melon fruit fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae). All four compounds exerted growth-and development-inhibitory effects on the fly. Coumarin was most potent, followed by kinetin, GA3 and IAA. The first and second instars of the fly were more sensitive than the third instar. Treatment with the PGRs also prolonged the fly's developmental period, reduced percentage emergence and increased percentage of abnormal flies emerging. At the higher concentrations tested (125, 625 and 3125 µg/ml) coumarin, kinetin and GA3 caused 100% mortality in first instars.