Dacus Ciliatus Research Articles

Seasonal fluctuation and alternative host plants of vegetable crop-infesting tephritids in non-vegetable growing areas in South Sudanese zone of Burkina Faso.

This study was carried out in 3 types of biotopes where vegetable crops are not grown to highlight their contribution to the dynamics of vegetable-infesting flies. To this end, a trapping system based on a sexual attractant, the Cuelure associated with an insecticide was set up in 18 biotopes (6 natural areas, 6 mango orchards, and 6 agroforestry parks) in the regions of Hauts Bassins and Cascades in the South-West of Burkina Faso. During the trapping monitoring, which was done every 2wk to collect insects captured, fruits present in 3 types of biotopes were sampled and incubated for insect emergence. Ten Dacus (Fabricius) [Diptera: Tephritidae]species and Zeugodacus cucurbitae (Coquillett) [Diptera: Tephritidae] were trapped in the study area. The predominant species captured was Z. cucurbitae (52.93%) followed by Dacus punctatifrons (Karsch) [Diptera: Tephritidae] (29.89%) and Dacus humeralis (Bezzi) (12.71%). Six tephritid species were emerged from 6 wild fruit species belonging to Cucurbitaceae, Apocynaceae, and Passifloraceae families. Fruit flies were more abundant from Jul to Nov with peaks observed in Aug or Oct depending on the species. Citrullus colocynthis L. (Cucurbitaceae), Lagenaria sp. (Cucurbitaceae), Passiflora foetida L. (Passifloraceae), and Passiflora sp. acted as reservoir host plants of Dacus ciliatus (Loew), Dacus bivittatus (Bigot), Dacus vertebratus (Bezzi) [Diptera: Tephritidae], D. punctatifrons, and Z. cucurbitae, the major vegetable insect pests in West Africa. The 3 types of biotopes acted as suitable refuge areas of vegetable crop-infesting fruit flies either for the favorable microclimate or for the alternative host plants.

Laboratory Evaluation of the Efficiency of The Entomopathogenic Fungus Beauvaria bassiana as a Biological Control Factor Against the Cucurbit Fly, Dacus ciliates

Al-Shweily, B.M., J.B. El-Zidawi and M.J. Hinnawi. 2024. Laboratory Evaluation of the Efficiency of The Entomopathogenic Fungus Beauvaria bassiana as a Biological Control Factor Against the Cucurbit Fly, Dacus ciliates. Arab Journal of Plant Protection, 42(3): 335-339. https://doi.org/10.22268/AJPP-001260 The cucurbit fly, Dacus ciliatus is a major pest which attack a wide range of crops and causes significant losses in agricultural production. Due to the high toxicity of chemical pesticides on human health and the environment, scientists focused on developing alternative safe methods to control this insect, including the use of biocontrol agents. Beauveria bassiana is one of the common fungi used as a bio-control agent. This entomopathogenic fungus was cultivated on Petri dishes containing PDA. The spore suspension of this fungus was prepared using sterilized distilled water, and three concentrations were used: 20×106 , 10×106 and 5×106 spores/ml. The effectiveness of these three concentrations was tested on larvae and pupae of the studied insect. The larval mortality rate ranged from 73.33% at the highest concentration to 33.33% at the lowest concentration used. Pupal mortality reached 66.66% at the highest concentration and 16.66% at the lowest concentration of spore suspension. Mortality rate was directly proportional to the spore suspension concentration of the entomopathogenic fungus. Keywords: Cucurbit fly, agricultural pest, biological control, Dacus ciliates, Beauveria bassiana, entomopathogenic fungi.

A Study of The Biological Effect of Egy Pride on The Quantitative Genetic Variation of The Cucurbit Fruit Fly, Dacus Ciliatus (Diptera: Tephritidae)

This study investigates the influence of the insecticide Egy Pride on the quantitative genetic variation and wing morphology of the Cucurbita fruit fly, Dacus ciliatus, a pest of agricultural significance. Geometric morphometrics were applied to analyze the shape and size of right wings from 30 specimens, half of which were treated with Egy Pride. The analysis revealed a 67% match rate in landmark coordinates between treated and untreated specimens, with notable deviations at landmarks 2, 6, 8, 9, and 15. Treated specimens exhibited variations in wing shape and size, with a central size measurement of 868.6 microns compared to 850.8 microns in the control group. Statistical analysis showed a Mahalanobis distance of 9.49, indicating differentiation between the groups. Classification rates based on wing morphology were 74% for treated and 53% for untreated specimens, with an 83% rate when based on the Mahalanobis distance. The study suggests that Egy Pride induces quantitative genetic variation and morphological changes in D. ciliatus, potentially affecting their flight and mobility. These findings highlight the unique properties of Egy Pride in pest control and its impact on the genetic and morphological aspects of targeted species.

Efficacy of Food Attractants and Attract-and-Kill System to Control Dacus ciliatus (Loew) (Tephritidae: Diptera): New Recorded Pest in Northern Tunisia

Some morphological features of Dacus ciliatus (Loew) reported for the first time in Tunisia were studied herein. Also during this study, the efficacy of food attractants and attract-and-kill devices were tested against D. ciliatus. To do so, McPhail® traps baited with diammonium phosphate (DAP©) and protein hydrolysate (Ceratrap©), already known as food attractants for fruit flies, were compared in zucchini and cucumber crops. A novel attract and kill system (Ceranock© female and male) was also applied in the two cited crops. Moreover, our data highlighted the usefulness of DAP© as effective food attractant with a high number of trapped adults compared to Ceratrap© baited traps. Few adults were recorded by Ceratrap© only in Zucchini treated crop 1 (0.42±0.49 and 0.28±0.69 respectively for males and females) compared to the other surveyed crops. Attract and kill system achieved good control of the pest by decreasing the number of captured flies in treated crops compared to the untreated crops. The use of attract and kill system showed promising results and can successfully be used to manage the lesser pumpkin fly in Tunisian cucurbit crops.

Effectiveness of Local and Commercial Isolates of Heterohabditis bacteriophora Nematodes in Controlling the Cucurbit Fly Dacus ciliatus (Loew)

The cucurbit fly is a pest with significant economic impact because it affects numerous agricultural crops and leads to fruit damage. This experiment was conducted to evaluate the efficacy of the local and commercial isolates of Heterohabditis bacteriophora nematodes on the larvae and pupae of the cucurbit fly insect Dacus ciliatus. Four concentrations were pre-pared for each isolate (10, 25, 50, and 100 infective juveniles/milliliter). The results showed clear variations in the isolates' ability to control the insects, and the effectiveness of the used concentrations varied in their impact on the mortality rate of the larvae and pupae. It was found that all concentrations could infect and control the cucurbit fly at both stages: larvae and pupae, but with varying percentages. Results showed that 100 IJs/mL scored the highest mortality rate compared to the other concentrations. The percentage of larvae and pupae mortality was higher when treated with the local isolate of nematodes compared to the commercial isolate at the same concentration.

Implement of Some Biocontrol Tactics as an Innovative Management Against Cucurbit Fly, Dacus ciliatus and Western Flower Thrips, Frankliniella occidentalis on Squash Crop

Implement of Some Biocontrol Tactics as an Innovative Management Against Cucurbit Fly, Dacus ciliatus and Western Flower Thrips, Frankliniella occidentalis on Squash Crop

Some aspects of the integrated control of cucurbits fruit fly Dacus ciliatus (Loew) (Diptera: Tephritidae) on cucumber crop

Field experiment was carried out during the autumn season in the Alam area in the east of Tikrit to study the integration of the three types of chemical pesticides (Media, Wide and Decis) and four cucumber varieties (Gazer, Amin, Najim and Zena) and Mass trapping technique by using Macphil traps that they contained female food attractive FLYCAP MASS to control cucurbits fruit fly Dacus ciliatus (Loew) in three open fields, the first field applied pesticides only, the second field applied pesticides and Mass trapping technique traps, and the third field for comparison (without pesticides and traps), was conducted two sprays for pesticides, the first spray after fruits setting directly and the second spray after week of the first spray . 
 Results showed that the application of pesticides alone in the first field had not been able to give good protection to the cucumber fruits from injury with cucurbits fruit fly Dacus ciliatus while the treatment of pesticides , varieties and Macphil traps in the second field that integrated each other in reducing the percentage of infected fruits to achieve good protection of the fruits and they showed that Integration between Mass traping technique by using Macphil traps that they contained FLYCAP MASS and Najim variety and Decis pesticide gave lower infected fruits percentage from 84.15% to 18.61% after one week of second spray, and reduce the number of larvae in Najim variety fruits from 7 Larva / fruit to 0.67 Larva / fruit and they reduced numbers of adults in the second field to 69.15% compared with the reduction percentage of the adults did not exceed 27.15% in the first field (treated with pesticides only) after one week of second spray.

Evaluate Efficacy of Malathion and Spinosad Alone and Mixed with Some Food Attractants Against Cucurbit Fly Dacus ciliatus

Evaluate Efficacy of Malathion and Spinosad Alone and Mixed with Some Food Attractants Against Cucurbit Fly Dacus ciliatus

Host status of fruit flies (Diptera: Tephritidae) on French beans in Kenya

Production of French bean (Phaseolus vulgaris L.) as a vegetable is important as a source of livelihood and income generation to smallholder farmers. However, production of this crop has not been optimal due to various constraints. Among the most important ones is pest and diseases. In Kenya, major pests reported in French beans include the western flower thrips (WFT) (Frankliniella occidentalis), Bean fly (Ophiomyia phaseoli) aphids (Aphis fabae), red spider mites (Tetranychus spp.), the African bollworm (Helicoverpa armigera), the legume pod borer (Maruca vitrata) and white flies (Bemisia tabaci). Although Tephritidae flies are major pests of fruits and vegetables in Africa, Kenya included, they are no reports to indicate that they attack French beans. However, a previous pest risk analysis report indicates that the crop is host to some species such as Dacus ciliatus and Bactrocera cucurbitaceae. In an effort to secure the international market, we conducted a study to assess French beans from Kenya to establish whether they are indeed hosts to fruit flies or not. The study was conducted in Machakos, Meru, Murang’a, Laikipia and Nyeri regions in the year 2020. In each of the study regions, sampling of pods was carried out in private farms that were planting French beans for export. A total of 2375 samples were collected from various locations in the field and from exit point for analysis. Results showed that, none of the developmental stages of fruit flies (Tephritidae) was present in any of the sampled French beans pods (Field and exit point samples). However, bean seed fly (Delia platura), bean fly (Ophiomyia phaseoli) and one beetle was recorded in some of the samples. From our study we conclude that French beans is not a host to Tephritidae fruit flies. However, we recommend host preference tests in the laboratory and greenhouse to establish the oviposition potential of the fruit flies to French beans. Key words: Phaseolus, samples, fruit, pods, preference, oviposition

Qualitative modeling of fruit fly injuries on chayote in Réunion: Development and transfer to users

Intensive chayote cultivation in Réunion almost disappeared in the 2000s due to significant yield losses from fruit fly attacks on this historically important crop (Dacus ciliatus, Zeugodacus cuurbitae and Dacus demmerezi). Since the late 2000s, the adoption of agroecological crop protection practices have led to the effective management of fruit fly populations, a significant reduction in pesticide use, an increase in chayote production and plantations, and the development of organic production. To assist in fruit fly management, a qualitative model which simulates fruit fly damage to chayote crops, known as IPSIM-chayote, was developed, providing satisfactory prediction results. It has a user-friendly interface and is now available free of charge online, in three languages (French, English and Spanish): https://pvbmt-apps.cirad.fr/apps/ipsim-chayote/?lang=en. The IPSIM-chayote modeling platform can be used by farmers as a diagnosis to simulate fruit fly damage to their crops and as a decision-making tool for their agricultural practices. The model can be used as a training resource in agroecological crop protection. Public authorities and local government can use it as a tool in planning and forecasting agricultural development. Finally, researchers can use it as a prediction tool and a resource for the exchange of information, allowing them to review scientific knowledge or identify new, relevant research areas suited to the context and challenges. IPSIM-chayote can be considered as a forum for exchange and can stimulate collaborative work between individuals. It is a flexible model, as it allows variables to be added. IPSIM-chayote is the first qualitative model developed for crop pests in a tropical environment. It could serve as a basis for the development of other similar models simulating crop pest incidence, thus contributing significantly to the development of agroecological crop protection.

Watermelon-infesting Tephritidae fruit fly guild and parasitism by Psyttalia phaeostigma (Hymenoptera: Braconidae)

An ecological guild of Tephritidae fruit flies exploits cucurbit vegetable fruits, tremendously reducing their production worldwide. Knowledge of the composition of the guild of infesting flies in the field and information on their natural enemy species, might improve pest management strategies. Our aim was therefore to identify Tephritidae species infesting the watermelon Citrullus lanatus (Thunb.) Matsum. & Nakai in the Republic of Benin. Morphological and molecular identification of parasitoid species present in the field collections was also done. Infested watermelons were sampled in one of the main watermelon-production areas in the country. Adult tephritid flies emerging from watermelons were identified as Dacus bivittatus (Bigot), D. ciliatus Loew, D. punctatifrons Karsch, D. vertebratus Bezzi, Zeugodacus cucurbitae (Coquillet), and Ceratitis cosyra (Walker). In this study period, D. vertebratus was consistently the most abundant species emerging from watermelon. Dacus ciliatus was the second most common species followed by Z. cucurbitae. The number of emerging fruit flies per kilogram of watermelon varied with collection date and month, and was most variable for D. vertebratus. Parasitism in the fruit flies was 1.6 ± 6.4% and occurred through one wasp species that was identified as Psyttalia phaeostigma Wilkinson (Hymenoptera: Braconidae). This solitary parasitoid is closely related to other members of the P. concolor species complex, some of which are used in biological control. Problems associated with identifying Psyttalia species and possibility of using this wasp as a biological control agent against tephritid flies were discussed.

An Integrated Decision Support System for Environmentally-Friendly Management of the Ethiopian Fruit Fly in Greenhouse Crops

The Ethiopian fruit fly (EFF), Dacus ciliatus, is a key, invasive pest of melons in the Middle East. We developed and implemented a novel decision support system (DSS) to manage this pest in a greenhouse environment in Southern Israel. Dacus ciliatus is commonly controlled in Israel with repeated calendar-sprayings (every 15 days) of pyrethroid pesticides. The current study compares the performance of a DSS against calendar-spraying management (CSM). DSS was based on EFF population monitoring and infestation. DSS took into consideration concerns and observations of expert managers and farmers. During 2014, EFF damage was concentrated in the spring melon production season. Fall and winter production did not show important damage. Damage during the spring of 2014 started to increase when average EFF/trap/day reached 0.3. This value was suggested as the threshold to implement pesticide spraying in DSS greenhouses. EFF/trap/day trends were derived from monitoring with conventional traps and a novel electronic remote sensing trap, developed by our group. CSM during the spring of 2015 included 3 EFF control sprays, while DSS-managed greenhouses were only sprayed once. At the end of the spring season, damage was slightly higher in DSS greenhouses (1.5%), but not significantly different to that found in CSM greenhouses (0.5%). Results support continuing DSS research and optimization to reduce/remove pesticide use against EFF in melon greenhouses. Interactions with farmers and managers is suggested as essential to increase adoption of DSS in agriculture.

The first two complete mitochondrial genome of Dacus bivittatus and Dacus ciliatus (Diptera: Tephritidae) by next-generation sequencing and implications for the higher phylogeny of Tephritidae

Dacus bivittatus and Dacus ciliatus are destructive pests of Cucurbitaceae crops including cucumber, zucchini and melons. Recent molecular phylogenetic studies conflicted with morphological taxonomy regarding relationships between Bactrocera, Dacus and Zeugodacus. In this study, we sequenced the complete mitochondrial genomes of the above species which are representatives of two subgenera of Dacus (Dacus and Didacus) not previously sequenced and reconstructed the phylogeny of Tephritidae. The mitochondrial genomes of D. bivittatus and D. ciliatus were 15,833 bp and 15,808 bp in length, respectively. The 37 genes, including 13 protein-coding genes (PCGs), 2 rRNA genes and 22 tRNA genes, with a long non-coding region (A + T-rich control region) were in the same arrangement as the ancestral insect mitochondrial genome. Phylogenetic analysis showed that Dacus has a closer relationship of Zeugodacus rather than Bactrocera. Our phylogenetic results further support the recent proposals that Zeugodacus should be considered as a genus not a subgenus of Bactrocera. Whole mitochondrial genomes of D. bivittatus and D. ciliatus could be useful in further studies for species diagnosis, evolution and phylogeny research within Tephritidae.

Host Susceptibility and Pest Status of Fruit Flies (Diptera: Tephritidae) Attacking Cucurbits in Two Agroecological Zones of Cameroon, Central Africa

Cucurbits are among the most valuable food crops in various developing countries of sub-Saharan Africa. The development of integrated strategies in their pest management is limited by lack of information on fruit losses, especially by tephritids and their pest status on crops. Thus, based on fruit damage rates and infestation rates, cucurbits' susceptibility to tephritids was assessed in Yaounde and Koutaba, two localities situated in different agroecological zones in Southern Cameroon. From systematic samplings in trap plots, 6009 damaged fruits from nine cucurbit species were collected weekly and bimonthly and incubated during 2009–2011. Fruit losses, which were evaluated at 36.73±1.90%atYaounde and 37.08 ± 3.22 % at Koutaba, did not vary in relation to locality. Losses due to tephritids were more important on Sechium edule and Cucurbita moschata at Yaounde and on S. edule, Citrullus lanatus (watermelon), Cucumis melo (sweet melon), Cucumis sativus and Cucurbita moschata at Koutaba. At each site, Cucumis melo var. agrestis was the less susceptible species. With the exception of S. edule, developing fruits were more susceptible to tephritids as 80% of positive fruits weighed less than 100 g. Moreover, four tephritids emerged from fruits; Dacus bivittatus and Dacus ciliatus appeared to be the major pests and Dacus vertebratus a minor pest. Pest status of Dacus punctatifrons depends on border plants. Also, D. ciliatus exhibited preference for Cucurbita moschata and D. bivittatus for S. edule and Cucumeropsis mannii. Our findings provide useful data for the conception of Integrated Pest Management (IPM) strategies against tephritids.

Composition, Host Range and Host Suitability of Vegetable-Infesting Tephritids on Cucurbits Cultivated in Kenya

Damage incidence and interactions between native and invasive vegetable-infesting fruit flies (Diptera: Tephritidae) on high-value crops have rarely been studied, despite their threats to the horticultural industries in Africa and quarantine implications.We established the composition and host range of tephritid flies in the field and carried out comparative host suitability studies of major fruit flies: Dacus bivittatus (Bigot), Dacus ciliatus Loew and Zeugodacus cucurbitae (Coquillet) on watermelon [Citrullus lanatus (Thunb.)], cucumber (Cucumis sativus L.), courgette (Cucurbita pepo L.) and butternut (Cucurbita moschata Duchesne) in the laboratory. Five new host species were recorded. Zeugodacus cucurbitae was the most destructive fruit fly, infesting 17 hosts from five families, followed by D. ciliatus and D. bivittatus. Direct field damage inflicted on immature to mature crops on the plants ranged from 2.1%on eggplant (Solanum melongena L.) to 66.8%on bitter gourd (Momordica charantia L.). The most preferred hosts of Z. cucurbitae were bitter gourd, watermelon and tomato (Solanum lycopersicum L.) (16.2, 13.3 and 12.1 flies/kg fruit, respectively). Mango (Mangifera indica L.) (24.1 flies/kg fruit) and guava (Psidium guajava L.) (14.7 flies/kg fruit) were recorded for the first time as hosts of D. ciliatus. The relative abundance index showed high variation among host species, suggesting a differential use of these hosts by the different fruit fly species. Choice versus no-choice experiments revealed a significant variation in pupal recovery, pupal size, adult emergence, percentage females, adult wing deformity and body size. These results are significant for the decision-making process for effective monitoring and management of fruit fly species on cucurbitaceous vegetable crops.

Microbial composition affects the performance of an artificial Tephritid larval diet.

The present study investigated the patterns of microorganisms in an artificial larval diet during Dacus ciliatus (Diptera; Tephritidae) larval development. Microbial population contents in the diet of total heterotrophic bacteria, yeast and molds, coliform and lactobacilli, and their dynamics during development, were monitored. Initially, the microbial composition in diet trays failing to produce viable pupae and in trays successfully producing pupae and adult flies was characterized. The failing diet trays contained large populations of lactobacilli that increased during larval development, and low populations of coliforms. In contrast, the successful diet showed an increasing population of coliforms and a low, or undetected, population of lactobacilli. To study the hypothesis that lactobacilli affect D. ciliatus larval development, we conducted controlled inoculation experiments in which Lactobacillus plantarum was added into fresh diet at the time of egg seeding. L. plantarum inoculated trays showed no production of D. ciliatus. Control trays without lactobacilli inoculation showed variable results. One tray successfully produced viable pupae and adults, and showed a slight and slow increase in the indigenous populations of lactobacilli. The second tray, however, failed to produce pupae and showed a fast increase of the indigenous lactobacilli to very high levels. Monitored pH trends in L. plantarum-inoculated diet showed a sharp pH decrease during the first 4 days of larval development from 5 to less than 4 units, while successful diet, producing viable D. ciliatus pupae and adults, showed a moderate pH drop during most of the larval development period. The paper discusses the possible ecological interactions between D. ciliatus larvae, the microbial content of the diet and the physical properties of the diet. The discussion also points out at the usefulness of this approach in understanding and managing mass production parameters of tephritid fruit flies industrial diets used for Sterile Insect Technique.

Electronic traps for detection and population monitoring of adult fruit flies (Diptera: Tephritidae)

AbstractDuring the last decades, the economic importance of tephritid fruit flies (FF) has increased worldwide because of recurrent invasions and expansions into new areas, and reduced control capabilities of current control systems. Efficient monitoring systems, thus, are required to provide fast information to act promptly. With this aim in mind, we developed two electronic trap (e‐trap) versions for adult FF: one with specific volatiles for male and female adult Ceratitis capitata, and the second, based on the attraction of adult FF to yellow colour, targeting Dacus ciliatus, Rhagoletis cerasi and Bactrocera oleae. In the case of B. oleae, the female pheromone and ammonium bicarbonate were added as synergists. In the two versions, attracted FF were retained in the trap on glued surfaces. Real‐time images of the surfaces were automatically taken and transmitted to a server. We tested the two e‐trap versions in insect‐proof cages, where flies were released and recaptured, and in commercial orchards throughout the Mediterranean: C. capitata in peach orchards in Italy; R. cerasi in cherry orchards in Greece; B. oleae in olive orchards in Spain and in Greece; and D. ciliatus in melons in plastic tunnels in Israel. The e‐trap showed excellent abilities to transmit real‐time images of trapped FF and a high specificity for trapping different FF species. The ability of the entomologist to correctly classify FF from images in the office was >88%. In addition, average number of flies/trap in e‐trap grids did not differ from numbers reported on grids of conventional traps that were operating simultaneously. The e‐traps developed and tested in this study provide the basis for the real‐time monitoring of FF were no olfactory attractants are available, and for the surveillance of alien FF incursions where generic, but not specific, olfactory attractants exists.

Loop-Mediated Isothermal Amplification Combined with PCR for Rapid Identification of the Ethiopian Fruit Fly (Diptera: Tephritidae).

Nowadays, with increasing trend of trans-boundary transportation of agricultural products and higher probability of introduction of many invasive species into new areas, fast and precise species diagnosis is of great significance particularly at the port of entry, where morphological identification often requires adult insect specimens especially with specialist insects. The cucumber fruit fly, Dacus ciliatus Loew (Diptera: Tephritidae), ranks as one of the most destructive agricultural pests attacking mainly fruits of Cucurbitaceae. This pest is also widespread and highly invasive; thus, it is a high priority for pest detection and quarantine programs. Although cucumber fruit fly adults can usually be identified and distinguished from the other species by morphological keys, it is often difficult or impossible to distinguish this species from the other tephritids that share host plants by using material from other stages of development. In such situations, using a quick and robust alternative species diagnostic tool would be valuable. In this study, we assessed a technique combining loop-mediated isothermal amplification (LAMP) with PCR (PCR-LAMP) for the rapid detection and discrimination of cucumber fruit fly DNA from some other common tephritid species attacking Cucurbitaceae, using material from different stages of development. The described method was species-specific and sensitive and provided a rapid diagnostic tool to detect D. ciliaus even by non-experts.

Laboratory longevity and competitiveness of Dacus ciliatus Loew (Diptera: Tephritidae) following sub-sterilizing gamma irradiation

The effect of a sub-sterilizing gamma radiation dose on Dacus ciliatus adults was investigated to assess the suitability of the sterile insect technique (SIT) as an alternative method to control this pest. Late pupae (48 h prior to adult emergence) from a laboratory strain were irradiated with 120 Gy of gamma rays emitted by a 60Co source. Following adult emergence, the mortality of irradiated and non-irradiated cohorts was recorded. Over a period of 50 days after emergence, no significant negative effects of irradiation upon the longevity of male or female laboratory flies were observed. A laboratory competitiveness study (Fried test), using irradiated laboratory and wild males at a ratio of 3:1 was conducted to assess the ability of irradiated males to reduce the egg hatch rates of a wild population. The overall competitiveness was found to be ca. 0.32, suggesting a reduced, but satisfactory, quality of irradiated laboratory as compared with wild males. Based on the above findings, we calculated and proposed effective male release ratios for field application of SIT against D. ciliatus.

Mating behaviour of Dacus ciliatus (Loew) [Diptera:Tephritidae]: comparisons between a laboratory and a wild population

AbstractAs part of the development of a sterile insect technique (SIT) application for the Ethiopian fruit fly, Dacus ciliatus, we studied the mating behaviour of a laboratory‐adapted strain (a 4‐year‐old colony kept for more than 40 generations) and a wild population. Effects of laboratory rearing and irradiation were assessed by carrying out mating compatibility and male mating competitiveness tests using a 1:1 ratio between irradiated (120 Gy) laboratory males and non‐irradiated wild males. Mating behaviour was studied on host and non‐host plants under field cage conditions. To assess the effect of mass rearing upon male performance, we repeated the mating competitiveness test using non‐irradiated laboratory insects. The findings indicated a high degree of compatibility among the two populations and satisfactory competitiveness of the irradiated laboratory males (ca. 35%). The competitiveness of non‐irradiated laboratory males was also ca. 35%, suggesting that no adverse effects resulted from their irradiation. Mating occurred only at twilight and mainly on the underside of leaves of non‐host plants (lemon trees). Findings are discussed in view of their implications for a future application of SIT against this fruit fly pest.