Mediterranean Fruit Fly Ceratitis Capitata Research Articles

Alternatives to ginger root oil aromatherapy for improved mating performance of sterile Ceratitis capitata (Diptera: Tephritidae) males

AbstractAutocidal control of the Mediterranean fruit fly Ceratitis capitata (Wiedemann) is an environmentally friendly and safe practice employed successfully worldwide. A key component in the Sterile Insect Technique (SIT) is to release sterile males that can compete with wild males in nature. Exposure of sterile males to ginger root oil (GRO) in the form of aromatherapy prior to release has been shown to significantly improve male competitiveness and performance. However, alternatives to GRO exposure are desired to (i) reduce personnel costs and handling‐time requirements and (ii) find new aromatherapeutic compounds. In this study, alternatives to GRO aromatherapy were investigated, such as incorporating GRO into the post‐teneral diet, or employing other molecules (limonene and linalool) occurring naturally in citrus release areas. Our results reveal that both the GRO‐supplemented diet and linalool aromatherapy were equal to the GRO aromatherapy control in improving mating performance in sterile males. In contrast, exposure to limonene did not afford a mating advantage to sterile mates when compared to the control. In addition, sterile male survival was not affected by any of the treatments tested. Implications for how both new approaches could be implemented in SIT programmes in citrus production areas are discussed.

Use of a multiple logistic regression model to determine the effects of soil moisture and temperature on the virulence of entomopathogenic fungi against pre-imaginal Mediterranean fruit fly Ceratitis capitata

Last-instar larvae of the Mediterranean fruit fly, Ceratitis capitata, were exposed to Beauveria bassiana and Metarhizium anisopliae isolates in sterile soil under controlled conditions. A multiple logistic regression model for mycosis was applied, and different temperature and moisture patterns for each of the four isolates were observed (Bb-1333, EABb 01/33-Su, EAMa 01/58-Su, EAMa 01/158-Su). In general, B. bassiana isolates were less virulent than M. anisopliae isolates. For all of the fungal isolates, lower mycosis values were observed under extreme moisture conditions (1% and 17% wt.:wt.). For the most virulent isolate, M. anisopliae EAMa 01/58-Su, higher mycosis values were observed at intermediate temperatures. Conversely a direct relationship between temperature and puparia mortality was observed for M. anisopliae isolate EAMa 01/158-Su. Both B. bassiana isolates displayed a parabolic relationship with moisture, and mycosis was observed at low temperatures (15–20.1 °C). This work provides additional evidence on the fact that for each fungal species, each isolate is an independent biological entity with different responses to environmental conditions; therefore, entomopathogenic fungal isolates for pest control should have a range of temperatures and humidities that can be matched to the desired environment.

Influence of different tropical fruits on biological and behavioral aspects of the Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera, Tephritidae)

Influence of different tropical fruits on biological and behavioral aspects of the Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera, Tephritidae). Studies on Ceratitis capitata, a world fruit pest, can aid the implementation of control programs by determining the plants with higher vulnerability to attacks and plants able to sustain their population in areas of fly distribution. The objective of the present study was to evaluate the influence of eight tropical fruits on the following biological and behavioral parameters of C. capitata: emergence percentage, life cycle duration, adult size, egg production, longevity, fecundity, egg viability, and oviposition acceptance. The fruits tested were: acerola (Malpighia glabra L.), cashew (Anacardium occidentale L.), star fruit (Averrhoa carambola L.), guava (Psidium guajava L.), soursop (Annona muricata L.), yellow mombin (Spondias mombin L.), Malay apple (Syzygium malaccense L.), and umbu (Spondias tuberosa L.). The biological parameters were obtained by rearing the recently hatched larvae on each of the fruit kinds. Acceptance of fruits for oviposition experiment was assessed using no-choice tests, as couples were exposed to two pieces of the same fruit. The best performances were obtained with guava, soursop, and star fruit. Larvae reared on cashew and acerola fruits had regular performances. No adults emerged from yellow mombin, Malay apple, or umbu. Fruit species did not affect adult longevity, female fecundity, or egg viability. Guava, soursop, and acerola were preferred for oviposition, followed by star fruit, Malay apple, cashew, and yellow mombin. Oviposition did not occur on umbu. In general, fruits with better larval development were also more accepted for oviposition.

Biological control of the Mediterranean fruit fly in Israel: Biological parameters of imported parasitoid wasps

Three braconid species that parasitize the Mediterranean fruit fly (Medfly) Ceratitis capitata (Wiedemann) were recently imported into Israel. Several of their key biological parameters were studied. The longevities of the egg-attacking parasitoids Fopius arisanus (Sonan) and Fopius ceratitivorus (Wharton), and the larval parasitoid Diachasmimorpha kraussii (Fullaway) in the laboratory at 24±1°C were 42.1±2.0d, 36.9±2.0d and 18.6±1.6d, respectively. These wasps oviposited for 17.8±0.9d, 17.7±0.8d and 12.7±1.6d, during which they produced 133.0±20.5, 103.9±12.4 and 282.7±43.1 offspring/female, respectively. The daily fecundity rates were 6.8±1.8, 5.0±1.0 and 15.3±2.0, offspring/female/day, with sex ratios (females) of 43.0±7.9%, 69.4±3.3% and 59.0±1.8%, respectively. F. arisanus and F. ceratitivorus preferred to oviposit into 48h-old eggs, while D. kraussii preferred to oviposit in 7d-old (late 2nd to early 3rd instar) larvae, a spherical, artificial oviposition unit was developed for the egg-prepupal parasitoid F. ceratitivorus.

Cloning and purification of protein kinase CK2 recombinant alpha and beta subunits from the Mediterranean fly Ceratitis capitata

The Mediterranean fruit fly Ceratitis capitata is an insect capable of wreaking extensive damage to a wide range of fruit crops. Protein kinase CK2 is a ubiquitous Ser/Thr kinase that is highly conserved among eukaryotes; it is a heterotetramer composed of two catalytic (α) and a dimer of regulatory (β) subunits. We present here the construction of the cDNA molecules of the CK2α and CK2β subunits from the medfly C. capitata by the 5'/3' RACE and RT-PCR methods, respectively. CcCK2α catalytic subunit presents the characteristic and conserved features of a typical protein kinase, similar to the regulatory CcCK2β subunit, that also possess the conserved features of regulatory CK2β subunits, as revealed by comparison of their predicted amino acid sequences with other eukaryotic species. The recombinant CcCK2α and CcCK2β proteins were purified by affinity chromatography to homogeneity, after overexpression in Escherichia coli. CcCK2α is capable to utilize GTP and its activity and is inhibited by polyanions and stimulated by polycations in phosphorylation assays, using purified acidic ribosomal protein P1 as a substrate.

Sexual behaviour of the Mediterranean fruit fly (Diptera: Tephritidae): the influence of female size on mate choice

Most studies of the sexual behaviour of the Mediterranean fruit fly Ceratitis capitata Wiedemann 1824 (Tephritidae: Ceratitidini) have concentrated on determining which male characteristics influence their copulatory success and little is known about the female’s influence on this process. The present study investigated the influence of female size on the selection of different sized males. The experiments were undertaken using a colony maintained under laboratory conditions for 15 years with the frequent introduction of wild flies. Adults of different sizes (‘larger’ and ‘smaller’) were obtained by providing two groups of larvae with different concentrations of protein (7.0 g of yeast/100 ml of water = high protein content, 3.0 g of yeast/100 ml of water = low protein content). Mate choice tests were performed in a laboratory environment as well as in a field cage, with larger or smaller females being simultaneously exposed to larger and smaller males. The results indicated that in both the laboratory and field cage tests both larger and smaller females preferred mating with larger males. The data is discussed in terms of the possible advantages to the females associated with their choice of males with large body sizes.

Composition and Anti-insect Activity of Essential Oils from Tagetes L. Species (Asteraceae, Helenieae) on Ceratitis capitata Wiedemann and Triatoma infestans Klug

Essential oils from four species of the genus Tagetes L. (Asteraceae, Helenieae) collected in Tucumán province, Argentina, were evaluated for their chemical composition, toxicity, and olfactory activity on Mediterranean fruit fly Ceratitis capitata Wiedemann adults and for repellent properties on Triatoma infestans (Klug) (Chagas disease vector). Yields of essential oils range from 0.2 to 0.8% (v/w). The same main constituents among Tagetes minuta L., Tagestes rupestris Cabrera, and Tagetes terniflora Kunth, (cis-trans)-ocimenes, (cis-trans)-tagetones, and (cis-trans)-ocimenones showed important differences in their relative compositions. Tagetes filifolia Lag. was characterized by the recognized phenylpropanoids methylchavicol and trans-anethole as the main components. LD(50) was ≤20 μg/insect in topical bioassays. T. rupestris was the most toxic to C. capitata females, whereas the other oils presented similar toxicities against males and females. Tagetes rupestris oil attracted both sexes of C. capitata at 5 μg, whereas T. minuta showed opposite activities between males (attractant) and females (repellent). Oils from T. minuta and T. filifolia were the most repellent to T. infestans. The results suggest that compositions of essential oils influence their insecticidal and olfactory properties. The essential oils from Tagetes species show an important potential as infochemical agents on insects' behaviors. This study highlights the chemical variability of essential oils as a source of variation of anti-insect properties.

Host Status of Purple Passionfruit for the Mediterranean Fruit Fly (Diptera: Tephritidae)

ABSTRACT The Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a key pest of a wide range of fruit crops and the focus of rigid quarantine restrictions and eradication measures in several countries. In Colombia, the susceptibility of purple passionfruit (Pasiflora edulis f. edulis Sims; Violales: Passifloraceae) to C. capitata is uncertain. Field collections of fruit were made to evaluate natural infestation. Forced infestation studies were conducted in the laboratory with punctured and intact fruit to determine the acceptability of fruit at different stages of maturity and physiological suitability of fruit to development. No C. capitata larvae were found and no adults emerged from a total of 976 hand-picked fruit and 623 fallen fruit. In the meantime, trap data indicated that C. capitata is not present in the principal passionfruit production regions. For intact fruit, C. capitata females oviposited exclusively in fruit of maturity level zero, with 41.67% of fruit accepted...

Cloning, sequence identification and expression profile analysis of α-l-fucosidase gene from the Mediterranean fruit fly Ceratitis capitata

The Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae) is one of the most destructive agricultural pests, a polyphagus insect of relevant economic importance and is widespread in many regions around the world. It is the best-studied fruit fly pest at genetic and molecular level and much has been learned on its ecology and behaviour. An α-l-fucosidase has been recently hypothesized to be involved in sperm–egg interactions in Drosophila melanogaster and in other Drosophila species. Here, a complete cDNA encoding a putative α-l-fucosidase of the medfly was amplified using the reverse polymerase chain reaction (RT-PCR) with degenerate based on the conserved coding sequence information of several insect α-l-fucosidases, cloned and sequenced (GenBank accession no. FJ177429). The coding region consisted of 1482bp which encoded a 485-residues protein (named CcFUCA) with a predicted molecular mass of 56.1kDa. The deduced protein sequence showed 75% amino acid identity to D. melanogaster α-l-fucosidase, and in fact the phylogenetic tree analysis revealed that CcFUCA had closer relationships with the α-l-fucosidases of drosophilid species. The tissue expression analysis indicated that CcFuca was expressed in a single transcript in all tissues, suggesting a ubiquitous localization pattern of the encoded protein. Our findings provide novel insights on a gene encoding a protein potentially involved in primary gamete interactions in C. capitata.

Intensity of attack caused by Mediterranean fruit fly Ceratitis capitata Wiedem. (Diptera, Tephritidae) on mandarin along the Montenegrin seacoast

Along the Montenegrin seacoast, all cultivated citrus species (mandarin, orange, lemon, grapefruit), fig, loquat and ziziphus were detected as host plants of the Ceratitis capitata Wiedem. Among those found, in economic sense, the most important host plant is mandarin Unsiu. Intensity of the attack were monitored on mandarin in 2003 and 2004 in localities Baosici, Lastva Grbaljska and Bar, and was determined as higher in 2003. The first symptoms of attack were detected, depending on locality, from middle of September until beginning of October, one to two months earlier then in 2004. The maximum number of larvae per fruit were detected in October and November (average from 13.44?0.16 to 22.82?0.13). Time of the first symptoms appearence on mandarin in September and October 2003 and in November 2004, indicate on crucial importance of alternative host plants (figs and loquat) for reproduction and increasing of C. capitata population, because later during a season its intensity of attack on mandarin, depend largely on their presence.

Optimum dose of ginger root oil to treat sterile Mediterranean fruit fly males (Diptera: Tephritidae)

AbstractThe sterile insect technique (SIT) is widely used as part of an integrated approach to reduce field populations of the Mediterranean fruit fly (Ceratitis capitata, Diptera: Tephritidae). Aromatherapy based on exposure to ginger root oil (GRO) volatiles is known as a method to significantly improve the sexual performance of sterile medfly males, and is being used in many mass‐rearing facilities around the world. However, the optimum dose of GRO is not well defined. This work evaluated in laboratory cages four different doses of GRO and a control (0, 0.1, 0.25, 0.5 and 0.75 ml/m3), and two different methods to hold flies prior to release (paper bags and plastic cages). The objective was to find the lowest dose that provides optimal improvement in mating performance of sterile males when competing with wild males for wild females and optimal reduction in fertility of wild females. Egg hatch, copula duration, the Relative Sterility Index (RSI), and a Competitiveness (C) value (based on RSI) were calculated for each treatment to assess male sexual performance and induction of sterility. The method used to hold flies did not influence the aromatherapy effect. The mean time spent by wild females in copula with wild males was significantly longer than with sterile males for all treatments, except when sterile males were treated with 0.1 ml of GRO/m3. Amongst all doses studied, it is recommended to apply the lowest dose, 0.1 ml of GRO/m3, since at this dose both the RSI and induced sterility reached the highest levels, and were not statistically different from the 0.25 and 0.5 GRO/m3 doses. Indeed, this dose showed a very significant improvement in the mating competitiveness of sterile males aromatically treated with GRO.

Glycosidases in the plasma membrane of Ceratitis capitata spermatozoa

Fruit flies in the family Tephritidae are rated among the world’s most destructive agricultural pests. The Mediterranean fruit fly Ceratitis capitata is emerging as a model organism to study the fertilization in Insects. Three integral proteins with glycosidase activity are present in the plasma membrane of spermatozoa. The glycosidases have been purified and characterized. We have demonstrated the presence of three enzymes, a β-N-acetylhexosaminidase, an α-mannosidase and an α- l-fucosidase. The molecular mass of the native enzymes estimated by gel filtration was 160 kDa for β-N-acetylhexosaminidase, 310 kDa for α-mannosidase and 140 kDa for α- l-fucosidase. SDS-PAGE showed that β-N-acetylhexosaminidase is a dimer of a single protein of 73 kDa, α-mannosidase consists of six subunits with different molecular weights and α- l-fucosidase is a dimer made up by two different monomers. Characterization of the purified enzymes included glycosylation pattern, pI, optimal pH, substrate preference, kinetic properties and thermal stability. Soluble forms similar to the sperm associated glycosidases are present. Polyclonal antibodies raised against synthetic peptides designed from the predicted products of the Drosophila melanogaster genes encoding β-N-acetylhexosaminidase and α- l-fucosidase were used. Immunofluorescence labelling of spermatozoa showed that the enzymes are present in the sperm plasma membrane overlying the acrosome and the tail. This work represents the first report on the characterization in C. capitata of sperm proteins that are potentially involved in primary gamete recognition.

A comparative assessment of the response of three fruit fly species (Diptera: Tephritidae) to a spinosad-based bait: effect of ammonium acetate, female age, and protein hunger

Ammonia-releasing substances are known to play an important role in fruit fly (Diptera: Tephritidae) attraction to food sources, and this information has been exploited for the development of effective synthetic food-based lures and insecticidal baits. In field studies conducted in Hawaii, we examined the behavioural response of wild female oriental fruit fly (Bactrocera dorsalis (Hendel)), melon fly (B. cucurbitae (Coquillett)), and Mediterranean fruit fly (Ceratitis capitata (Wiedemann)) to spinosad-based GF-120 NF Naturalyte Fruit Fly Bait(©) formulated to contain either 0, 1 or 2% ammonium acetate. Use of visually-attractive yellow bait stations for bait application in the field allowed for proper comparisons among bait formulations. Field cage tests were also conducted to investigate, using a comparative behavioural approach, the effects of female age and protein starvation on the subsequent response of F1 generation B. cucurbitae and B. dorsalis to the same three bait formulations that were evaluated in the field. Our field results indicate a significant positive effect of the presence, regardless of amount, of AA in GF-120 for B. dorsalis and B. cucurbitae. For C. capitata, there was a significant positive linear relationship between the relative amounts of AA in bait and female response. GF-120 with no AA was significantly more attractive to female C. capitata, but not to female B. dorsalis or B. cucurbitae, than the control treatment. Our field cage results indicate that the effects of varying amounts of AA present in GF-120 can be modulated by the physiological stage of the female flies and that the response of female B. cucurbitae to GF-120 was consistently greater than that of B. dorsalis over the various ages and levels of protein starvation regimes evaluated. Results are discussed in light of their applications for effective fruit fly suppression.

The ground beetle Pseudophonus rufipes revealed as predator of Ceratitis capitata in citrus orchards

The Mediterranean fruit fly Ceratitis capitata (Wiedemann) is a major citrus pest in Spain. Although medfly is being controlled chemically, alternative biorational strategies should be developed, like those based on conservation biological control of polyphagous predators. The ground beetle Pseudophonus rufipes (De Geer) is the most abundant carabid inhabiting the ground of citrus orchards in eastern Spain. However, little is known about its activity–density and predatory role against C. capitata in the citrus agroecosystem. Here, we report on its predatory potential on the medfly’s developmental stages that take place in the citrus ground. This carabid species preyed efficiently on C. capitata third instar larvae and especially on pupae but not on teneral adults. Moreover, predation under field conditions was evaluated by detecting C. capitata DNA remains using PCR-based gut-content analysis. Half-life DNA detectability of C. capitata was of 32.33 h. Pseudophonus rufipes specimens were field-collected after C. capitata sterilized pupae were deployed in a commercial citrus orchard. Thereafter, the carabids captured by pitfall traps were analyzed, being DNA-remains of C. capitata detected in 22.2% of them. Data reported here clearly suggest that P. rufipes could play an important role in regulating medfly populations in citrus orchards. This information is particularly useful when biological control conservation strategies are being considered to control this pest.

Changes in sperm tail development associated with Y chromosome meiotic drive leading to an excess of males in the medfly Ceratitis capitata (Diptera: Tephritidae)

The Mediterranean fruit fly Ceratitis capitata (Wied.) normally produces the sexes in equal ratio but strains carrying the Y chromosome meiotic drive MP (male-producing) factor show an excess of males. This is associated with a loss of sperm, and abnormal sperm structure in terms of multiple axonemes, atypical numbers of mitochondrial derivatives, and sometimes an incorrect initial orientation of paracrystalline bodies to the axoneme. Sperms are bundled together within spermatocysts, and those with depleted content and abnormalities occur in the same MP testes as normal spermatocysts. The maximum number of sperms per cyst in control strains was 256, each with a single axoneme originating from a single centriole (kinetosome). The maximum per cyst in MP strains was also 256 but MP cysts contained up to 300 axonemes, providing evidence of multiplication of centrioles. The structural changes in MP sperm are discussed in relation to similar abnormalities reported in the mosquito Aedes aegypti inheriting the Y chromosome meiotic drive haplotype MD. The evolutionary significance of this phenomenon is considered.

Survival of sterile male Mediterranean fruit flies in large field cages after release at different ages

AbstractIn Mediterranean fruit fly (Ceratitis capitata) sterile insect technique (SIT) programs worldwide, sterile flies are usually released at 2–3 days of age. However, they usually do not reach full sexual maturity until ca. 5 days of age. We tested whether holding sterile males longer at a fly emergence and release facility, until they were 5 days old, might result in significantly more flies surviving to reach sexual maturity in the field. In large field cages in Hawaii, we released sterile Mediterranean fruit fly males 2 or 5 days old under conditions where food and water were provided, or not provided. Flies were released 2 days after peak emergence in one field cage, while they were released 5 days after peak emergence in a second field cage. The numbers of flies flying out and remaining (dead, dying or non‐flying) in the holding boxes were recorded on the day of fly release. At 5 and 8 days of fly age, the size of the male fly populations were estimated using trimedlure‐baited traps placed into each of the two field cages for a 30‐min period when the numbers of flies trapped were compared. Following six tests (three replications each with and without water and sugar provided), the differences in fly captures (i.e. survival) between 2 days vs. 5 days old releases were highly significant. With food and water provided, several times as many flies from the 5‐day‐old release field cage were captured at 5 and 8 days of age compared to the 2‐day‐old release field cage. These differences were magnified under conditions of no food and water provided. Holding Mediterranean fruit flies longer prior to release, requires more holding space and food, but will lead to significantly greater numbers of sexually mature flies in the field.

Field evaluation of Mediterranean fruit fly mass trapping with Tripack® as alternative to malathion bait-spraying in citrus orchards

The mass trapping technique based on the use of the female-targeted attractant lure Tri-pack® as an alternative to malathion bait-spraying (control treatment) was tested in two citrus orchards in the North of Tunisia against the Mediterranean fruit fly Ceratitis capitata during 2006 and 2007. Results of mass trapping trials in 2006 and 2007 indicated that adult males Medfly captures showed reductions respect to control of 37.62% and 40.2% respectively in mandarin orange variety (Citrus reticulata) orchard compared to 36.48% and 47.29% in Washington navel orange variety (Citrus sinensis) field. Fruit damage assessment showed significant differences between the mass trapping with Tripack® and malathion bait-spraying techniques in the reduction of the percentage of fruit punctures. The percentage of punctured fruit at harvest was significantly different between the treated and the control field in 2006 and in 2007 in the mandarin orange orchard. Nevertheless, in the Washington navel orange orchard, the percentage of punctured fruit at harvest was significantly different between the treated and the control field only in 2006. Thus, results obtained from this study showed that the mass trapping technique based on the use of the female-targeted lure Tri-pack® could be involved as an appropriate strategy for the control of the Medfly and is as effective as malathion bait spraying treatment without leaving pesticide residues on fruit.

Evaluation of the efficiency of luring food and colored traps in attracting Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephretidae)

This study was conducted in order to evaluate the efficiency of Luring and colors traps in attracting and catching the adult of med. fruit fly Ceratitis capitata in citrus orchards in Baghdad and Salah Eldeen provinces during planting season 2008. Results indicated that different traps have had different effect to attract the adult flies. The New fly luring bait was more effective than the Dap fertilizer bait; higher numbers of flies were caught in the case of first bait in both locations respectivety. On the other hand a less number of flies were caught when Goldben bait and vinegar bait were used. None of adults had been caught in control treatment. البحث مستل من رسالة ماجستیر للباحث الثانی As for colored traps, there was a significance variation. The Yellow and white traps seemed to have a good attraction for flies. Whereas the orange, green, and blue traps had no attracting effect. According to the results of this study the (New fly luring bait) and (Dap fertilizer) placed in yellow and white traps would be recommended against this pest within an IPM programmed.

Population fluctuations and interspecific competition between Tephritid flies attacking fruit crops in the New Valley oases, Egypt

Population fluctuations of the Mediterranean fruit fly Ceratitis capitata (Wiedemann) and the peach fly Bactrocera zonata (Saunders) were monitored with lure trap collections in three provinces in the New Valley oases, Western Desert, Egypt. Results showed marked temporal differences in peak trap catches of the two flies in the selected sites all over the entire studied areas. One annual peak of C. capitata was recorded during both October 2005 and February 2006 and coincided with the ripening period of citrus trees in Kharga oases. However, two annual peaks were recorded during June and September 2005 in Bodkholow province and coincided with the ripening period of apple and mango. On the other hand, two annual peaks of B. zonata were recorded in Kharga oases throughout May and September and coincided with the ripening periods of apricot, mango and guava. One annual peak only was recorded in the round up of September and/or October in both Moot and Bodkholow in Dakhla oases and coincided with the ripening period of mango, guava and citrus. The occurrence of C. capitata was very limited in comparison with B. zonata. Population fluctuations of the two pests in the studied sites were significantly different. The ability of the traps used in capturing both C. capitata and B. zonata indicated that the yellow sticky trap was more effective in capturing C. capitata. However, the Abdel-Kawi trap was significantly efficient at trapping B. zonata. The occurrence of B. zontata in high numbers all over the study period compared to C. capitata is considered as good proof that this invading fly may be considered as a vigorous competitive tephritid fly to the native fly C. capitata.

Effect of ant predation and abiotic factors on the mortality of medfly larvae, Ceratitis capitata, in the Argan forest of Western Morocco

The Argan Argania spinosa (L.) Skeels (Ericales: Sapotaceae) is an endemic and emblematic tree growing in the centre and the southwest of Morocco. Argan fruits are frequently infested by the Mediterranean fruit fly Ceratitis capitata Wied (Diptera: Tephritidae). To date, no control program has been undertaken in the Argan forest. This research is the first investigation of natural mortality factors of C. capitata larvae in the Argan forest. The study was conducted at two localities near the city of Essaouira with different climatic conditions. Observations were conducted using 260 late instar larvae which were individually deposited on the ground, under fruiting host trees, where they naturally fall to find a suitable pupation site. Overall, 42% of the larvae died before being able to burrow into the ground, irrespectively of the location. Larval survival and their likelihood of burrowing decreased with increasing ground temperature, as 53% of all the larvae deaths occurred at temperatures over 48°C. However, at lower ground temperature, predation by ants and spiders accounted for 47% of all mortality. Four species of ants carried out 94% of the captures. Monomorium subopacum Mayr (Hymenoptera: Formicidae), which frequently forages under Argan trees, was by far the most efficient predator, due to a powerful sting that rapidly immobilizes the prey. Our results suggest that the burrowing performance of larvae is constrained by high thermal conditions and the presence of ant predators at lower temperatures.