Medfly Ceratitis Capitata Research Articles

Evidence that recent climatic changes have expanded the potential geographical range of the Mediterranean fruit fly

The species distributions migration poleward and into higher altitudes in a warming climate is especially concerning for economically important insect pest species, as their introduction can potentially occur in places previously considered unsuitable for year-round survival. We explore the expansion of the climatically suitable areas for a horticultural pest, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera, Tephritidae), with an emphasis on Europe and California. We reviewed and refined a published CLIMEX model for C. capitata, taking into consideration new records in marginal locations, with a particular focus on Europe. To assess the model fit and to aid in interpreting the meaning of the new European distribution records, we used a time series climate dataset to explore the temporal patterns of climate suitability for C. capitata from 1970 to 2019. At selected bellwether sites in Europe, we found statistically significant trends in increasing climate suitability, as well as a substantial northward expansion in the modelled potential range. In California, we also found a significant trend of northward and altitudinal expansion of areas suitable for C. capitata establishment. These results provide further evidence of climate change impacts on species distributions and the need for innovative responses to increased invasion threats.

Differential responses of Ceratitis capitata to infection by the entomopathogenic fungus Purpureocillium lilacinum.

The medfly Ceratitis capitata is one of the most damaging fruit pests with quarantine significance due to its extremely wide host range. The use of entomopathogenic fungi constitutes a promising approach with potential applications in integrated pest management. Furthermore, developing insect control methods can involve the use of fungal machinery to cause metabolic disruption, which may increase its effectiveness by impairing insect development. Insect species, including C. capitata, relies on reproduction potential, nutrient reserves, metabolic activities, and immune response for survival. Accordingly, the purpose of this study was to investigate the impacts of the entomopathogenic fungus Purpureocillium lilacinum on C. capitata pre-mortality. The medfly V8 strain was subjected to laboratory bioassays, which consisted on determining the virulence of P. lilacinum on the medfly. Purpureocillium lilacinum was applied on abdominal topical of 5-day-old males and females. Following the fungal inoculation, we have confirmed (i) a significant increase in tissue sugar content, (ii) a significant decrease in carbohydrase activities, digestive glycosyl hydrolase, and proteinase activities in whole midguts of treated flies, (iii) the antimicrobial peptides (AMPs) genes expression profile was significantly influenced by fly gender, fly status (virgin, mature, and mated), and time after infection, but infection itself had no discernible impact on the AMPs for the genes that were examined. This study provides the first insight into how P. lilacinum could affect C. capitata physiological mechanisms and provides the foundation for considering P. lilacinum as a novel, promising biocontrol agent.

Two Better Than One? Potential Effects of Intraguild Predation on the Biological Control of Ceratitis capitata (Diptera: Tephritidae) by the Parasitoid Aganaspis daci (Hymenoptera: Figitidae) and the Predator Pseudoophonus rufipes (Coleoptera: Carabidae)

The use of more than one species to manage a single insect pest is a common practice among biological control programs. However, the beneficial effects of natural enemies are not always additive, which in many cases may be attributed to interspecific interactions such as intraguild predation (IGP). Herein, we investigated the potential IGP between two relevant natural enemies of the Medfly (Ceratitis capitata), the predator Pseudoophonus rufipes and the parasitoid Aganaspis daci, as well as the possible implications of this phenomenon in their efficiency as biocontrol agents. To this end, we assessed their functional responses and different demographic parameters when acting alone and together against C. capitata under laboratory conditions. Coexistence led to a switch in the functional response of both species, from type III to type II in A. daci and the opposite in P. rufipes. Regarding demographic parameters, coexistence resulted in higher parasitoidism and population reduction by A. daci only at low host densities, probably due to competition pressure. In the same circumstances, P. rufipes reduced its predatory activity, rejecting those larvae that were presumably parasitized and causing negligible IGP. At high Medfly densities, A. daci efficiency decreased, and the reduced encounter probability enhanced the predatory activity by P. rufipes. As a result of these trends, Medfly population reduction reached almost 100% at all densities, which suggests an additive effect of both natural enemies and recommends combined releases of these agents as a strategy for the control of the Medfly.

Chemical Composition and Bioinsecticidal Effects of Thymus zygis L., Salvia officinalis L. and Mentha suaveolens Ehrh. Essential Oils on Medfly Ceratitis capitata and Tomato Leaf Miner Tuta absoluta.

The present work was aimed to study the toxicity of the essential oils of three aromatic and medicinal plants on the tomato leaf miner Tuta absoluta and the Medfly Ceratitis capitata as an alternative to conventional pesticides. We carried out a phytochemical and insecticide study of T. zygis L., S. officinalis L. and M. suaveolens Ehrh. essential oils (EOs) through the study of their chemical composition and their toxicity on C. capitata adults and T. absoluta larvae. The extraction of the EOs by hydrodistillation showed yields of 3.87 ± 0.03, 4.09 ± 0.23 and 4.35 ± 0.11 for T. zygis, S. officinalis L. and M. suaveolens Ehrh., respectively. The identification of the chemical composition of the EOs by GC/MS showed that oxygenated monoterpenes constituted the most abundant group for all the extracted EOs. The major compounds were rather diversified depending on plant species. In fact, the S. officinalis L. EO mainly contained trans-thujone (21.80 %), the M. suaveolens Ehrh. EO mainly contained piperitenone oxide (71.19%), and carvacrol (61.60%) was the main component of the T. zygis L. EO. An insecticidal effect was observed for the three studied EOs on C. capitata adults and T. absoluta larvae. The observed LD50 values were 0.80 µL/mL and 11.04 µL/mL for M. suaveolens and S. officinalis, respectively, on T. absoluta larvae. For C. capitata adults, the obtained LD50 values were 0.9 µL/mL and 11.78 µL/mL for M. suaveolens and T. zygis, respectively. The presented findings could contribute to the development of biopesticides for plants as a component of integrated pest management strategies in citrus and tomato crops.

Which artificial larval diet is better for Ceratitis capitata (Diptera: Tephritidae) rearing?

BackgroundThere is an increasing demand for biological agents for integrated pest management programs, requiring a constant supply of insects in terms of quantity and quality. In this context, the development of insect-rearing methods and quality control parameters are essential in order to provide best-quality and economic viability products. The medfly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is one of the most economically important species of fruit flies in several fruit-producing areas of Brazil, being massively reared in many countries for Sterile Insect Technique (SIT) programs. To achieve mass production scale, suitable larval diets are necessary for medfly rearing at laboratory conditions. Therefore, the objectives of this study were to determine the best artificial larval diet and the respective larval density for C. capitata on diets based on corn flour (CF), sugarcane bagasse (SB), and lyophilized carrot powder (CP), considering biological parameters of quality control and economic viability.ResultsBased on the obtained results and although all diets produced quality pupae according to FAO/IAEA/USDA standards, the SB artificial diet promoted better results in the number of larvae, larval weight, number of pupae, and pupal weight, in comparison with CF and CP diets, as well as being the most economically viable. The optimal larval densities on CF, SB, and CP diets were, respectively, 0.5, 2.0, and 1.0 mL of eggs/kg of diet.ConclusionsThe diet that was most suitable for insect yield and economic viability was the SB diet, followed by the CF and CP diets, in this order.

Maleness-on-the-Y (MoY) orthologue is a key regulator of male sex determination in Zeugodacus cucurbitae (Diptera: Tephritidae)

The initiation of sex differentiation in insects is regulated by primary sex determination signals. In the Medfly Ceratitis capitata and other Tephritids, Maleness-on-the-Y (MoY) is the master gene for male sex determination. However, the primary signal in Zeugodacus cucurbitae (Coquillett), a very destructive Tephritid pest across the world, remains ambiguous. In this study, we have isolated and characterized the Medfly MoY homolog in Z. cucurbitae, ZcMoY. ZcMOY protein shows high sequence conservation to its homologs in Bactrocera species. ZcMoY transcription begins and peaks at very early embryonic stages and then becomes undetectable except the testes and heads of day 1 male adults. Silencing ZcMoY in early embryos by RNAi causes abnormal external genitalia and interior reproductive organs, giving rise to intersexes and feminization of XY individuals. The expression pattern and knockdown phenotypes of ZcMoY indicate that ZcMoY plays a key role in regulating sex determination of Z. cucurbitae males. Our findings will help the understanding of sex determination in Z. cucurbitae and facilitate the development of genetic sexing strains in its biological control.

Effect of surround WP (a Kaolin-based particle film) on Ceratitis capitata infestation, quality and postharvest behavior of cactus pear fruit cv Gialla

• Medfly can cause high preharvest and postharvest losses to cactus pear • Preharvest kaolin treatments effectively prevented medfly damage • Kaolin treatments reduced postharvest losses from decay caused by fungi or bacteria • Kaolin did not negatively affect the ripening process of cactus pear • Kaolin increased the postharvest level of betaxantins and polyphenols in cactus pear A Kaolin-particle film (Surround WP) was applied at 3% to cactus pear (Opuntia ficus-indica cv Gialla) to assess its capacity to Control medfly (Ceratitis capitata Wiedemann) infestation and to evaluate its effects on the quality and postharvest behavior of treated fruit. In the first trial, Kaolin was applied at the end of July when fruit were green and about two weeks later, at color breakage. Its efficacy was compared with a standard organophosphate insecticide (Phosmet). The experiment was conducted in two locations in 2014 and 2015. Kaolin application was very effective in preventing medfly attacks until natural fruit drop in November. Kaolin treated fruit were harvested at the commercial maturity stage and stored 2 weeks at 8 °C plus 1 week at 20 °C, or 3 weeks at 2 °C plus 1 week at 20 °C. The incidence of decay in the presence of medfly larvae or only due to molds was 2 -13%. Phosmet was ineffective in preventing medfly attacks. The second study of Kaolin on fruit quality and postharvest behavior demonstrated that Kaolin slightly delayed fruit coloration when fruit was once or twice before harvest. Respiratory activity, ethylene rates, juice chemical composition and color at harvest time and after 1 or 2 weeks of storage at 8 °C plus 4 d at 20 °C demonstrated slight differences between Control fruit and Kaolin. Vitamin C, betaxantins levels and the antioxidant capacity of Kaolin treatments were lower or not different than Control fruit at harvest but increased at a higher rate than in Control fruit over storage. Total phenols decreased in all treatments during storage but at a slower rate in Kaolin treatments. Overall results show that Kaolin treatments are effective to prevent medfly attacks in cactus pears with no negative effect on fruit quality and shelf life.

Assessment of mating competitiveness of sterile Ceratitis capitata in laboratory and field cage tests in northern Iran

AbstractIn recent years, damage by Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) on commercial fruit crops has reached a critical point in Iran. The sterile insect technique is considered the most effective strategy for the area‐wide suppression or eradication of tephritid fruit flies, particularly the medfly. In this study, an area of citrus trees, including 39 field cages in Sari‐Mazandaran province, was used for an experiment to test various irradiation doses and overflowing ratios on male competitiveness‐induced sterility. Treatments 1 and 2 consisted of non‐irradiated females (NF), non‐irradiated males (NM), and irradiated males (IM) which emerged from pupae irradiated with 80 or 100 Gy. The IM:NM:NF ratios per field cage were varied as follows: 0:1:1, 1:0:1, 1:1:1, 3:1:1, 5:1:1, 10:1:1, and 15:1:1. We found that the mating rate of NF copulating with IM was significantly lower than that of NF mated with NM. The numbers of eggs and the percentages of egg hatching were significantly lower in IM × NF than in NM × NF crosses, and no eggs hatched in the 80–130 Gy dose range. The results of Fried's CV (male mating competitiveness value based on egg hatch) ranged from 0.41 to 0.78 at a dose of 80 Gy and from 0.35 to 0.63 at 100 Gy for various mating rates. It can be concluded that IM was fully competitive with NM at the dose range of 80–100 Gy of gamma radiation.

Insecticidal potential of Brevibacillus laterosporus against dipteran pest species in a wide ecological range

In order to increase our understanding of the insecticidal potential of the entomopathogenic bacterium Brevibacillus laterosporus strain UNISS 18 against insect pests, investigations were conducted on a selection of dipteran species including fruit flies, house flies, blow flies, and mosquitoes, characterized by adaptations to very diverse habitats.According to lethal concentration (LC50) values, the common house mosquito Culex pipiens (LC50 = 0.10 × 106 spores/mL) and the yellow fever mosquito Aedes aegypti (LC50 = 0.18 × 106 spores/mL) were significantly more susceptible than the flies. The blow flies were the second taxon in term of susceptibility to B. laterosporus spores, with a higher mortality in Calliphora vomitoria (LC50 = 78.84 × 106 spores/mL) than Lucilia caesar (LC50 = 148.30 × 106 spores/mL). The effectiveness of B. laterosporus spores was reduced by half in the house fly Musca domestica (LC50 = 82.41 × 106 spores/mL). The lowest susceptibility was observed in the fruit flies, among which the spotted wing drosophila (SWD), Drosophila suzukii, was the most susceptible (LC50 = 217.51 × 106 spores/mL) in comparison with the medfly Ceratitis capitata and the olive fly Bactrocera oleae (LC50 = 2567.32 and 2567.36 × 106 spores/mL, respectively). The present study demonstrated that significantly different degrees of susceptibility are associated with diverse dipteran species including plant and animal parasites, and we suggest that B. laterosporus established different relationships with dipteran species in different ecosystems.

Effectiveness of Sterile Insect Technique for Medfly (Ceratitis capitata, Wiedemann, 1824) Control in Citrus Orchards of Moulouya Perimeter North East of Morocco

The Sterile Insect Technique (SIT) is an effective pest control method developed worldwide against many species of Fruit Flies. It involves the release of male insects sterilized, at pupae instar, by exposure to ionizing radiation. The Area-wide control of medfly (Ceratitis capitata), with SIT based on sterile males release combined to other control techniques, was implemented since 2017 as a pilot area in Moulouya Perimeter in North-eastern Morocco. The main objective of this study is to evaluate the effectiveness of this tool in controlling Medfly and estimate sterile male population densities from data collected from trap catches after the release of a pre-determined number of sterile males in five Citrus orchards (0, 500, 1000 and 3000 sterile males per hectare) and the calculation of FTD (fly/trap/day) of sterile and wild males. The result showed that the percentage of recaptured males and FTD Sterile indices were related to release density by power function regression, while the sterile to wild ratio and release density were linear regression-adjusted. The finding confirmed the effectiveness of release in reducing the fly population in the TIS area by reducing the rate of citrus infestation in field and export shipments.

Competitive interactions and partial displacement of Anastrepha obliqua by Ceratitis capitata in the occupation of host mangoes (Mangifera indica)

AbstractWe examined the competitive interactions between a native fruit fly species (Anastrepha obliqua Macquart) and the invasive medfly (Ceratitis capitata Wiedemann) when these co‐occur on a shared mango fruit host (Mangifera indica L.). Using mango fruits of distinct levels of ripeness, we investigated both competition among larvae and among adult females for oviposition. We quantified competition by the numbers of eggs laid and the intensity of agonistic interactions between adult females. Interactions between immature fruit flies led to reduced size and number of emerged adults of both species. These impacts were felt more acutely in the native species. Interspecific competition between females led to fewer eggs laid on semi‐ripe fruit by both species, which may be the result of niche overlap associated with oviposition. Intraspecific interactions between A. obliqua individuals led to intense agonistic behaviour, with a concurrent decrease in number of landings on these host fruits. These results suggest that the native species undergoes a partial niche displacement when facing the invasive species. A portion of the fundamental niche of A. obliqua remained unoccupied by the invading C. capitata, which may allow their coexistence under natural conditions.

Physalis peruviana L. (Solanaceae) Is Not a Host of Ceratitis capitata (Diptera: Tephritidae): Evidence from Multi-Year Field and Laboratory Studies in Colombia.

Scientifically-based, tephritid fly host status determination lies at the heart of strategic regulatory decisions impinging on international fruit trade. Here we conducted intensive field and laboratory studies with peaches as controls, to determine the host status of Physalis peruviana for the Medfly—Ceratitis capitata, as this fruit is experiencing a consumption boom worldwide. A total of 98,132 Uchuvas (local name), collected in Colombia from the plant or the ground over a three-year period (2016–2018) did not yield a single C. capitata larva or pupa, thus reaching a Probit 9 level with 99.9968% efficacy and 96% confidence level. Field-cage studies with enclosed fruit-bearing Uchuva plants, exposing fruit with an intact, damaged or totally removed husk to the attack of C. capitata, also failed to yield infestations. Highly artificial choice experiments, exposing gravid females to unripe and fully ripe fruit, resulted in an absence of infestations, even when overripe Uchuvas were artificially damaged. The husk and surface resins/waxes inhibit fly landings on fruit and oviposition activity. Considering our results and the fact that the foliage, husk and fruit of P. peruviana are repellent/toxic to insects, we conclude that this plant should be treated as a non-natural and non-conditional host of C. capitata.

Mate choice and gene expression signatures associated with nutritional adaptation in the medfly (Ceratitis capitata)

Evolutionary responses to nutrition are key to understanding host shifts and the resulting potential for reproductive isolation. Experimental evolution has previously been used to describe the responses of the medfly (Ceratitis capitata) to larval diets with different nutritional properties. Within 30 generations this led to divergence in larval development time, egg to adult survival and adaptation in adult body size. Here we used mRNA-seq to identify differences in gene expression patterns in these same populations, using males from the 60th generation of nutritional selection. We validated differential expression by using qRT-PCR and found that genes linked to metabolism, oxidative phosphorylation and proteolysis were significantly over-represented among the differentially expressed genes. The results provide the first genome-wide survey of the putative mechanisms underpinning evolved responses to nutritional adaptation. In addition, we tested the hypothesis that nutritional adaptation can alter mating patterns. We found evidence for assortative mating by diet at generation 60, but not 90. Hence, the pattern was variable across generations and there was no evidence overall for any isolating mating divergence between the lines. Overall, the results provide insight into the mechanisms underpinning dietary adaptation and extend our knowledge of which traits represent core responses to nutritional selection.

Contribution of maternal effects to dietary selection in Mediterranean fruit flies.

Individual responses to dietary variation represent a fundamental component of fitness, and nutritional adaptation can occur over just a few generations. Maternal effects can show marked proximate responses to nutrition, but whether they contribute to longer term dietary adaptation is unclear. Here, we tested the hypotheses that maternal effects: (i) contribute to dietary adaptation, (ii) diminish when dietary conditions are constant between generations, (iii) are trait‐specific and (iv) interact with high‐ and low‐quality food. We used experimental evolution regimes in the medfly (Ceratitis capitata) to test these predictions by subjecting an outbred laboratory‐adapted population to replicated experimental evolution on either constant high calorie sugar (‘A’) or low‐calorie starch (‘S’) larval diets, with a standard adult diet across both regimes. We measured the contribution of maternal effects by comparing developmental and adult phenotypes of individuals reared on their own diet with those swapped onto the opposite diet for either one or two generations (high and low maternal effect conditions, respectively), both at the start and after 30 generations of selection. Initially, there were strong maternal effects on female body mass and male mating success but not larval survival. Interestingly, the initial maternal effects observed in female body mass and male mating success showed sex‐specific interactions when individuals from high calorie regimes were tested on low calorie diets. However, as populations responded to selection, the effects of maternal provisioning on all traits diminished. The results broadly supported the predictions. They show how the contribution of maternal effects to dietary responses evolves in a context‐dependent manner, with significant variation across different fitness‐related traits. We conclude that maternal effects can evolve during nutritional adaptation and hence may be an important life history trait to measure, rather than to routinely minimize.

Combined use of the larvo‐pupal parasitoids Diachasmimorpha longicaudata and Aganaspis daci for biological control of the medfly

In biological control programmes, it is very common to employ multiple species to manage a single insect pest. However, the beneficial effects of natural enemies are not always additive because of several factors, including interspecific competition between these biocontrol agents. For this reason, in the present study we assessed several biological parameters (percentage parasitism, fertility, induced mortality and population reduction) of the parasitoids Diachasmimorpha longicaudata and Aganaspis daci when used together against the medfly Ceratitis capitata under laboratory and greenhouse conditions. Our results showed that, under laboratory conditions, fertility and percentage parasitism corresponded to a different functional response for each species (D. longicaudata: type II; A. daci: type III), whilst under greenhouse conditions, and unlike what occurs with single releases, both parasitoids showed a type III functional response; this is the only response which may lead to direct density dependence when host densities are low. Our results also revealed that when both species acted together, they produced a very high total percentage parasitism compared to that reported for single releases under both laboratory (64–76%) and greenhouse (21–51%) conditions. The parasitism was also higher for A. daci except when medfly larvae were provided in an artificial diet. Furthermore, host mortality induced by the two parasitoids acting together was very high, especially at low‐host densities; medfly population was almost completely reduced under greenhouse conditions. In summary, the data reported here supports the combined use of these species in biological control programmes against the medfly and highlights the importance of several factors, such as climatic conditions and host density, when planning their field releases.

Evaluation of the attractant effect and lipid profile modulation of natural fixed oils on the medfly Ceratitis capitata (Wiedemann).

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann, 1824; Diptera: Tephritidae), is a polyphagous pest in horticulture, mainly targeting Citrus fruits. Natural essential and fixed oils are currently under investigation for their broad-spectrum in pest control. To gain better knowledge aboutmedfly behavior and biochemistry, we examined withbehavioral and biochemical assays, the effects on C. capitatafromsix natural fixed oils obtained from vegetable (five) or animal (one) matrices using the eco-friendly supercritical CO 2 extraction. Oils were obtained at 250/300 bar and 40°C from the seeds of Laurus nobilis and Citrus paradisi, the fruits of Myristica fragrans and Pistacia terebinthus, wheat germ, and mullet roes (marine oil). Behavioral experiments were performed by means of two-choice tests to analyze the oil attractant effect compared with control (water or standard diet). The fatty acid composition of oils and the total lipid and fatty acid profile of medflies were characterized by chromatographic techniques. Behavioral bioassays showed that fixed oil obtained from M. fragrans (nutmeg butter) was more attractive than other oils. Medflies fed (24 hr) on marine oil showed significant changes in the total lipid and fatty acid profile induced by oil ingestion without toxic effects. However, 56% mortality was observed in insects fed on M. fragrans oil and no biochemical changes ascribable to oil ingestion were detected in the medflies that survived. Our results advance knowledge about the behavioral and biochemical response of medflies to fixed oils and will be potentially useful in developing new pest management strategies.

Modelling optimal timing and frequency of insecticide sprays for knockdown in preparation for other control measures

ABSTRACTA modelling investigation was conducted into optimizing the number of sprays and inter-spray interval to reduce an insect population to a low level, for example, prior to pheromone trapping or the release of sterile males. The model population was age-structured and density-dependent. If spray mortality is 100% for each spray, then the ideal spraying schedule is easily determined from the durations of the various life stages. For spray mortality of less than 100%, a simulation was used to determine optimal spraying schedules. Relative length of the larval period, fertility rate and age to first oviposition were found to be the most important biotic parameters for this determination. Their importance is magnified as spray mortality decreases. The stage targeted by sprays and the percent mortality caused by each spray are also important in determining the required number of sprays. Using medfly (Ceratitis capitata Wiedmann) biotic parameters as an example when the spray targets adults, it appeared that neither the stage at which density-dependent mortality takes effect, nor the form of the adult survivorship curve are important in determining the optimal spray schedule.

Abiotic factors affecting Diachasmimorpha longicaudata (Hymenoptera: Braconidae) activity as a natural enemy of Ceratitis capitata (Diptera: Tephritidae) under semi‐natural conditions in the Mediterranean region

AbstractThe larval–pupal endoparasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae) is currently the most commonly employed biological control agent against Tephritid fruit flies in the Americas. However, this parasitoid remains largely ignored and is not used in many regions, including the Mediterranean Basin. In this study, the potential of D. longicaudata as a biocontrol agent against the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae) was addressed in an area of eastern Spain (the Valencian community). The parasitic activity of parasitoids and the effects of climatic conditions were evaluated throughout a 1‐year period in field‐cage experiments in which parasitoids were confined with apples artificially infested with medfly larvae. The following parameters were calculated and related statistically to several environmental conditions: the parasitism rate, the induced mortality and progeny sex ratio. The results show that D. longicaudata is able to parasitize medfly larvae throughout the year under semi‐natural conditions. Important fluctuations in the parasitism rate (from almost zero to 42%) and the induced mortality (from 6% to 80%) were partially influenced by climatic conditions. The parasitism rate increased with mean temperature and decreased with mean relative humidity, while the induced mortality decreased with minimum relative humidity. The optimal climatic conditions for the activity of the parasitoid were a mean temperature of 16–24°C combined with a relative humidity of 45%–60%. Overall, these results suggest that reduction in the medfly population due to D. longicaudata activity is feasible and provide information about the optimal time period for parasitoid release in the field. In conclusion, D. longicaudata has a significant potential to control C. capitata in the Mediterranean region.

Evaluation of Providencia rettgeri pathogenicity against laboratory Mediterranean fruit fly strain (Ceratitis capitata).

The Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is often referred to as the most severe agricultural pest. Its biological control is mainly through the Sterile Insect Technique (SIT). Colonization, mass-rearing conditions and the irradiation process impact the competitiveness of sterile males and disrupt symbiotic associations by favoring some bacterial species and suppressing others. Levels of Providencia species have been shown to fluctuate considerably in the gut of the medfly laboratory strain Vienna 8 under irradiation, increasing by up to 22%. This study aimed to determine the pathogenicity of Providencia rettgeri isolated from the gut of laboratory Vienna 8 medfly strains by examining the effects of 1) two different treatment doses on egg-hatching and development and 2) two infection methodologies (ingestion and injection) of male and female adults according to their mating status. Treatment of eggs with P. rettgeri (2%) significantly decreased the mean egg to pupae recovery rate. Our data showed significant high mortality in flies with both injection and ingestion after 24 hours without any effect of sex. Microbial counts demonstrated that the bacteria could proliferate and replicate in adult flies. There was a significant sex-dependent effect after infection, with mortality decreasing significantly for males more than females. Providencia rettgeri can be considered as a potential pathogen of C. capitata. Mating protected males and females against infection by P. rettgeri by triggering an immune response leading to double the levels of Cecropin being secreted compared to infected virgin adults, thus reducing the virulence of the bacteria.

Larval Diet Affects Male Pheromone Blend in a Laboratory Strain of theMedfly, Ceratitis capitata (Diptera: Tephritidae).

The Mediterranean fruit fly (medfly) Ceratitis capitata is a polyphagous pest of fruits and crops with a worldwide distribution. Its ability to use different larval hosts may have multiple effects, including impacts on adult reproductive biology. The male sex pheromone, which plays a key role in attracting both other males to lekking arenas and females for mating, is a mixture of chemical compounds including esters, acids, alkanes and terpenes known to differ between laboratory strains and wild-type populations. The relationship between larval diet and adult pheromone composition remains unexplored. Here, we investigated the effect of larval diet, including laboratory media and fresh fruits, on the composition of the male pheromone mixture. Using HeadspaceSolid Phase Microextraction we collected the pheromone emitted by males reared as larvae on different substrates and found both qualitative and quantitative differences. A number of alkanes appeared to be typical of the pheromone of males reared on wheat bran-based larval medium, and these may be cuticular hydrocarbons involved in chemical communication. We also detected differences in pheromone composition related to adult male age, suggesting that variations in hormonal levels and/or adult diet could also play a role in determining the chemical profile emitted. Our findings highlight the plasticity of dietary responses of C. capitata, which may be important in determining the interactions of this pest with the environment and with conspecifics. These results also have appliedrelevance to increase the mating competitiveness of mass-reared C. capitata used in Sterile Insect Technique programs.