Validation of degree-day models for predicting the emergence of two fruit flies (Diptera: Tephritidae) in northeast Egypt.

We estimated thermal developmental thresholds (T0 ) and degree-day (DD) constants for the immature stages of two tephritid pests, Bactrocera zonata (Saunders) and Ceratitis capitata (Weidenmann). Males of both species were trapped in an Egyptian guava orchard during the fruiting seasons of 2016 and 2017 and trap catches were compared with peak flights predicted by the DD model based on local weather data. Ceratitis capitata had faster development than B. zonata at 20 and 25 °C, but their overall developmental rate was similar at 30 and 35 °C. The thermal threshold of development (T0 ) of B. zonata was higher than that of C. capitata, indicating greater sensitivity to cold. Although 35 °C yielded the fastest development of both species, survival was higher at 30 °C, with B. zonata experiencing a slight advantage, suggesting better tropical adaptation. Immature development of B. zonata and C. capitata was estimated to require 338 and 373 d, respectively, and 616 and 424 DD for a complete generation. Trap catches over both seasons showed good correspondence to peaks of fly activity predicted by the DD models; deviations from expectation ranged from 0 to 7 d for both fly species. Both species had four overlapping generations per season, with B. zonata abundance peaking in the first generation in both years, but only in 2016 for C. capitata. The models predict about eight and 12 generations per year in northeast Egypt for B. zonata and C. capitata, respectively. These models should be useful for timing pest control measures to coincide with periods of peak fly activity in fruit orchards.

Effect of host fruit, temperature and Wolbachia infection on survival and development of Ceratitis capitata immature stages.

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), holds an impressive record of successful invasions promoted by the growth and development of international fruit trade. Hence, survival of immatures within infested fruit that are subjected to various conditions during transportation seems to be a crucial feature that promotes invasion success. Wolbachia pipientis is a common endosymbiont of insects and other arthropods generating several biological effects on its hosts. Existing information report the influence of Wolbachia on the fitness traits of insect host species, including the Mediterranean fruit fly. However, little is known regarding effects of Wolbachia infection on immature development in different host fruits and temperatures. This study was conducted to determine the development and survival of immature stages of four different Mediterranean fruit fly populations, either infected or uninfected with Wolbachia, in two hosts (apples, bitter oranges) under three constant temperatures (15, 25 and 30°C), constant relative humidity (45-55 ± 5%), and a photoperiod of 14L:10D. Our findings demonstrate both differential response of two fruit fly lines to Wolbachia infection and differential effects of the two Wolbachia strains on the same Mediterranean fruit fly line. Larva-to-pupa and larva-to-adult survival followed similar patterns and varied a lot among the four medfly populations, the two host fruits and the different temperatures. Pupation rates and larval developmental time were higher for larvae implanted in apples compared to bitter oranges. The survival rates of wildish medflies were higher than those of the laboratory adapted ones, particularly in bitter oranges. The Wolbachia infected medflies, expressed lower survival rates and higher developmental times, especially the wCer4 infected line. High temperatures constrained immature development and were lethal for the Wolbachia infected wCer4 medfly line. Lower temperatures inferred longer developmental times to immature stages of all medfly populations tested, in both host fruits. Implications on the ecology and survival of the fly in nature are discussed.

Comparative demography of Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) on deciduous fruit.

Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann) are highly polyphagous fruit fly species and important pests of commercial fruit in regions of the world where they are present. In South Africa, B. dorsalis is now established in the north and northeastern parts of the country. B. dorsalis is currently absent in other parts of the country including the Western Cape Province which is an important area for the production of deciduous fruit. C. capitata is widespread in South Africa and is the dominant pest of deciduous fruit. The demographic parameters of B. dorsalis and C. capitata on four deciduous fruit types Prunus persica (L.) Batsch, Prunus domestica L., Malus domestica Borkh. and Pyrus communis L. were studied to aid in predicting the potential population establishment and growth of B. dorsalis in a deciduous fruit growing environment. All deciduous fruit types tested were suitable for population persistence of both B. dorsalis and C. capitata. Development was fastest and survival highest on nectarine for both species. B. dorsalis adults generally lived longer than those of C. capitata, irrespective of the fruit types that they developed from. B. dorsalis had a higher net reproductive rate (Ro) on all deciduous fruit tested compared to C. capitata. However, the intrinsic rate of population increase was estimated to be higher for C. capitata than for B. dorsalis on all fruit types tested primarily due to C. capitata's faster generation time. Provided abiotic conditions are optimal, B. dorsalis would be able to establish and grow in deciduous fruit growing areas.

The host fruit amplifies mutualistic interaction between Ceratitis capitata larvae and associated bacteria.

BACKGROUND: The Mediterranean fruit fly Ceratitis capitata is a major pest in horticulture. The development of fly larvae is mediated by bacterial decay in the fruit tissue. Despite the importance of bacteria on larval development, very little is known about the interaction between bacteria and larvae in their true ecological context. Understanding their relationship and inter-dependence in the host fruit is important for the development of new pest control interfaces to deal with this pest. RESULTS: We find no negative effects on egg hatch or larval development brought about by the bacterial isolates tested. The various symbionts inhabiting the fly's digestive system differ in their degree of contribution to the development of fly larvae depending on the given host and their sensitivity to induced inhibition caused by female produced antimicrobial peptides. These differences were observed not only at the genus or species level but also between isolates of the same species. We demonstrate how the microbiota from the mother's gut supports the development of larvae in the fruit host and show that larvae play a major role in spreading the bacterial contagion in the infected fruit itself. In addition, we present (for the first time) evidence for horizontal transfer of bacteria between larvae of different maternal origin that develop together in the same fruit. CONCLUSIONS: Larvae play a major role in the spread and shaping of the microbial population in the fruit. The transfer of bacteria between different individuals developing in the same fruit suggests that the infested fruit serves as a microbial hub for the amplification and spread of bacterial strains between individuals.

Age, sex, adult and larval diet shape starvation resistance in the Mediterranean fruit fly: an ecological and gerontological perspective.

The ability of an animal to withstand periods of food deprivation is a key driver of invasion success (biodiversity), adaptation to new conditions, and a crucial determinant of senescence in populations. Starvation resistance (SR) is a highly plastic trait and varies in relation to environmental and genetic variables. However, beyond Drosophila, SR has been studied poorly. Exploiting an interesting model species in invasion and ageing studies-the Mediterranean fruit fly (Ceratitis capitata)- we investigated how age, food and gender, shape SR in this species. We measured SR in adults feeding in rich and poor dietary conditions, which had been reared either on natural hosts or artificial larval diet, for every single day across their lifespan. We defined which factor is the most significant determinant of SR and we explored potential links between SR and ageing. We found that SR declines with age, and that age-specific patterns are shaped in relation to adult and larval diet. Females exhibited higher SR than males. Age and adult diet were the most significant determinants of SR, followed by gender and the larval diet. Starvation resistance proved to be a weak predictor of functional ageing. Possible underlying mechanisms, ecological and gerontological significance and potential applied benefits are discussed.

Adult diet does not compensate for impact of a poor larval diet on stress resistance in a tephritid fruit fly.

Adult holometabolous insects may derive metabolic resources from either larval or adult feeding, but little is known of whether adult diets can compensate for deficiencies in the larval diet in terms of stress resistance. We investigated how stress resistance is affected and compensated for by diet across life stages in the marula fruit fly Ceratitis cosyra (Diptera: Tephritidae). Larvae were fed diets containing either 8% torula yeast, the standard diet used to rear this species, or 1% yeast (low protein content similar to known host fruit). At emergence, adults from each larval diet were tested for initial mass, water content, body composition, and desiccation and starvation resistance or they were allocated to one of two adult diet treatments: sucrose only, or sucrose and yeast hydrolysate. The same assays were then repeated after 10 days of adult feeding. Development on a low protein larval diet led to lower body mass and improved desiccation and starvation resistance in newly emerged adults, even though adults from the high protein larval diet had the highest water content. Adult feeding decreased desiccation or starvation resistance, regardless of the diet provided. Irrespective of larval diet history, newly emerged, unfed adults had significantly higher dehydration tolerance than those that were fed. Lipid reserves played a role in starvation resistance. There was no evidence for metabolic water from stored nutrients extending desiccation resistance. Our findings show the possibility of a nutrient-poor larval environment leading to correlated improvement in adult performance, at least in the short term.

Oviposition preference of Ceratitis capitata (Diptera: Tephritidae) at different times after pruning 'Italia' table grapes grown in Brazil.

Studies investigating oviposition preference of Ceratitis capitata (Wiedemann, 1824) in table grapes (Vitis vinifera L.) cultivated in the São Francisco River Valley can provide important information to guide control measures, therefore minimizing damage caused by this species in the region. The aim of this study was to evaluate the oviposition preference of C. capitata females for berries cv. 'Italia' collected at five different times (60, 70, 80, 90, and 100 d after production pruning [DAPP]), representing five grapevine growth stages. We also assessed the performance of immature stages of C. capitata regarding the physiological development of the berry. The total soluble solid content was significantly higher in berries at more advanced physiological developmental stages (90 and 100 DAPP). Conversely, these berries showed the lowest values of firmness and titratable acidity. With the onset of physiological development, the average number of punctures per berry increased and reached 5.2 per berry in 100 DAPP berries. The infestation level and pupal weight showed a positive correlation with the growth stage. The highest recovery of pupae was observed in 100 DAPP berries (1.54). Pupal viability values ranged from 50.9 to 64.7% independent of berry maturity stage. The physiological developmental stage of the berry did not affect offspring sex ratio. Results obtained suggest that regardless of the female preference for laying eggs on berries in a more advanced physiological developmental stage, females can initiate the attack to bunches of this cultivar at 60 DAPP, even if the berries have unfavorable physicochemical parameters for oviposition and development of larvae.

Rearing two fruit flies pests on artificial diet with variable pH / Criação de duas moscas-das-frutas praga em dieta artificial com variação de pH

Abstract Fruit flies (Diptera: Tephritidae) are considered the main fruit pests worldwide. In Brazil, two species are predominant: the South American fruit fly, Anastrepha fraterculus and the Mediterranean fruit fly, Ceratitis capitata. In this study, we evaluated the effect of artificial diets with variable pH in their larval development and adult performance. The experiments were carried out in the laboratory at 25 ± 2 °C, 70 ± 10% RH and 12:12h (L:D) photoperiod. Semisolid diets with pH values of 6.0, 5.0, 4.0, 3.0, 2.0, 1.5, and 1.0, adjusted by adding hydrochloric acid were tested. Results indicated that the diet with pH 6.0 did not support larval development of both species of fruit fly. Diets with greater acidic pH values did not allow egg, larvae or pupae development and adult reproduction of A. fraterculus. For C. capitata , the pH of artificial diet exerts greater influence compared to A. fraterculus on the duration and viability of the larval stage, number of pupae, sex ratio and longevity of males.

Resumo As moscas-das-frutas (Diptera: Tephritidae) são consideradas as principais pragas da fruticultura mundial. No Brasil, duas espécies são predomindantes: a mosca-das-frutas Sul-americana, Anastrepha fraterculus e a mosca-do-Mediterrâneo, Ceratitis capitata. Neste estudo avaliamos o efeito de dietas artificiais com pH variável no seu desenvolvimento larval e performance de adultos. Os experimentos foram realizados em laboratório a 25 ± 2 °C, 70 ± 10% UR e fotoperíodo de 12:12 horas. Foram testadas dietas semi-sólidas com valores de pH de 6,0; 5,0; 4,0; 3,0; 2,0; 1,5 e 1,0, ajustados pela adição de ácido clorídrico. Os resultados indicaram que a dieta com pH 6,0 não suportou o desenvolvimento larval de ambas as espécies de mosca-das-frutas. As dietas com pH ácido não permitiram o desenvolvimento de ovos, larvas ou pupas e a reprodução de adultos de A. fraterculus. Para C. capitata o pH da dieta artificial exerceu maior influência do que para A. fraterculus nos parâmetros de duração e viabilidade do estágio larval, número de pupas, razão sexual e longevidade de machos.

Rearing two fruit flies pests on artificial diet with variable pH.

Fruit flies (Diptera: Tephritidae) are considered the main fruit pests worldwide. In Brazil, two species are predominant: the South American fruit fly, Anastrepha fraterculus and the Mediterranean fruit fly, Ceratitis capitata. In this study, we evaluated the effect of artificial diets with variable pH in their larval development and adult performance. The experiments were carried out in the laboratory at 25 ± 2 °C, 70 ± 10% RH and 12:12h (L:D) photoperiod. Semisolid diets with pH values of 6.0, 5.0, 4.0, 3.0, 2.0, 1.5, and 1.0, adjusted by adding hydrochloric acid were tested. Results indicated that the diet with pH 6.0 did not support larval development of both species of fruit fly. Diets with greater acidic pH values did not allow egg, larvae or pupae development and adult reproduction of A. fraterculus. For C. capitata , the pH of artificial diet exerts greater influence compared to A. fraterculus on the duration and viability of the larval stage, number of pupae, sex ratio and longevity of males.

Highly efficient genome editing by homology-directed repair using Cas9 protein in Ceratitis capitata.

The Mediterranean fruit fly Ceratitis capitata is a highly polyphagous and invasive insect pest, causing enormous economic damage in horticultural systems. A successful and environment-friendly control strategy is the sterile insect technique (SIT) that reduces pest populations through infertile matings with mass-released, sterilized insects. However, the SIT is not readily applicable to each pest species. While transgenic approaches hold great promise to improve critical aspects of the SIT to transfer it to new species, they are suspect to strict or even prohibitive legislation regarding the release of genetically modified (GM) organisms. In contrast, specific mutations created via CRISPR-Cas genome editing are not regulated as GM in the US, and might thus allow creating optimal strains for SIT. Here, we describe highly efficient homology-directed repair genome editing in C. capitata by injecting pre-assembled CRISPR-Cas9 ribonucleoprotein complexes using different guide RNAs and a short single-stranded oligodeoxynucleotide donor to convert an enhanced green fluorescent protein in C. capitata into a blue fluorescent protein. Six out of seven fertile and individually backcrossed G0 individuals generated 57-90% knock-in rate within their total offspring and 70-96% knock-in rate within their phenotypically mutant offspring. Based on the achieved efficiency, this approach could also be used to introduce mutations which do not produce a screenable phenotype and identify positive mutants with a reasonable workload. Furthermore, CRISPR-Cas HDR would allow to recreate mutations formerly identified in classical mutagenesis screens and to transfer them to related species to establish new (SIT-like) pest control systems. Considering the potential that CRISPR-induced alterations in organisms could be classified as non-GM in additional countries, such new strains could potentially be used for pest control applications without the need to struggle with GMO directives.

Larval Diet Affects Male Pheromone Blend in a Laboratory Strain of the Medfly, 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 Headspace Solid 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 applied relevance to increase the mating competitiveness of mass-reared C. capitata used in Sterile Insect Technique programs.

Highly efficient DNA-free gene disruption in the agricultural pest Ceratitis capitata by CRISPR-Cas9 ribonucleoprotein complexes.

The Mediterranean fruitfly Ceratitis capitata (medfly) is an invasive agricultural pest of high economic impact and has become an emerging model for developing new genetic control strategies as an alternative to insecticides. Here, we report the successful adaptation of CRISPR-Cas9-based gene disruption in the medfly by injecting in vitro pre-assembled, solubilized Cas9 ribonucleoprotein complexes (RNPs) loaded with gene-specific single guide RNAs (sgRNA) into early embryos. When targeting the eye pigmentation gene white eye (we), a high rate of somatic mosaicism in surviving G0 adults was observed. Germline transmission rate of mutated we alleles by G0 animals was on average above 52%, with individual cases achieving nearly 100%. We further recovered large deletions in the we gene when two sites were simultaneously targeted by two sgRNAs. CRISPR-Cas9 targeting of the Ceratitis ortholog of the Drosophila segmentation paired gene (Ccprd) caused segmental malformations in late embryos and in hatched larvae. Mutant phenotypes correlate with repair by non-homologous end-joining (NHEJ) lesions in the two targeted genes. This simple and highly effective Cas9 RNP-based gene editing to introduce mutations in C. capitata will significantly advance the design and development of new effective strategies for pest control management.

Housekeeping in Tephritid insects: the best gene choice for expression analyses in the medfly and the olive fly.

Real-time quantitative-PCR has been a priceless tool for gene expression analyses. The reaction, however, needs proper normalization with the use of housekeeping genes (HKGs), whose expression remains stable throughout the experimental conditions. Often, the combination of several genes is required for accurate normalization. Most importantly, there are no universal HKGs which can be used since their expression varies among different organisms, tissues or experimental conditions. In the present study, nine common HKGs (RPL19, tbp, ubx, GAPDH, α-TUB, ß-TUB, 14-3-3zeta, RPE and actin3) are evaluated in thirteen different body parts, developmental stages and reproductive and olfactory tissues of two insects of agricultural importance, the medfly and the olive fly. Three software programs based on different algorithms were used (geNorm, NormFinder and BestKeeper) and gave different ranking of HKG stabilities. This confirms once again that the stability of common HKGs should not be taken for granted and demonstrates the caution that is needed in the choice of the appropriate HKGs. Finally, by estimating the average of a standard score of the stability values resulted by the three programs we were able to provide a useful consensus key for the choice of the best HKG combination in various tissues of the two insects.

Cold Disinfestation of "Hass" Avocado (Persia americana) of Three Species of Fruit Fly (Diptera: Tephritidae)-Ceratitis capitata, Ceratitis rosa, and Ceratitis cosyra.

The avocado industry is important in South Africa, but access to certain markets is impeded by the presence of phytosanitary pests. One of the ways of securing entry to these markets is to demonstrate that a mitigating treatment will result in there being a negligible chance of accidental importation. In cold treatment comparative studies at 0 °C and 2 °C of immature stages of Ceratitis capitata (Wiedemann), Ceratitis rosa Karsch, and Ceratitis cosyra (Walker) in "Hass" avocado, the third instar of C. cosyra was shown to be the most cold tolerant. This larval life stage was used in a large-scale trial to test treatment efficacy at 2 °C, a temperature known to be the better for fruit quality. There were no survivors from the 49,795 individual fruit fly larvae subjected to the cold treatment at 2 °C for 20 d. It is argued that, although this level of assessment falls short of the Probit 9 level normally required for fruit fly, they are rarely found in avocado fruit and that the level of disinfestation obtained is more than sufficient to achieve quarantine security.

An Additional Phytosanitary Cold Treatment Against Ceratitis capitata (Diptera: Tephritidae) in 'Oroblanco' Citrus Fruit.

For 'Oroblanco' ('Sweetie'), the sweet seedless pummelo-grapefruit hybrid, when exported from Israel to Japan, the standard cold treatment against Ceratitis capitata (Wied.) (Diptera: Tephritidae) is conducted at ≤ 1.5 °C, for 16 d. In recent years, the transportation means of exported citrus was changed from reefer vessels to individual refrigerated containers, where the fruit bulk is relatively small and may be exposed to temperature fluctuations and to the risk of chilling injuries. To reduce this risk, Israel proposed to Japan to increase the treatment temperature and extend its duration to 2.2 °C and 18 d, respectively. This study shows that the proposed treatment effectively kills the third instar larva of C. capitata, in Oroblanco.

Adaptation to divergent larval diets in the medfly, Ceratitis capitata.

Variation in diet can influence the timing of major life-history events and can drive population diversification and ultimately speciation. Proximate responses of life histories to diet have been well studied. However, there are scant experimental data on how organisms adapt to divergent diets over the longer term. We focused on this omission by testing the responses of a global pest, the Mediterranean fruitfly, to divergent selection on larval diets of different nutritional profiles. Tests conducted before and after 30 generations of nutritional selection revealed a complex interplay between the effects of novel larval dietary conditions on both plastic and evolved responses. There were proximate-only responses to the larval diet in adult male courtship and the frequency of copulation. Males on higher calorie larval diets consistently engaged in more bouts of energetic courtship. In contrast, following selection, larval development time, and egg to adult survival showed evidence of evolved divergence between diet regimes. Adult body size showed evidence for adaptation, with flies being significantly heavier when reared on their "own" diet. The results show the multifaceted responses of individuals to dietary selection and are important in understanding the extreme generalism exhibited by the medfly.

Biology of Fopius arisanus (Hymenoptera: Braconidae) in Two Species of Fruit Flies.

Fopius arisanus (Sonan, 1932) (Hymenoptera: Braconidae) is an egg-larval parasitoid used in control programs of Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann). In Brazil, C. capitata and Anastrepha fraterculus (Wiedemann) are considered the main tephritid pests of exotic and indigenous fruits. The objective of this study was to study the biology of F. arisanus in C. capitata and A. fraterculus Eggs of the two fruit fly species were used to determine the parasitism rate, number of offspring, emergence rate, sex ratio, adult weight and longevity of male and female F. arisanus These biological parameters were used to develop a fertility life table. We observed higher parasitism and emergence rates of adults, a shorter duration of the egg-adult period and a sex ratio biased to females when F. arisanus was reared in eggs of C. capitata than in those of A. fraterculus However, adults of F. arisanus from eggs of A. fraterculus were heavier and had greater longevity than those obtained from C. capitata eggs. The fertility life table showed better biological and reproductive performance for F. arisanus reared in eggs of C. capitata, although eggs of A. fraterculus also provided positive values for population increase.

Temporal Diversity and Abundance Patterns of Parasitoids of Fruit-Infesting Tephritidae (Diptera) in the Argentinean Yungas: Implications for Biological Control.

A 4-yr study was done to analyze seasonal patterns underlying host plant-fruit fly-parasitoid interactions in a secondary forest in the Argentinean Yunga and its importance for the implementation of conservation and augmentative biological control. Larval-pupal hymenopteran parasitoids associated with all host plants and fruit fly species were identified and the seasonal occurrence of fruit, infestation levels, parasitism percentage, and relative parasitoid abundance were determined. Three fruit fly species in two genera were found in association with surveyed plants, two of which (Ceratitis capitata (Wiedemann) and Anastrepha fraterculus (Wiedemann)) are of major economic importance. Infestation levels were strongly influenced by environmental factors and peak fruit availability. Five fruit fly parasitoid species were recovered from fly pupae, four braconid species, and one figitid. Time windows for fruit fly population growth were pinpointed. Based on results, the present analysis proposes an effective fruit fly biological control strategy tailored for the northwestern Argentinean citrus-producing area.

Population Fluctuation of Ceratitis capitata (Diptera: Tephritidae) as a Function of Altitude in Eastern Guatemala.

Population fluctuations of Ceratitis capitata (Wiedemann) were evaluated over a period of 12 mo in four altitudinal strata (400-750, 750-1,100, 1,100-1,450, and 1,450-1,800 meters above sea level, masl) in Eastern Guatemala. Within each altitudinal range, sampling plots were established in coffee plantations and adjacent areas, in which Jackson traps were set and baited with Trimedlure. Coffee berries and other host fruits were collected. Population density was lowest at the 400-750 masl stratum and highest at 1,450-1,800 masl. At every altitudinal range, the fluctuations of the pest were associated mainly with the availability of ripe coffee berries as a primary host. From 750-1,450 masl, the pest was also associated with the availability of sweet orange and mandarins in commercial and backyard orchards. The highest densities of the pest were recorded in the dry season. Citrus were the main alternate host where ripe coffee berries were not available. This knowledge on population dynamics of C. capitata will contribute to develop more effective area-wide pest management strategies including the use of sterile insects, natural enemies, and bait sprays.

Exploitation of the Medfly Gut Microbiota for the Enhancement of Sterile Insect Technique: Use of Enterobacter sp. in Larval Diet-Based Probiotic Applications.

The Mediterranean fruit fly (medfly), Ceratitis capitata, is a pest of worldwide substantial economic importance, as well as a Tephritidae model for sterile insect technique (SIT) applications. The latter is partially due to the development and utilization of genetic sexing strains (GSS) for this species, such as the Vienna 8 strain, which is currently used in mass rearing facilities worldwide. Improving the performance of such a strain both in mass rearing facilities and in the field could significantly enhance the efficacy of SIT and reduce operational costs. Recent studies have suggested that the manipulation of gut symbionts can have a significant positive effect on the overall fitness of insect strains. We used culture-based approaches to isolate and characterize gut-associated bacterial species of the Vienna 8 strain under mass rearing conditions. We also exploited one of the isolated bacterial species, Enterobacter sp., as dietary supplement (probiotic) to the larval diet, and we assessed its effects on fitness parameters under the standard operating procedures used in SIT operational programs. Probiotic application of Enterobacter sp. resulted in improvement of both pupal and adult productivity, as well as reduced rearing duration, particularly for males, without affecting pupal weight, sex ratio, male mating competitiveness, flight ability and longevity under starvation.