Olive Fly Research Articles (Page 1)

ABSTRACT The olive fly ( Bactrocera oleae (Rossi)), the major pest of olives, primarily recognises visual, olfactory, acoustic, gustatory and tactile signals that regulate its behavioural activity, courtship and reproductive success, as well as the search for ideal conditions for its offspring. Recent studies highlight the importance of chemical compounds present in olive fruits, particularly volatile organic compounds (VOCs), in these processes. This paper aims to further explore the relationships between B. oleae and specific chemical traits in fresh sound fruits that might trigger and enhance infestations, namely VOCs, their precursors (fatty acids) and lipidic antioxidants (tocopherols). The study has been performed within the framework of a table olive cross‐breeding program in order to develop predictive models to identify genotypes less susceptible to olive fly infestation. Significant differences in chemical traits were observed among the genotypes studied, highlighting their role in oviposition preference of the olive fly. ‘Hojiblanca’ and ‘Kalamon’, known for their lower susceptibility, stood out for their high concentrations of D‐limonene among the 33 identified VOCs and low saturated fatty acid content. Specific VOCs like α‐pinene, copaene, nonanal and o‐xylene, along with some minor fatty acids, were key predictors for developing multivariate models that estimate susceptibility to olive fly oviposition.

The olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is a specialist of Olea fruits and is a major pest of commercial olives due to their adverse impacts to fruit quality. In support of genomic and physiological research of the olive fly, we sequenced, assembled, and annotated two independent genomes: one from a wild-collected male and one from a wild-collected female. The resulting genomes are highly contiguous, collinear, and complete, attesting to the accuracy and quality of both assemblies. In addition to the autosomes captured as single contigs, the X and Y chromosomes were also identified as evidenced by the X chromosome showing diploid coverage in the female assembly compared to haploid coverage in the male assembly and the Y chromosome being entirely absent from the female assembly. These assemblies represent the first full chromosome-level assembly for olive fly. In addition, a complete genome assembly of a known obligate symbiont, Candidatus Erwinia dacicola, was fully sequenced. The Ca. E. dacicola genome we report here is the most contiguous to date, represented by a gapless chromosome and two separate gapless plasmids. These genome assemblies, along with bacterial symbiont assembly, provide foundational resources for future genetic and genomic research in support of its management as an agricultural pest.

The olive fruit fly (Bactrocera oleae) is a significant pest threatening olive production worldwide. Bactrocera oleae relies on symbiotic bacteria for nutrition, development, and adaptation to its environment. Among these, Candidatus Erwinia dacicola is the most dominant symbiont and plays a key role in the fly's physiology and ecological adaptation. Understanding the dynamics between B. oleae, Ca. E. dacicola, and other components of the B. oleae microbiome is essential for developing effective targeted area‐wide pest management strategies. This study aims to leverage full 16S rRNA gene sequencing to enhance the characterization of microbiome diversity in wild B. oleae populations from different regions in Morocco: Ouezzane, Rabat, Tanger, Errachidia, and Beni‐Mellal. The results revealed distinct microbiome compositions influenced by geographic locations, with Candidatus Erwinia dacicola as the dominant symbiont, followed by Erwinia persicina as a secondary contributor. Other bacterial taxa, including Asaia bogorensis, were also identified, highlighting the functional diversity within the olive fly microbiome. These findings provide insights into the microbial ecology of B. oleae, contributing to the development and enhancement of sustainable pest control strategies.

Artificial Intelligence and image processing technologies in combating olive fly

Olive cultivation faces increasing challenges from environmental stressors such as extreme heat, water scarcity, and pest infestations, especially the olive fruit fly (Bactrocera oleae). Kaolin clay, a naturally occurring aluminum silicate mineral, has gained prominence as an eco-friendly solution in sustainable agriculture. This review explores the diverse functions of kaolin particle film applications in olive production, emphasizing its physical barrier properties against pests, its role in mitigating physiological stress, and its compatibility with organic farming systems. Kaolin reduces oviposition and feeding behaviors in B. oleae, limits pest mobility, and demonstrates synergistic effects when combined with biopesticides and pheromone traps. Moreover, kaolin enhances olive oil quality by preserving phenolic compounds, enhancing oxidative stability, and positively influencing aroma profiles. The review also examines kaolin’s impact on beneficial insects, plant anatomy, and transpiration regulation, highlighting its potential in climate-resilient agriculture. Regional effectiveness and optimal application strategies under varying climatic conditions are discussed, alongside economic evaluations and future recommendations for integrated pest management. Overall, kaolin emerges as a strategic input for sustainable olive growing, offering multifaceted benefits in ecological protection, crop quality, and adaptation to climate change.

Bactrocera oleae (Rossi) (Diptera: Tephritidae) is a key pest of olive groves. Adult monitoring is carried out by means of attractant traps of different shapes, which give relevant information for pest control such as the presence of adult flies in the field and their trend, female maturity and sex ratio. However, it is still not entirely clear whether a given density is sufficient for providing a reliable representation of flies in an olive grove. To investigate this question, an experiment was planned, consisting of arranging a high-density network of unbaited sticky panels (UTs) between panels baited with ammonium carbonate (BTs) deployed at a density of 2 traps/ha. The experiment was carried out in Greece, Italy, Lebanon, Spain and Tunisia. The percentage of BT over UT catches varied significantly among the different countries, with BTs ranging from 82% of catches in Italy to 27% in Greece. The Pearson correlation between BTs and UTs was significant under high captures but not significant at low densities. The index of aggregation showed an inverse relationship with baited catches. The distributions of males and females were nearly always positively spatially associated. According to the field data, BTs at the density of 2/ha provide a realistic estimate of the population in the field in the cases of established populations. However, in the periods without population establishment, a denser monitoring trap network is likely required to obtain a reliable estimation of the field population.

Study of the olive fruit fly biology (Bactrocera oleae) on its natural host

The management of Bactrocera oleae (Rossi, 1790) has relied on chemical insecticides, applied as bait or cover sprays. However, concerns over insecticide resistance and environmental impact have driven the search for more effective and eco-friendly alternatives, such as mass trapping. The aim of the study was to assess a novel food-based attractant, derived from Tenebrio molitor Linnaeus, 1758 excreta "Frass", for its attractiveness to B. oleae adults compared to widely used commercial food-based attractants. Over a four-year period, five field trials were conducted in two organic olive groves in Crete, Greece, using a randomized complete block design with five or six replicate blocks. Results showed that frass-based attractants captured significantly higher number of B. oleae adults than the other tested attractants. Additionally, trap-attractant combinations were assessed to determine the most efficient mass-trapping system. Frass-based attractant deployed in Anel or container traps demonstrated significantly higher attractiveness than all commercial traps and lures tested. The significant advantages of mealworm frass as an attractant highlight its potential to enhance the monitoring and suppression of B. oleae in olive orchards. Its consistent performance, sustainability, and environmental safety make it a promising tool in integrated pest management strategies.

Greece's olive oil production is significantly affected by the olive fruit fly Bactrocera oleae (Diptera: Tephritidae), and its presence is perceived when it is too late to act for damage recovery. In this work, some unexplored entomopathogenic fungi (EPFs) were studied for their efficacy on olive fruit fly pupae in soil samples. Olive grove soil samples were collected to evaluate the effect of EPFs in their natural environment. The parameters that were analyzed to evaluate the performance of EPFs on B. oleae included the adult survival time, pupa hatch time, and the presence of mycelium on B. oleae pupae and dead adults. The efficacy of some EPFs was highlighted by the mycelium present on dead B. oleae adults after treating pupae with fungal isolates on the soil substrate. The results showed that for the soil substrate, external fungal growth was observed in dead adults with A. contaminans, A. keveii, A. flavus P. lilacinum, and T. annesophieae (100%). Remarkably, the lowest male proportion for soil and non-soil substrates was for A. flavus (0.41-0.42) for the first time, for A. keveii (0.36), and for P. citreosulfuratum (0.41) on the soil-only substrate in contrast to the control treatment (0.5 for both substrates). Given the high infestation caused by the olive fruit flies in Greece, the results of the study emphasize to use of incorporating certain EPF-based biopesticides into integrated pest management (IPM) programs.

Seasonal population density of the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae) and its relationship to cumulative degree-gays using McPhail traps containing ammonium phosphate 3% as attractant during the two successive years 2021 and 2022, was studied in an olive field in Tartous Governorate, Syria. The traps were placed from the beginning of May and data were collected on a weekly basis until the olive fruit fly disappeared. Weekly samples of olive fruits were examined for signs of laying eggs until fruit harvest. The results showed that the fly activity started from late May until early December in 2021 and from early July to late November in 2022. The highest density for B. oleae was in July as it averaged 165 and 114.67 insects/trap in 2021 and 2022, respectively. According to the cumulative degree-days, it was found that B. oleae has 4 generations in the two seasons with a fifth partial generation in 2021 and with a thermal constant that reached in the first season 848.75, 956.25, 917.5, 879, 589.75 DD for each generation, respectively, and in the second season 869.5, 909.5, 878, 804 DD for each generation, respectively, without significant differences between the two seasons (x² = 7.21, P = 0.06 and x² = 6.86, P = 0.07), respectively. However, according to the model followed, a simplified table was proposed to calculate the cumulative degree-days instead of using mathematical models, based on the daily maximum and minimum temperatures. Keywords: Bactrocera oleae, degree-days, generations, prediction, Tartous, Syria.

The olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) is regarded as the most harmful pest insect for olive trees worldwide. In order to control olive fruit fly populations and mitigate the damage and economic losses they produce, the development of novel strategies to control the olive fruit fly within an integrated pest management scope has become a major concern. Here we show that a 24-h pre-exposure to the male-specific γ-hexalactone significantly reduces the oviposition on an artificial substrate. The number of eggs per female laid by those females pre-exposed to 1 mg of γ-hexalactone was significantly reduced (6.8 ± 6.1 eggs/female) in comparison to naïve (i.e., non-exposed) females (22.4 ± 10.9 eggs/female), yielding a mean oviposition activity index (OAI) of -0.56 ± 0.22. Contrarily, no significant effect was observed when females were pre-exposed to 0.5 mg of compound, even though the number of eggs per female (14.2 ± 6.3) was lower than that of naïve females, resulting in a mean OIA of -0.24 ± 0.17. Overall, this research represents a preliminary basis for delving into the potential of γ-hexalactone for being used as an oviposition disruptant, albeit further research is still required to address this issue.

A new multitrophic model for olive tree, olive fly and fly predators to support risk management in operational contexts

This study analyzes the potential of olive pomace fly ash (OPFA) as an alternative alkaline activator for electric arc furnace slag (EAFS) in the manufacture of sustainable cementitious materials. Cements were prepared by replacing 30-50 wt% of EAFS with OPFA and compared with control cements activated with potassium hydroxide (KOH) at concentrations of 4 and 8 M. Cements were characterized by bulk density, water absorption, total porosity, compressive and flexural strength, as well as analytical techniques such as XRD, FTIR and SEM-EDS. The results reveal that the incorporation of 40 wt% OPFA provides optimum properties, reaching maximum compressive and flexural strengths of 20.0 MPa and 5.7 MPa, respectively, after 28 days of curing. These improvements are attributed to the increased formation of C,K-A-S-H gel, which incorporates Fe, the main reaction product that densifies the matrix and reduces porosity. However, 30 wt% OPFA provides insufficient alkali content, which limits the reaction, while excess alkali at 50 wt% OPFA reduces mechanical performance due to unreacted residues and increased interconnected porosity. Compared to KOH-activated cements, which achieve maximum flexural and compressive strengths of 4.4 and 9.5 MPa (EAFS/KOH-8M binders), the results confirm the potential of OPFA as an alternative activator, with significant sustainability advantages.

The olive fly (Bactrocera oleae, OLF) is a major pest of global significance that occurs in places where olive cultivation thrives. This paper highlights the economic and environmental damage caused by OLF infestations, including reduced olive oil yield and quality, disrupted supply chains, and ecosystem imbalances due to heavy insecticide use. Understanding olive fly ecology is crucial for developing effective control strategies. The review explores the fly's life cycle, its relationship with olive trees, and how environmental factors like temperature and humidity influence population dynamics. Additionally, studying the role of natural enemies and agricultural practices can pave the way for sustainable control methods that minimize environmental harm. Climate change, intensive cultivation, and the development of resistance to insecticides necessitate a shift towards sustainable practices. This includes exploring alternative control methods like biological control with natural enemies and attract-and-kill strategies. Furthermore, a deeper understanding of OLF ecology, including its response to temperature and its ability to find refuge in diverse landscapes, is critical for predicting outbreaks and implementing effective protection strategies. By employing a holistic approach that integrates ecological knowledge with sustainable control methods, we can ensure the continued viability of olive cultivation, protect the environment, and produce high-quality olive oil.

The olive fruit fly, Bactrocera oleae (Rossi), is the most important widespread pest in olive-growing areas worldwide, causing significant yield losses and deterioration of olive oil quality. This study hypothesized that olive cultivars differ in their susceptibility to B.oleae and that the cultivar in which the pest develops may affect population variability. The primary goal was to assess susceptibility across 6 olive cultivars, while the secondary goal was to analyze population variability using geometric morphometrics to identify cultivar-specific phenotypic differences. Conducted at 2 sites, Banjevci (Dalmatia) and Vodnjan (Istria), the study revealed significant differences in infestation levels, emergence, and wing morphology. Higher humidity in Vodnjan favored increased fly populations. Larger-fruited cultivars such as Oblica, Istarska bjelica, and Ascolana tenera experienced higher infestation rates, whereas smaller-fruited cultivars like Frantoio and Leccino exhibited lower infestation levels. Wing shape analysis highlighted sexual dimorphism, with female flies exhibiting broader wings that may enhance dispersal and oviposition efficiency, particularly in larger fruits. The observed phenotypic plasticity of B. oleae across cultivars and locations indicates an ability to adapt to varied host and cultivation conditions, enhancing pest resilience. The findings underscore the role of cultivar selection as a passive pest management strategy and demonstrate the utility of geometric morphometrics in capturing cultivar-specific morphological adaptations.

Chemical control of olive fruit fly in olives, 2024

This work aimed to optimize olive fruit fly (OFF) Bactrocera oleae (Rossi) (Diptera: Tephritidae) monitoring and integrated management, thereby ensuring optimal and less-costly decision-making and timely intervention. Field trials in Andalusia (Spain) were undertaken over 2 years to optimize trap model, color, size, and density for the accurate determination of pest spatial distribution and damage as a function of olive cultivar. McPhail traps and yellow sticky panels outperformed the other 4 models with respect to the number of OFF captured. However, McPhail traps caught more natural enemies than yellow sticky panels and so sticky panels were selected to unravel the effect of color on the number of both OFF and natural enemies [hymenopteran parasitoids (Psyttalia concolor) and lacewings (Chrysopidae)] captured. Yellow sticky panels outperformed white, green, and blue ones for the number of OFF captured and captured the fewest natural enemies. When comparing the surface area of yellow sticky panels, 20 × 25 and 10 × 25 cm double-sided panels were equally effective at catching OFF. However, large double-sided yellow sticky panels caught significantly more natural enemies than the small double-sided panels, a key result for developing a less costly and environmentally friendly monitoring system. Furthermore, it was shown that the damage curve had a cultivar-based shape, i.e., for the same population size of OFF the damage caused varied depending on cultivar. Finally, 15 sticky panels per hectare were the optimal number for estimation of OFF spatial distribution. The present research provides key information for new trap design, OFF forecasting, and IPM development.

Bactrocera oleae Rossi causes important agricultural losses in olive growing regions. Despite its economic relevance, the expansion history and biogeography of B. oleae and other olive-feeding fruit flies remain unclear. We used mitogenomic data of Bactrocera species from a broad geographic range to explore possible historical biogeographic patterns in B. oleae and other olive-feeding fruit flies. Our data suggest that (1) the transition from stenophagy on Oleaceae to oligophagy on Olea most likely occurred in Africa more than 6 million years ago (MYA), and (2) the subsequent transition to monophagy on Olea europaea took place in Asia or in Africa in the Early Pleistocene. Our results support equally the hypotheses that the ancestors of modern B. oleae underwent two waves of migration from Asia to Africa or that they zigzagged between Asia and Africa.

In this work, the ability of certain entomopathogenic fungi to control the olive fruit fly Bactrocera oleae (Diptera: Tephritidae), which significantly affects olive cultivation, was assessed. First, entomopathogenic fungi that often contribute to reducing pests, as well as B. oleae, were sought out. Puparia of B. oleae were collected from oil mills, and soil samples were collected from various olive grove regions of Greece. These soils were used as the substrate in which the effect of the entomopathogenic fungi on the B. oleae pupae was studied. In addition, the same treatments were studied in non-soil conditions. The results show that certain known entomopathogenic fungi are able, in their natural environment, to kill B. oleae pupae to a significant extent. The survival time for adults (days) was lower in the presence of Beauveria bassiana (Hypocreales: Cordycipitaceae), at 13.20 in the soil (5.56 ± 0.42) and non-soil (6.76 ± 0.46) conditions, compared to that of the control in soil (9.83 ± 083) and non-soil (9.90 ± 0.72) conditions. This is encouraging for Mediterranean regions where the presence of B. oleae significantly affects olive cultivation, while quality olive oil is in high demand.

The olive tree (Olea europaea L.) holds significant economic importance, especially in the Mediterranean region, including Algeria, where diverse olive cultivars thrive due to the heterogeneous climate. This study presents a comparative analysis of phenolic and antioxidant properties in olive fruits from two Algerian cultivars, ‘Chemlal’ and ‘Sigoise’, focusing on the influence of different locations and varying attack rates of the olive fruit fly (Bactrocera oleae). Key biological parameters, including fruit weight, maturity index, and pest attack rates, alongside the content of phenolics, flavonoids, and condensed tannins were measured. Antioxidant activity was evaluated by measuring free radical scavenging, total antioxidant capacity, and ferric-reducing power. Significant variation in fruit characteristics and insect susceptibility between the two cultivars and locations was found. Cv. ‘Sigoise’ exhibited greater fruit weight but higher vulnerability to Bactrocera oleae attacks than cv. ‘Chemlal’. Fruits of cv. ‘Chemlal’ from Ain Arnat showed greater insect attack resistance and higher condensed tannin content. Antioxidant assays revealed that cv. ‘Chemlal’, especially from Ain Azel, had superior free radical scavenging and ferric-reducing ability, despite its lower phenolics content, indicating a robust antioxidant profile. This study demonstrates the potential of selecting and cultivating specific olive cultivars to optimize their health-promoting benefits and resistance to biotic stress. This underlines the need for tailored agronomic practices that consider genetic, environmental, and pest management factors for enhanced productivity and quality.