Spatio-temporal Distribution of Bactrocera carambolae with and without Irrigation using CLIMEX Modeling.

The carambola fruit fly Bactrocera carambolae Drew and Hancock (Diptera: Tephritidae) is an invasive fruit fly reported in North Brazil that threatens Brazilian fruit culture. Assessing the potential risk of establishing this pest is necessary to reduce the threat of B. carambolae dispersion to other countries and Brazilian regions and to avoid damage to the fruit trade. In this study, the CLIMEX model was used to understand the response of B. carambolae to climate change and to determine its potential global distribution with and without irrigation practices. Based on ecophysiological parameters, the model simulates factors limiting species distribution concerning the climate. To assess the seasonal variation in the density of B. carambolae, monitoring data in Uiramutã municipality, Roraima, from 2013 to 2019 was used. According to the CLIMEX forecast, large parts of America, Africa, and Asia, mainly in areas closest to the equator, are highly suitable for the survival of B. carambolae. Brazil is a good part of its territory with high suitability for B. carambolae, especially the North, South, and Southeast regions and the entire coastal area. The periods of the highest climatic suitability in the five Brazilian regions were January-May and October-December. The potential distribution area expands under irrigation and is highly suitable for most areas without cold stress. The CLIMEX model for B. carambolae generated in the present study provides important information for the Brazilian eradication program and other surveillance activities established in pest-free areas.

Slightly acidic electrolyzed water treatment improves the quality and storage properties of carambola fruit.

This study aimed to explore the impacts of slightly acidic electrolyzed water (SAEW) treatment on the physiology, quality, and storage properties of postharvest carambola. The carambolas were immersed in SAEW with a pH value of 6.0, ORP of 1340 mV and ACC of 80 mg/L. Results demonstrated that SAEW could significantly reduce the respiration rate, inhibit the increase in cell membrane permeability, and delay apparent color change. Relatively higher contents of bioactive compounds and nutritional components, such as flavonoids, polyphenols, reducing sugars, sucrose, vitamin C, total soluble sugar, and total soluble solid, as well as higher titratable acidity were maintained in SAEW-treated carambola. In addition, SAEW-treated carambola exhibited a higher commercial acceptability rate and a higher firmness, but lower weight loss and peel browning index than control fruits. Our results indicated that SAEW treatment achieved high fruit quality and nutritional values, potentially contributing to improve storage properties of harvested carambola.

Alleviation of Postharvest Chilling Injury of Carambola Fruit by γ-aminobutyric Acid: Physiological, Biochemical, and Structural Characterization.

Chilling injury is a physiological disorder affecting the quality of carambola fruit. In the present study, the effect of exogenous γ-aminobutyric acid (GABA) on CI development in carambola fruit during storage at 4°C for 15 days was investigated. The results showed that 2.5-mM GABA reduced CI index, maintained pericarp lightness, and decreased the electrolyte leakage (EL) and malondialdehyde content (MDA) while increased the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzyme activities. Endogenous GABA content was significantly higher in the treated fruit than in the control fruit during the whole storage. Besides, the treatment promoted the accumulation of proline and ascorbic acid (AsA) under chilling stress. Compared to the control, GABA-treated fruit exhibited a higher activity of phenylalanine ammonia-lyase (PAL) and total phenolic compounds, and a lower activity of polyphenol oxidase (PPO). In addition, the Safranin O/fast green staining revealed via microscopic images that the GABA treatment reduced the cell walls degradation of carambola fruit. Moreover, the results displayed a lower activity of phospholipase D (PLD) and lipoxygenase (LOX) enzymes, which coincided with a higher content of oleic acid (C18:1), linoleic acid (C18:2n6), and α-linolenic acid (C18:3n3) after 15 days of treatment, leading to the maintenance of the integrity and prevention of the membrane of the rapid softening of carambola fruit. The findings of the present work showed particularly new insights into the crosstalk between GABA and fatty acids. GABA might preserve the pericarp of carambola fruit by increasing the content of the unsaturated fatty acid (UFA) γ-linolenic acid and reducing the saturated fatty acid (SFA) such as caproic acid (C6:0), caprylic acid (C8:0), myristic acid (C14:0), and palmitic acid (C16:0) progressively. GABA can be used as an appropriate postharvest technology for improving the quality of carambola fruit during low-temperature storage.

Exogenous 2,4-Epibrassinolide Treatment Maintains the Quality of Carambola Fruit Associated With Enhanced Antioxidant Capacity and Alternative Respiratory Metabolism.

Brassinosteroids act by delaying fruit ripening. The effects of different concentrations of 2,4-epibrassinolide (eBL) treatments on carambola fruit ripening were investigated. The results show that treatment of 2.8 mg L-1, eBL with 10 min effectively delays ripening and maintains the quality of carambola fruit. This is achieved by retarding color changes and firmness losses while maintaining high level of soluble protein content and vitamin C, and low organic acid content. eBL-delayed senescence may be due to the inhibition of respiration rate and enhanced antioxidant system. It is noteworthy that eBL treatment markedly reduces the content of fructose-6-phosphate (6-P-F) and enhances the activity of cytochrome oxidase (CCO), and the total activity of glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphate gluconate dehydrogenase (6-PGDH). eBL treatment induces the IAA and GA contents but reduces that of ABA. In general, senescence retardation and quality improvement by eBL treatment may be due to the enhanced antioxidant capacity and altered respiratory pathways.

Effect of soil class and moisture on the depth of pupation and pupal viability of Bactrocera carambolae Drew & Hancock (1994)

Abstract Bactrocera carambolae is a quarantine pest present in Brazil and today represents the main phytosanitary barrier to the export of the fresh fruits produced in the country. The effect of soil classes and moisture on the pupation depth and pupal viability of this insect was evaluated. Soils with three textural classes (sandy, sandy clay loam and clay loam) and four moisture levels (0%, 30%, 60% and 90% of field capacity of each soil) were used, for a total of 12 treatments with six repetitions. The pupation depths varied from the surface to 5 cm. The soil class was the most significant variable regarding the pupal development of B. carambolae. The moisture level did not have a significant effect on the pupation depth or pupal emergence, but there was a strong effect of the interaction of soil texture and moisture on the pupal viability, with an increase in emergence with higher moisture in the clay loam and sandy clay loam soils.

Τhe Complete Mitochondrial Genome of Bactrocera carambolae (Diptera: Tephritidae): Genome Description and Phylogenetic Implications.

Bactrocera carambolae is one of the approximately 100 sibling species of the Bactrocera dorsalis complex and considered to be very closely related to B. dorsalis. Due to their high morphological similarity and overlapping distribution, as well as to their economic impact and quarantine status, the development of reliable markers for species delimitation between the two taxa is of great importance. Here we present the complete mitochondrial genome of B. carambolae sourced from its native range in Malaysia and its invaded territory in Suriname. The mitogenome of B. carambolae presents the typical organization of an insect mitochondrion. Comparisons of the analyzed B. carambolae sequences to all available complete mitochondrial sequences of B. dorsalis revealed several species-specific polymorphic sites. Phylogenetic analysis based on Bactrocera mitogenomes supports that B. carambolae is a differentiated taxon though closely related to B. dorsalis. The present complete mitochondrial sequences of B. carambolae could be used, in the frame of Integrative Taxonomy, for species discrimination and resolution of the phylogenetic relationships within this taxonomically challenging complex, which would facilitate the application of species-specific population suppression strategies, such as the sterile insect technique.

Biology of Bactrocera carambolae (Diptera: Tephritidae) on four hosts

ABSTRACT Bactrocera carambolae is a quarantine pest found in Brazil, restricted to the states of Amapá, Pará and Roraima. This fruit fly can potentially cause extensive socioeconomic and environmental damage in the country, if it disperse into areas where fruit is grown for exporting. The objective of this work was to study the biology of B. carambolae on fruits of Averrhoa carambola L. (Oxalidaceae), Psidium guajava L. (Myrtaceae), Spondias mombin L. (Anacardiaceae) and Eugenia stipitata McVaugh (Myrtaceae). The following parameters were investigated: duration of egg-larva, pupal, egg-adult, pre-oviposition, oviposition and post-oviposition periods, pupal weight and viability, sex ratio, fecundity, fertility and longevity. All parameters except pupal weight, oviposition and post-oviposition period, egg fertility and sex ratio were influenced by the host plant on which the larvae were reared. The carambola fruit fly completes its development on all those hosts studied here, with the highest fecundities on A. carambola and P. guajava.

AMAZONIAN ISOLATES OF Metarhizium ARE EFFECTIVE FOR KILLING Bactrocera carambolae (DIPTERA: TEPHRITIDAE) / Aislados Amazónicos de Metarhizium son efectivos para matar Bactrocera carambolae (Diptera: Tephritidae)

ABSTRACT Bactrocera carambolae Drew & Hancock is a quarantine pest present in Brazil and is the main phytosanitary barrier for the export of fresh fruits from that country. In this work, we evaluated the effect of Amazonian isolates of Metarhizium on kill larvae, pupae, and adults of B. carambolae in soil applications. The mortality of larvae and pupae in sterile soil treated with Metarhizium anisopliae was 70 %. In addition, 100 % of the adults that emerged from this substrate died up to five days later. This isolate caused the mortality of larvae and pupae in non-sterile soil, but its effect was more evident after adult emergence (70 % mortality up to ten days after emergence). Metarhizium robertsii was effective in killing larvae and pupae of the pest, especially in non-sterile soil, and caused a 60 % reduction in adult survival 50 days after emergence. These results indicated the possible use of these isolates for the control of B. carambolae, suggesting the possibility of using this biocontrol mode as another alternative in controlling this quarantine pest.

RESUMEN Bactrocera carambolae Drew & Hancock es una plaga cuarentenaria presente en Brasil y es la principal barrera fitosanitaria para la exportación de frutas frescas de este país. En este trabajo, evaluamos el efecto de los aislados amazónicos de Metarhizium para matar larvas, pupas y adultos de B. carambolae en aplicaciones de suelo. La mortalidad de larvas y pupas en suelo estéril tratado con Metarhizium anisopliae fue del 70 %. Además, el 100 % de los adultos que emergieron de este sustrato murieron hasta cinco días después. Este aislado causó la mortalidad de larvas y pupas en suelo no estéril, pero su efecto fue más evidente después de la emergencia del adulto (70 % de mortalidad hasta diez días después de la emergencia). Metarhizium robertsii fue eficaz para matar larvas y pupas de la plaga, especialmente en suelos no estériles, y causó una reducción del 60 % en la supervivencia de los adultos 50 días después de la emergencia. Estos resultados indican que es posible el uso de estos aislados para el control de B. carambolae, lo que sugiere la posibilidad de utilizar este modo de control biológico como otra alternativa para controlar esta plaga cuarentenaria.

Gene flow and genetic structure of Bactrocera carambolae (Diptera, Tephritidae) among geographical differences and sister species, B. dorsalis, inferred from microsatellite DNA data.

The Carambola fruit fly, Bactrocera carambolae, is an invasive pest in Southeast Asia. It has been introduced into areas in South America such as Suriname and Brazil. Bactrocera carambolae belongs to the Bactrocera dorsalis species complex, and seems to be separated from Bactrocera dorsalis based on morphological and multilocus phylogenetic studies. Even though the Carambola fruit fly is an important quarantine species and has an impact on international trade, knowledge of the molecular ecology of Bactrocera carambolae, concerning species status and pest management aspects, is lacking. Seven populations sampled from the known geographical areas of Bactrocera carambolae including Southeast Asia (i.e., Indonesia, Malaysia, Thailand) and South America (i.e., Suriname), were genotyped using eight microsatellite DNA markers. Genetic variation, genetic structure, and genetic network among populations illustrated that the Suriname samples were genetically differentiated from Southeast Asian populations. The genetic network revealed that samples from West Sumatra (Pekanbaru, PK) and Java (Jakarta, JK) were presumably the source populations of Bactrocera carambolae in Suriname, which was congruent with human migration records between the two continents. Additionally, three populations of Bactrocera dorsalis were included to better understand the species boundary. The genetic structure between the two species was significantly separated and approximately 11% of total individuals were detected as admixed (0.100 ≤ Q ≤ 0.900). The genetic network showed connections between Bactrocera carambolae and Bactrocera dorsalis groups throughout Depok (DP), JK, and Nakhon Sri Thammarat (NT) populations. These data supported the hypothesis that the reproductive isolation between the two species may be leaky. Although the morphology and monophyly of nuclear and mitochondrial DNA sequences in previous studies showed discrete entities, the hypothesis of semipermeable boundaries may not be rejected. Alleles at microsatellite loci could be introgressed rather than other nuclear and mitochondrial DNA. Bactrocera carambolae may be an incipient rather than a distinct species of Bactrocera dorsalis. Regarding the pest management aspect, the genetic sexing Salaya5 strain (SY5) was included for comparison with wild populations. The SY5 strain was genetically assigned to the Bactrocera carambolae cluster. Likewise, the genetic network showed that the strain shared greatest genetic similarity to JK, suggesting that SY5 did not divert away from its original genetic makeup. Under laboratory conditions, at least 12 generations apart, selection did not strongly affect genetic compatibility between the strain and wild populations. This knowledge further confirms the potential utilization of the Salaya5 strain in regional programs of area-wide integrated pest management using SIT.

Methyl eugenol aromatherapy enhances the mating competitiveness of male Bactrocera carambolae Drew & Hancock (Diptera: Tephritidae).

Males of Bactrocera carambolae Drew & Hancock (Diptera: Tephritidae) are strongly attracted to methyl eugenol (ME) (1,2-dimethoxy-4-(2-propenyl)benzene), a natural compound occurring in variety of plant species. ME-feeding is known to enhance male B. carambolae mating competitiveness 3 days after feeding. Enhanced male mating competitiveness due to ME-feeding can increase the effectiveness of sterile insect technique (SIT) manifolds. However, the common methods for emergence and holding fruit flies prior to field releases do not allow the inclusion of any ME feeding treatment after fly emergence. Therefore this study was planned to assess the effects of ME-aromatherapy in comparison with ME feeding on male B. carambolae mating competitiveness as aromatherapy is pragmatic for fruit flies emergence and holding facilities. Effects of ME application by feeding or by aromatherapy for enhanced mating competitiveness were evaluated 3d after treatments in field cages. ME feeding and ME aromatherapy enhanced male mating competitiveness as compared to untreated males. Males treated with ME either by feeding or by aromatherapy showed similar mating success but mating success was significantly higher than that of untreated males. The results are discussed in the context of application of ME by aromatherapy as a pragmatic approach in a mass-rearing facility and its implications for effectiveness of SIT.