Bactrocera Correcta Research Articles

Molecular Characterization, Evolution and Expression Analysis of Ammonium Transporter from Four Closely Related Bactrocera Species (Tephritidae).

Numerous insects are attracted to low levels of ammonia, utilizing it as a cue to locate food sources. The Ammonium Transporter (Amt), a highly conserved, atypical olfactory receptor, has been shown to mediate the detection of ammonia in insects. While the attraction of Tephritidae to ammonia is well established, knowledge about the Amt in this family is limited. The species Bactrocera dorsalis (Hendel 1912), Bactrocera cucurbitae (Coquillett 1899), Bactrocera correcta Bezzi 1916 and Bactrocera tau (Walker 1849), which are common agricultural pests within Tephritidae, exhibit numerous ecological similarities, offering a solid foundation for studying Amt characteristics in this family. In this study, we elucidated the sequences, evolutionary relationships, and expression patterns of Amt in these four species. The results indicated that these Amts share the same open reading frame, containing 1770 bp that encode a protein of 589 amino acid residues. These Amt proteins exhibit the typical structural characteristics of Amts, including an 11-transmembrane domain with an extracellular N-terminus and an intracellular C-terminus. They also have the ability to form trimers in the membrane. Additionally, they contain three conserved amino acid residues essential for ammonia transport: A189, H195, and H352. Phylogenetic and expression pattern analyses showed that they are highly conserved in Diptera and are significantly expressed in antennae. This study is the first report characterizing the Amt gene in four Tephritidae species. These findings provide a foundation for further exploration into the roles of these genes in their particular biological contexts.

Comparative Biology of Guava Fruit Fly <i>Bactrocera correcta</i> (Bezzi)

Fruit flies are polyphagous insect pests, infesting various fruits and vegetables. The host preference and biology of guava fruit fly Bactrocera correcta (Bezzi) were studied on 17 hosts. Biological parameters such as incubation period, maggot and pupal period, maggot and pupal weight, pupal recovery, adult emergence, total fecundity and adult longevity were studied. All biological parameters were significantly influenced by the host fruits. The results showed that the total developmental period was longer on pomegranate (26.7± 2.1 days), ber (26.1± 2.4 days) and custard apple (25.1± 1.5 days); while shorter period was observed on sweet banana (20.1± 1.6 days). Pupal recovery was maximum on sweet banana (93.33%) and lowest on mango (Totapuri) (42%). The adult emergence was also more on sweet banana (90%) and survived for longer period. Sweet banana was preferred for oviposition followed by guava, papaya, and sapota.

Application of recombinase polymerase amplification with CRISPR/Cas12a and multienzyme isothermal rapid amplification with lateral flow dipstick assay for Bactrocera correcta.

Bactrocera correcta is a quarantine pest that negatively impacts the fruit and vegetable industry. Differentiating B. correcta from similar species, especially in non-adult stages, remains challenging. Rapid molecular identification techniques, such as recombinase polymerase amplification (RPA) combined with CRISPR/Cas12a and multienzyme isothermal rapid amplification with lateral flow dipstick (MIRA-LFD), play a crucial role in early monitoring and safeguarding agricultural production. Our study introduces two methods for the rapid visual identification of B. correcta. Bactrocera correcta specific RPA primers, CRISPR RNA (crRNA), and the LFD probe were designed based on the cox1 genes. The RPA reaction conditions were optimized (at 37 °C for 8 min) for effective template DNA amplification. Two nucleic acid detection methods were established to visualize RPA. In the RPA-CRISPR/Cas12a system, the optimal LbCas12a/crRNA concentration ratio was 200:400 nmol L-1. Successful amplification was determined by the presence or absence of green fluorescence following 15 min incubation at 37 °C. The MIRA-LFD system achieved precise identification of the target species within 4 min at 37 °C. Both methods exhibited high specificity and sensitivity, allowing for detection from 1.0 × 10-1 ng μL-1 of DNA. Combined with rapid DNA extraction, rapid identification of individual B. correcta at different developmental stages was achieved, enhancing the practicality and convenience of the established methods. Our research findings demonstrate that both the RPA-CRISPR/Cas12a and MIRA-LFD methods for B. correcta detection was accurate and rapid (within 30 min and 10 min, respectively), at 37 °C. Our methods do not rely on expensive equipment, thus possess high practical value, providing improved identification solutions for port quarantine pests and field applications. © 2024 Society of Chemical Industry.

Attractancy of a Sesquiterpene, β-caryophyllene to Males of the Oriental Fruit Fly, Bactrocera dorsalis (Diptera: Tephritidae).

The recent discovery of a sesquiterpene, β-caryophyllene (CP) as a male attractant of the guava fruit fly, Bactrocera correcta (Bezzi) (Diptera: Tephritidae) prompted investigations into the attractancy of CP to the Oriental fruit fly, B. dorsalis (Hendel). This is because males of both species of fruit flies are attracted to, and feed on a phenylpropanoid compound, methyl eugenol (ME). Although CP was a more potent attractant than ME for B. correcta, it is not known if males of B. dorsalis are also attracted to CP. The possible attraction of B. dorsalis to CP as a sesquiterpene may indicate its wide host range through its attraction to different groups of plant volatiles i.e., phenylpropanoids and sesquiterpenes. In this paper, we report that males of B. dorsalis were also attracted to, and feed on CP. Subsequently, we conducted a probit regression analysis to determine the quantal response of sexually mature male flies that were attracted to CP in cage bioassays. Therefore, as a measure of male B. dorsalis' sensitivity of CP, the median dose of CP required to elicit a positive response in 50% of the tested B. dorsalis population (ED50) was calculated as 3.7mg. This value was over 10,000x higher than known ED50 of B. dorsalis' male attraction ME (between 171 and 268 ng). We propose that the attraction of male B. dorsalis flies to CP was much weaker than to ME. Further, we suggest that in any fruit fly surveillance and monitoring programme, application of lures must consider the specificity and potency of each compound to target fruit fly species. The probit regression analysis of male fly quantal response to lure offers such information.

Chromosome-level genome assembly of Bactrocera correcta provides insights into its adaptation and invasion mechanisms

Bactrocera correcta is an invasive polyphagous pest with significant ecological and economic implications. Understanding its genetic characteristics and the molecular mechanisms that drive its rapid adaptation to new environments requires genomic information. In this study, we successfully assembled the chromosome-level genome of B. correcta using PacBio long-read sequencing, Illumina sequencing, and chromatin conformation capture (Hi-C) methods. The final genome assembly spans a total length of 702.65 Mb. We managed to anchor approximately 86.88% of the assembled contigs into 6 linkage groups, ranging from 17.97 Mb to 166.49 Mb. Additionally, our analysis predicted a total of 21,015 genes, with repetitive sequences accounting for 58.22% of the genome. We further identified retroelements and DNA transposons as the major contributors to the larger size of the B. correcta genome, constituting 36.06% and 30.92% of the repetitive sequences, respectively. Our divergence time estimation placed B. correcta's split from other Bactrocera species at around 5.99–16.71 million years ago. Through gene family analyses, we discovered significant expansions in chemosensory-related gene families (IR, GR), heat shock proteins (HSP60), and resistance-related gene families (ABC) in B. correcta compared to its closest relatives. Transcriptomic analysis revealed substantial upregulation of HSP genes, especially those from the HSP20 subfamily, in response to high temperatures. The availability of this reference genome serves as a foundation for the identification of precise target genes in B. correcta, facilitating molecular prevention and control strategies.

Comparison of fumigation efficacy of methyl bromide alone and phosphine applied either alone or simultaneously or sequentially against Bactrocera correcta in Selenicereus undatus (red pitaya) fruit.

Bactrocera correcta (Bezzi) is a significant pest of the red pitaya fruit (Selenicereus undatus). This study investigated the insecticidal effects of methyl bromide (MB) alone, phosphine (PH3 ) alone, both applied simultaneously (PH3 + MB), and PH3 application followed sequentially by MB (PH3 → MB) against B. correcta in red pitaya fruits. The 3rd instar larvae of B. correcta were the most tolerant to MB alone and the combined treatments, whereas eggs were the most susceptible stage. Both the PH3 + MB and PH3 → MB treatments resulted in higher mortality at all stages than MB alone, demonstrating a synergistic effect between MB and PH3 . The toxicity of the combined treatments increased with increasing PH3 concentrations, with the optimal concentration recorded being 1.42 to 2.84 g m-3 . Further probit analysis revealed that compared to the MB treatment alone, the median lethal dose values of MB in PH3 + MB and PH3 → MB treatment, were reduced to 63.73% and 66.82%, respectively. Fruit quality was not adversely affected by either of the combined treatments. This work provides robust evidence that combining MB and PH3 to control B. correcta is highly effective, especially the PH3 → MB treatment. This combination decreased the amount of MB required for effective control at all life stages, while protecting fruit quality against MB phytotoxicity to a greater extent than conventional MB fumigation alone. © 2023 Society of Chemical Industry.

Farmer's Survey and Monitoring of Fruit Flies (Diptera: Tephritidae) in Citrus Orchards of Ramechhap District, Nepal

Fruit flies (Diptera: Tephritidae) are devastating pests in citrus orchards of Nepal causing huge losses of fruits. A farmer's survey was carried from March to December, 2021 randomly selecting 40 citrus orchard owners, and at the same time, a field monitoring of fruit flies organised in randomized complete block design with 7 times replicated 3 treatments (Cue lure and malathion in Steiner trap, Methyl eugenol and malathion in Steiner trap and protein bait in McPhail trap) were conducted in Ramechhap district of Nepal. Survey revealed that Chinese citrus fly was the most problematic insect pest of citrus orchard. However, only few farmers were practising effective control measures against this pest. Nine species of fruit flies were trapped in different lures and protein bait, when the number of fruit flies differed significantly (p<0.05) except Bactrocera correcta and Zeugodacus cucurbitae, which were found attracted in negligible number in Methyl eugenol and Cue lure, respectively. Z. scutellaris, Z. tau, B. nigrofemoralis were attracted to Cue lure. B. dorsalis and B. zonata were attracted to Methyl eugenol and B. minax, B. nigrofemoralis and Dacus sphaeroidalis were attracted in protein bait. The study concluded that the male lures and protein bait were useful to monitor specific fruit fly species in citrus orchards, hence their management strategies should be made accordingly.

Lethal and sublethal effects of broflanilide on four tephritid pests (Diptera: Tephritidae).

Fruit flies are internationally important quarantine or invasive pests of many fruits and vegetables and can cause serious economic losses. Long-term reliance on insecticides for controlling these pests has led to increasing resistance to multiple insecticides; hence, a new agent is needed. In this study, the acute toxicity and sublethal effects of the novel insecticide broflanilide on four adult fruit fly species, Bactrocera dorsalis, Bactrocera cucurbitae, Bactrocera tau, and Bactrocera correcta, were evaluated. Broflanilide was effective against B. dorsalis and B. correcta, with lethal concentration values (amount required to kill 50% of animals; LC50 ) of 0.390 and 1.716 mg/L. However, for B. cucurbitae (19.673 mg/L) and B. tau (24.373 mg/L), the LC50 was 50-60 times higher than that of B. dorsalis. The survival rates of B. correcta and B. cucurbitae were significantly lower under LC50 treatment than those of the control (corrected for mortality rate). Sublethal concentrations of broflanilide stimulated fecundity in all species except B. tau. The hatching rate at LC50 was significantly lower for B. correcta and B. tau compared with the control and even more so for B. correcta, which was zero. Broflanilide is potentially an effective insecticide for controlling B. dorsalis and B. correcta. However, the variation in toxicity of broflanilide to the four fruit flies suggests that species variation needs to be carefully considered. Our results highlight the importance of clarifying the sublethal effects of insecticides on target insects to ensure the comprehensive evaluation and rational use of insecticides. © 2023 Society of Chemical Industry.

Identification of Cucurbit Fruit Flies and Their Relative Attractiveness to Different Cues and Releasers

Tephritids are the major challenges for fruit and fleshy vegetable growers of the tropics and subtropics. Nepal also incurs huge losses of fruits and vegetables to the tephritids. This study was designed to identify the tephritid flies in Malepatan and Lumle of Gandaki Province. Bucket traps baited with methyl eugenol (ME) in Malepatan, and ME, cue lure (CL) and a mixture of ME and CL (ME+CL) with different releasers; tube, cotton and paper were installed at Lumle in 2020 summer. Three species of the fly (Bactrocera dorsalis, Bactrocera zonata and Bactrocera correcta) were recorded from Malepatan, dominated by B. dorsalis. The B. correcta count was negligible. While in Lumle, B. dorsalis was the most dominant, followed by B. zonata till July, after which, till August, B. tau followed the B. dorsalis. Seven species of the tephritids (B. zonata, B. dorsalis, B. tau, B. diversa, B. scutellaris, B. correcta and B. cucurbitae) were recorded from this region. Among the releasers, paper releaser was found more effective as compared to cotton and tube. However, the lures should be changed in a short interval, by two weeks, to acquire a satisfactory result. This study unveils that the study site already inhabits seven species of fruit flies. So, the monitoring with different cues could be an effective tool for species actuation. Additionally, the paper releasers could be recommended for further use in the traps for monitoring and mass trapping purposes.

Abnormal Antennal Olfactory Sensilla Phenotypes Involved in Olfactory Deficit in Bactrocera correcta (Diptera: Tephritidae).

Simple SummaryTephritidae fruit flies sense odorants mainly through antennal olfactory sensilla with nanopores. Therefore, theoretically, the development of nanopore-targeted pest control technologies is an important direction in the future. Here, we report naturally occurring abnormal antennal trichoid and basiconic olfactory sensilla phenotypes consisting of abnormal bulges and reduced nanopore numbers in a long-term laboratory rearing colony of the guava fruit fly Bactrocera correcta, and further find that the reduction of nanopore numbers in these sensilla led to an olfactory deficit. Our findings provide a basis for developing nanopore-targeted pest control technologies in the future.The guava fruit fly, Bactrocera correcta, is one of the most destructive pests in the genus Bactrocera and detects environmental odorants mainly through antennal olfactory sensilla phenotypes with nanopores. However, it is unclear whether there are naturally occurring abnormal antennal olfactory sensilla phenotypes that affect olfaction. Here, we found that there were abnormal bulges besides nanopores on the surface of trichoid and basiconic olfactory sensilla in the antennal flagellum of long-term laboratory rearing colony (LTC), and that nanopore number in these olfactory sensilla was also remarkably reduced. Notably, the electroantennogram (EAG) responses of LTC insects to methyl eugenol or β-caryophyllene were inhibited, and their behavioral responses elicited by the same odorants were also impaired. These results revealed naturally occurring abnormal antennal olfactory sensilla phenotypes which were involved in olfactory deficit in B. correcta, providing a platform to further study nanopore-targeted pest control technologies in the future.

Report of Guava Fruit Fly Bactrocera correcta Bezzi from Temperate Kashmir

In this study the guava fruit fly Bactrocera correcta Bezzi (1916) (Diptera: Tephritidae) is reported fromKulgam, a major peach growing area in South Kashmir through July-August, 2020. District Kulgamwas the leading producer of peaches with an annual production of 412MT during the 2018-19 growingseason. This potential pest was trapped along with B. zonata and B. dorsalis in a simple bottle-type trapcontaining methyl eugenol and SPLAT.

Including climate change to predict the global suitable area of an invasive pest: Bactrocera correcta (Diptera: Tephritidae)

Bactrocera correcta (Diptera: Tephritidae), as known as invasive pest guava fruit fly, can attack numerous host plants including many horticultural crops and cause huge destruction. Whilst its distribution is currently restricted in Southeast Asia, under the context of global trade and climate change, guava fruit fly can be transported with goods and spread with regional climate. Many countries have included the species on their quarantine pest lists, in order to offer the strategy for specific surveillance and early warnings, the research of predicting the suitable areas under climate change is essential. In this study, 56 environmental variables were initially tested, and six selected for final analysis using MaxEnt to predict suitable habitat, ENMeval package was used in R to avoid overfitting and run the models under two different greenhouse gas emission scenarios in 2030 and 2070 based on CMIP6. The total suitable area of the historical scenario is 3235.42 × 10 4 km 2 , and it accounts for 24.06% of the world’s total area and includes India and neighboring countries in Asia, pacific islands, and North Australia, Central and South America, central Africa. Water vapor pressure and solar radiation were the most influential variables for B. correcta , the rising temperature could lead increasing of suitable area slightly. The predictive results of the research can provide support for quarantine and management for the high-risk countries.

Bactrocera correcta (guava fruit fly)

Bactrocera correcta (guava fruit fly)

Predicting impact of climate change on habitat suitability of guava fruit fly, Bactrocera correcta (Bezzi) using MaxEnt modeling in India

Maximum entropy (MaxEnt) modeling was used to predict impact of climate change on habitat suitability of guava fruit fly, Bactrocera correcta in India. It is a polyphagus pest on a wide variety of fruit crops. Future prediction of potential habitat of B.correcta was done for the year 2050 and 2070 with RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5 climate scenarios. The model preformed better than random with an average test AUC value of 0.75 of 100 replicate tests run. Under the present and future climatic conditions, the model predicted high habitat suitable category for B. correcta in the areas of south-western coastal (Kerala, Karnataka, Tamilnadu, Maharashtra and Gujarat) part of India by 2050 and 2070. Presently absolute unsuitable areas of Indian sub-continent are projected to be slightly suitable for B. correcta by 2070 due to increase in temperature coupled with decrease in cold stress. The predictive modeling approach presented here provides an outline for future risk of B.correcta in India under climate change scenarios, which can be used for its better management strategies.

Imaginal Disc Growth Factor 6 (Idgf6) Is Involved in Larval and Adult Wing Development in Bactrocera correcta (Bezzi) (Diptera: Tephritidae).

In insects, imaginal disk growth factors (IDGFs), an important component of the glycoside hydrolase 18 (GH18) family of chitinases, have been reported to be associated with the maintenance of the cuticle and molting. However, there is little knowledge of their function. In this study, imaginal disk growth factor 6 (Idgf6), which is an Idgf, was first identified and cloned from the guava fruit fly Bactrocera correcta (Bezzi) (Diptera: Tephritidae), one of the most serious pest insects in South China and surrounding Southeast Asian countries. This gene encodes IDGF6 protein with a conserved domain similar to ChiA chitinases, the glycoside hydrolase 18 (GH18) family of chitinases, according to NCBI BLAST. Phylogenetic analysis indicated that all Idgf6s were highly conserved among similar species. Subsequent temporal expression profiling revealed that Idgf6 was highly expressed in both the late-pupal and mid-adult stages, suggesting that this gene plays a predominant role in pupal and adult development. Furthermore, RNA interference experiments against Idgf6 in B. correcta, which led to the specific decrease in Idgf6 expression, resulted in larval death as well as adult wing malformation. The direct effects of Idgf6 silencing on B. correcta indicated its important role in development, and Idgf6 might be further exploited as a novel insecticide target in the context of pest management.

Highly variable COI haplotype diversity between three species of invasive pest fruit fly reflects remarkably incongruent demographic histories

Distance decay principles predict that species with larger geographic ranges would have greater intraspecific genetic diversity than more restricted species. However, invasive pest species may not follow this prediction, with confounding implications for tracking phenomena including original ranges, invasion pathways and source populations. We sequenced an 815 base-pair section of the COI gene for 441 specimens of Bactrocera correcta, 214 B. zonata and 372 Zeugodacus cucurbitae; three invasive pest fruit fly species with overlapping hostplants. For each species, we explored how many individuals would need to be included in a study to sample the majority of their haplotype diversity. We also tested for phylogeographic signal and used demographic estimators as a proxy for invasion potency. We find contrasting patterns of haplotype diversity amongst the species, where B. zonata has the highest diversity but most haplotypes were represented by singletons; B. correcta has ~7 dominant haplotypes more evenly distributed; Z. cucurbitae has a single dominant haplotype with closely related singletons in a ‘star-shape’ surrounding it. We discuss how these differing patterns relate to their invasion histories. None of the species showed meaningful phylogeographic patterns, possibly due to gene-flow between areas across their distributions, obscuring or eliminating substructure.

Phylogenetic relationship and characterization of the complete mitochondrial genome of Bactrocera caudata (Diptera: Tephritidae) from China

The complete mitochondrial genome (mitogenome) of Bactrocera caudata (Diptera: Tephritidae: Dacinae) was sequenced and annotated. The mitochondrial genome is 15,311 bp (GenBank No. MT180970), containing 72.7% A + T (A 39.1%, C 17.0%, G 10.3%, and T 33.6%), which is the classical structure for insect mitogenome. All PCGs were started with ATN (ATA/ATG/ATT/ATC) and terminated with TAA except ND3, which ends with TAG. Additionally, the phylogenetic tree confirmed that Bactrocera caudata was closely related to Bactrocera dorsalis and Bactrocera correcta. The current study would enrich the mitogenomes of the fruit flies.

Suppressive effects of trap capture on fertilized egg production in Bactrocera correcta (Bezzi) (Diptera: Tephritidae): comparison of two attractants, ß-caryophyllene and methyl eugenol, in laboratory cages

Suppressive effects of trap capture on fertilized egg production in Bactrocera correcta (Bezzi) (Diptera: Tephritidae): comparison of two attractants, ß-caryophyllene and methyl eugenol, in laboratory cages

Spatio-temporal temperature variations in MarkSim multimodel data and their impact on voltinism of fruit fly, Bactrocera species on mango

Fruit flies are the most serious economic insect pests of mango in India and other parts of the world. Under future climate change, shifts in temperature will be a key driver of ecosystem function especially in terms of insect pest dynamics. In this study, we predicted the voltinism of the three economically important fruit fly species viz., Bactrocera dorsalis (Hendel), Bactrocera correcta (Bezzi) and Bactrocera zonata (Saunders) of mango from 10 geographical locations in India using well established degree day approaches. Daily minimum and maximum temperature data were generated by using seven General Circulation Models (GCMs) along with their ensemble, in conjunction with the four representative concentration pathways (RCPs) scenarios (RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5) and three time periods (2020, 2050 and 2080) generated from MarkSim® DSSAT weather file generator. Historical data from 1969–2005 of these 10 locations were considered as baseline period. Under future predicted climates, model outputs indicates that all three fruit fly species will produce higher number of generations (1–2 additional generations) with 15–24% reduced generation time over the baseline period. The increased voltinism of fruit fly species due to increased temperature may lead to ≃5% higher infestation of mango fruits in India by the year 2050. Analysis of variance revealed that ‘geographical locations’ explained 77% of the total variation in voltinism followed by ‘time periods’ (11%). Such increase in the voltinism of fruit flies and the consequent increases in the infestation of mango fruits are likely to have significant negative impacts on mango protection and production.

A transcriptional and functional analysis of heat hardening in two invasive fruit fly species, Bactrocera dorsalis and Bactrocera correcta.

Many insects have the capacity to increase their resistance to high temperatures by undergoing heat hardening at nonlethal temperatures. Although this response is well established, its molecular underpinnings have only been investigated in a few species where it seems to relate at least partly to the expression of heat shock protein (Hsp) genes. Here, we studied the mechanism of hardening and associated transcription responses in larvae of two invasive fruit fly species in China, Bactrocera dorsalis and Bactrocera correcta. Both species showed hardening which increased resistance to 45°C, although the more widespread B. dorsalis hardened better at higher temperatures compared to B. correcta which hardened better at lower temperatures. Transcriptional analyses highlighted expression changes in a number of genes representing different biochemical pathways, but these changes and pathways were inconsistent between the two species. Overall B. dorsalis showed expression changes in more genes than B. correcta. Hsp genes tended to be upregulated at a hardening temperature of 38°C in both species, while at 35°C many Hsp genes tended to be upregulated in B. correcta but not B. dorsalis. One candidate gene (the small heat shock protein gene, Hsp23) with a particularly high level of upregulation was investigated functionally using RNA interference (RNAi). We found that RNAi may be more efficient in B. dorsalis, in which suppression of the expression of this gene removed the hardening response, whereas in B. correcta RNAi did not decrease the hardening response. The different patterns of gene expression in these two species at the two hardening temperatures highlight the diverse mechanisms underlying hardening even in closely related species. These results may provide target genes for future control efforts against such pest species.