Dataset Information

Mitochondrial DNA Variation Among Populations of Rhynchophorus ferrugineus (Coleoptera: Curculionidae) From Pakistan.

ABSTRACT: The Red Palm Weevil (RPW) Rhynchophorus ferrugineus (Olivier) is a voracious pest of palm species. In recent decades its range has expanded greatly, particularly impacting the date palm industry in the Middle East. This has led to conjecture regarding the origins of invasive RPW populations. For example, in parts of the Middle East, RPW is commonly referred to as the "Pakistani weevil" in the belief that it originated there. We sought evidence to support or refute this belief. First reports of RPW in Pakistan were from the Punjab region in 1918, but it is unknown whether it is native or invasive there. We estimated genetic variation across five populations of RPW from two provinces of Pakistan, using sequences of the mitochondrial cytochrome oxidase subunit I gene. Four haplotypes were detected; two (H1 and H5) were abundant, accounting for 88% of specimens across the sampled populations, and were previously known from the Middle East. The remaining haplotypes (H51 and H52) were newly detected (in global terms) and there was no geographic overlap in their distribution within Pakistan. Levels of haplotype diversity were much lower than those previously recorded in accepted parts of the native range of RPW, suggesting that the weevil may be invasive in Pakistan. The affinity of Pakistani haplotypes to those reported from India (and the geographical proximity of the two countries), make the latter a likely "native" source. With regards the validity of the name "Pakistani weevil", we found little genetic evidence to justify it.

SUBMITTER: Yasin M

PROVIDER: S-EPMC5029037 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Mitochondrial DNA Variation Among Populations of Rhynchophorus ferrugineus (Coleoptera: Curculionidae) From Pakistan.

Yasin Muhammad M Rugman-Jones Paul F PF Wakil Waqas W Stouthamer Richard R

Journal of insect science (Online) 20160920 1

The Red Palm Weevil (RPW) Rhynchophorus ferrugineus (Olivier) is a voracious pest of palm species. In recent decades its range has expanded greatly, particularly impacting the date palm industry in the Middle East. This has led to conjecture regarding the origins of invasive RPW populations. For example, in parts of the Middle East, RPW is commonly referred to as the "Pakistani weevil" in the belief that it originated there. We sought evidence to support or refute this belief. First reports of R ...[more]

PMID: 27651423

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Project description:BACKGROUND: The red palm weevil (RPW) Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) is one of the major pests of palms. The larvae bore into the palm trunk and feed on the palm tender tissues and sap, leading the host tree to death. The gut microbiota of insects plays a remarkable role in the host life and understanding the relationship dynamics between insects and their microbiota may improve the biological control of insect pests. The purpose of this study was to analyse the diversity of the gut microbiota of field-caught RPW larvae sampled in Sicily (Italy). RESULTS: The 16S rRNA gene-based Temporal Thermal Gradient Gel Electrophoresis (TTGE) of the gut microbiota of RPW field-trapped larvae revealed low bacterial diversity and stability of the community over seasons and among pools of larvae from different host trees. Pyrosequencing of the 16S rRNA gene V3 region confirmed low complexity and assigned 98% of the 75,564 reads to only three phyla: Proteobacteria (64.7%) Bacteroidetes (23.6%) and Firmicutes (9.6%) and three main families [Enterobacteriaceae (61.5%), Porphyromonadaceae (22.1%) and Streptococcaceae (8.9%)]. More than half of the reads could be classified at the genus level and eight bacterial genera were detected in the larval RPW gut at an abundance ?1%: Dysgonomonas (21.8%), Lactococcus (8.9%), Salmonella (6.8%), Enterobacter (3.8%), Budvicia (2.8%), Entomoplasma (1.4%), Bacteroides (1.3%) and Comamonas (1%). High abundance of Enterobacteriaceae was also detected by culturing under aerobic conditions. Unexpectedly, acetic acid bacteria (AAB), that are known to establish symbiotic associations with insects relying on sugar-based diets, were not detected. CONCLUSIONS: The RPW gut microbiota is composed mainly of facultative and obligate anaerobic bacteria with a fermentative metabolism. These bacteria are supposedly responsible for palm tissue fermentation in the tunnels where RPW larvae thrive and might have a key role in the insect nutrition, and other functions that need to be investigated.

Project description:External secretions play a vital role in external immune defense. However, the functions and components of these exudates are largely unknown in the red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae). In order to determine their role in external immunity, the immunosuppressive efficacy of the secretions in vitro against microbes, including bacteria and fungi, was clarified. In the present study, we found that these secretions had antimicrobial activity in vitro, implying external immunizing potency against pathogens. Surprisingly, all liquid phases of secretions could not significantly inhibit the growth of microbes in vitro compared to solid phases. To explain this phenomenon, the composition and emission differentia of secretions from the exocrine glands associated with different developmental stages, secretory regions, and phases were identified and analyzed based on metabonomics techniques. A total of more than 200 compounds, including quinines, phenols, aldehydes, acids, alcohols, saccharides, ketones, esters, amines, salts, ureas, and heterocycles, were identified in the secretions of larvae and adults. The liquid phase shared a number of metabolites with the solid phase, but the emission types and amounts were significantly different in the two phases, resulting in differences in external immunological activity. Tyrosine and p-benzoquinone were the dominant metabolites in all of the secretions, accounting for approximately 11.29% of emissions, with the portion in the solid phase being generally higher than that in the liquid phase. Moreover, only p-benzoquinone was entirely significantly upregulated in the solid phase compared to the liquid phase. Therefore, metabolome analysis suggested that p-benzoquinone, which may potentially be developed to be a valuable marker for determining external immunity, was considered to be the main substance responsible for external immune functions. This hypothesis was further demonstrated by the antimicrobial activity of p-benzoquinone.

Project description:Several studies demonstrated that in insects cuticle melanism is interrelated with pathogen resistance, as melanin-based coloration and innate immunity possess similar physiological pathways. For some insects, higher pathogen resistance was observed in darker individuals than in individuals with lighter cuticular coloration. Here, we investigated the difference in immune response between two color morphs (black and red) and between the life stages (pupa and adult) of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae). Here in this study, cuticle thickness, microbial test (antimicrobial activity, phenoloxidase activity, and hemocyte density), and immune-related gene expression were evaluated at different stages of RPW. Study results revealed that cuticle thickness of black phenotype was thicker than red phenotype at old-pupa stage, while no significant difference found at adult stage. These results may relate to the development processes of epidermis in different stages of RPW. The results of antimicrobial activity, phenoloxidase (PO) activity, and hemocyte density analyses showed that adults with a red phenotype had stronger pathogen resistance than those with a black phenotype. In addition to antimicrobial activity and PO activity, we tested relative gene expression in the fat body of old pupae. The results of hemolymph antimicrobial analysis showed that old pupae with a red phenotype were significantly different from those with a black phenotype at 12 hr after Staphylococcus aureus injection, suggesting that red phenotype pupae were more sensitive to S. aureus. Examination of gene expression in the fat body also revealed that the red phenotype had a higher immune response than the black phenotype. Our results were inconsistent with the previous conclusion that dark insects had increased immune function, suggesting that the relationship between cuticle pigmentation and immune function in insects was not a direct link. Additional possible factors that are associated with the immune response, such as life-history, developmental, physiological factors also need to be considered.

Dataset Information

Mitochondrial DNA Variation Among Populations of Rhynchophorus ferrugineus (Coleoptera: Curculionidae) From Pakistan.

Publications

Mitochondrial DNA Variation Among Populations of Rhynchophorus ferrugineus (Coleoptera: Curculionidae) From Pakistan.

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