The Asian palm weevil, Rhynchophorus ferrugineus, is a tremendously important agricultural pest primarily adapted to palm trees and causes severe destruction, threatening sustainable palm cultivation ...worldwide. The host plant selection of this weevil is mainly attributed to the functional specialization of odorant receptors (ORs) that detect palm-derived volatiles. Yet, ligands are known for only two ORs of R. ferrugineus, and we still lack information on the mechanisms of palm tree detection. This study identified a highly expressed antennal R. ferrugineus OR, RferOR2, thanks to newly generated transcriptomic data. The phylogenetic analysis revealed that RferOR2 belongs to the major coleopteran OR group 2A and is closely related to a sister clade containing an R. ferrugineus OR (RferOR41) tuned to the non-host plant volatile and antagonist, α-pinene. Functional characterization of RferOR2 via heterologous expression in Drosophila olfactory neurons revealed that this receptor is tuned to several ecologically relevant palm-emitted odors, most notably ethyl and methyl ester compounds, but not to any of the pheromone compounds tested, including the R. ferrugineus aggregation pheromone. We did not evidence any differential expression of RferOR2 in the antennae of both sexes, suggesting males and females detect these compounds equally. Next, we used the newly identified RferOR2 ligands to demonstrate that including synthetic palm ester volatiles as single compounds and in combinations in pheromone-based mass trapping has a synergistic attractiveness effect to R. ferrugineus aggregation pheromone, resulting in significantly increased weevil catches. Our study identified a key OR from a palm weevil species tuned to several ecologically relevant palm volatiles and represents a significant step forward in understanding the chemosensory mechanisms of host detection in palm weevils. Our study also defines RferOR2 as an essential model for exploring the molecular basis of host detection in other palm weevil species. Finally, our work showed that insect OR deorphanization could aid in identifying novel behaviorally active volatiles that can interfere with weevil host-searching behavior in sustainable pest management applications.
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•This study reports host plant detection of the most destructive, invasive insect pest on palm trees, the Asian palm weevil R. ferrugineus.•We identified a highly expressed odorant receptor (RferOR2) tuned to natural palm-emitted odors, most notably to palm esters.•The newly identified palm esters' inclusion in the pheromone-based mass trapping increased weevil catches in the field.•The insect odorant receptor deorphanization could help identify novel behaviorally active volatiles (reverse chemical ecology) for sustainable palm protection.
The red palm weevil, Rhynchophorus ferrugineus (Olivier 1790) caused a high economic loos in date palm in gulf region especially in Saudi Arabia. Previous estimations of palm weevil haplotype ...diversity in Saudi Arabia was not satisfactory because of choice of marker and small sampling area. Assessing haplotype diversity using COI gene was found ineffective. The present study was carried out to estimate the haplotypes of R. ferrugineus using internal transcribed spacer (ITS) sequences. Results showed 3 haplo-groups, among which, the haplotype UT9 was a singleton haplotype. The haplotypes UT16, UT2, UT6 UT10, UT14 and UT5 formed the second haplo-group whereas the remaining haplotypes were clustered as third group. K2P distance varied between 0 and 0.06 among the sequenced haplotypes and the maximum distance was recorded between two sets of haplotypes; viz; UT4 and UT3, UT4 and UT8. The overall distance of all the sequenced haplotypes were 0.02. Tajima’s neutrality value was < 0 indicating the potentiality for further haplotype diversification. Median joining haplotype network diagram reveals the presence of 10 haplotypes and most mutations were at 244th and 381st nucleotide positions. Overall, total number of mutations leading to the evolution of the documented 10 haplotypes was 34. Through genetic data, we have provided a strong evidence that there were multiple haplotypes of R. ferrugineus which were bound to expand its diversity. Higher nucleotide diversity and Tajima’s neutrality test values suggest that there were higher movement of infested palm trees, as desserts were natural barriers for movement of H. ferrugineus. The findings of this study will be useful for pest controlling agencies and to the workers involved in infested date palm quarantining.
Smart agriculture and Internet of Things (IoT) technologies have become the key points for many intelligent decision-making applications to support agricultural experts and farmers, especially for ...crop pest management and control. In this work, we present an IoT-based sound detection model for identifying red palm weevil (RPW) larvae to protect date palm trees at the early stage of infestation. The proposed detection system is mainly based on a modified mixed depthwise convolutional network (MixConvNet) as a recent deep learning classifier. The public TreeVibes dataset, which contains short audio recordings of feeding and/or moving RPWs, was successfully tested and assessed with the proposed MixConvNet classifier. There were 146 and 351 specimens of infested and clean sounds examined, respectively. The classification results showed that our proposed MixConvNet is efficient and superior to other deep learning classifiers, such as Xception and residual network (Resnet) models in previous related studies, obtaining the best accuracy score of 97.38. Moreover, the MixConvNet classifier is capable of identifying RPW infestation cases precisely with a high accuracy value of 95.90% ± 1.46, using 10-fold cross-validation. Therefore, practical implementation of our proposed IoT-enabled early sound detection system of RPWs is considered the future milestone of this study.
Emergent and potentially invasive weevils are a permanent threat to the survival of palm plantations. Hence, understanding the role of emergent pests may be key for preventing future phytosanitary ...emergencies. In the present study, the role of Rhynchophorus palmarum L. and Dynamis borassi F. (both Coleoptera: Curculionidae) as main causative agents of the peach palm (Bactris gasipaes Kunth; Arecaceae) crown toppling problem were investigated, and the damage was described in 36 farms in the principal production areas of Colombia. A management strategy with the use of 2 pheromones (Rhynchophorol and Ferrolure) in 2 production areas also was evaluated. In total, 4,098 palms were examined from Nov 2017 to Feb 2019. Visible damage oscillated between 0 to 70% of palms affected and was highest on the Pacific coast. Larvae of D. borassi were found exclusively in the inflorescences suggesting that it initiates the damage. Meanwhile, adults of D. borassi and all stages of R. palmarum were recovered from stem damages. Also, new reports of damage were confirmed at the southern Pacific coast, the Andes, and the Amazon region. A total of 8,239 D. borassi and 2,886 R. palmarum were captured in pheromone traps for 14 mo on the Pacific coast. The traps baited with Ferrolure + Rhynchophorol captured a greater number of D. borassi specimens. The data strongly confirm the central role of D. borassi in peach palm damage. Therefore, it is recommended strongly that pheromones be used to prevent further spread of this pest in other countries of this region and to protect palm industries.
Rhynchophorus ferrugineus is the serious insect pest of palm groves. Chemical control against this species is an important constituent for developing an IPM strategy. But repeated use of the same ...class of synthetic chemicals to control a pest can cause resistance. The research was conducted to evaluate resistance in R. ferrugineus against commonly used synthetic insecticides (chlorpyrifos, imidacloprid and lambda-cyhalothrin) with intense selection pressure for seven successive generations under laboratory conditions. Further, biochemical assays were performed after selection with chlorpyrifos (Chlor-SEL), imidacloprid (Imida-SEL), and lambda-cyhalothrin (Lam-SEL) from G1 to G7 to estimate possible resistance mechanism against tested insecticides. The Imida-SEL, Chlor-SEL and Lam-SEL showed very high resistance 1883-fold, 488-fold and 112-fold, respectively at G7 compared to the susceptible population. Biochemical results showed that the highest activity of AChE (71.43 μmol/min mg protein) was majorly contributed in imidacloprid resistance, EST in chlorpyrifos resistance (87.18 μmol/min mg protein) and GST (83.93 μmol/min mg protein) in lambda-cyhalothrin resistance. The outcomes of the present research propose that the increased levels of enzymes have their possible role for the resistance development in R. ferrugineus and their suppression can aid in the breaking of resistance. The rotation or replacement of chlorpyrifos, and imidacloprid with lambda-cyhalothrin can be integrated for the management of R. ferrugineus.
•Field collected Rhynchophorus ferrugineus developed high resistance ratio (1883-fold) to Imida-SEL, followed by Chlor-SEL (488-fold) and Lam-SEL (112-fold) from G1-G7 after laboratory selection.•Highest activity of AChE (71.43 μmol/min mg protein) in imidacloprid, EST in chlorpyriphos (87.18 μmol/min mg protein) and GST (83.93 μmol/min mg protein) in lambda-cyhalothrin resistance.•The high activities of these enzymes are the major cause of resistance in Rhynchophorus ferrugineus.
The red palm weevil (RPW), Rhynchophorus ferrugineus (Coleoptera: Curculionidae), is the most devastating pest of palm trees worldwide. Mitigation of the economic and biodiversity impact it causes is ...an international priority that could be greatly aided by a better understanding of its biology and genetics. Despite its relevance, the biology of the RPW remains poorly understood, and research on management strategies often focuses on outdated empirical methods that produce sub-optimal results. With the development of omics approaches in genetic research, new avenues for pest control are becoming increasingly feasible. For example, genetic engineering approaches become available once a species's target genes are well characterized in terms of their sequence, but also population variability, epistatic interactions, and more. In the last few years alone, there have been major advances in omics studies of the RPW. Multiple draft genomes are currently available, along with short and long-read transcriptomes, and metagenomes, which have facilitated the identification of genes of interest to the RPW scientific community. This review describes omics approaches previously applied to RPW research, highlights findings that could be impactful for pest management, and emphasizes future opportunities and challenges in this area of research.
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•Sago palm weevil larvae (SPWL) can be regarded as a sustainable food choice.•Growth performance and composition of SPWL have been dependent on the supplement.•SPWL fed with ...supplemented diets were richer in protein, lipid and mineral.•Qualities of amino acid and fatty acid in SPWL were improved by dietary supplement.•Perilla seed was the best supplement to improve the nutritional quality of SPWL.
Nutritional composition and growth performance of sago palm weevil larvae (SPWL) fed with ground sago palm trunk mixed with different supplements including commercial pig feed, rice bran, cornmeal, soybean meal, and perilla seed were evaluated. SPWL fed with supplemented diets were richer in protein, lipid, and mineral contents (p < 0.05). Marked increases in polyunsaturated fatty acids (10.75-fold) and omega-3 fatty acids (25.42-fold) with the lowest n-6:n-3 ratio, atherogenicity index, and thrombogenicity index were found in SPWL fed with perilla seed (p < 0.05). Perilla seed, cornmeal, and soybean meal improved essential amino acid content and essential amino acid index of SPWL. Growth performance varied, depending on feed compositions, where a comparable or even greater effect was observed in SPWL fed with supplemented diets compared to control. Therefore, plant-based supplements, especially perilla seed, efficiently improved nutritional quality of SPWL, making them more attractive in terms of nutritional and economical value.
Red palm weevil (RPW) is a detrimental pest, which has wiped out many palm tree farms worldwide. Early detection of RPW is challenging, especially in large-scale farms. Here, we introduce the ...combination of machine learning and fiber optic distributed acoustic sensing (DAS) techniques as a solution for the early detection of RPW in vast farms. Within the laboratory environment, we reconstructed the conditions of a farm that includes an infested tree with ∼12 day old weevil larvae and another healthy tree. Meanwhile, some noise sources are introduced, including wind and bird sounds around the trees. After training with the experimental time- and frequency-domain data provided by the fiber optic DAS system, a fully-connected artificial neural network (ANN) and a convolutional neural network (CNN) can efficiently recognize the healthy and infested trees with high classification accuracy values (99.9% by ANN with temporal data and 99.7% by CNN with spectral data, in reasonable noise conditions). This work paves the way for deploying the high efficiency and cost-effective fiber optic DAS to monitor RPW in open-air and large-scale farms containing thousands of trees.
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