Rhinoceros Beetle Research Articles

The hindgut microbiota of coconut rhinoceros beetles (Oryctes rhinoceros) in relation to their geographical populations.

The coconut rhinoceros beetle (CRB, Oryctes rhinoceros) is a palm tree pest capable of rapidly expanding its population in new territories. Previous studies identified a digestive symbiosis between CRB and its gut microbes. However, no research compared the genetic variation of CRBs with their hindgut microbiota on a global scale. This study aims to investigate the genetic divergence of CRB and the compositional variation of CRB's microbiota across different geographical locations, and explore the association between them and their predicted functional profiles and environmental data. The research reveals a distinct and consistent microbial community within local populations, but it varies across different geographical populations. The microbial functional profiles linked to the production of digestive enzymes, including cellulases and ligninases, are nonetheless globally conserved. This suggests that CRBs employ specific mechanisms to select and maintain microbes with functional benefits, contributing to host adaptability, stress tolerance, and fitness. The CRB microbial communities did not appear to recapitulate the genetic variation of their hosts. Rather than depend on obligate symbionts, CRBs seem to establish similar digestive associations with whatever environmentally acquired microbes are available wherever they are, aiding them in successfully establishing after invading a new location.IMPORTANCECoconut rhinoceros beetles (CRBs) are notorious pests on Arecaceae plants, posing destructive threats to countries highly reliant on coconut, oil palm, and date palm as economic crops. In the last century, CRBs have rapidly expanded their presence to territories that were once free of these beetles. The United States, for instance, has officially designated CRBs as invasive and alien pests. Given their remarkable ability to swiftly adapt to new environments, their gut microbes may play a crucial role in this process. While the microbiota of CRBs vary depending on geographical location, these beetles consistently exhibit a functionally identical digestive association with locally acquired microbes. This underscores the significance of CRB-microbe association in shaping the adaptive strategies of this agricultural pest.

Prediction and Analysis of the Global Suitable Habitat of the Oryctes rhinoceros (Linnaeus, 1758) (Coleoptera: Scarabaeidae) Based on the MaxEnt Model.

The Asiatic rhinoceros beetle, Oryctes rhinoceros (Linnaeus, 1758) (Coleoptera: Scarabaeidae), is a destructive invasive species that poses a serious threat to palms, oil palms, and other plants. Defining a suitable area for the distribution of O. rhinoceros is essential for the development of appropriate policies and preventive measures. In this work, the MaxEnt niche model and ArcGIS software were used to predict the potential geographic distribution of O. rhinoceros in the world based on occurrence data and related environmental variables and to speculate on the influence of environmental variables on the distribution of O. rhinoceros. The results showed that the suitable areas of O. rhinoceros beetle were mainly distributed in 30° N-30° S, and the highly suitable areas were concentrated in South Asia, East Asia, Southeast Asia, and northern Oceania. The key environmental variables that determine the distribution location of O. rhinoceros are Precipitation of Wettest Month (bio13), Temperature of July (tmin7), Minimum Temperature of November (tmin11), and Precipitation of September (prec9). The prediction results of the MaxEnt model can reflect the global distribution of O. rhinoceros. This study can provide a theoretical basis for the prevention and control of O. rhinoceros and the development of relevant quarantine measures.

Genomic identification of Oryctes rhinoceros nudivirus isolates, a biocontrol agent for coconut rhinoceros beetle

The coconut rhinoceros beetle (Oryctes rhinoceros, CRB) is a serious pest of coconut and oil palms. It is native to South and Southeast Asia and was inadvertently introduced to Samoa in 1909. It has invaded many other Pacific countries throughout the last century. Oryctes rhinoceros nudivirus (OrNV), a natural pathogen of CRB in its native range, was successfully introduced as a classical biocontrol agent and has effectively suppressed invasive CRB populations for decades. However, resurgence of CRB has been recorded, with new invasions detected in several Pacific Island Countries and Territories. Additionally, new populations of CRB are emerging in some invaded areas that have a degree of resistance to the virus isolates commonly released for CRB biocontrol. Here, we designed a fast and reliable tool for distinguishing between different OrNV isolates that can help with the selection process to identify effective isolates for management of new CRB invasions. A comparison of 13 gene/gene region sequences within the OrNV genome of 16 OrNV isolates from native and invaded ranges allowed us to identify unique Single Nucleotide Polymorphisms (SNPs). With these SNPs, we developed an assay using multiplex PCR-amplicon-based nanopore sequencing to distinguish between OrNV isolates. We found that as few as four gene fragments were sufficient to identify 15 out of 20 OrNV isolates. This method can be used as a tool to monitor the establishment and distribution of OrNV isolates selected for release as biocontrol agents in CRB-infected areas.

The Rhino Shield for The Coconut Palm: An Automated Protection System for Coconut Tree

This paper will provide the concept and installation of the automated Rhino Beetle Sheild system, which defends coconut plants against attacks by rhinoceros beetles, are presented in this work. The system makes use of chemical sprayers that are managed by an Arduino board, poles, pumps and electrical valves. It is talked about how well the technique works to keep the coconut trees healthy and prevents beetle infestations. The Rhino Beetle Sheilds potential for use in agriculture is demonstrated by experimental results.

Characterization and screening of new Metarhizium isolates to control the coconut rhinoceros beetle in the Pacific islands

The coconut rhinoceros beetle (CRB; Oryctes rhinoceros) is one of the most destructive insect pests of coconut and oil palms in tropical Asia and the Pacific islands. Members of a new variant, known as CRB-G (clade I), have recently spread into the Pacific islands, causing significant damage. Biopesticides containing Metarhizium spp. are the strongest candidates for inundative biological control against the emerging CRB threat. Selection of the most virulent and robust isolate may determine the impact of this control option on the pest. In this work, CRB specimens with natural fungal infection were collected in Papua New Guinea (PNG) and Solomon Islands (SI). Putative entomopathogenic fungi were isolated and identified. These new isolates and some previously obtained from other Pacific countries were molecularly identified, characterized, and tested for virulence against CRB larval populations in PNG and SI in laboratory bioassays. Of the new isolates collected, four obtained from SI were identified as Metarhizium majus (conidia length ⁓11–15 μm), and four from PNG were identified as Metarhizium pingshaense (conidia length ⁓4–6 μm). The most virulent isolate was M. majus AgR-F717, which caused 100 % mortality in 20–23 days against a CRB variant from the CRB-S grouping (clade II) in laboratory bioassays carried out in PNG. Isolates of M. pingshaense did not show pathogenicity against CRB larvae. M. majus AgR-F717 was also the most virulent in laboratory bioassays using the mixed SI population (from both CRB-S and CRB-G groupings) and was selected for further evaluation using artificial breeding sites. Under field conditions, this isolate demonstrated its ability to infect CRB, dispersal up to 100 m from treated artificial breeding sites, and persistence in soil for at least four months. The new isolate AgR-F717 of M. majus has demonstrated potential as an augmentative biological control agent for CRB in PNG and SI.

Passive wing deployment and retraction in beetles and flapping microrobots.

Birds, bats and many insects can tuck their wings against their bodies when at rest and deploy them to power flight. Whereas birds and bats use well-developed pectoral and wing muscles1,2, how insects control their wing deployment and retraction remains unclear because this varies among insect species. Beetles (Coleoptera) display one of the most complex mechanisms. In rhinoceros beetles, Allomyrina dichotoma, wing deployment is initiated by complete release of the elytra and partial release of the hindwings at their bases. Subsequently, the beetle starts flapping, elevates the hindwing bases and unfolds the hindwing tips in an origami-like fashion. Although the origami-like fold has been extensively explored3-8, limited attention has been given to the hindwing base movements, which are believed to be driven by the thoracic muscles5,9-11. Here we demonstrate that rhinoceros beetles can effortlessly deploy their hindwings without necessitating muscular activity. We show that opening the elytra triggers a spring-like partial release of the hindwings from the body, allowing the clearance needed for the subsequent flapping motion that brings the hindwings into the flight position. After flight, the beetle can use the elytra to push the hindwings back into the resting position, further strengthening the hypothesis of passive deployment. We validated the hypothesis using a flapping microrobot that passively deployed its wings for stable, controlled flight and retracted them neatly upon landing, demonstrating a simple, yet effective, approach to the design of insect-like flying micromachines.

Effect of Baculovirus oryctes concentration on mortality of Oryctes rhinoceros L.

One of the key plantation crops in Indonesia, particularly in the expanding Riau region, is oil palm (Elaeis guineensis Jacq.). The frequent attacks by Rhinoceros beetles (Oryctes rhinoceros), are the greatest barrier to oil palm development in Riau region. Integrated Pest Management (IPM), which puts an emphasis on ecologically friendly controls one of which uses the entomopathogen Baculovirus oryctes, is the preferred control strategy. This study sought to determine the optimal suspension concentration of Baculovirus oryctes infected larvae on the mortality of the Oryctes rhinoceros beetle. The treatment given was concentration of Baculovirus oryctes suspension of, 0 ml.500 ml−1 water (0 x 106 PIBs.ml−1), 40 ml.500 ml−1 water (6 x 106 PIBs.ml−1), 50 ml.500 ml−1 water (7.6 x 106 PIBs.ml−1), 60 ml.500 ml−1 water (9.3 x 106 PIBs.ml−1) and 70 ml.500 ml−1 water (9.6 x 106 PIBs.ml−1). The results showed that the suspension concentration of 70 ml.500 ml−1 water (9.6 x 106 PIBs/ml) is the best trend concentration because it generates the fastest initial time of death which is 180 hours, lethal time 50 for 288 hours after application and total mortality of 70.83%. The conclusion is that Baculovirus oryctes can be used to kill rhinoceros beetle Oryctes rhinoceros best at a concentration of 70 ml.500 ml−1 water (9.6 x 106 PIBs ml−1).

Three new strategies for improving biosecurity and invasive species management to build resilience in Pacific Islands

The inaugural Pacific Ecological Security Conference (PESC) was held in October 2022, bringing together over 100 island leaders, policy-makers, natural resource managers and global and regional invasive species experts to prioritise the critical issue of invasive species in the Pacific Islands Region. Participants confirmed that invasive species are a major threat to building and maintaining climate resilience and adaptability of Pacific Island ecosystems, as well as food security, biodiversity, sustainable livelihoods and the protection of cultural resources and way of life. Three region-wide strategic action plans were developed to guide interventions focused on the topics of invasive ants, coconut rhinoceros beetle and the use of biological control as a pest and weed management tool. These plans were the major outcome of the PESC and, when implemented, will result in coordinated activities that take a “whole-of-Pacific” approach to invasive species biosecurity and management. Here, we briefly describe the background, planning and engagement process for the three plans, summarise any country- and territory-level data obtained through the process and detail what is planned to occur over the next few years. In addition to the adoption and implementation of the strategies as a result of this inaugural PESC, we anticipate that the PESC will become the premier regional conference aimed at reducing the entry and impacts of invasive species to improve sustainability of environments and peoples of the Pacific.

Comparative effectiveness of packaging design pheromone product to sustainable pest management of rhinoceros beetle in oil palm plantation

Comparative effectiveness of packaging design pheromone product to sustainable pest management of rhinoceros beetle in oil palm plantation

Coconut rhinoceros beetle digestive symbiosis with potential plant cell wall degrading microbes

Coconut rhinoceros beetle (CRB, Oryctes rhinoceros) is an invasive palm pest whose larvae eat wood, yet lack the necessary digestive enzymes. This study confirmed endogenous CRB cellulase is inactive, suggesting microbial fermentation. The inner lining of the CRB hindgut has tree-like structures covered with a conspicuous biofilm. To identify possible symbionts, 16 S rRNA amplicon sequencing was used on individuals from across Taiwan. Several taxa of Clostridia, an anaerobic class including many cellulolytic bacteria, were highly abundant in most individuals from all locations. Whole metagenome sequencing further confirmed many lignocellulose degrading enzymes are derived from these taxa. Analyses of eggs, larvae, adults, and soil found these cellulolytic microbes are not transmitted vertically or transstadially. The core microbiomes of the larval CRB are likely acquired and enriched from the environment with each molt, and enable efficient digestion of wood.

Drone-mounted remote-controlled arm for monitoring and precision spraying coconut rhinoceros beetle infestations

This paper presents a low-cost (locally-assembled) drone system with a sprayer arm and a remote control for monitoring and precisely applying pesticides to coconut trees infested by the Rhinoceros Beetle. A modified RGB IP camera continuously monitors potential coconut beetle infestation points, capturing real-time spray images, and displaying the results through a smartphone interface. The system provides real-time monitoring, allowing immediate remote control of the spray operation from the ground upon detecting beetle infestations. The drone-mounted sprayer arm is controlled in response to the ground-based signals, to accurately extend or contract while effectively dispensing spray chemicals onto the target areas at the upper canopy of coconut trees. In our tests using Nam-Hom coconut trees, which averaged a height of 10.4 m, the system operated at a speed of 1.25 km/h, achieving a spraying flow rate of 0.333 l/h and a working capacity of 0.352 ha/h. The controlled spraying setup emits a solid jet, ensuring precision and effective atomization of chemicals within a distance range of 1.0 to 4.0 m from the target. The spray quality attributes (droplet size, pattern, and coverage) were not significantly affected by the wind speed. The system could potentially reduce labor costs, chemical usage, and health risks associated with pesticide application.

Rhinoceros beetle (Trypoxylus dichotomus) cuticular hydrocarbons contain information about body size and sex.

Japanese rhinoceros beetle (Trypoxylus dichotomus) males have exaggerated horns that are used to compete for territories. Larger males with larger horns tend to win these competitions, giving them access to females. Agonistic interactions include what appears to be assessment and often end without escalating to physical combat. However, it is unknown what information competitors use to assess each other. In many insect species chemical signals can carry a range of information, including social position, nutritional state, morphology, and sex. Specifically, cuticular hydrocarbons (CHCs), which are waxes excreted on the surface of insect exoskeletons, can communicate a variety of information. Here, we asked whether CHCs in rhinoceros beetles carry information about sex, body size, and condition that could be used by males during assessment behavior. Multivariate analysis of hydrocarbon composition revealed patterns associated with both sex and body size. We suggest that Rhinoceros beetles could be communicating information through CHCs that would explain behavioral decisions.

Adhesion and shrinkage transform the rounded pupal horn into an angular adult horn in Japanese rhinoceros beetle.

Clarifying the mechanisms underlying shape alterations during insect metamorphosis is important for understanding exoskeletal morphogenesis. The large horn of the Japanese rhinoceros beetle Trypoxylus dichotomus is the result of drastic metamorphosis, wherein it appears as a rounded shape during pupation and then undergoes remodeling into an angular adult shape. However, the mechanical mechanisms underlying this remodeling process remain unknown. In this study, we investigated the remodeling mechanisms of the Japanese rhinoceros beetle horn by developing a physical simulation. We identified three factors contributing to remodeling by biological experiments - ventral adhesion, uneven shrinkage, and volume reduction - which were demonstrated to be crucial for transformation using a physical simulation. Furthermore, we corroborated our findings by applying the simulation to the mandibular remodeling of stag beetles. These results indicated that physical simulation applies to pupal remodeling in other beetles, and the morphogenic mechanism could explain various exoskeletal shapes.

Automatic Holonomic Mobile Micromanipulator for Submillimeter Objects Inspired by the Rhinoceros Beetle

Holonomic mobile micromanipulators driven by piezoelectric actuators offer precision and compact design. However, attaining both high speed and positioning repeatability with sufficient load capacity poses challenges, given that lightweight robots are susceptible to nonuniform driving surfaces and external forces. A holonomic beetle (HB) is proposed to realize a wide range, compact size, precise holonomic motion, automatic micromanipulation, and high‐speed movement simultaneously. Inspired by the biological makeup of a Rhinoceros Beetle, a length, weight, and load capacity of 8 cm, 74 g, and of 2000 g, respectively, are used. The HB is a two‐legged robot with a pseudoalternating tripod gait locomotion principle, with five piezoelectric actuators for XYθ displacement and switching of the contact leg. It achieves maximum walking velocities of 11.6 mm s−1 for translational motion and 19.3 deg s−1 for rotation, with a displacement resolution of 12 nm. Notably, under open‐loop control, the HB demonstrates high repeatability with a coefficient of variation of 0.3%. It exhibits the capability to climb 30°‐inclined surfaces, traverse flat surfaces with 0.1 mm bumps, and navigate 30 mm pits. Furthermore, the HB showcases practical automatic micromanipulation through visual servo control and machine learning, presenting potential applications in biomedical and microassembly fields.

Isolation, molecular characterization, and virulence assays of entomopathogenic fungi of Oryctes rhinoceros larvae from Asahan origin

Palm oil is the most important plantation commodity in Indonesia. One factor that can suppress oil palm productivity in the field is due to pest attacks, one of which is the attack of the Rhinoceros beetle called Oryctes rhinoceros. This study aims to isolate entomopathogenic fungi found in Oryctes rhinoceros larvae at oil palm plantations in Tanjung Alam Village, Asahan, North Sumatra. The results showed that the fungus isolates had conidia that were greenish and could cause mummification which varied for 7-24 days. The results of molecular identification by PCR (polymerase chain reaction) using ITS1-ITS4 primers showed that the isolates of the entomopathogenic fungi were Metarhizium majus and Metarhizium anisopliae species with DNA bands measuring around 500 base pairs (bp).

The use of unmanned aerial vehicle for controlling Oryctes rhinoceros beetle on Immature Oil Palm

Current constraints on labor supply and human error have triggered interest in using automated technology as an alternative to conventional operations. Hence, Minamas Plantation has embarked on an exploratory trial using unmanned aerial vehicles (UAV) in one of the labor-intensive works in the oil palm industry, which is the prophylactic fortnightly spraying of beetles on immature palms. The trial was conducted between October 2021 and January 2022 at PT Aneka Inti Persada. Three treatments, namely UAV, conventional, and no control, were investigated under two different environments (straight-line and terrace plantings). A randomized complete block design was adopted, with three replicates of immature oil palms planted in 2020. Prior to treatment implementation, all treated palms were georeferenced. The insecticide used was Cypermethrin (5.5% EC) at 20 ml/L of water. Insecticide application by point-to-point spraying was conducted for 4 seconds on each palm (250 ml solution/palm) at 0.5 – 1.5 m above the canopy. Knapsack spraying was performed as per estate practice. No significant difference in fresh damage was recorded between the UAV and knapsack spraying as compared to the control plots. Palms in control plots continued to be inflicted by beetles with more than 5% fresh damage throughout the trial period. The trial concluded that UAV technology has great potential for adoption in daily estate operations. The next step of the trial was to compare the cost-effectiveness between treatments. This study did not carry out the economic analysis due to the scale of the trial.

Farmers’ Knowledge and Perceptions in the Production of Coconut Rhinoceros Beetle (Oryctes rhinoceros) for Enhanced Food Security in Kenya

Local knowledge and perceptions regarding the value of edible insects among smallholder farmers are critical to introducing such enterprises and designing effective insect productivity-enhancing interventions. However, limited studies have been done in Kenya regarding insects as agricultural enterprises, specifically in the Kilifi region. A survey was carried out among 207 smallholder farmers of coconut palm in Kilifi North and South sub-counties to assess their knowledge and perceptions about Oryctes rhinoceros as a farm enterprise. The primary data was collected using a structured questionnaire triangulated by key informant interviews from the Department of Agriculture, Nuts and Oil Crop Directorate, and farmer group leaders. Descriptive statistics and a chi-square test were the major analyses. Results showed farmers had adequate knowledge and positive perceptions regarding the beetle and its useful larval stage, represented by the mean of 0.97 and 3.44, respectively. The age, education level, prior exposure to training on edible insect farming, religion, and years of coconut farming of the farmers are associated with the levels of knowledge and perceived values of the Oryctes rhinoceros farming. Considering the positive knowledge levels and perceptions among Kilifi farmers, rather than focusing on general awareness creation, there is a need to enhance the access to and use of agricultural training resources to learn the importance of agricultural innovations as a tool for food insecurity alleviation through intensive processes. The extension systems need to incorporate the concepts of edible insects. This will render an innovation sustainable and useful for economically disadvantaged people. Further studies should be done among livestock feed traders and even food and feed processors to enable effective commercialisation interventions

A novel approach for automated rhinoceros beetle control in oil palm replanting: pineapple peel-derived pheromone trap

Oil palm (Elaeis guineensis Jacq) is a crucial plant for Indonesia's economy, serving as a major non-oil foreign exchange earner. A significant pest affecting oil palm cultivation, especially during replanting, is the rhinoceros beetle (Oryctes rhinoceros L.). Attractant pheromones, derived from pineapples, contain volatile compounds that attract insects. This research aims to develop an automated rhinoceros beetle trap equipped with an automatic pheromone spray system utilizing natural peel pineapple extract. The analysis includes tests for fluid density, spray distribution, and normality. The fluid density of the sample closely resembles that of water (1 g/cm³). Spray distribution results indicate particle sizes (60-112 μm) larger than airborne aerosols (0.001-50 μm). Kolmogorov-Smirnov normality tests reveal mostly normal data distribution, with minor deviations. Overall, this trap exhibits promise as an effective solution for rhinoceros beetle control in oil palm cultivation.

Population’s preference of rhinoceros beetle (Oryctes rhinoceros) between oil palm (Elaeis guineensis) and coconut palm (Cocos nucifera l.): Contributing to pest’s controlling strategy

The rhinoceros beetle (Oryctes rhinoceros) began to establish itself in Malaysia with the emergence of coconut cultivation. Rhinoceros beetles were well adapted to survive on oil palm (Elaeis guineensis) and coconut (Cocos nucifera L.) trees. Different host plants could have different interactions and food preferences with the Rhinoceros beetle against their host plant, even within the same family. Additionally, climatic change, particularly rainfall, could also influence the population dynamics of O. rhinoceros especially in terms of the biological aspect of the pest. This study was carried out to evaluate the difference in population of rhinoceros beetles between oil palm and coconut palm as a preference host comparison in relation to the climatic factors on the plantation scale. The population of rhinoceros beetles was found to be higher in oil palm as compared to coconut palm. It can be concluded that rhinoceros beetles highly prefer oil palms when compared to coconut palms. This study highlighted the importance of planting similar families in order to reduce the risk of pest attacks. This study also found that climate is one of the factors influences the population dynamics of rhinoceros beetles and puts pressure on plants, subsequently making it a favorable condition for rhinoceros beetles in the field. Interestingly, female rhinoceros beetle in an oil palm field was significantly correlated with the rainfall. Therefore, preventive measures need to be taken during the rainy season, considering the high risk of planting nearby and/or similar plants.

Assessment of coconut palm damage caused by coconut rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae)

ABSTRACT Coconut production in the Pacific Islands is threatened by coconut rhinoceros beetle (CRB). Distinctive feeding damage caused by adults is often the first indicator of CRB activity in a new location. Multiple approaches to damage assessment have been used, reflecting observers’ experience. The lack of standardisation makes it difficult to compare CRB impacts on coconut palms over time. We examine damage assessment from three perspectives: participants, power and purpose. Participants applied binary, 3-point and 5-point damage scales consecutively to photographs of damaged palms. Participant responses were more accurate using the binary scale compared with the 5-point scale. Experience with CRB improved accuracy, but this did not wholly compensate for the effect of scale complexity. Calculations of statistical power determined minimum sample sizes to detect a 20% change in palm damage was 50 palms for the binary scale, 150 palms for the 3-point scale and > 200 palms for the 5-point scale, when the change in damage was spread across damage categories. More complex damage scales did not increase the likelihood of detecting significant changes in palm damage. With real-world examples, including detecting new outbreaks and managing established populations, recommendations were developed to standardise damage assessment for CRB on coconut palms.