Predation behaviour of Myopopone castaneae SMITH ants against some insect larvae in the laboratory

Myopopone castaneae ants are known to be predators of the larvae of Oryctes rhinoceros. These ants attack their prey alive by biting and stinging them to death before the hemolymph fluid is consumed. Despite the minimal information available, these ants have the potential to prey on 2.8 - 3 larvae for a period of 5 days. Therefore, the purpose of this research was to evaluate the predation behavior of M. castaneae ants against several types of insect larvae in the laboratory. This investigation was performed at the pest laboratory, Faculty of Agriculture, North Sumatra University from May to July 2020. The results showed the fastest prey time of 2-3 days on 3 Omphisa fuscidentalis larvae, while the longest was observed against Rhynchophorus ferrugineus species, at 3 larvae for 6-7 days. In addition, the typical predation behavior and symptoms include the presence of scars and gradual blackening on the cuticles. Moreover, ants tend to carry their offspring to the dead larvae of O. rhinoceros and R. ferrugineus, while O. fuscidentalis is conveyed to the nest for consumption by the colony.

Whole-Genome Sequence of Oryctes rhinoceros Nudivirus from Riau Province, Indonesia

A double-stranded DNA virus, Oryctes rhinoceros nudivirus (OrNV), was detected in the total DNA of diseased larvae of O. rhinoceros in Riau Province, Indonesia. The complete genome sequence was 124,926 bp long and encodes 123 open reading frames (ORFs). This strain belongs to the family Nudiviridae and was designated LiboV.

The contents availability of N, P, K, and Mg in empty fruit composting of oil palms with symbiont bacteria from rhinoceros beetle larvae (Oryctes rhinoceros) (Coleoptera: Scarabidae)

The using of palm oil waste had not been optimal lately. It could be seen in oil empty fruit bunches (EFB). It was placed along the oil palm plantations. The condition was not only the trigger of air pollution but also could invite rhinoceros beetle pests (Oryctes rhinoceros) to lay their eggs and carry out reproductive activities due to availability organic matter of the trees. Oil palm plants required large amounts of macro nutrients, especially potassium. However, the potassium nutrient was found in EFB was too slow available because of its relatively long breakdown. That was the reason why it was needed a method of using EFB waste into a capable of high use value product, environmentally friendly, and could give a lot of benefits to oil palm farmers. The purpose of this study was to determine the availability of nutrient content in EFB composting by the using of symbiont bacteria from larvae O. rhinoceros. The research was experimentally conducted a factorial randomized block design (RBD) with 2 factors, namely the type of bacteria and the time of decomposition. The composting stage was carried out by coarsely chopping the EFB then 75 ml of bacterial culture was applied to 1 kg of EFB. Analysis, results indicated C/N ratio (35.56% and 36.97%) and high K content (1.64% and 1.48%). The EFB composting method is achievable in 6 weeks with activators of Bacillus stratosphericus and Bacillus siamensis.

Identification of Components of the Aggregation Pheromone of the Guam Strain of Coconut Rhinoceros Beetle, Oryctes rhinoceros, and Determination of Stereochemistry

The coconut rhinoceros beetle, Oryctes rhinoceros (Linnaeus 1758) (Coleoptera: Scarabaeidae: Dynastinae) (CRB), is endemic to tropical Asia where it damages both coconut and oil palm. A new invasion by CRB occurred on Guam in 2007 and eradication attempts failed using commonly applied Oryctes rhinoceros nudivirus (OrNV) isolates. This and subsequent invasive outbreaks were found to have been caused by a previously unrecognized haplotype, CRB-G, which appeared to be tolerant to OrNV. The male-produced aggregation pheromone of the endemic, susceptible strain of O. rhinoceros (CRB-S) was previously identified as ethyl 4-methyloctanoate. Following reports from growers that commercial lures containing this compound were not attractive to CRB-G, the aim of this work was to identify the pheromone of CRB-G. Initial collections of volatiles from virgin male and female CRB-G adults from the Solomon Islands failed to show any male- or female-specific compounds as candidate pheromone components. Only after five months were significant quantities of ethyl 4-methyloctanoate and 4-methyloctanoic acid produced by males but not by females. No other male-specific compounds could be detected, in particular methyl 4-methyloctanoate, 4-methyl-1-octanol, or 4-methyl-1-octyl acetate, compounds identified in volatiles from some other species of Oryctes. Ethyl 4-methyloctanoate elicited a strong electroantennogram response from both male and female CRB-G, but these other compounds, including 4-methyloctanoic acid, did not. The enantiomers of ethyl 4-methyloctanoate and 4-methyloctanoic acid were conveniently prepared by enzymatic resolution of the commercially-available acid, and the enantiomers of the acid, but not the ester, could be separated by gas chromatography on an enantioselective cyclodextrin phase. Using this approach, both ethyl 4-methyloctanoate and 4-methyloctanoic acid produced by male CRB-G were shown to be exclusively the (R)-enantiomers whereas previous reports had suggested male O. rhinoceros produced the (S)-enantiomers. However, re-examination of the ester and acid produced by male CRB-S from Papua New Guinea showed that these were also the (R)-enantiomers. In field trapping experiments carried out in the Solomon Islands, both racemic and ethyl (R)-4-methyloctanoate were highly attractive to both male and female CRB-G beetles. The (S)-enantiomer and the corresponding acids were only weakly attractive. The addition of racemic 4-methyloctanoic acid to ethyl 4-methyloctanoate did significantly increase attractiveness, but the addition of (R)- or (S)-4-methyloctanoic acid to the corresponding ethyl esters did not. Possible reasons for the difference in assignment of configuration of the components of the CRB pheromone are discussed along with the practical implications of these results.

Isolation and screening of local cellulolytic fungi from the digestive tract larvae of Oryctes rhinoceros L., North Sumatra

Cellulose, which is the main component of plant cell walls from higher plants, has been studied from different aspects. It is insoluble in a wide variety of solvents and is resistant to various chemicals treatments. Fungi are a group of cellulose-degrading microbes and plays major role in recycling of lignocellulosic material in nature. This study aimed to obtain cellulolytic fungi from the digestive tract of Oryctes rhinoceros L. larvae and to determine cellulolytic activity. Isolation and screening of cellulolytic fungi in the digestive tract of insects were carried out with specific medium Carboxymethyl Cellulose (CMC) and the Congo Red method to obtain potential cellulolytic isolates. Eleven fungal isolates showed positive results as cellulolytic fungi. The highest cellulolytic activity was obtained from isolate F05L with a cellulolytic index of 0.90 and isolate F10L of 0.66. The smallest cellulolytic activity was obtained from isolate F02L with a cellulolytic index of 0.14. All isolates would be identified to the species level and analyzed its potential applications. Our result can provide in addition to the environmental and industrial fields, cellulolytic fungi can a solution to the problem of pollution, namely reducing the amount of cellulose waste, and can be added value to the use of waste into processed organic fertilizers to be able to provide solutions to the problem of organic waste degradation.

Confirmation of Oryctes rhinoceros nudivirus infections in G-haplotype coconut rhinoceros beetles (Oryctes rhinoceros) from Palauan PCR-positive populations

Coconut rhinoceros beetle (CRB), Oryctes rhinoceros, is a pest of palm trees in the Pacific. Recently, a remarkable degree of palm damage reported in Guam, Hawaii, Papua New Guinea and Solomon Islands has been associated with a particular haplotype (clade I), known as “CRB-G”. In the Palau Archipelago, both CRB-G and another haplotype (clade IV) belonging to the CRB-S cluster coexist in the field. In this study, more than 75% of pheromone trap-captured adults of both haplotypes were Oryctes rhinoceros nudivirus (OrNV)-positive by PCR. No significant difference in OrNV prevalence between the haplotypes was detected. In PCR-positive CRB-G tissue specimens from Palau, viral particles were observed by electron microscopy. Hemocoel injection of CRB larvae with crude virus homogenates from these tissues resulted in viral infection and mortality. OrNV isolated from Palauan-sourced CRB was designated as OrNV-Palau1. Both OrNV-Palau1 and OrNV-X2B, a CRB biological control isolate released in the Pacific, were propagated using the FRI-AnCu-35 cell line for production of inoculum. However, the OrNV-Palau1 isolate exhibited lower viral production levels and longer larval survival times compared to OrNV-X2B in O. rhinoceros larvae. Full genome sequences of the OrNV-Palau1 and -X2B isolates were determined and found to be closely related to each other. Altogether these results suggest CRB adults in Palau are infected with a less virulent virus, which may affect the nature and extent of OrNV-induced pathology in Palauan populations of CRB.

Diverse Host Immune Responses of Different Geographical Populations of the Coconut Rhinoceros Beetle to Oryctes Rhinoceros Nudivirus (OrNV) Infection

Oryctes rhinoceros nudivirus (OrNV) is a double-stranded DNA (dsDNA) virus which has been used as a biocontrol agent to suppress coconut rhinoceros beetle (CRB) in the Pacific Islands. Recently a new wave of CRB incursions in Oceania is thought to be related to the presence of low-virulence isolates of OrNV or virus-tolerant haplotypes of beetles (CRB-G).

A high-quality de novo genome assembly based on nanopore sequencing of a wild-caught coconut rhinoceros beetle (Oryctes rhinoceros)

Background: An optimal starting point for relating genome function to organismal biology is a high-quality nuclear genome assembly, and long-read sequencing is revolutionizing the production of this genomic resource in insects. Despite this, nuclear genome assemblies have been under-represented for agricultural insect pests, particularly from the order Coleoptera. Here we present a de novo genome assembly and structural annotation for the coconut rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae), based on Oxford Nanopore Technologies (ONT) long-read data generated from a wild-caught female, as well as the assembly process that also led to the recovery of the complete circular genome assemblies of the beetle's mitochondrial genome and that of the biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). As an invasive pest of palm trees, O. rhinoceros is undergoing an expansion in its range across the Pacific Islands, requiring new approaches to management that may include strategies facilitated by genome assembly and annotation. Results: High-quality DNA isolated from an adult female was used to create four ONT libraries that were sequenced using four MinION flow cells, producing a total of 27.2 Gb of high-quality long-read sequences. We employed an iterative assembly process and polishing with one lane of high-accuracy Illumina reads, obtaining a final size of the assembly of 377.36 Mb that had high contiguity (fragment N50 length = 12 Mb) and accuracy, as evidenced by the exceptionally high completeness of the benchmarked set of conserved single-copy orthologous genes (BUSCO completeness = 99.11%). These quality metrics place our assembly as the most complete of the published Coleopteran genomes. The structural annotation of the nuclear genome assembly contained a highly-accurate set of 16,371 protein-coding genes showing BUSCO completeness of 92.09%, as well as the expected number of non-coding RNAs and the number and structure of paralogous genes in a gene family like Sigma GST. Conclusions: The genomic resources produced in this study form a foundation for further functional genetic research and management programs that may inform the control and surveillance of O. rhinoceros populations, and we demonstrate the efficacy of de novo genome assembly using long-read ONT data from a single field-caught insect.