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.

CURRENT STATUS, CHALLENGES, MANAGEMENT AND FUTURE PERSPECTIVES OF THE RED PALM WEEVIL Rhynchophorus ferrugineus OLIVIER (COLEOPTERA, CURCULIONIDAE) ERADICATION - A REVIEW

The date palm is a cultural and economic heritage of many nations. The red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera, Curculionidae) is among the world’s most serious insect pests of palms that have rapidly expanded its geographical distribution and host plant range during the last decades. Integrated pest management (IPM) is followed to suppress the pest using the most economical and least hazardous methods to humans and the environment. Since R. ferrugineus is a serious pest of date palm production worldwide, farmers, researchers, and scientists have developed many tactics to eradicate this pest. However, there was no published article covering and integrating the current status, biology, ecology, and future control tactics of R. ferrugineus and proposes an IPM program. Therefore, in this review, R. ferrugineus geographical distribution, host plant range, economic importance, infestation symptoms, morphology, biology, and its management tactics were thoroughly discussed. These tactics include early detection of R. ferrugineus infestation, trapping, chemical applications, use of bio-agents, bioinsecticides (plant extracts), resistance cultivars, cultural practices, sterile insect technique, gene silencing technology, quarantine, and geographical information system. In conclusion, all available control tactics suggest that R. ferrugineus could be successfully managed by developing IPM programs comprising several means of control. It is hoped that this review will highlight some aspects of date palm management and raise research gaps and directions deserving further investigations to develop a better understanding of R. ferrugineus management and therefore contributes to the sustainability of date palm cultivation worldwide.

Efek tepung ulat sagu (Rhynchophorus ferrugineus) terhadap penurunan kadar malondialdehyde (MDA) pada tikus Wistar dengan diet rendah protein

Kwashiorkor is protein-energy malnutrition (PEM) caused by protein deficiency. Sago worm flour (Rhynchophorus ferrugineus) can reduce malondialdehyde (MDA) caused by the high content of the amino acids glycine, lysine, and phenylalanine. The study aimed to prove the effect of sago worm flour on MDA levels in Wistar rats with a low protein diet. A true experimental-pre-post control group. The intervention was given for 28 days to 28 Wistar rats, divided into four groups with each group of seven rats. The dose of sago starch was 0,36 g/100 g rat body weight/day (P1), and a dose of 1,36 g/100 g rat body weight/day (P2) for rats fed a low diet protein. The treatment group was compared with a group of mice given a low diet protein (K +) and a group of healthy mice (K-). Serum MDA levels were measured by the TBARs method. Statistical analysis used paired t-test or Wilcoxon test and one-way ANOVA/Kruskal Wallis test. The results of decreasing MDA levels were in the P1 and P2 groups (p= 0,000). There was a difference in MDA levels in the P1 and P2 groups compared to the K + group (P= 0,000). There was a difference that decreased MDA levels between P1 and P2 (p= 0,000). In conclusion, sago worm flour at a dose of 0,36 g/100 g of rats/day and a dose of 1,36 g/100 g of body weight of rats/day can reduce MDA levels

Silencing of vitellogenin gene contributes to the promise of controlling red palm weevil, Rhynchophorus ferrugineus (Olivier)

Red palm weevil [Rhynchophorus ferrugineus (Olivier)], is native to South Asia and expanding its distribution range globally. Recent invasions of red palm weevil around the world, including Saudi Arabia, has become a global constraint for the production of palm species. Although, several control measures have been tested, none of them seemed successful against this invasive species. Therefore, we focused on silencing the reproduction control gene vitellogenin (Vg) based on RNA interference (RNAi) strategy for its possible application in the management of R. ferrugineus. The Vg is a major yolk protein precursor critical for oogenesis. To do this, fat body transcriptome of R. ferrugineus female adults was sequenced, which provided partial Vg gene transcript (FPKM 5731.60). A complete RfVg gene transcript of 5504 bp encoding 1787 amino acids was then sequenced using RCAE-PCR strategy and characterized. Phylogenetic analysis suggested that RfVg has closer ancestry to the coleopteran insects. The RfVg-based RNAi significantly suppressed the expressions of Vg gene. The 15, 20 and 25 days post-injection periods suppressed Vg expressions by 95, 96.6 and 99%, respectively. The suppressed Vg expressions resulted in the dramatic failure of Vg protein expression, which caused atrophied ovaries or no oogenesis and ultimately eggs were not hatched. These results suggest that knockdown of Vg gene involved in R. ferrugineus reproduction is a promising target for RNAi-based management of R. ferrugineus.

Biocontrol potential of entomopathogenic fungi, nematodes and bacteria against Rhynchophorus ferrugineus (Olivier)

Background The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae), is a serious threat to date palms across the globe, causing heavy yield losses. The pest inflicts damage to palms stem and destroys vascular system; resultantly lower the vigor and affect the growth and yield. For ecological farming system, biological control of the pest is gaining increased interest due to hosts’ specificity, safety to human, animal and non-target organisms, and their compatibility to environment. Results In laboratory assay, Beauveria bassiana, Heterorhabditis bacteriophora and Bacillus thuringiensis var. kurstaki (Bt-k) alone and in combination against sixth instar larvae and adults of four distinct populations of RPW were applied. H. bacteriophora was more effective, followed by B. bassiana and Bt-k in alone treatments. While in combined treatments, the highest mortality was recorded for H. bacteriophora + B. bassiana combination (100% for both stages), followed by H. bacteriophora + Bt-k, (larvae 100%; adults 94.24%) and B. bassiana + Bt-k treatments (larvae: 87.01%; adults: 80.53%). Maximum rate of mycosis (larvae 85.74%; adults 69.07%), sporulation (larvae 189.22 conidia ml−1; adults 164.56 conidia ml−1), cadavers affected by nematodes (larvae 92.4%; adults 81.29%) and nematode production (larvae 178.78 IJs ml−1; adults 153.44 IJs ml−1) was observed where B. bassiana or H. bacteriophora was applied alone and the lowest (larvae 122.78 IJs ml−1; adults: 103.22 IJs ml−1) was recorded for H. bacteriophora + B. bassiana combination. Conclusions Entomopathogens can be effectively used alone and/or in integration to control RPW populations. Natural capability of entomopathogens to infect and disseminate into other hosts makes them excellent biocontrol agents to be incorporated in the IPM plan of RPW and to make palm growers confident with the use of the most promising microbial control agents.

A Comparative Study on the Microbial Communities of Rhynchophorus ferrugineus (Red Palm Weevil)-Infected and Healthy Palm Trees

Several studies have investigated palm trees’ microbiota infected with red palm weevil (RPW) (Rhynchophorus ferrugineus), the major pest of palm trees. This study compared the microbial communities of infected and uninfected palm trees in the Hail region, Northern Saudi Arabia, determined by high-throughput 16S rRNA gene sequencing by Illumina MiSeq. The results indicated that taxonomic diversity variation was higher for infected tree trunk than the healthy tree trunk. Soil samples from the vicinity of healthy and infected trees did not have a significant variation in bacterial diversity. Myxococcota, Acidobacteriota, and Firmicutes were the dominant phyla in RPW-infected tree trunk, and Pseudomonadaceae was the most prominent family. This study is the first report on the characterization of RPW-infected and healthy palm trees’ microbiome.

Characterisation of pH-shift-produced protein isolates from sago palm weevil (Rhynchophorus ferrugineus) larvae

Farm-raised sago palm weevil (Rhynchophorus ferrugineus) larvae (SPWL) can be used as a protein source for food sustainability. This study aimed to investigate the potential of pH-shift processing as a cold refinery approach to produce protein isolate from SPWL. Maximum solubility of SPWL protein was observed at pH 2.0 (acid-aided process) and pH 11.5 (alkaline-aided process). The zeta-potential of the protein solution was close to zero with the lowest solubility at pH 4.5. So, the protein precipitation was performed at this pH. Although both acid and alkaline methods yielded roughly 66% protein, their nutritional and techno-functional features differed based on the pH-shifting process. The alkaline-produced protein isolate had higher essential amino acid (EAA) content and EAA index but it was darker in colour. The acid-produced protein isolate had larger levels of umami-taste-active and functional amino acids, as well as a higher emulsifying capability.

Non-palm Plant Volatile α-Pinene Is Detected by Antenna-Biased Expressed Odorant Receptor 6 in the Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

The majority of insects rely on a highly complex and precise olfactory system to detect various volatile organic compounds released by host and non-host plants in environments. The odorant receptors (ORs) are considered to play an important role in odor recognition and the molecular basis of ORs, particularly in coleopterans they are relatively poorly understood. The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae), is one of the most destructive pests of the global palm industry. Although feeding and egg oviposition behaviors of RPW can be repelled by some non-palm plant volatiles, such as α-pinene, geraniol, or 1-octen-3-ol, there is limited understanding of how RPW recognizes the non-host plant volatiles. In this study, three candidate RferOrs were identified from the Rfer-specific clade, and the tissue expression analysis used was mainly expressed in the antennae of both sexes. Functional characterization of RferOr6, RferOr40, and RferOr87 was analyzed by using the Xenopus oocyte expression system, and the results indicated that RferOr6/RferOrco was narrowly tuned to α-pinene. The behavioral experiment showed that α-pinene at the concentrations of 10 and 100 μg/μl can cause a significantly repelled behavioral response of RPW. In conclusion, this study reveals that RferOr6 is an antenna-biased expressed OR used by RPW to detect the volatile compound α-pinene in non-palm plants, and our results provide a foundation for further in vivo functional studies of Or6 in RPW, including in vivo knockout/knockdown and feeding/ovipositing behavioral studies of RPW and further pest control.