Ferrugineus Larvae Research Articles

Rhynchophorus ferrugineus larvae: A novel source for combating broad-spectrum bacterial and fungal infections.

Antimicrobial resistance is a growing concern due to the growth of antibiotic-resistant microorganisms, which makes it difficult to treat infection. Due to its broad-spectrum antimicrobial properties against a diverse array of bacteria, both Gram-positive and Gram-negative bacteria, and fungi, Rhynchophorus ferrugineus larval antimicrobial peptides (AMPs) have demonstrated potential as antimicrobial agents for the treatment of microbial infections and prevention of antibiotic resistance. This study emphasizes the unexplored mechanisms of action of R. ferrugineus larvae against microorganisms. Among the most widely discussed mechanisms is the effect of AMPs in larvae in response to a threat or infection. Modulation of immune-related genes in the intestine and phagocytic capacity of its hemocytes may also affect the antimicrobial activity of R. ferrugineus larvae, with an increase in phenoloxidase activity possibly correlated with microbial clearance and survival rates of larvae. The safety and toxicity of R. ferrugineus larvae extracts, as well as their long-term efficacy, are also addressed in this paper. The implications of future research are explored in this paper, and it is certain that R. ferrugineus larvae have the potential to be developed as a broad-spectrum antimicrobial agent with proper investigation.

Chemical and Nutritional Fat Profile of Acheta domesticus, Gryllus bimaculatus, Tenebrio molitor and Rhynchophorus ferrugineus.

The use of edible insects in the human diet is gaining importance because they are characterized by high nutritional value, and their cultivation is much more environmentally friendly than traditional livestock farming. The objective of this study was to determine the chemical and nutritional fat profile of selected edible insects as follows: house cricket (Acheta domesticus adult), field cricket (Gryllus bimaculatus adult), mealworm (Tenebrio molitor larvae), and palm weevil (Rhynchophorus ferrugineus larvae) which are now commercially available worldwide. Additionally, the degree of implementation of nutrition standards for selected nutrients by these insects was assessed. Freeze-dried insects were studied using infrared-attenuated total reflectance mid-infrared spectroscopy for basic differentiation. The content of fat and fatty acids was determined, and dietary indicators were calculated. The spectroscopic findings align with biochemical data, revealing that Rhynchophorus ferrugineus larvae contain the highest fat content and the least protein. Unsaturated fatty acids (UFAs) predominated in the fat of the assessed insects. The highest content of saturated fatty acids (SFAs), along with the lowest content of polyunsaturated fatty acids (PUFAs), was observed in the larvae of the Rhynchophorus ferrugineus species. From a nutritional standpoint, Tenebrio molitor larvae exhibit the most favorable indicators, characterized by minimal athero- and thrombogenic effects, along with an optimal balance of hypo- and hypercholesterolemic acids. Knowledge of the composition and quantities of fats in different insect species is valuable for planning and preparing meals with accurate nutritional profiles, among other applications.

Effectiveness of botanical insecticides on larval stage of red palm weevil Rhynchophorous ferrugineus and survival of entomopathogenic nematodes

Botanical oils are considered ecofriendly compounds with insecticidal characteristics. In this study, the effects of basil (Ocimum basilicum), camphor (Cinnamomum camphora), cinnamon (Cinnamomum verum), lemon (Citrus limon), clove (Syzygium aromaticum), ginger (Zingiber officinale), black pepper (Piper nigrum), and orange (Citrus sinensis var balady) oil extracts on the survival of four entomopathogenic nematode strains belonging to the Steinernema and Heterorhabditis genera, as well as their impacts on Rhynchophorus ferrugineus egg hatching and larvae, were assessed. The results for the camphor, lemon, black pepper, and orange oils were promising as 50 μL/mL of each resulted in 0%, 0%, 16%, and 0% hatchability for the R. ferrugineus eggs, respectively. Furthermore, the mortality of R. ferrugineus larvae was up to 95% with the similar concentrations and an exposure time of 48 h, for the other investigated oils. Various morphohistopathological alterations were found in the cuticle; outer cuticle folds swelling or shrinkage and subcuticular muscle degeneration, as well as midgut; fat globules in the epithelial lining with marked degeneration and/or necrosis, of the R. ferrugineus larvae when compared with those of controls replicates. Mortality percentage of infective juveniles (IJs) of Steinernema carpocapsae (S2) was significantly lower than Heterorhabditis marelatus (D1), Steinernema riobravae (Sr) and Steinernema carpocapsae (All) when using camphor oil compared to the other oils (50%). From the obtained observations on oils lethal effects, the target of developing integral biocontrol product formulated from combinations of essential oils and nematode with insecticidal properties against R. ferrugineus (not nematode survival) is possible; a sustainable and ecofriendly product for pest management.

Identification of two Bacillus thuringiensis Cry3Aa toxin-binding aminopeptidase N from Rhynchophorus ferrugineus (Coleoptera: Curculionidae).

Rhynchophorus ferrugineus is a quarantine pest that mainly damages plants in tropical regions, which are essential economic resources. Cry3Aa has been used to control coleopteran pests and is known to be toxic to R. ferrugineus. The binding of the Cry toxin to specific receptors on the target insect plays a crucial role in the toxicological mechanism of Cry toxins. However, in the case of R. ferrugineus, the nature and identity of the receptor proteins involved remain unknown. In the present study, pull-down assays and mass spectrometry were used to identify two proteins of aminopeptidase N proteins (RfAPN2a and RfAPN2b) in the larval midguts of R. ferrugineus. Cry3Aa was able to bind to RfAPN2a (Kd = 108.5 nM) and RfAPN2b (Kd = 68.2 nM), as well as midgut brush border membrane vesicles (Kd = 482.5 nM). In silico analysis of both RfAPN proteins included the signal peptide and anchored sites for glycosyl phosphatidyl inositol. In addition, RfAPN2a and RfAPN2b were expressed in the human embryonic kidney 293T cell line, and cytotoxicity assays showed that the transgenic cells were not susceptible to activated Cry3Aa. Our results show that RfAPN2a and RfAPN2b are Cry3Aa-binding proteins involved in the Cry3Aa toxicity of R. ferrugineus. This study deepens our understanding of the action mechanism of Cry3Aa in R. ferrugineus larvae.

Immune Responses of Rhynchophorus ferrugineus to a New Strain of Beauveria bassiana

Evaluating a novel fungal strain’s pathogenicity to important pests and their involved immune responses may give crucial data on a broad scale for future use in pest management strategies. Date palms are mostly destroyed by invading populations of red palm weevils; thus, developing natural biopesticides for them requires a comprehensive screening program of plant secondary metabolites. In this research, we examined the pathogenicity of a new strain of Beauveria bassiana on an important agricultural pest, Rhynchophorus ferrugineus, by measuring the relative activity of defensive enzymes and detoxifying enzymes in certain larval instars. Our findings reveal that the B. bassiana strain may infect the instars of R. ferrugineus, and its pathogenicity to the larvae steadily increases as the spore concentration increases. Seven days after inoculation, the LC50 (the median lethal concentration) of B. bassiana was 490.42 × 105 and 2974.47 × 108 spores/mL for the second and fourth instar R. ferrugineus, respectively, and the LC50 of B. bassiana for each R. ferrugineus instar decreased with infection time, indicating a significant dose effect. Infected R. ferrugineus larvae of the second instars showed considerable changes in the activity of both protecting and detoxifying enzymes (peroxidase, catalase, superoxide dismutase, Cytochrome P450, glutathione S transferase (GST), and esterase) as infection time progressed. In addition, R. ferrugineus larvae that were infected with B. bassiana had enzyme activity that persisted from 24 to 48 h, which was much longer than in the control group. Lethality of B. bassiana resulted in elevated expressions of GST, Esterase, and Cytochrome P450 responsive genes. In conclusion, the results of this research indicate that B. bassiana may be utilized as a bio-insecticide to suppress young larvae of R. ferrugineus in an integrated pest management program.

Efficiency of Bacillus thuringiensis and Bacillus cereus against Rhynchophorus ferrugineus.

Simple SummaryRynchophorus ferrugineus Olivier, the red palm weevil (RPW), is a damaging insect that often severely infests palm trees. Since insecticides have a detrimental environmental impact and may lead to pesticide resistance, new biological control methods are needed. Bacteria from many different species affect the RPW larval growth, health, and immunity. The work evaluates the crosstalk between the RPW and rhizosphere bacteria. Four bacterial isolates, three belonging to Bacillus cereus and one belonging to B. thuringiensis, had a significantly higher impact on the mortality of the larvae and adults of the RPW than other bacteria that were tested did. The results emphasize the significant potential of developing new microbial resource-based management techniques for this pest.The Red Palm Weevil (Rhynchophorus ferrugineus (Oliv.) (Coleoptera, Dryophthoridae) is a well-known palm tree pest that has caused enormous economic damage all over the globe. Insecticides are still the primary method of controlling this pest at this period. However, field populations of RPW have been shown to be resistant to pesticides. Using Bacillus spp. might be one of the options for controlling R. ferruginous. In this study, 23 species of Bacillus spp. were isolated from the rhizosphere of date palm trees in Al Ahsa Oasis, Saudi Arabia. The isolates were identified using 16S rRNA gene sequencing. R. ferrugineus larvae and adults were tested on sugarcane pieces that were treated with the B. thuringiensis strain PDC-AHSAA1 and B. cereus strains (PDC-AHSAA2, PDC-AHSA3 and PDC-AHSA4). The LC50 values for larvae and adults were quite low when they were compared with those of the other isolated strains. The B. thuringiensis strain PDC-AHSAA1 was more effective against both the larvae and adults. The determined LC50 values for B. thuringiensis ranged from 4.19 × 107–3.78 × 109. After 21 days, the data on larval mortality and body weight were evaluated. The surviving larvae that were treated with the bacterial isolates did not acquire a substantial weight. For the RPW larvae and adults, the mortality and corrected mortality death rates were increased by increasing the concentration of B. thuringiensis. In conclusion, Bacillus-treated diets negatively influenced the growth and development of the RPW. This research reported on the interaction between the RPW and the rhizosphere Bacillus spp. and highlighted the tremendous potential for the development of microbial resource-based control strategies for this pest.

Defense status in larval stage of red palm weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

Red palm weevil (RPW), Rhynchophorus ferrugineus, is a severe pest of wide genera of palm species with a worldwide distribution, destroys the vascular system of the trunk and leads to death of the infested palm. Grub, the larval stage, is the main destructive stage. The distribution of antioxidant (AO) enzymes in different major organs of R. ferrugineus as an efficient antioxidant mechanism for detoxifying the harmful reactive oxygen species (ROS) has been investigated. The AO enzymes included superoxide dismutase (SOD), polyphenol oxidase (PPO), peroxidase (PO), glutathione reductase (GR), glutathione peroxidase (GPO) and glutathione S-transferase (GST). Fat body exhibited the highest enzymatic activities of SOD and GST (291.0 ± 22 and 6.9 ± 0.3 U/organ), respectively. Hemolymph and whole gut displayed the highest activities of PPO and PO (94 ± 4.6 and 399.0 ± 23 U/organ), respectively. However, low activities of GR and GPO (0.7 ± 0.04 and 0.31 ± 0.02 U/organ), respectively were detected. The variation of AO enzyme activities in the examined organs may be mirrored the physiological adaptation of R. ferrugineus larvae for scavenging ROS generated. The AO enzymes enhanced during larval development and 12th instar larvae have the highest enzyme activities. The enhancement is a defense mechanism to regulate and protect the larvae from the cytotoxicity effects of ROS. SOD, PPO and PO have the prime role for scavenging ROS. Fat body, hemolymph and whole gut play the major physiological roles of defense of R. ferrugineus. The larval instars from 5th-7th that have the lowest AO enzyme activities are the best stages for controlling.

Does Bacillus thuringiensis Affect the Stress and Immune Responses of Rhynchophorus ferrugineus Larvae, Females, and Males in the Same Way?

Simple SummaryRhynchophorus ferrugineus is a destructive quarantine pest of palm trees, now widely distributed. Although broad-spectrum insecticides are often used to protect palm against R. ferrugineus, there is increasing concern about their effects on the environment and human health, especially where palm trees are located in urban areas. As an environmentally friendly entomopathogen, Bacillus thuringiensis (Bt) has been widely used to prevent other pest infestations. Although Bt products are the most sold bio-insecticides, there are still many interesting features to be investigated in the relationship of Bt and its hosts. We investigated the effect of Bt on larvae, females, and males. This research yielded experimental evidence of significant mortality and significant effects on immune system and stress answer. Within a few hours, stress due to Bt infection was detected in the hemocytes and in the brain providing better insights into the insect-pathogen interaction and highlighting the potential use of Bt in R. ferrugineus management.Bacillus thuringiensis (Bt) is considered a potentially useful entomopathogen against red palm weevil (RPW) Rhynchophorus ferrugineus. We compared the effects of Bt on mature larvae, females, and males. The pathogenicity of Bt was evaluated, estimating: Median Lethal Dose (LD50), Median Lethal Time (LT50), Total Hemocyte Count (THC), and Differential Hemocyte Counts (DHC), and the expression of the stress protein Heat Shock Protein 70 (Hsp 70) in hemocytes and the brain. Mortality exhibited a positive trend with the dosage and duration of exposure to Bt. Larvae were more susceptible than adults, and the LD50 of females was almost double the value of that of the larvae. LT50 value was higher for females than for males and larvae. Treatment with sub-lethal doses of Bt induced a decrease in THC in larvae, females, and males. In treated larvae, plasmatocytes decreased, while oenocytes and spherulocytes increased. In treated females, all types of hemocytes decreased, while in males the number of plasmatocytes decreased and granulocytes increased. We also registered the stress response directly on hemocytes showing that, already at 3 h after eating Bt, the expression of the stress protein Hsp 70 was modulated. This effect was also observed in brain tissue at 6 h after treatment. The results confirm that Bt treatment induces a pathogenic state in larvae and adults of both sexes, with effects after only a few hours from ingestion; however, the effects are different in magnitude and in type of target.

Nanochitosan to control the red palm weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

The red palm weevil Rhynchophorus ferrugineus infest more than nearly 40 palm species around the world. They damage the internal tissues of palms by the larval stage which is the serious stage. Nanoparticles represent a new generation of environmental remediation technologies that can provide cost-effective solution to some of the most challenging environmental clean-up problems. They also help to produce new pesticides. Nanochitosan is used to control the red palm weevil larvae and adults. The results show that it affects the mortality percentage of R. ferrugineus larvae. The mortality percentage increased by increasing the time and concentrations of nanochitosan, since 100% mortality was obtained at the concentration 80000 ppm after (15–20) days time interval. The percentage of mortality of R. ferrugineus female and male showed that the most effective concentration of nanochitosan was 20000 ppm, where 100% mortality was obtained in time interval 10–20 days. In addition, nanochitosan affects the biology of red palm weevil by decreasing pupation percentage, emergence percentage, pupal duration number of eggs/female, hatchability percentage and longevity of males and females as compared to the control. LC50 and Lc25 of nanochitosan disturbs the total protein and total carbohydrates. The activity of enzymes (protease, invertase and amylase) of larvae and adult (males and females) was disordered. We conclude that nanochitosan can be used as a control tool to the red palm weevil.

A Review of Entomopathogenic Nematodes as a Biological Control Agent for Red Palm Weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae).

Simple SummaryThe red palm weevil, Rhynchophorus ferrugineus, is a significant pest to palm plantations globally and directly impacts economic activities. These weevils’ cryptic attack on palms is inconspicuous until the damage is irreparable. Chemical pesticides were used extensively in plantations to mitigate RPW infestation, and the results were impressive. However, their negative impact on the environment, nontarget organisms, and insecticide resistance is a primary concern. Therefore, alternative preventive and curative solutions based on the natural enemy concept are safer for the environment and more sustainable. This review highlights the use of entomopathogenic nematodes and their symbiotic bacteria as biological control agents against the red palm weevil and storage formulation.Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is a severe pest of palm trees worldwide. The development and feeding activities of R. ferrugineus larvae inside the trunk damage palm trees. However, the absence of noticeable infestation signs at an early stage contributes to the spread of the attack. Integrated pest management (IPM) has been introduced to control R. ferrugineus infestation by implementing various approaches and techniques. The application of chemical pesticides has shown impressive results. However, biological control should be applied as an alternative solution due to adverse environmental impacts and pest resistance issues. One example is the use of entomopathogenic nematodes (EPNs) as biological control agents, which can forage and attack targeted pests without compromising the environment and other nontarget organisms. EPNs and their symbiotic bacteria have a mutualistic interaction that can kill the host within a short period of time. Therefore, this review emphasizes the effectiveness of entomopathogenic nematodes and their symbiotic bacteria against R. ferrugineus.

Macrozoobenthos communities in the Kuybyshev reservoir Priplotinnyi Reach: long-term dynamics

The authors analyzed the dynamics of benthic communities in the Kuybyshev Reservoir Priplotinnyi Reach, over a long-term observation period 1958-2020. The authors note a certain frequency of changes in the ratio of macrozoobenthos coenoses and biomass of benthic communities at the stations of the former Volga channel and the Priplotinnyi Reach floodplain. During the research period in 2005, 2020 there was a decrease in the biomass of benthos. The stage of destabilization of the Kuybyshev reservoir ecosystem, noted since the mid-1980s, against the background of anthropogenic eutrophication processes, is accompanied by a sharp decrease in the biomass of benthos and structural changes in benthic communities. In 2020, the benthos biomass, compared to 1985, decreased in deep-water areas and in the Priplotinnyi Reach coastal zone by about 8 times and amounted to 2.0 g / m2, which is due to a decrease in the proportion of pelophilic coenosis of oligochaetes Tubifex tubife and Limnodrilus hoffmeisteri. The biomass of forage benthos in the coastal zone decreased from 5.48 g / m2 to 2.94-1.75 g / m2 due to anthropogenic impact. The authors revealed similar processes of development of the chironomid coenosis on the former channel and the flooded floodplain. During the autumn survey, 9 species were recorded in shallow waters, the proportion of which is 19.5%. There was found a low biomass of Procladius ferrugineus larvae -0.05 -0.08 g / m2. The authors discuss the data of hydrobiological monitoring at the stations of the former channel and the flooded floodplain of the Priplotinnyi Reach, including the change in the coenosis of chironomids (Diptera, Chironomidae) as an object of indication of the ecological state of the reservoir.

Eugenol and Thymol Derivatives as Antifeedant Agents against Red Palm Weevil, Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) Larvae

Simple SummaryRhynchophorus ferrugineus or the red palm weevil (RPW) is a major invasive insect pest that causes severe problems for palm cultivations and, in turn, for the palm industries worldwide. The current practice for controlling RPW in Malaysia mainly involves the use of synthetic pesticides. However, synthetic pesticides should not be encouraged because they are highly toxic and persistent in the environment and as such, can cause deterioration to the ecosystem and human health. Essential oil (EO) derivatives from eugenol and thymol were tested as potential natural compounds for controlling RPW. We evaluated the effect of eight EO derivatives from eugenol and thymol against the fourth instar larvae of RPW. Feeding contact bioassay was conducted for 14 days with different concentrations of these derivatives, in three replications for each treatment. All the derivatives showed feeding deterrent effects against RPW larvae, particularly 4-allyl-2-methoxy-1-(4-trifluoromethyl-benzyloxy)-benzene and 2-isopropyl-4-methyl-2-((4-nitrobenzyl) oxy) benzene, which demonstrated the most effective antifeedant properties in the eugenol and thymol derivative group. Overall, our findings revealed that both eugenol and thymol derivatives showed similar antifeedant activity against RPW larvae. However, the ether derivatives showed a stronger antifeedant effect than that of esters. Both eugenol and thymol are effective against RPW and have the potential to be investigated further as botanical insecticides for the management of RPW in the future.Coconut palms in Malaysia are infested by a destructive invasive pest, RPW since 2007, and the pest’s population is difficult to control. At present, RPW control management mainly relies on the use of monocrotophos, which is administered by the trunk injection method. However, this pesticide can negatively impact human health and the ecosystem. Plant EO that can be used as a bio-pesticide is highly recommended as an alternative to monocrotophos because of its target-specific and eco-friendly properties. The antifeedant activity of eight eugenol and thymol derivatives from clove and thyme EOs were tested against the fourth instar larvae of RPW through oral bioassay for 14 days. Relative growth rate (RGR), relative consumption rate (RCR), the efficiency of conversion of ingested food (ECI), and the feeding deterrent index (FDI) were compared and analyzed. All of the derivatives showed antifeedant activity, particularly the eugenol derivative, 4-allyl-2-methoxy-1-(4-trifluoromethyl-benzyloxy)-benzene (FDI = 54.14%) and the thymol derivative, 2-isopropyl-4-methyl-2-((4-nitrobenzyl) oxy) benzene (FDI = 53.88%). Both of them showed promising results on their ability to be the most effective antifeedant agents in each derivative group. There was no significant difference in the effectiveness of the eugenol-based and thymol-based derivatives, but the ether derivative group (FDI = 45.63%) had a significantly stronger effect than the ester derivative group (FDI = 39.71%). This study revealed that the compound in ether form is more effective than the compound in ester form as an antifeedant agent against RPW larvae, regardless of the plant EO that the compound is derived from.

Virulence of Beauveria bassiana Balsamo to red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

BackgroundThe red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae), is a cosmopolitan pest of palms. Current management strategies largely depend on insecticides, and use of insect pathogenic fungi is needed in integrated pest management (IPM) programs.ResultsThe effectiveness of Beauveria bassiana was determined against 3rd instar R. ferrugineus larvae by using the following concentrations, i.e., 3 × 108, 2 × 108, 1 × 108, 1 × 107, and 1 × 106 spores/ml. The lowest LC50 value (1.3×107 spores/ml) was recorded at the Khyber Pakhtunkhwa (KPK) population, followed by those populations from Punjab, Sindh, and Baluchistan, which had LC50 values of 1.5×107, 5.3 ×107, and 1.02 ×108 spores/ml, respectively, on the 7th day post-treatment; the highest mortality rates were 90.0, 85.0, 77.5, and 75.0% for the KPK, Punjab, Sindh, and Baluchistan populations, respectively, at the highest tested concentration of B. bassiana.ConclusionThe findings of this study indicate the potential use of B. bassiana in IPM programs for R. ferrugineus that are more ecologically sound than those programs that are heavily reliant on insecticides.

Histopathological studies of red palm weevil Rhynchophorus ferrugineus, (Olivier) larvae and adults to evaluate certain nano pesticides.

Rhynchophorus ferrugineus (RPW) (Olivier) (Coleoptera: Curculionidae) is one of the most destructive pest of palm according to dozens of literature, a lot of effort have been made since three decades up to date to solve this problem, one of newest solution raised is using nano pesticides. Imidacloprid and Chloropyrophos and their nano form were tested against 10 days-old larvae and newly emerged adults of the red palm weevil. The pesticides had toxicological and pathological effects on Rh. ferrugineus larvae and adults. The toxicity effect of nano chloropyrophos was more than others. The damage included vaculation of cytoplasm, analyzes and destroyed nuclei of the epithelial cells. The larvae were more sensitive in the total damages in comparison with adults. This investigation is the first record to the histopathological effects of nano pesticides.

Behavioral and molecular response of the insect parasitic nematode Steinernema carpocapsae to cues emitted by a host, the red palm weevil, Rhynchophorus ferrugineus

As the larvae of the date palm pest, the red palm weevil, Rhynchophorus ferrugineus, feeds on the host tissue, they emit a distinctive sound which can be recorded outside of the infected tree. We evaluated the response of infective juveniles (IJs) of the entomopathogenic nematodes Steinernema carpocapsae to the R. ferrugineus larvae and it’s sound source, separately. In the presence of the insect larvae, 50.2 % of total IJs moved toward those larvae. Recorded insect larvae sound emitted by the speaker resulted in 7% of total IJs near the sound source. RNA-Seq data indicated that more genes were downregulated in S. carpocapsae IJs exposed to insect and speaker compared to non-stimulated IJs. IJs exposed to insect exhibited more up-regulated genes than IJs exposed to speaker. Enriched pathways and biological processes in IJs were similar for both stimuli. The inhibition of locomotion, regulation of neurotransmitter secretion, response to biotic stimulus, and cellular response to chemical stimuli were enriched with unique GO terms for speaker treatment. The regulation of localization, sodium ion transmembrane transport, regulation of response to stress and response to organic substances were the GO categories enriched unique to insect. The host-parasitic interaction was regulated by the differential expression of Ras/MAP kinase, TGF-beta signaling, insulin signaling, AMPK signaling, PPAR signaling pathways and many developmental pathways. More prominent R. ferrugineus host localization by S. carpocapsae was primarily due to the differential transcriptional regulation of olfactory signal transduction, FOXO-family proteins, calcium signaling, WNT and mTOR signaling pathway. The neural basis for the nematode attraction to insect host is based on the chemosensation and the mechanosensation. Many neuropeptides and neuromodulators are involved in regulating the foraging behavior of S. carpocapsae. The results of this study provide new insights into the molecular mechanisms that allow these nematodes to seek insect hosts. Our finding, especially the molecular ones suggest that chemical cues emitted by the active insect host are stimulants of nematodes attraction. Whereas the sound emitted by the insect has minor effects on the nematode behavior.

Impact of the invasive plant species “Nicotiana glauca” toxins on the larvae of the invasive insect species “Rhynchophorus ferrugineus”: A damaging pest of date palm trees in Saudi Arabia

The wild tree tobacco (Nicotiana glauca) is an alien species that invaded vast areas of the Southwestern region of Saudi Arabia. While, the Red Palm Weevil (RPW) (Rhynchophorus ferrugineus) is considered to be the most damaging invasive insect species of palm trees all over the kingdom of Saudi Arabia, causing major economic losses to farmers and the economy of the country. Using conventional insecticides to control harmful insects such as RPW has undesirable effects on the environment and human health. Alternatively, using biocontrol agents such as poisonous extracts from N. glauca might be a better approach in pest management and can be considered as an eco-friendly, cost-effective, and safe alternative. Therefore, the current study aimed to evaluate the larvicidal effect of N. glauca aqueous extracts against the red palm weevil larvae. The plant specimens were collected from Al-Baha region in the Southwest of Saudi Arabia. Each single test consisted of 20 larvae, and N. glauca preparations were; 1, 1.5, 2, 2.5, and 3 ml, besides the control test. Results obtained for the effect of botanical extracts; leaf, flower, stem and root against R. ferrugineus larvae for an exposure period of 24 hr. at the concentrations of 2.8, 4.2, 6.0, 7.0 and 8.0 ppm. The concentrations for N. glauca extracts reflected an LC50 of 2.7 ppm for leave, 2.6 ppm for flower, 2.8 ppm for stem and 7.00 ppm for root. While, the same concentrations extracts reflected an LC95of 11 ppm for leaf, 9.6 ppm for flower, 8.9 ppm for stem and 13.00 ppm for root. These results showed that N. glauca extracts have a remarkable potentiality as insecticidal substances that can be used as an ecofriendly integrated approach for the management of R. ferrugineus.

Characterization of Bacterial Communities Associated with Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) and its Host Phoenix sylvestris.

This study measured the changes of microorganisms in the midgut and habitat niche of Rhynchophorus ferrugineus Olivier, an invasive quarantine pest, by Illumina sequencing. The bacterial diversity in the R. ferrugineus larvae midgut and their habitat niche was compared to the uninfected P. sylvestris. The Proteobacteria and Firmicutes occupied a dominant position in the R. ferrugineus midgut and infected P. sylvestris, while in the uninfected P. sylvestris the predominant bacterial phylum was the Cyanobacteria. Enterobacter, Dysgonomonas, and Entomoplasma were the dominant bacterial genera in R. ferrugineus midgut and also within the infected trees and uninfected trees with low relative abundance. These bacteria could be exploited as the biopesticide vector to control R. ferrugineus population. Besides, Sphingobacterium, Shinella, and Rhodobacter genera had the same distribution pattern in the infected and uninfected P. sylvestris, and these bacteria were not found in the midgut of R. ferrugineus. Interestingly, Paludibacter and Parabacteroides were only distributed in the wood fiber of the infected P. sylvestris, which could be used as potential microbial markers to detect if the palm plants are damaged by the R. ferrugineus. The results of this study will be beneficial to the development of control strategies for R. ferrugineus.

INSECTICIDAL ACTIVITY OF PUNICA GRANATUM L. EXTRACT FOR THE CONTROL OF RHYNCHOPHORUS FERRUGINEUS (OLIVIER) (COLEOPTERA: CURCULIONIDAE) AND SOME OF ITS HISTOLOGICAL AND IMMUNOLOGICAL ASPECTS

ABSTRACT The spread of the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera:Curculionidae), is a serious challenge at present due to the serious damage it causes to the date palm tree. This study investigated the ethanolic extract of Punica granatum peel and found that it leads to significant mortalities in both the larvae and adult stages of R. ferrugineus after exposure to four concentrations (4.7, 9.3, 18.7, and 37.4 mg/mL). The larvicidal effect reached 48% at day 6 for the 37.4 mg/mL concentration, and adults exhibited full mortality at the same concentration. In addition, the cuticle of treated larvae was investigated histopathologically, and corrugation and a thinning surface were found. Scanning electron microscopy revealed a strong uptake and aggregation of the extract on the glandular pores of the back wings of adults. The impact of P. granatum peel extract on the total protein content of the hemolymph of R. ferrugineus larvae was also studied. Compared to controls, larvae had 12 different bands before treatment, 4, 3 and 2 bands in common after treatment at concentrations 4.7, 9.3, and 37.4 mg/mL, respectively. These results suggest that P. granatum peel extract is a promising alternative to chemical pesticides and can be used as a biopesticide against larvae and adult red palm weevil.

Nano essential oils against the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae)

AbstractThe red palm weevil, Rhynchophorus ferrugineus, is the biggest pest of various palm species. The aim of this study was to evaluate the impact of the essential oils of purslane, mustard and castor (bulk and nano) on R. ferrugineus and to evaluate the oviposition deterrent effect to prevent new infestations. Prepared concentrations of essential oils (bulk and nano) were tested for their impact on R. ferrugineus larvae, pupae and adults. The most effective oil was purslane oil (bulk and nano), followed by mustard and the least effective was castor. The percent mortality of larvae was 75.2, 45.3 and 17.9% (bulk phase) and 92.5, 84.4 and 65.5% (nano phase) in purslane, mustard and castor, respectively, when treated with the high concentration. The percent mortality of adults was 67.2, 40.0 and 15.6% (bulk phase) and 83.5, 72.9 and 60.0% (nano phase) in purslane, mustard and castor, respectively, when treated with the high concentration. The number of eggs laid decreased with increasing concentration of the tested oils. Purslane essential oil showed good impact on R. ferrugineus larvae and adults followed by mustard and castor oils as bulk and as nano.

Pathogenicity of Saudi Arabian fungal isolates against egg and larval stages of Rhynchophorus ferrugineus under laboratory conditions

The pathogenicity of various local entomopathogenic fungal isolates from the kingdom of Saudi Arabia has been tested in the laboratory against the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae). Fungi were coded, isolated, and purified. Beauveria bassiana (Balsamo-Crivelli) Vuillemin, coded as: BbSA-1 PDA-15 and Metarhizium anisopliae (Metsch.) Sorokin, coded as: MaSA-1 PDA-15, isolates demonstrated significant potential against R. ferrugineus larvae. A 1 × 1010 conidia/mL concentration of positive fungal isolates along with natural B. bassiana was used against different stages of R. ferrugineus. Rhynchophorus ferrugineus larvae were supplied with synthetic diets that contain preservatives and non-preservatives. The fungal isolates BbSA-1 PDA-15 and MaSA-1 PDA-15 affected the egg hatchability and caused significant larval mortality of red palm weevil. It was shown that MaSA-1 PDA-15 is one of the most pathogenic fungi against R. ferrugineus larvae followed by BbSA-1 PDA-15 and Natural B. bassiana isolates. Therefore, these local fungal isolates have the potential to be used against R. ferrugineus. Further development in the research could facilitate the farmers to save their valuable palm trees from the notorious pest.