Functional compounds from the integument of adult red palm weevil Rhynchophorus ferrugineus

This study deals with the analysis of the integument of the red palm weevil Rhynchophorus ferrugineus of both sexes using the GC–MS technique. The results of the study revealed many promising compounds. These include aspidofractinine-3-methanol (kopsinyl alcohol) which was found in the acetone extract of the sternum of females, and 3-buten-2-ol (32-B) which was found in the extracts of sternum and tergum of males. This compound the aggregation pheromone was secreted by males. Additionally, compounds with methoxy groups were found. These may be responsible for insects’ resistance. This study, through separation and identification of these compounds, aims to open a new possibility for their future medical and therapeutic usage.     

Entomopathogenic fungi-mediated biological control of the red palm weevil Rhynchophorus ferrugineus

The red palm weevil (RPW), Rhynchophorus ferrugineus, is an important pest of palms, and difficult to control by conventional methods. Therefore, microbial control is an alternative strategy for controlling RPW. Herein, a total of 15 entomopathogenic fungi (EPFs) were subjected to primary pathogenicity screening against last stage of RPW larvae. The preliminary data showed that four Beauveria bassiana isolates (JEF-484, 158, 462 and 507) and one Isaria fumosorosea isolate (JEF-014) resulted in 100 % mortality within 5–10 days post inoculation (d.p.i.), respectively. According to the time required for RPW mortality, JEF-484, 158, 462 and 014 were further subjected to bioassays using 10⁷ conidia/ml suspensions by spraying method. Based on the results, JEF-484 showed the highest mortality and shortest LT₅₀ on the last stage of RPW larvae, followed by JEF-158. The two isolates also showed good conidial production and high thermal stability compared to the other isolates. Therefore, JEF-484 and JEF-158 were selected for bioassays against RPW egg and the last larval stage with different concentrations of 10⁵, 10⁶ and 10⁷ conidia/ml conidial suspensions by spraying method. For the bioassay at the egg stage, JEF-158 showed a significantly higher ovicidal effect than JEF-484. In the larval bioassay, both EPF isolates showed a dosage-dependent effect on the RPW larvae. JEF-484 caused higher mortality in RPW larvae than JEF-158. In summary, the combination of the 2 promising EPF isolates might provide an opportunity for the practical microbial control of RPW at different life stages in palm tree fields.     

Spatial patterns of the red palm weevil and applied entomopathogenic nematode Heterorhabditis bacteriophora

The distribution and abundance of red palm weevil (Rhynchophorus ferrugineus) within palm tree-infected stems at Ismaelia governorate, Egypt, were investigated. Taylor's power law was fit (P ≤ 0.01) to its larvae, pupae and/or adults. The slope value of this power law indicated the clumped distribution of these insect stages. Sample size optimisation needed to achieve a predetermined level of sampling error for the insect stages was calculated. Also, soil samples were taken after uniform application of entomopathogenic nematode Heterorhabditis bacteriophora strain EG₁ to the soil under citrus tree canopies at the rate of 10⁴ infective juveniles/400 cm² plots, and assayed for the nematode using the Galleria bait method. At the first and second sampling dates, the nematode displayed contagious distribution and attained mean insect mortality of 15.3 and 4, respectively. At the third date of sampling, the nematode showed random distribution according to chi-squared test and caused 1.8 mean insect mortality. Evaluation of H. bacteriophora EG₁ as a biocontrol measure for the weevil was discussed based on their investigated dispersion indices.     

Production of a biopesticide on host and Non-Host serine protease inhibitors for red palm weevil in palm trees

Serine proteases are essential metabolic enzymes in the midgut of many pests, including the red palm weevil (RPW), Rhynchophorus ferrugineus Olivier, which has a significant impact economically, environmentally and socially worldwide especially in the middle east. Some methods have been used to manage this pest such as trapping of RPW with pheromones, chemicals, and X-rays. However, these methods are costly, not effective and negatively impact the human. The main objective of this study is to contribute to the discovery of an eco-friendly pesticide to eradicate this infection by using serine protease inhibitors (SPIs) extracted from different parts of plant resources. In this research, both in vitro and in vivo effects of SPIs activity against RPW were examined. The protease inhibitors (PIs) activity was recorded in the crude extract that was isolated from the date’s kernel (DKE), host and Calotropis latex (CLE), non-host. These PIs were partially purified by ammonium sulfate precipitation. The midgut tissue of RPW was extracted and analyzed for protases activity assay. PIs assays were consistent with the increased in the inhibitory activity against the midgut proteases after treatment with a DKE and CLE. The reduction of gut proteases by DKE solution and CLE was 39%, 18%, respectively. Partially purified DKE showed the most prominent inhibition pattern of protease activity of the gut extract. While, latex exhibited acute toxicity, imparting the least LC₅₀ (5.132 mg/mL) against RPW larvae. Taken together, these findings provide evidence for the hypothesis that SPIs activity may play an important role in enhancing the mortality of RPW and relieving the toxicity of insecticide in palm trees.     

Insecticidal potential of cardamom and clove extracts on adult red palm weevil Rhynchophorus ferrugineus

Toxicity of cardamom and clove seed powder and extracted compounds against the red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae), was assessed in laboratory exposure experiments. The treatments comprised different amounts of seed powder of cardamom (0.8, 1, 3, and 5 mg) and clove (1, 3, 5, 7 mg), and extract concentrations (0.2, 0.4, 0.5, 0.6, 0.7, and 0.8) for both plants using ether petroleum or chloroform. Data showed that 5 mg of cardamom powdered seed resulted in 93% mortality after one day and 100% mortality after two days. Whereas after two days, lower amounts (0.8, 1, and 3 mg) resulted in 26%, 40%, 46%, respectively. A similar result was obtained for clove seed powder, where 7 mg caused 53% mortality after one day and 100% mortality after three days, other amounts (1, 3, and 5 mg) resulted in 33%, 73%, and 80%, mortality respectively, after three days. We found that all amounts of extract of both plants resulted in 100% mortality after three days. GC-MS analysis of the cardamom and clove extracts revealed the presence of a large number of terpenes of particular note was eugenol and two novel compounds Hydroxy-alpha-Terpenyl Acetate and Labda -8(17),13(E)- Diene- 15. The current work aims at the possibility of benefiting from natural plants pesticides as being safer as well as on the separation of volatile oils, which was known to be important in the control pests.     

Evaluation of some non-invasive approaches for the detection of red palm weevil infestation

Red palm weevil (RPW) causes severe damage to date palm trees, leading to the death of trees if not detected and treated in time. A major obstacle in RPW control is the difficulty in identifying an early stage infestation In the present study, we measured the efficacy of some non-invasive optical devices including cameras (digital camera and thermal camera), TreeRadarUnit™ (TRU) (Radar 2000, Radar 900), resistograph, magnetic DNA biosensor, and Near-infrared Spectroscopy (NIRS) to detect RPW infestation in date palm trees under field conditions at Riyadh, Saudi Arabia. Date palm trees used in these experiments were selected based on visual observations. After inspection of date palm trees with different devices to detect RPW infestation, each tree was taken down and dissected in detail to validate the accuracy of each device. Results indicated that the visual RPW detection approach presented the highest accuracy (87%) followed by Radar 2000 (77%), Radar 900 (73%), resistograph (73%), thermal camera (61%), and digital camera (52%).Moreover, different stages of RPW placed in plastic cups were fastened onto the healthy date palm trunks to judge RPW presence, the magnetic DNA biosensor correctly detected RPW eggs 75% of the time, followed by detection of larvae (64%) and the control (empty cup) (54%). In another experiment where determinations were made in an open area, the efficiency of the DNA biosensor for detecting adults was 100%, followed by 83%, 63%, 60%, and 39% for pupae, larvae, eggs, and control, respectively. Absorption spectra generated through NIRS for infested, wounded, and control samples of date palm tissue showed a remarkable variation in the gradient of the corresponding peaks between 1850 nm and 1950 nm. Based on the detection efficiency of the tested devices, the resistograph and NIRS have the best potential to detect RPW infestation in date palm trees.     

Studies on the morphology and histology of the ovary of red palm weevil female irradiated with gamma rays

The present study involves red palm weevil adults Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae) irradiated with 5, 10 or 15 Gy of gamma radiation. The biological effects of gamma irradiation on the F₁ adult females, descendant of irradiated parental male pupae, were studied. The percentage egg hatch decreased significantly, as the dose increased, compared with the untreated control.The effect of gamma irradiation on the morphology of the ovaries showed a remarkable effect on size, shape and measurement of the paired ovaries.Additionally, histological studies showed some damages by irradiation of the oocytes maturation, which increased with increasing dose. These symptoms were elongation of the terminal filament, rupture, separation, or shrinkage of external sheath and follicular epithelium, degenerated or absent of nurse cells, and ruptured oocytes at 15 Gy.Vacuolation appeared in different degrees inside the oocytes and the nurse cells were absent in some areas. The damage in the oocytes was more severe as the dose was increased. The follicular epithelium was thin, oocytes clumped together throughout the ovariole causing some oocytes become abnormal or rectangular in shape.     

The effect of red wood ant abundance on feeding damage by the pine weevil Hylobius abietis

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Production of food yeasts from the solid fraction of palm oil

Summary Growth parameters of different species of yeast on ammonium soaps have been determined. All tested strains are able to use the solid part of palm oil, transformed into ammonium soaps. Growth parameters are acceptable for industrial use and it is possible to produce single cell protein from this substrate.     

Attraction of entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora to the red palm weevil (Rhynchophorus ferrugineus)

The red palm weevil (RPW), Rhynchophorus ferrugineus, is a serious pest of date palms. Its larvae bore deep into the trunk disrupt the vascular tissues and kill the infested trees. Behavioral features of entomopathogenic nematodes (EPNs), reflected by attraction and distribution patterns, are fundamental aspect in determining their parasitic ability and potential management of RPW. We studied the attraction behavior of the EPNs Steinernema carpocapsae and Heterorhabditis bacteriophora to the RPW under simulated natural conditions in tubes to evaluate their infective potential. In all experiments, a certain proportion of infective juveniles (IJs) (16–20%) stayed near the inoculated site and a major proportion (38–48%) was attracted to the host end. Both H. bacteriophora and S. carpocapsae were efficient crawlers, climbing up and descending when locating their insect host. They were efficiently attracted to the various larval sizes and stages of the RPW life cycle. Host localization by ascending movement was more prominent in S. carpocapsae than in H. bacteriophora. In general, H. bacteriophora is classified as a cruiser forager and S. carpocapsae as an ambusher. However, in this study, we discovered a higher percentage of cruiser foragers among S. carpocapsae IJs. They dispersed much faster and their cruising behavior was prominent characteristic in controlling the cryptic RPW concealed in organic habitats.     

A note on the leavening activity of yeasts isolated from Nigerian palm wine

The role of the yeast flora of Nigerian palm wine in the leavening activity of the beverage was investigated by subjecting organisms from the wine to dough-raising tests. Those with appreciable leavening activity were identified as Saccharomyces cerevisiae and Candida spp. They produced maximum dough volumes in 3–4 h at 37°C. The study has provided experimental evidence that yeasts contribute to the leavening activity of palm wine and has identified strains which have potential utility in commercial bread baking.     

土壤拮抗放线菌的分离筛选及其抑菌物质特性的研究

目的从土壤中筛选拮抗能力强且抑菌特性稳定的放线菌菌株。方法采用双层琼脂法筛选出4株拮抗放线菌菌株,然后采用杯碟法测这4株菌株发酵液提取物的抗菌谱、最小抑菌浓度、热稳定性和酸碱稳定性。结果 4株菌株发酵液提取物都能抑制金黄色葡萄球菌、大肠埃希菌、铜绿假单胞菌和白色念珠菌的生长。以金黄色葡萄球菌为指示菌测发酵液提取物的最小抑制浓度,6#和9#拮抗作用较强,发酵液提取物稀释0.125mg/ml仍有抑菌作用。6#菌株在100℃处理30min后仍有40%的抑菌活性。6#菌株发酵液提取物在碱性环境条件下比在酸性环境条件下稳定。结论 4株菌株中6#菌株发酵液提取物具有拮抗能力强、最小抑菌浓度低和在碱性条件下活性较稳定的特点。     

Characterization of kinetic parameters and the formation of volatile compounds during the tequila fermentation by wild yeasts isolated from agave juice

The production of aroma compounds during tequila fermentation using four native yeast strains isolated from agave juice was quantified at controlled (35 degrees C) and uncontrolled temperatures (room temperature) by gas chromatography (FID). Three of the four strains were identified as Saccharomyces cerevisiae (MTLI 1, MALI 1 and MGLI 1) and one as Kloeckera apiculata (MALI 2). Among the aroma compounds produced, acetaldehyde has the highest accumulation at the controlled temperature and before 50% of sugar was consumed. The S. cerevisiae strains produced ethyl acetate in almost the same quantity at a concentration of 5 mg/L and the K. apiculata produced six-times more (30 mg/L) than the S. cerevisiae strains, independent of the fermentation temperature. The rate and amount of 1-propanol, amyl alcohols and isobutanol production were affected by the type of yeast used. The K. apiculate strain produced 50% less of the higher alcohols than the Saccharomyces strains. The results obtained showed that indigenous isolated yeasts play an important role in the tequila flavor and suggest that mixtures of these yeasts may be used to produce tequila with a unique and desirable aroma.     

Isolation and fluorescence studies on a lipophorin from the weevil diaprepes abbreviatus

Lipophorin was isolated from larvae of a root weevil, Diaprepes abbreviatus (Coleoptera: Curculionidae), using density gradient ultracentrifugation. D. abbreviatus lipophorin contained two apoproteins, apolipophorin-I (M_r = 226,000) and apolipophorin-II (M_r = 72,100) and had a density of 1.08. Relative to other larval lipophorins, D. abbreviatus lipophorin contained little cysteine (determined as cysteic acid) and methionine. Fluorescence spectroscopy of intrinsic tyrosine and tryptophan residues excited at 290 nm revealed a single broad emission peak at 330 nm. Upon denaturing and delipidating lipophorin in guanidine HCl, this peak resolved into two peaks with maxima at 305 and 350 nm. Excitation spectra suggested that the two peaks were due to tyrosine and tryptophan, respectively. Fluorescence quenching agents, iodide and acrylamide, were used to determine accessibility of tyrosine and tryptophan residues to the aqueous environment. Iodide, a polar quenching agent, did not quench fluorescent emission from native lipophorin; quenching by iodide increased to moderate levels when lipophorin was denatured in guanidine HCl. Acrylamide quenched the fluorescence of native lipophorin moderately and very efficiently quenched fluorescence of denatured lipophorin. No difference was observed between fluorescence quenching of denatured vs. denatured and delipidated lipophorin by either iodide or acrylamide.     

Potential of certain natural extracts for the control of the red palm weevil,Rhynchophorus ferrugineus (Oliver)

Abstract

Laboratory bioassays were conducted to evaluate the potential of 13 plant extracts for the control of the red palm weevil, Rhynchophorus ferrugineus. Results indicated that the ethanol extracts of sea ambrosia (Ambrosia maritima), French cotton (Calotropis procera) and curcuma (Curcuma longa) have superior toxicity as compared to the extracts of other tested plants, estimated LC 50 were 0.723, 0.978 and 1.092%, respectively. In field experiments, the percentage of recovered date palm trees reached 90.91% within 15 days when A. maritima extract was applied. The injection of C. procera and C. longa extracts into the tunnels of infested trees resulted in 86.36% and 85.00% of tree recovery, respectively.     

Studies on host preference and its biological effects on the red palm weevil,Rhynchophorus ferrugineus Olivier in Egypt The fruit trees

A comparative bioassay (choice or non-choice) was developed to evaluate the efficacy of different species of fruit trees as alternative host plants on the morphological and biological aspects of the red palm weevil, Rhynchophorus ferrugineus and also the latent effect of feeding the larvae on pupal and adult stages. Highly significant differences exist between averages of larval body weight of R. ferrugineus larvae fed on fruit trees. The lowest average of larval weight occurred in the larvae fed on the pieces of sour orange, mandarin followed by olive and lime trees. A small increase in body weight appeared in larvae fed on mango, fig and guava in comparison with those fed on date palm trees (control). The larval mortality reached the highest percentages (100%) by obligatory feeding of R. ferrugineus insects on olive, lime, sour orange and mandarin followed by mango (97%) and guava (96%) compared with control (0%), respectively. The latent effect of obligatory feeding on the larvae of R. ferrugineus was highly decreased during pupation (4%, 4% and 8%) when the insect fed on mango, guava and fig, compared with 100% pupation in the case of larvae fed on ornamental palm or date palm, respectively. Most pupae resulting from the treated larvae by R. ferrugineus failed in adult emergence especially those insects fed on olive, lime, sour orange and mandarin trees compared to untreated insects (95.6–96.2%), respectively. Data also proved that if an insect is forced to feed on a non-preferred host plant, this results in death of the insect often during the larval stage, a decrease of pupation or failure of adult emergence. These results led to the conclusion that mango, fig, and guava trees are believed to be vulnerable hosts for red weevil attack. The lowest percentage of food consumption appeared in those larvae fed on mandarin, sour orange, lime and olive trees compared with those fed on palm. The present results emphasise the need to test the efficiency of the compounds extracted from these host plants if it is considered as an insecticide or an alternative host protectant for management of the red palm weevil R. ferrugineus.     

Discrimination of sunflower volatiles by the red sunflower seed weevil

Five principle monoterpenoid and other constituent volatile chemicals of sunflower heads were combined to resemble two lines of sunflower (Helianthus annuus L.): one U.S.D.A. standard line and one French line which was poorly visited by insects (Etievant et al., 1984). Field trials of attraction to red sunflower seed weevils (Smicronyx fulvus Le Conte, Coleoptera: Curculionidae) showed that one was clearly preferred over the other. The more attractive mixture contained -pinene, -pinene, limonene, camphene and bornyl acetate in a ratio resembling that of Flath et al. (1985) rather than that described by Etievant et al. (1984). One or two volatiles were deleted from the optimal blend but only mixtures of five volatiles showed the highest attraction. Substitution of sabinene, another volatile prominent in sunflower, for one of the five in the optimal blend also decreased attraction of seed weevils. When the monoterpenoid components and green leaf volatiles in the traps resembled the ratios of most of the prominent volatiles of sunflower, attraction was significantly greater than controls.