Rhynchophorus Research Articles

Performance of Ferrolure+ pheromone in the red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) management in date palm growing areas of Sindh, Pakistan

Red palm weevil (RPW), Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) has caused huge losses to date palm in Sindh province, main producer of dates in Pakistan. Due to lack of knowledge and availability regarding aggregation pheromones, mainly pesticides are used for its management. Therefore, seasonal monitoring of RPW was conducted at five talukas of Khairpur (Khairpur, KIngri, Kot Diji) and Sukkur (Rohri, Saleh Pat) districts of Sindh using Ferrolure+® (4-methyl-5-nonanol and 4-methyl-5-nonanone), ChemTica International, Costa Rica. Data was collected during pre-sucker transplanting season (after hibernation), main-sucker transplanting season (very active period due to the sucker transplantation) and post-sucker transplanting season (period after sucker’s plantation). Results indicated that significantly higher populations of RPW were recorded during main sucker planting seasons, followed by pre- and post-sucker planting seasons. Comparatively more RPW were captured at Sukkur than Khairpur during pre-sucker transplanting season only, whereas no significant difference in RPW captures was recorded during main- and post transplanting seasons. The sex ratio of captured females was almost double than males at all study locations during entire study. Relative humidity along with minimum and maximum temperature showed a significant effect on performance of Ferrolure+ to attract RPW. Therefore, use of Ferrolure+ pheromone traps should be included as the key integrated component in date palm orchards of Pakistan in general and Sindh in particular to keep the RPW below threshold.

Recent Methods and Technologies for an Early Detection of Red Palm Weevil Infestation: A Review

The red palm weevil (RPW) (Rhynchophorus ferrugineus) is one of the world’s most destructive pest of oil palm plantation as it can damage the entire palm and incur a total loss to the planters. Early detection of the RPW is difficult, and when the symptoms of infestation are discovered, usually the plant is not salvageable. The adult RPW lays the eggs inside the tree trunk and starts feeding on the tissue of the plant and remains inside until the tree dies. Intensive efforts have been explored to enhance the early detection process of RPW in the field. There are numerous detection methods for discovering the infected trees, such as manual visual inspection, acoustic detection, chemical odour/signal detection, canine detection, thermal sensing, remote sensing, Geographic Information System mapping (GIS), Internet of Things (IoT), cloud platform and data mining-based technology. In this article, the current methods and technologies used for the early detection of RPW are explored and discussed.

Cryoprotective Response as Part of the Adaptive Strategy of the Red Palm Weevil, Rhynchophorus ferrugineus, against Low Temperatures.

Simple SummaryLow environmental temperature acts as a barrier that imposes limits on the geographic distribution of insects. However, due to Earth’s global warming, temperature might no longer be an impediment for insects to colonize some new areas. The spread of pest insects will depend on their adaptive response to cold periods and to thermal anomalies associated with climate change. In this study we analyzed whether the red palm weevil (RPW), one of the worst palm pests worldwide and native to warm areas, has physiological mechanisms that could configure an adaptive response to cold. We find that RPW is capable of rapidly producing substances that reduce chill injuries, primarily glucose as well as glycerol and several amino acids (mainly alanine). Therefore, this work shows for the first time that RPW is able to develop adaptive biochemical responses to deal with low temperatures, similar to those used by overwintering insects. Our results could be useful to improve models predicting the possible spread of RPW to new geographical areas, and also to try to prevent its adaptive response by disrupting the metabolic pathways regulating the involved substances.The red palm weevil (RPW), Rhynchophorus ferrugineus, is one of the worst palm pests worldwide. In this work, we studied the physiological basis underlying its adaptive strategy against low temperatures. Specifically, we analyzed the main low-molecular-weight biochemical substances acting as possible endogenous cryoprotectants, as well as their efficiency in reducing cold injury by preserving K+/Na+ homeostasis. Wild pre-pupae were cold-treated (5.0 ± 0.5 °C) or non-treated (23 ± 1 °C) for 7 days. We then determined the levels of: (a) glucose, trehalose and glycerol, spectrophotometrically, (b) amino acids, by liquid chromatography and (c) potassium and sodium, by inductively coupled plasma mass-spectrometry. Cold-treated larvae increased their potassium level, suggesting some degree of chill injury. However, part of the cold-exposed animals was able to develop an efficient overall cryoprotective response which primarily includes glucose, as well as glycerol and several amino acids (mainly alanine). Our study shows for the first time that RPW is capable of deploying effective physiological mechanisms for a rapid response to cold, which could be relevant to improving predictive models of geographic distribution, especially in a context of climate change. The knowledge of the specific molecules involved would allow future studies to try to prevent its adaptive strategy, either by natural or chemical methods.

Persistency of Indigenous and Exotic Entomopathogenic Fungi Isolates under Ultraviolet B (UV-B) Irradiation to Enhance Field Application Efficacy and Obtain Sustainable Control of the Red Palm Weevil.

Simple SummaryEntomopathogenic fungi have the potential to control insect pests However, field application has issues with germination and pathogenicity due to ultraviolet irradiation. The purpose of this study was to investigate the persistence of different local and exotic fungal isolates of Beauveria bassiana and Metarhizium anisopliae in the laboratory under various ultraviolet exposure times, to obtain a fungal isolate enabling long-term management of red palm weevil Rhynchophorus ferrugineus Olivier (Coleoptera: Dryophthoridae), a major pest of palm trees around the globe. After 300 min of ultraviolet radiation, the colony-forming unit of a certain fungal isolate has survived. The persistence of certain fungal isolates to ultraviolet irradiation has shown to be promising. Finding a persistent fungal isolate would be helpful in increasing fungal germination and increase its sustainability against harsh environmental conditions in the field. The overall aim of this research was to obtain sustainable control of the red palm weevil, which has become a major invasive pest in many areas outside its native range.The red palm weevil Rhynchophorus ferrugineus Olivier (Coleoptera: Dryophthoridae) has become a key invasive pest and major threat to the palm tree worldwide. Several entomopathogenic fungi are used in insect biological control programs. In the present study, persistency of different local and exotic fungal isolates of Beauveria bassiana and Metarhizium anisopliae was evaluated under UV-B irradiation with different exposure intervals. Several factors, including ultraviolet (UV) light, significantly decrease germination rate of fungi, as UV penetrates and damages their DNA. Several studies have investigated that UV-resistant conidia germinate better under harsh environmental conditions. Seven local and exotic fungi isolates (“BbSA-1”, “BbSA-2”, “BbSA-3”, “MaSA-1”, “BbIDN-1”, “MaIDN-1”, and “MaIDN-2”) were tested in the current study under UV-B irradiation having different UV exposure times (i.e., 15, 30, 60, 120, 180, 240, and 300 min). The colony-forming unit (CFU) in each isolate was used to calculate the survival rate. Results indicated that survival rate of all the isolates decreased under UV-B irradiation for all exposure times compared to no exposure to UV-B irradiation. The CFU number decreased as the exposure time increased. Fungi isolates “MaSA-1”, “BbSA-1”, “BbSA-2”, “MaIDN-1”, and “MaIDN-2” could persist after 300 min exposure to UV-B, while the remaining isolates, such as “BbIDN-1”, and “BbSA-3”, could not persist after 300 min exposure to UV-B. The ultimate objective of the present research was to explore an ultraviolet-tolerant fungal isolate that might be useful in the field application for the sustainable management of the red palm weevil, which has become a key invasive pest in many regions rather than its native range. Most of the fungus isolates studied in the present work were collected from Saudi Arabia’s Al-Qatif region, where the red palm weevil has infested more than ten thousand trees, worth millions of riyals.

Management of Deleterious Effect of Fusarium oxysporum Associated with Red Palm Weevil Infestation of Date Palm Trees

Red palm weevil (RPW) is a dangerous pest that infects the date palm tree and makes tunnels in the tree’s trunk. RPW infection is followed by secondary invaders of microorganisms that cause degradation of the trunk tissues leading to toppling the crown and death of the tree in a short time. This study showed that Fusarium oxysporum Schlecht. was the common fungal species isolated from the root and trunk tissues of the date trees infested with RPW, which recorded 100% of frequency. Pathogenicity of 4 isolates of F. oxysporum was confirmed on date palm seeds and seedlings. The results confirmed that all isolates involved in rot of the germinated seeds (40–100% incidence), root rot, and death of palm seedlings (20–100%) under artificial infection as well as degradation of date palm petioles. Application of 20 L/palm of systemic fungicide (Topsin) at 1% as foliar and soil drench of date palm for successive three times successfully reduced development of the deterioration and suppressed the growth of F. oxysporum. Interestingly this fungicide did not suppress the growth of Trichoderma viride Pers. So, our results recommend this fungicide to suppress the pathological and degradable activities of F. oxysporum during the integrated pest management of RPW on date palm trees.

Bioatividade de fungos isolados de áreas de cultivo de coco contra Rhynchophorus palmarum

Abstract The objective of this work was to evaluate the chitinolytic activity and bioactivity of fungi isolated from the palm weevil (Rhynchophorus palmarum) and from soil samples from coconut (Cocos nucifera) crops against the insect itself. Initially, to determine the chitinolytic properties of the isolated fungi, their ability to hydrolyze chitin in a liquid culture medium was evaluated. Then, preliminary pathogenicity assays were carried out, using the bean weevil (Acanthoscelides obtectus) as a reference, to select the fungal isolates to be used in the experiments with the palm weevil. Fi n a l ly, the bioactivity of two selected entomopathogenic fungi on palm weevil larvae and adults was assessed. There was no direct correlation between chitinolytic activity and pathogenicity capacity on the bean weevil nor between the isolates and bioactivity on the palm weevil. Beauveria bassiana CSU9 shows the highest activity on palm weevil larvae and adults, with a median lethal time of 0.8 and 14.4 days, respectively.

Basic nutrient compositions of the larva of Raphia Palm Weevil

Basic nutrient compositions of the larva of Raphia Palm Weevil

Field Exploration of the Efficacy of Some Friendly Products in Combination with Some Pesticides against the Red Palm Weevil <i>Rhynchophorus ferrugineus</i> (Olivier) (Coleoptera: Curculionidae) and Its Effect on Total Carbohydrates and Micronutrients in the Resulting Date Fruits

Experiments were carried out against the red palm weevil, Rhynchophorus ferrugineus (Oliv.) (RPW in a private palm orchard containing varieties of Samani (domestic) and Ikhlas (imported) infested with the red palm weevil Rhynchophorus ferrugineus (Oliv.) (RPW) in El-Marg area, Cairo Governorate, Egypt, using Petroleum oil, Jojoba oil, and Inorganic salts, singly and mixed with each of insecticides (Acetamiprid, Profenofos, Dimethoate) by injection and spraying of infested palm trunks, as well as pouring these substances into pits around the roots of the affected palm trees. The data showed that Acetamiprid was the most effective against RPW. The effective mixtures against R. ferrugineus were Jujuba oil with Acetamiprid, also used car oil with inorganic salts, which resulted in 100% recovery of treated palm. Continuing treatment of infested palms for 6 consecutive months by injecting used car oil mixed with inorganic saline solution resulted in 100% recovery for both date palm cultivars. Spraying these substances on the affected trunks had no effect on RPW. Pouring the tested solutions around the roots of the affected palm had the least effect against RPW. Injection of the tested pesticides into the infested trunks increased the concentrations of carbohydrates and total micronutrients (Fe+, Mn+, Zn+, and Cu+) in the produced fruits more than those obtained by palms treated with mineral oils and inorganic salt, compared to the control group. There is a significant difference between the treatments.

Disruption impact of citronella and menthol insecticides on adults behavior and hemocytes morphology in the red palm weevil Rhynchophorus ferrugineus "Oliver" (Coleoptera: Curculionidae).

This study was conducted to evaluate some terpenes effect on the behavior and immune function of hemocytes in adults of the red palm weevil Rhynchophorus ferrugineus. Six individual different terpenes these are: (±)-menthol, B-citronellol, ( + )-3-carene, (R)- ( + )- limonene, citronella oil and orange terpenes. The results revealed significant differences between the terpenes used on the olfactory response on this insect, in that half of the compounds were very attractive while the other half were repellant to them. This behavior study results with olfactometer citronella oil exhibited an 80% attraction response rate for both sexes, while menthol exhibited a 60% attraction response rate for females and 100% for males. By contrast, menthol had a more significant effect on adults than citronella, lethal concentration at 50 scale (LC50) values of 1.03, 0.89, and 0.9 mg, and LC95 values of 5.09, 2.01, and 1.59 mg, after 24, 48 and 72 h, respectively. For citronella oil, the LC50 values were 2.09, 1.76, and 1.70 mg after 24, 48, and 72 h, and the LC95 values were 5.5, 3.7, and 1.5 mg after 24, 48 and 72h, were noted. In the present study, the effects of citronella and methanol insecticides were observed on six types of hemocytes namely prohemocytes, granulocytes, plasmatocytes, oenocytes, coagulocytes and spherulocytes. Both citronella oil and menthol had a histopathological effect on the hemocytes of the adult red palm weevil, specifically, on the cell membrane, cytoplasm, and nucleus. The findings also revealed that the vacuoles in some hemocytes, specifically, the prohemocytes, plasmatocytes, and granulocytes were more sensitive than those in other hemocytes, which remained unaffected by the treatment.The effects of citronella and menthol on RPW immunity were demonstrated in this study, and this information may be applied to their usage in integrated pest control at sub-lethal dosages.

Monitoring of infestation percentages of the invasive red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae), and management tactics: a six-year study.

Red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera, Curculionidae), is a devastating invasive pest, that invaded Saudi Arabia's date palms in 1987. Evaluation of the infestations and the efficacy of both preventative and control treatments have been studied from 2015- 2020 in Qassim. The results indicated that the number of infested date palms varied according to the years and locations. The infested date palm trees percentage was relatively high in 2016 (2.24%) and 2017 (3.19%), then gradually decreased to reach its lowest in 2020 (0.73%) due to the management protocol applied by the Ministry of Environment, Water, and Agriculture. Furthermore, the infested palm trees' percentage varied among the eight study locations, reaching the highest percentage in location G (SA7) with a general average of 4.31%. While in the other locations, the general infested percentage average was very low when compared to location G (SA7) with 1.21 and 0.47% in locations A (SA1) and H (SA8), respectively. The effectiveness of control methods increased sharply from 52.141% in 2015 to 90.0% in 2020 with a general average of 72.73%. The quarantine and management protocols of R. ferruginous applied in Qassim decreased the number of palm infestations. Contrary, the intensive use of insecticide in the last two decades promoted genetic mutations within the Rhynchophorus, which led to the emergence of a new species R. bilineatus. This leads to increase pesticide pollution, and control costs and the insect becomes more resistant to pesticides.

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.

Nanotechnology Approaches as A Control to The Different Stages of the Red Palm Weevil, Rhynchophorus ferrugineus (Olivier) at LC50 and LC90

Nanotechnology Approaches as A Control to The Different Stages of the Red Palm Weevil, Rhynchophorus ferrugineus (Olivier) at LC50 and LC90

Proximate Composition of Okpokuru (Oryctes Rhinoceros) and Red Palm Weevil Larva (Rhynchophorus Ferrugineus)

There is need to know the nutritional composition information on any edible agricultural product known to man. This is a required information serves as a guide to consumers. In this work, the proximate composition and mineral content of Red palm weevil, (Rhynchophorus ferrugineus) and Orycytes rhinoceros (Izon Okpokuru) were studied This was done in line with AOAC standards in order to acquire insight into the samples' health advantages. These samples had acceptable concentrations of crude lipids, crude protein, fibre, nitrogen free extract, calcium, magnesium, iron, and zinc, implying that Red palm weevil (Rhynchophorus ferrugineus) and Orycytes rhinoceros (Izon Okpokuru) could be used as good sources of nutrients and minerals for human diet and animal feed production. Furthermore, the drying rates for both samples as a function of drying temperatures (50, 60, 70, 80, 90, and 100°C) reveal that they all dried quicker when the temperature was increased.

The Nutritional Profiles of Five Important Edible Insect Species From West Africa-An Analytical and Literature Synthesis.

Background: Undernutrition is a prevalent, serious, and growing concern, particularly in developing countries. Entomophagy—the human consumption of edible insects, is a historical and culturally established practice in many regions. Increasing consumption of nutritious insect meal is a possible combative strategy and can promote sustainable food security. However, the nutritional literature frequently lacks consensus, with interspecific differences in the nutrient content of edible insects generally being poorly resolved.Aims and methods: Here we present full proximate and fatty acid profiles for five edible insect species of socio-economic importance in West Africa: Hermetia illucens (black soldier fly), Musca domestica (house fly), Rhynchophorus phoenicis (African palm weevil), Cirina butyrospermi (shea tree caterpillar), and Macrotermes bellicosus (African termite). These original profiles, which can be used in future research, are combined with literature-derived proximate, fatty acid, and amino acid profiles to analyse interspecific differences in nutrient content.Results: Interspecific differences in ash (minerals), crude protein, and crude fat contents were substantial. Highest ash content was found in H. illucens and M. domestica (~10 and 7.5% of dry matter, respectively), highest crude protein was found in C. butyrospermi and M. domestica (~60% of dry matter), whilst highest crude fat was found in R. phoenicis (~55% of dry matter). The fatty acid profile of H. illucens was differentiated from the other four species, forming its own cluster in a principal component analysis characterized by high saturated fatty acid content. Cirina butyrospermi had by far the highest poly-unsaturated fatty acid content at around 35% of its total fatty acids, with α-linolenic acid particularly represented. Amino acid analyses revealed that all five species sufficiently met human essential amino acid requirements, although C. butyrospermi was slightly limited in leucine and methionine content.Discussion: The nutritional profiles of these five edible insect species compare favorably to beef and can meet human requirements, promoting entomophagy's utility in combatting undernutrition. In particular, C. butyrospermi may provide a source of essential poly-unsaturated fatty acids, bringing many health benefits. This, along with its high protein content, indicates that this species is worthy of more attention in the nutritional literature, which has thus-far been lacking.

Proteomics and Interspecies Interaction Analysis Revealed Abscisic Acid Signalling to Be the Primary Driver for Oil Palm's Response against Red Palm Weevil Infestation.

The red palm weevil (RPW; Rhynchophorus ferrugineus Olivier (Coleoptera Curculionidae)) is an invasive insect pest that is difficult to manage due to its nature of infesting the host palm trees from within. A holistic, molecular-based approach to identify proteins that correlate with RPW infestation could give useful insights into the vital processes that are prevalent to the host’s infestation response and identify the potential biomarkers for an early detection technique. Here, a shotgun proteomic analysis was performed on oil palm (Elaeis guineensis; OP) under untreated (control), wounding by drilling (wounded), and artificial larval infestation (infested) conditions at three different time points to characterise the RPW infestation response at three different stages. KEGG pathway enrichment analysis revealed many overlapping pathways between the control, wounded, and infested groups. Further analysis via literature searches narrowed down biologically relevant proteins into categories, which were photosynthesis, growth, and stress response. Overall, the patterns of protein expression suggested abscisic acid (ABA) hormone signalling to be the primary driver of insect herbivory response. Interspecies molecular docking analysis between RPW ligands and OP receptor proteins provided putative interactions that result in ABA signalling activation. Seven proteins were selected as candidate biomarkers for early infestation detection based on their relevance and association with ABA signalling. The MS data are available via ProteomeXchange with identifier PXD028986. This study provided a deeper insight into the mechanism of stress response in OP in order to develop a novel detection method or improve crop management.

Smart IoT-based system for detecting RPW larvae in date palms using mixed depthwise convolutional networks

Smart agriculture and Internet of Things (IoT) technologies have become the key points for many intelligent decision-making applications to support agricultural experts and farmers, especially for crop pest management and control. In this work, we present an IoT-based sound detection model for identifying red palm weevil (RPW) larvae to protect date palm trees at the early stage of infestation. The proposed detection system is mainly based on a modified mixed depthwise convolutional network (MixConvNet) as a recent deep learning classifier. The public TreeVibes dataset, which contains short audio recordings of feeding and/or moving RPWs, was successfully tested and assessed with the proposed MixConvNet classifier. There were 146 and 351 specimens of infested and clean sounds examined, respectively. The classification results showed that our proposed MixConvNet is efficient and superior to other deep learning classifiers, such as Xception and residual network (Resnet) models in previous related studies, obtaining the best accuracy score of 97.38. Moreover, the MixConvNet classifier is capable of identifying RPW infestation cases precisely with a high accuracy value of 95.90% ± 1.46, using 10-fold cross-validation. Therefore, practical implementation of our proposed IoT-enabled early sound detection system of RPWs is considered the future milestone of this study.

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)

BackgroundThe 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.ResultsIn 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.ConclusionsEntomopathogens 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.

Automatic large scale detection of red palm weevil infestation using street view images

The spread of the Red Palm Weevil has dramatically affected date growers, homeowners and governments, forcing them to deal with a constant threat to their palm trees. Early detection of palm tree infestation has been proven to be critical in order to allow treatment that may save trees from irreversible damage, and is most commonly performed by local physical access for individual tree monitoring. Here, we present a novel method for surveillance of Red Palm Weevil infested palm trees utilizing state-of-the-art deep learning algorithms, with aerial and street-level imagery data. To detect infested palm trees we analyzed over 100,000 aerial and street-images, mapping the location of palm trees in urban areas. Using this procedure, we discovered and verified infested palm trees at various locations.We demonstrate that computer vision provides an efficient and practical solution for large scale monitoring of infested palm trees. The results indicate that by the use of publicly available online data and without a need of specialized equipment, the proposed framework can be used to automatically map palm trees at large scales and detect ones that are potentially infested. We show that the framework can be effective in both urban and open environments. This method can revolutionize current old school practices for Red Palm Weevil management, proposing much cheaper cost-effective and efficient monitoring.

Proteolytic Activation of Bacillus thuringiensis Cry3Aa Toxin in the Red Palm Weevil (Coleoptera: Curculionidae).

The red palm weevil (RPW), Rhynchophorus ferrugineus (Oliver) is an important pest of palms that causes significant damage by boring into and feeding within palm stem tissues. Here, we studied the proteolytic process of Cry3Aa in the RPW to understand the mechanism of Cry toxicity. The bioassays showed that Cry3Aa toxin is weakly toxic to the RPW. Proteolytic activation assays indicated the Cry3Aa protein is digested into smaller fragments than the 55-kDa activated fragments under different conditions. In particular, at higher mass ratios of gut protease and Cry3Aa protein (5:1, 2:1, and 1:1, respectively), and at 36.9°C for 16 h in a solution of pH 8.6, the Cry3Aa protoxin is over-digested by the gut proteases of weevil larvae. Moreover, the zymogram analysis of the gut proteases revealed the RPW larvae harbors intestinal digestive enzymes mainly composed of serine proteases. This study describes the proteolytic activation process of Cry3Aa in the midgut of RPW larvae.