Rhynchophorus Research Articles

Balancing the Growth Performance and Nutritional Value of Edible Farm-Raised Sago Palm Weevil (Rhynchophorus ferregineus) Larvae by Feeding Various Plant Supplemented-Sago Palm Trunk Diets.

Herein, the effect of supplementing ground sago palm trunk (GSPT) with varying concentrations of plant-based ingredients (PIs), including rice bran (RB), soybean meal (SM), and perilla seed (PS), on the nutritional profile of sago palm weevil larvae (SPWL) was investigated. Increased PS intake induced an increase in α-linolenic acid level and a reduction in the n-6/n-3 ratio in SPWL (p < 0.05). The presence of fatty acids in SPWL was determined predominantly by the fatty acid profile in the feed. The activities of Δ5 + Δ6 desaturases and thioesterase were not different among SPWL fed different diets (p < 0.05); however, PI intake resulted in low suppression of fads2 gene expression. RB, SM, and PS at the appropriate concentrations of 17.5%, 8.8%, and 7.0% in GSPT (F3 diet), respectively, boosted both protein quantity and quality of SPWL, as indicated by higher levels of essential amino acids, particularly lysine, than the FAO protein reference. Therefore, incorporating PIs into a regular diet is a viable method for enhancing the nutritional value and sustainability of farm-raised SPWL as a potential alternative source of high-quality lipid and protein.

Sequential Isolation of Essential Oils Repellent to the Red Palm Weevil Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae).

The push-pull approach using semiochemicals in pest control requires both an attractant and a repellent. Many previous studies have arbitrarily tested one or more known insect repellents or plant essential oils (EOs) hoping to find repellents of an insect pest. We used a comprehensive approach that synergistically tests in the field numerous natural volatiles from commercial EOs to identify repellents of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae), a worldwide pest of palms and date palms. Volatiles from 79 EOs in slow-release devices were divided into five groups and tested in traps with attractive pheromone compared to traps with pheromone alone. EO-treatment groups exhibiting repellency due to significant trap shutdown, were further subdivided into subgroups of four EOs each and tested further. Two groups of four EOs (cypress, desert wormwood, elemi, and Eucalyptus citriodora) and (niaouli, nutmeg, oregano, and orange sweet), or their corresponding mixtures of major volatiles, caused pheromone trap reductions of up to 92%. Further tests showed that seven of the eight EOs are similarly repellent as the corresponding subgroup. This systematic approach of successively testing sub-fractions of EOs in the field for trap shutdown should be useful to identify repellents of other insect pests of crops.

The Nutritive, textural and sensory attributes of frankfurter fortified with graded levels of edible Palm weevil larvae (Rhynchophorus phoenicis F)

Consumption of excessive dietary fat has been linked to health-related diseases necessitating reduction of fat in meat products as a response to consumers’ preferences. Replacement of fat in frankfurter have been achieved with different ingredients. However, there is little information on Palm weevil larvae (PWL) as fat replacement in frankfurter. Hence, the quality of frankfurter incorporated with PWL was assessed. The PWL were cleaned, head removed and ground (GPWL). Frankfurter ingredients and production was done following standard procedures. Five treatments (T110% lard) T2, T3, T4 and T5 contains 2.5, 5.0, 7.5 and 10% GPWL substituted for lard. Five independent replicates of each treatment were prepared separately. Yield, proximate composition, iodine value, fatty acid, Texture Profile Analysis (TPA) and sensory characteristics were determined using standard procedures. Data were subjected to ANOVA at Pα0.05 . The yield (80.38- 87.85%), crude protein (54.95- 67.55%) and ash (6.01-6.80%) contents of GPWL frankfurters were higher (P&lt;0.05) while ether extract (15.50-18.10%) was (P&lt;0.05) lower. The iodine values of 10% lard (1.73) and 2.5% GPWL frankfurters were not different (P&gt;0.05) but these were significantly higher (P&lt;0.05) than 0.40, 0.90 and 0.80 recorded for 5.0, 7.5 and 10% GPWL frankfurters, respectively. No statistical variation (P&gt;0.05) exist among the selected fatty acids of the frankfurters. The TPA showed chewiness (16.40N) and hardness (48.58N) of 10% lard frankfurter were significantly (P&lt;0.05) lower while the springiness (0.69) was higher (P&lt;0.05). Sensory attributes revealed appearance (7.37; 7.03), flavour (7.53; 7.17), after taste (5.93; 6.00) and acceptability (7.73; 7.04) of 10% lard and 2.5% GPWL frankfurters, respectively were similar (P&gt;0.05). Juiciness of 10% lard (6.80), 2.5%, (6.73), 5% (6.63) and 7.5% (6.57) GPWL frankfurters were similar (P&gt;0.05). Partial replacement of lard with palm weevil larvae resulted in a more nourishing frankfurter however, replacement with lard should not exceed 5% in order to obtain frankfurter with good colour appeal and organoleptic characteristics.&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; La consommation excessive de graisses alimentaires a été associée à des maladies liées à la santé nécessitant une réduction des graisses dans les produits carnés en réponse aux préférences des consommateurs. Le remplacement de la graisse dans la saucisse de Francfort a été réalisé avec différents ingrédients. Cependant, il existe peu d'informations sur les larves de charançon du palmier (LCP) comme substitut de graisse dans la saucisse de Francfort. Par conséquent, la qualité de la saucisse de Francfort incorporée au LCP a été évaluée. Les LCP ont été nettoyés, étêtés et meulés (GPWL). Les ingrédients et la production de Frankfurter ont été effectués selon des procédures standard. Cinq traitements (T110 % saindoux) T2, T3, T4 et T5 contiennent 2,5, 5,0, 7,5 et 10 % de GPWL substitué au saindoux. Cinq répliques indépendantes de chaque traitement ont été préparées séparément. Le rendement, la composition immédiate, l'indice d'iode, les acides gras, l'analyse du profil de texture (APT) et les caractéristiques sensorielles ont été déterminés à l'aide de procédures standard. Les données ont été soumises à une ANOVA à Pα0,05 Le rendement (80,38-87,85 %), la teneur en protéines brutes (54,95-67,55 %) et en cendres (6,01-6,80 %) des saucisses de Francfort GPWL étaient plus élevées (P&lt;0,05) tandis que l'extrait d'éther (15,50- 18,10 %) était (P&lt;0,05 ) inférieur. Les valeurs d'iode des saucisses de Francfort 10 % saindoux (1,73) et 2,5 % GPWL n'étaient pas différentes (P&gt;0,05) mais elles étaient significativement plus élevées (P&lt;0,05) que les valeurs de 0,40, 0,90 et 0,80 enregistrées pour les saucisses de Francfort 5,0, 7,5 et 10 % GPWL, respectivement. Aucune variation statistique (P&gt;0,05) n'existe parmi les acides gras sélectionnés des saucisses de Francfort. L’APT a montré que la mastication (16,40 N) et la dureté (48,58 N) de la saucisse de Francfort à 10 % de saindoux étaient significativement (P &lt; 0,05) inférieures, tandis que l'élasticité (0,69) était supérieure (P &lt; 0,05). Les attributs sensoriels ont révélé que l'apparence (7,37 ; 7,03), la saveur (7,53 ; 7,17), l'arrière-goût (5,93 ; 6,00) et l'acceptabilité (7,73 ; 7,04) de 10 % de saindoux et de 2,5 % de saucisses de Francfort GPWL étaient similaires (P&gt; 0,05). La jutosité des saucisses de Francfort GPWL à 10 % (6,80), 2,5 %, (6,73), 5 % (6,63) et 7,5 % (6,57) était similaire (P&gt; 0,05). Le remplacement artificiel du saindoux par des larves de charançon du palmier a donné une saucisse de Francfort plus nourrissante. Cependant, le remplacement par du saindoux ne doit pas dépasser 5 % afin d'obtenir une saucisse de Francfort avec un bon attrait de couleur et des caractéristiques organoleptiques.

Early detection of red palm weevil infestations using deep learning classification of acoustic signals

The Red Palm Weevil (RPW), also known as the palm weevil, is considered among the world’s most damaging insect pests of palms. Current detection techniques include the detection of symptoms of RPW using visual or sound inspection and chemical detection of volatile signatures generated by infested palm trees. However, efficient detection of RPW diseases at an early stage is considered one of the most challenging issues for cultivating date palms. In this paper, an efficient approach to the early detection of RPW is proposed. The proposed approach is based on RPW sound activities being recorded and analyzed. The first step involves the conversion of sound data into images based on a selected set of features. The second step involves the combination of images from the same sound file but computed by different features into a single image. The third step involves the application of different Deep Learning (DL) techniques to classify resulting images into two classes: infested and not infested. Experimental results show good performances of the proposed approach for RPW detection using different DL techniques, namely MobileNetV2, ResNet50V2, ResNet152V2, VGG16, VGG19, DenseNet121, DenseNet201, Xception, and InceptionV3. The proposed approach outperformed existing techniques for public datasets.

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.

Enhanced YOLOv5 Object Detection Algorithm for Accurate Detection of Adult Rhynchophorus ferrugineus.

The red palm weevil (RPW, Rhynchophorus ferrugineus) is an invasive and highly destructive pest that poses a serious threat to palm plants. To improve the efficiency of adult RPWs' management, an enhanced YOLOv5 object detection algorithm based on an attention mechanism is proposed in this paper. Firstly, the detection capabilities for small targets are enhanced by adding a convolutional layer to the backbone network of YOLOv5 and forming a quadruple down-sampling layer by splicing and down-sampling the convolutional layers. Secondly, the Squeeze-and-Excitation (SE) attention mechanism and Convolutional Block Attention Module (CBAM) attention mechanism are inserted directly before the SPPF structure to improve the feature extraction capability of the model for targets. Then, 2600 images of RPWs in different scenes and forms are collected and organized for data support. These images are divided into a training set, validation set and test set following a ratio of 7:2:1. Finally, an experiment is conducted, demonstrating that the enhanced YOLOv5 algorithm achieves an average precision of 90.1% (mAP@0.5) and a precision of 93.8% (P), which is a significant improvement compared with related models. In conclusion, the enhanced model brings a higher detection accuracy and real-time performance to the RPW-controlled pest pre-detection system, which helps us to take timely preventive and control measures to avoid serious pest infestation. It also provides scalability for other pest pre-detection systems; with the corresponding dataset and training, the algorithm can be adapted to the detection tasks of other pests, which in turn brings a wider range of applications in the field of monitoring and control of agricultural pests.

Spatiotemporal dynamics of a palm weevils' outbreak and susceptibility of peach palm (Bactris gasipaes Kunth) landraces in a germplasm bank in southwestern Colombia

AbstractThe palm weevils Rhynchophorus palmarum and Dynamis borassi are prominent pest species in peach palms and coconut in Colombia. Nevertheless, knowledge of the population dynamics of these weevil species in the neotropical region is still scarce. In this study, we systematically sampled these weevils over 2 years using pheromone traps (1 trap ha−1) in an experimental peach palm plantation under heavy weevil infestation in southwestern Colombia. Additionally, we censused the palms in a portion of the plantation (a peach palm germplasm bank) before and after the weevil monitoring. We analysed the data to elucidate sex‐specific temporal and spatial patterns of both R. palmarum and D. borassi in a 19.13 ha area. Furthermore, we sought to detect peach palm landraces within the germplasm bank susceptible and resistant/tolerant to the weevil attack. During periods when insect populations were high, we observed that R. palmarum consistently outnumbered D. borassi. Specifically, we found that R. palmarum reached up to 80 insects trap−1 month−1, while D. borassi only reached around 30 insects trap−1 month−1 during the peak months. However, both species exhibited synchronous population peaks, which were not related to rainfall or temperature but rather to the phenological stage of the peach palm. Furthermore, the weevils had a highly aggregated spatial pattern; insect catchments were more prolific in areas where the landraces Nariño and Risaralda were sown. Moreover, the census evidenced that these two landraces were the most affected. Contrarily, weevil capture was overall low around the Guaviare landrace, this was the only landrace that exhibited an increase in stipes between census years. Our results highlight that complementary control strategies are needed to counteract sudden weevil population outbreaks, as pheromone traps are a good tool for monitoring but not for effective control. Furthermore, more importantly, a peach palm breeding programme based on the identified genotypes should be the basis for the integrated pest management of palm weevils.

Recognizing sounds of Red Palm Weevils (RPW) based on the VGGish model: Transfer learning methodology

The red palm weevil (RPW) is one of the most popular and damaging pests which threaten palm cultivation and production in many countries in the world. Recognizing RPW pests is not an easy task as it is difficult to detect the RPW insect in the early stages of infestation, because there are not many visible external signs on the palm trees, and once the tree is infested it is too late to save it. In response to this urgent problem, a proposed transfer learning methodology is developed to recognize RPW pests using the VGGish deep learning model based on the acoustic signal features of RPW pests sounds. The proposed model has been trained and validated using RPW sound samples taken from RPW public benchmarked dataset. The RPW dataset consists of 2485 audio samples divided into 1754 healthy samples and 731 infested samples. The validation results clarified the efficiency of the proposed transfer learning model in recognizing RPW pest' sounds based on the amplitude and phase features of the acoustic signals. The performance evaluation metrics showed promising results in detecting the RPW pest's sounds, where it achieved an accuracy of 94.5%, precision of 93%, recall of 95%, and F1-score of 94%. To validate the efficiency of the proposed VGGish model, four practical comparisons with four machine learning models (i.e. Support vector machine (SVM), decision tree (DT), Gaussian naïve Bayes (NB), and Logistic regression (LR)) and five practical comparisons with five deep learning models (i.e. InceptionResV3, ResNet50, DenseNet121, EfficientNetB0, and Xception) are conducted using the same dataset. The comparison results confirmed the superiority of the VGGish model in recognizing RPW pest's sounds compared to the four and five machine and deep learning models respectively.

Towards Monitoring and Identification of Red Palm Weevil Gender Using Microwave CSRR-Loaded TL Sensors.

This paper presents for the first time the design of a microwave sensing setup for the potential monitoring and identification of red palm weevil (RPW) gender type. The microwave sensor consists of a planar two-port transmission line (TL) with a single complementary split-ring resonant (CSRR) inclusion etched from the bottom metallic layer. The CSRR sensor is placed on top of a customized non-conductive container. The microwave sensing setup was designed, numerically demonstrated, fabricated and tested experimentally. Simulated results correlate quite well with the experimental data. Moreover, the sensitivity of the CSRR sensor when in close proximity to different RPW genders was evaluated both numerically and experimentally. Based on the measured results from 15 RPW samples with different body sizes, different RPW gender types showed unique microwave signatures. A notable shift in the sensor's resonance frequency was achieved, where on average a resonant frequency shift of 10% for adult RPWs was achieved, while a 2.4% frequency change was obtained for larvae (young) RPWs. Hence, the proposed microwave sensing setup can be adopted in field trials to examine and differentiate between various RPW genders at various developmental stages.

Edible insect powder for enrichment of bakery products– A review of nutritional, physical characteristics and acceptability of bakery products to consumers

Bakery products including bread are traditionally good sources of carbohydrate but not nutrient-dense. Enrichment with edible insect powder could improve the quantity and quality of protein, fat and dietary fibers to bakery products. A systematic search carried out on the databases PubMed, Scopus and ScienceDirect identified 44 articles that would answer the question: what is known about the effect of enrichment of bakery products with various edible insect powders on the physical, nutritional composition and sensory properties of bakery products. The search strategy and terms applied were (Insect* OR Edible insect* OR Entomophagy*) AND (Bakery product* OR Bake* product*). Bread was the most common bakery product that was insect-enriched, yet muffins/biscuits/crackers/cookies were also reported. Commonly reported edible insects and their larvae were crickets, mealworms, palm weevil larvae, grasshoppers and African emperor moth caterpillars. Before milling into powders, insects and larvae were pre-treated by freeze-drying, oven/tray and microwave drying, blanching and roasting but was not reported for all studies. Generally, bread with up to 10% and muffins/biscuits/crackers/cookies with 5% of insect powder were acceptable to consumers. New areas of research should focus on comparing the water activity, shelf-life and cost of pre-treatment processing methods alongside the nutritional properties of edible insect powders.

Red palm weevil olfactory proteins annotated from the rostrum provide insights into the essential role in chemosensation and chemoreception

Red palm weevil (RPW), Rhynchophorus ferrugineus (Coleoptera: Curculionidae), is rapidly infesting palm trees (Arecaceae) in several countries, threatening coconut, date, and oil cultivations. The male-produced aggregation pheromone in palm weevils has been reported to be secreted through the mouth to the rostrum, a snout-like projection key for pheromone emission and dispersion. The olfactory mechanisms that underlie peripheral odorant detection in RPW have been addressed at the antennal level. However, the rostrum remains unexplored. Through RNA-seq, 27 odorant-binding proteins (OBPs), 6 chemosensory proteins (CSPs), 4 sensory neuron membrane proteins (SNMPs), 21 gustatory receptors (GRs), 25 odorant receptors (ORs) (including one odorant receptor coreceptor, Orco) and 10 ionotropic receptors (IRs), were identified. We reported 27 novel rostrum-specific olfactory proteins (4 IRs, 11 GRs, 2 CSPs, 3 OBPs, and 7 ORs) in R. ferrugineus (Rfer). The OBPs (RferSOBPs) [Rfer with “S” indicating “snout” (rostrum)] were the most abundant transcripts compared with the rest of the olfactory proteins. We identified several rostrum OBPs, which predominately emerged through gene duplication, and were found expressed in both rostrum and antennae. Noticeably, we found R. ferrugineus pheromone-binding protein (RferOBP1768) paralog in the rostrum (RferOBP14) and mapped it in the same scaffold at a different position on the RPW genome as a recent duplicate. We found that an OR (RferSOR1) was the most abundant for both field-collected and lab-reared RPWs, in the rostrum and antennae. Likewise, up-regulated olfactory-related proteins were established in field conditions compared with those from laboratory-reared. We found a rostrum-specific, highly expressing RferSIR1 in IR93a-clade related to hygrosensation. The role of these olfactory proteins as targets for identifying more specific and powerful semiochemicals is discussed in the context of pest management.

Host plant recognition by two odorant-binding proteins in Rhynchophorus ferrugineus (Coleoptera: Curculionidae).

Rhynchophorus ferrugineus, the red palm weevil (RPW), is a key pest that attacks many economically important palm species and that has evolved a sensitive and specific olfactory system to seek palm hosts. Odorant-binding proteins (OBPs) not only play crucial roles in its olfactory perception process but are also important molecular targets for the development of new approaches for pest management. Analysis of the tissue expression profiles of RferOBP8 and RferOBP11 revealed that these two Rhynchophorus ferrugineus odorant binding proteins (RferOBPs) exhibited high expression in the antennae and showed sexual dimorphism. We analyzed the volatiles of seven host plants by gas chromatography-mass spectrometry and screened 13 potential ligands by molecular docking. The binding affinity of two recombinant OBPs to aggregation pheromones and 13 palm odorants was tested by fluorescence competitive binding assays. The results revealed that eight tested palm volatiles and ferrugineol have high binding affinities with RferOBP8 or RferOBP11. Behavioral trials showed that these eight odor compounds could elicit an attraction response in adult RPW. RNA interference analysis indicated that the reduction in the expression levels of the two RferOBPs led to a decrease in behavioral responses to these volatiles. These results suggest that RferOBP8 and RferOBP11 are involved in mediating the responses of RPW to palm volatiles and to aggregation pheromones and may play important roles in RPW host-seeking. This study also provides a theoretical foundation for the promising application of novel molecular targets in the development of new behavioral interference strategies for RPW management in the future. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of γ-Irradiation on Mating Behavior of Red Palm Weevil, Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Dryophthoridae).

Red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier 1790) is a highly invasive species originating from Southeast Asia and Melanesia. Over the past 30 years, this alien pest has spread extensively in the Middle East and the Mediterranean basin. Its endophagous larvae feed on various palm species, causing significant damage that leads to the death of palm trees. Controlling RPW infestations is challenging due to their gregarious nature and the lack of detectable early symptoms. Systemic insecticides are effective means of control, but their use in urban areas is prohibited and resistance can develop. Considering alternative options with minimal environmental impact, the Sterile Insect Technique (SIT) has been explored. Previous research has shown that male RPWs irradiated at 80 Gy or higher achieve full sterility. This study aimed to investigate in laboratory conditions whether RPW sterile males (irradiated at 60 and 80 Gy) could compete sexually with non-irradiate males. Laboratory bio-assays under both no-choice and choice conditions assessed sexual performance in terms of number of matings, mating duration and time elapsed until the first mating. The results confirmed that irradiation does not negatively affect the mating performance of sterile males, demonstrating their ability to compete successfully with non-irradiated males in both experimental setups.

Nutritional composition and consumer acceptance of tomato paste fortified with palm weevil larvae (Rhynchophorus phoenicis Fabricius) in the Ashanti region, Ghana.

Edible insects, such as palm weevil larvae, have been promoted as an alternative source of nutrients in developing countries for their nutritional benefits, cost-effective rearing, and yearly availability. Unfortunately, consumer acceptance remains a barrier to their utilization. A supplemental palm weevil larvae and tomato paste were developed as part of efforts to understand whether incorporating edible insects into staple foods could help overcome this barrier. Palm weevil larvae flour and tomato paste were mixed in three formulations that had 8, 15, and 30% of palm weevil larvae flour. Samples were subjected to proximate and mineral content analyses and sensory evaluation. Among the blends, tomato paste containing 30% palm weevil larvae had the highest protein, fat, and total solids content as compared to unfortified tomato paste. Iron and zinc levels also increased with increasing levels of palm weevil larvae flour. Carbohydrate and crude fiber concentrations of the samples, however, decreased with increasing fortification levels. The overall acceptance and willingness to purchase fortified tomato paste as determined by sensory evaluation was high for all samples and increased with increasing knowledge about palm weevil larvae's nutritional benefits. Overall acceptance and willingness to purchase fortified tomato paste were significantly dependent on the samples' color and consumers' overall liking of the products. Tomato paste fortified with palm weevil larvae can provide a complementary source of iron for Ghanaians.

Body size-dependent effects on the distribution patterns of phoretic mite species assemblages on Rhynchophorus ferrugineus (Olivier, 1790).

Phoretic mites attach to different body parts of the red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790), to disperse. However, the question of how the patterns of attachment sites are formed remains intriguing. Here, we examined RPW-associated phoretic mites in four districts in Northern Portugal (macrohabitat), and investigated the patterns of mite distribution on six body parts of RPW (microhabitat). At the macrohabitat level, we detected seven phoretic mite taxa using the RPW host in each of the four studied districts, all documented for the first time in association with this invasive exotic species in Portugal. However, their relative abundance (species evenness) varied between districts, as did species diversity. All examined weevils carried mites, and the prevalence of the different taxa did not differ between districts or sex of weevils. Measured by mean abundance and degree of aggregation, Centrouropoda sp. proved to be the dominant taxon, while Acarus sp. and Curculanoetus rhynchophorus were considered common subordinate taxa and Uroovobella sp., Mesostigmata, Nenteria extremica and Dendrolaelaps sp. sparse taxa. At the microhabitat level, all taxa were present on all body parts of the RPW; the highest abundance was in a region encompassing the inner surface of the elytra and the membranous hind wings (subelytral space). Analysis of niche overlap revealed that the distribution patterns of phoretic mite taxa on the RPW were not randomly structured. In the subelytral space, interspecific coexistence of mites increased as a function of body size difference with the dominant Centrouropoda sp. We found that in the subelytral space the large dominant species Centrouropoda sp. displaced the larger species Uroobovella sp. and the similarly sized species Nenteria extremica, but coexisted with smaller taxa.

The Filtering Effect of Oil Palm Plantations on Potential Insect Pollinator Assemblages from Remnant Forest Patches

Extensive oil palm plantations worldwide are dependent on insect pollination, specifically by introduced African weevils (Elaidobius spp.). The effectiveness of these weevils has been questioned following poor pollination and yield loss in Malaysia. Indigenous thrip (Thysanoptera) species, and moths (Lepidoptera) in the genus Pyroderces, may also be pollinators of oil palm, while the role of bees (Hymenoptera) and flies (Diptera) is unknown. The potential of native pollinators remains uncertain because of the almost total clearing of forest habitat from oil palm landscapes. In this study, we investigate the value of small high conservation value (HCV) forests as sources of potential native insect pollinators of oil palm in northern Sarawak. We further examine the filtering effect of oil palm-dominated landscapes on the species assemblages of six potential pollinator insect orders: Blattodea, Coleoptera, Diptera, Hemiptera, Hymenoptera and Lepidoptera. Orders differed in both species composition and abundance between forest and oil palm plantations, with an average of 28.1% of species unique to oil palm. Oil palm presented a soft permeable boundary to Coleoptera, Hymenoptera and Lepidoptera. Their species richness and abundance differed little between habitats with distance, despite species turnover. In contrast, oil palm presented a harder boundary to Diptera with a decline in both species richness and abundance with distance into oil palm. The abundance of the oil palm weevil (Elaedobius kamerunicus) was low compared to the native dominants, but similar to levels displayed by native thrips that may be pollinators of oil palm. The functional diversity of well-known pollinator guilds—bees and flies—was similar in forest and oil palm, suggesting that potential pollinators may yet exist among native orders of insects. Contrary to the prevailing opinion, even small forest patches in oil palm landscapes may provide native pollinator pressure.

Interactions between microorganisms associated with red palm weevil, Rhynchophorus ferrugineus, in Tunisia

Interactions between microorganisms associated with red palm weevil, Rhynchophorus ferrugineus, in Tunisia

Development of novel biological treatment for palms against the red palm weevil (Rhynchophorus ferrugineus) using RNAi

Development of novel biological treatment for palms against the red palm weevil (<i>Rhynchophorus ferrugineus</i>) using RNAi

Red palm weevil: governance and regional phytosanitary systems

Red palm weevil: governance and regional phytosanitary systems

Using microwave technology against red palm weevil: an innovative sustainable strategy to contrast a lethal pest of date palms

Using microwave technology against red palm weevil: an innovative sustainable strategy to contrast a lethal pest of date palms