Nineteen different isolates of the entomopathogenic fungi Beauveria bassiana sensu lato (s.l.) and Metarhizium anisopliae s.l. (Ascomycota: Hypocreales), recovered from different soil samples (field ...crops, fruit orchards, vegetable fields and forests) and insect cadavers were tested against Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) at two different spore concentrations (1 × 107 and 1 × 108 conidia mL−1). Three isolates of B. bassiana and two of M. anisopliae gave >88 % larval and >75 % adult mortality of R. ferrugineus on their highest dose rate respectively. More sporulating cadavers (mycosis) resulted from a high dose rate compared to low dose on both life stages of R. ferrugineus. The current study confirmed the lethal action of B. bassiana and M. anisopliae isolates with mortality levels usually directly proportional to the conidial concentration. This study further confirmed that the isolates recovered from R. ferrugineus dead cadavers gave more mortality compared to the other sources. In the virulence assay two isolates of B. bassiana caused the highest percentage of both larval and adult mortality at all exposure intervals which suggest that they may be the most promising for use in sustainable management programs aimed at microbial control in date palm orchards.
Metarhizium anisopliae Metchnikoff (Hypocreales: Clavicipitaceae) is a fungal pathogen that causes disease in various insect pests, and it can be exploited and developed as a biological control agent ...to combat the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Dryophthoridae). The study on indigenous isolates is crucial especially for development of bioinsecticides in the future. The M. anisopliae strain called MET-GRA4 was tested for pathogenicity against adult red palm weevil and treated in vitro with different spore viabilities. The isolates exhibited pathogenicity with 100% mortality 21 d postinfection. The median lethal time (LT50) for 85% viable spores was 8.6 d, while 39% viable spores had an LT50 value of 21.37 d, with 92 and 16.6% mycosis, respectively. The species MET-GRA4 strain was molecularly characterized using ITS1 and ITS4 from pure culture (Isolate A), mass-produced spores (Isolate B), and infected red palm weevil cadavers (Isolate C). The DNA sequences obtained matched M. anisopliae sequences, with 99% similarity. This new isolate of M. anisopliae has potential as a targeted bioinsecticide for management of red palm weevil.
Red palm weevil (RPW,
) is an invasive pest of palms. In China, coconut (
nucifera) production is being significantly affected by the RPW attack. To develop a long-term RPW control strategy, ...host-plant resistance is the most sustainable option. In this regard, the availability of transcriptome sequencing data from RPW-infected coconut plants can be highly useful. Therefore, the present study assessed coconut leaf physiological responses and transcriptional changes after different days of RPW attack i.e., 5, 10, 15, 20, and 25 days after infestation (DAI). A comparison of physiological data indicated that populations with the higher number of RPW insects i.e., population C (15 males +21 females) and D (20 males +28 females) triggered higher antioxidant enzyme activities. We used this data to study the transcriptomic responses on 5 and 20 DAI. Of the 38,432 detected transcripts, 3,984, 1,981, 3,925, and 2,257 were differentially expressed in CK (control/no RPW)_vs._C (5 DAI), CK_vs._D (5 DAI), CK_vs._C (20 DAI), and CK_vs._D (20 DAI), respectively. These transcripts were enriched in plant-pathogen interaction, phenylpropanoid/flavonoid biosynthesis, amino sugar and nucleotide sugar metabolism, plant hormone signal transduction, mitogen-activated protein kinase, and reactive oxygen scavenging pathway. We discuss these results and present several candidate genes to be manipulated for developing a sustainable strategy to control RPW attack regarding host-plant resistance. Furthermore, these findings provide a basis for developing effective early and late RPW attack detection strategies.
The Red Palm Weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790) is a devastating invasive pest of palm trees, invading the Iraqi date palm tree in 2015 for the first time in Safwan county, ...Basrah province. The Red Palm weevil has been categorized as a quarantine pest of date palm trees worldwide. In this study, a five years monitoring program has been achieved by scouting the invasive pest RPW population in Safwan county by using visual sampling and Pheromone baited traps. The results indicated that the number of infested palms, increased from 12 trees in 2015 to 111 in 16 orchards in 2016. The number of the infested palms was minimized to 3 trees in the county in 2019 due to the management protocol of the Ministry of Agriculture. Furthermore, the results of RPW adults appeared monthly in the county with two activity peaks during the moderate-temperature-months. In conclusion, the quarantine and management protocol of RPW decreased the population of the invasive pest which did not spread to other districts of Iraq.
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•The toxicity of Metarhizium anisopliae were estimated on Rhynchophorus ferrugineus.•The biological parameters of grubs were assessed by age-stage, two-sex life table.•R. ferrugineus ...grubs had 1.2 × 106 spores/mL LC50 values of M. anisopliae.•M. anisopliae infected grubs had reduced (Ro), (T) and (r) values.•Adult longevity and fecundity were also reduced in infected grubs.
Outbreaks of red palm weevil, Rhynchophorus ferrugineus Olivier, in Pakistan are considered a very serious threat to the date industry, owing to the sudden death of date palm trees. Current integrated management strategy largely depends on insecticides, with negative impacts on the environment. Integration of bio-control strategies incorporating entomopathogenic fungi (EPF) may provide an ecologically safe alternative. In the current study the effectiveness of Metarhizium anisopliae Sorokin against R. ferrugineus was investigated using the immersion method and the effects of this fungus on biological parameters of R. ferrugineus were estimated by age-stage, two-sex life table software. After treatment with M. anisopliae isolate (Ma-M2), lethal concentration (LC50) 1.2 × 106 spores/mL was determined against R. ferrugineus 3rd instar grubs. M. anisopliae infected grubs showed reduced net reproductive rate Ro (75.55) and mean generation time T (113.886 days) and intrinsic rate of increase r (0.03797) compared to the untreated group. Also, adult longevity of males and females were significantly reduced in the M. anisopliae-infected group (F1) as compared to the untreated group. Trans-generational studies revealed that grubs stage duration (69.34 days) and fecundity (181.32 eggs) of the M. anisopliae-infected group (F1) were decreased compared to the untreated group. The use of lasting and adverse effects on the biological parameters of R. ferrugineus, indicate that treatment with EPF may provide an eco-friendly management strategy for this pest.
In insects, perception of the environment-food, mates, and prey-is mainly guided by chemical signals. The dynamic process of signal perception involves transport to odorant receptors (ORs) by soluble ...secretory proteins, odorant binding proteins (OBPs), which form the first stage in the process of olfactory recognition and are analogous to lipocalin family proteins in vertebrates. Although OBPs involved in the transport of pheromones to ORs have been functionally identified in insects, there is to date no report for Coleoptera. Furthermore, there is a lack of information on olfactory perception and the molecular mechanism by which OBPs participate in the transport of aggregation pheromones. We focus on the red palm weevil (RPW)
, the most devastating quarantine pest of palm trees worldwide. In this work, we constructed libraries of all OBPs and selected antenna-specific and highly expressed OBPs for silencing through RNA interference. Aggregation pheromone compounds, 4-methyl-5-nonanol (ferrugineol) and 4-methyl-5-nonanone (ferruginone), and a kairomone, ethyl acetate, were then sequentially presented to individual RPWs. The results showed that antenna-specific
aids in the capture and transport of ferrugineol to ORs. Silencing of
, which is responsible for pheromone binding, significantly disrupted pheromone communication. Study of odorant perception in palm weevil is important because the availability of literature regarding the nature and role of olfactory signaling in this insect may reveal likely candidates representative of animal olfaction and, more generally, of molecular recognition. Knowledge of OBPs recognizing the specific pheromone ferrugineol will allow for designing biosensors for the detection of this key compound in weevil monitoring in date palm fields.
The efficacies of two trap types, bucket and Picusan traps, for capturing and retaining Rhynchophorus palmarum (L.), an invasive palm pest responsible for killing thousands of ornamental Canary ...Islands date palms (Phoenix canariensis Chabaud Arecales: Arecaceae) in San Diego County, CA, were compared. Digital video data were analyzed to determine how R. palmarum behavior toward each trap type affected capture and retention rates. Videography was conducted 24 h/d, 7 d/wk, for more than 7 mo resulting in 20,211 h of digital data for analysis. Weevil attraction to traps was observed only during daylight hours and no patterns in diel activity were found. Neither trap type tested captured 100% of weevils attracted to traps. Bucket traps suspended 1.5 m above the ground attracted 30% more weevils than ground deployed Picusan traps. Of those weevils attracted to bucket traps, 89% entered, 82% escaped, and 18% that entered traps were retained. Weevils that were not retained spent an average of 19 min 20 s entering and exiting entry holes and walking and flying around the bucket trap. By contrast, Picusan traps captured 89% of weevils that entered the trap.The time between weevils arriving (via walking or flight) on the sides of the Picusan trap and retention in the trap ranged between 90 and 376 s.These visual observations suggest that Picusan traps are more efficient than bucket traps for R. palmarum capture.
Background. Rhynchophorus palmarum is the main insect pest in Cocos nucifera orchards in the Pacific Centre of Mexico. The mass capture of adults is the strategy for control of this pest promoted by ...integrated pest management programs. It is essential to find an economic and efficient trap for farmers. Objective. The present study aimed to determine the efficacy and cost efficiency of five traps for capturing R. palmarum in a C. nucifera orchard and to correlate the capture with environmental parameters. Methodology. The bucket-trap (BT), trash-can trap (TCT), 20L-type trap (20LTT), bottle-type trap (BTT), and CSAT-type (Colegio Superior de Agricultura Tropical, a Spanish acronym) trap were evaluated. Total captured insects, number of males and females, cost of trapping, and cost-efficiency were measured. Total captured insects and environmental parameters were correlated using a Pearson model. Results. A total of 1065 insects were captured (60% females and 40% males). The TCT captured more (P=0.00001) insects than the BT, 20LTT and BTT. The CSAT ($540.5 USD) and TCT ($531.0 USD) were the most expensive traps during the period of the experiment (4.5 months), whereas the BTT was the cheapest ($515.5 USD). The cost of capture per insect in the TCT was $1.5 USD; therefore, this trap had the best cost efficiency overall of the studied traps (BT=2.6 USD, 20LTT=3.1 USD, CSAT=1.9 USD, and BTT=6.9 USD). The average (r=0.6115, P=0.0154) and maximum (r=0.6280, P=0.0122) wind speeds were correlated positively with the R. palmarum capture. Implications. This study demonstrates statistically that the TCT capture the same number of insects than the CSAT trap with lower cost. Conclusion. More females were caught than males, the TCT trap statistically captures the same amount of insects than the CSAT trap at a lower cost. Wind speed was positively correlated in the capture of R. palmarum.
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