scholarly journals Bioassay and molecular monitoring of insecticide resistance status in Aedes albopictus populations from Greece, to support evidence-based vector control

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Sofia Balaska ◽  
Emmanouil A. Fotakis ◽  
Ilias Kioulos ◽  
Linda Grigoraki ◽  
Spyridoula Mpellou ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Aedes Albopictus ◽  
Evidence Based ◽  
Molecular Monitoring ◽  
Support Evidence

scholarly journals Bioassay and molecular monitoring of insecticide resistance status in Aedes albopictus populations from Greece, to support evidence-based vector control

2020 ◽  
Author(s):  
Sofia Balaska ◽  
Emmanouil Alexandros Fotakis ◽  
Ilias Kioulos ◽  
Linda Grigoraki ◽  
Spyridoula Mpellou ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Aedes Albopictus ◽  
Pyrethroid Resistance ◽  
Disease Outbreaks ◽  
Evidence Based ◽  
Resistance Mutations ◽  
Molecular Monitoring ◽  
Allelic Frequencies ◽  
Control Programs

Abstract Background: Aedes albopictus has a well-established presence in southern European countries, associated with recent disease outbreaks (e.g. Chikungunya). Development of insecticide resistance in the vector is a major concern as its control mainly relies on the use of biocides. Data on the species’ resistance status is essential for efficient and sustainable control. To date the insecticide resistance status of Ae. albopictus populations from Greece against major insecticides used in vector control remains largely unknown. Methods: We investigated the insecticide resistance status of nineteen Ae. albopictus populations from 11 regions of Greece. Bioassays were performed against diflubenzuron (DFB), B. thuringiensis var. israelensis (Bti), deltamethrin and malathion. Known insecticide resistance loci were molecularly analysed, i.e. voltage-gated sodium channel (VGSC) mutations associated with pyrethroid resistance; presence and frequency of carboxylesterases 3 (CCEae3a) and 6 (CCEae6a) gene amplification associated with organophosphate (OP) resistance and; chitin synthase-1 (CHS-1) for the possible presence of DFB resistance mutations. Results: Bioassays showed full susceptibility to DFB, Bti and deltamethrin, but resistance against the OP malathion (range of mortality: 55.30-91.40%). VGSC analysis revealed a widespread distribution of mutations F1534C (in all populations, with allelic frequencies between 6.6% - 68.3%), and I1532T (in 6 populations; allelic frequencies below 22.70%), but absence of V1016G. CCE gene amplifications were recorded in 8 out of 11 populations (overall frequency: 33%). Co-presence of mutation F1534C and CCEae3a amplification was reported in 39 of the 156 samples commonly analysed. No mutations at the CHS-1 locus I1043 were detected. Conclusions: The results indicate: (i) the suitability of larvicides DFB and Bti for Ae. albopictus control in Greece, (ii) possible incipient pyrethroid resistance due to the presence of kdr mutations and (iii) possible reduced efficacy of OPs, in a scenario of re-introducing them for vector control. The study highlights the need for systematic resistance monitoring for developing and implementing appropriate evidence-based control programs.

scholarly journals Bioassay and molecular monitoring of insecticide resistance status in Aedes albopictus populations from Greece, to support evidence-based vector control

2020 ◽  
Author(s):  
Sofia Balaska ◽  
Emmanouil Alexandros Fotakis ◽  
Ilias Kioulos ◽  
Linda Grigoraki ◽  
Spyridoula Mpellou ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Aedes Albopictus ◽  
Pyrethroid Resistance ◽  
Disease Outbreaks ◽  
Evidence Based ◽  
Resistance Mutations ◽  
Molecular Monitoring ◽  
Allelic Frequencies ◽  
Control Programmes

Abstract Background: Aedes albopictus has a well-established presence in southern European countries, associated with recent disease outbreaks (e.g. chikungunya). Development of insecticide resistance in the vector is a major concern as its control mainly relies on the use of biocides. Data on the species’ resistance status are essential for efficient and sustainable control. To date the insecticide resistance status of Ae. albopictus populations from Greece against major insecticides used in vector control remains largely unknown. Methods: We investigated the insecticide resistance status of 19 Ae. albopictus populations from 11 regions of Greece. Bioassays were performed against diflubenzuron (DFB), Bacillus thuringiensis var. israelensis (Bti), deltamethrin and malathion. Known insecticide resistance loci were molecularly analysed, i.e. voltage-gated sodium channel (VGSC) mutations associated with pyrethroid resistance; presence and frequency of carboxylesterases 3 (CCEae3a) and 6 (CCEae6a) gene amplification associated with organophosphate (OP) resistance and; chitin synthase-1 (CHS-1) for the possible presence of DFB resistance mutations. Results: Bioassays showed full susceptibility to DFB, Bti and deltamethrin, but resistance against the OP malathion (range of mortality: 55.30–91.40%). VGSC analysis revealed a widespread distribution of the mutations F1534C (in all populations, with allelic frequencies between 6.6–68.3%), and I1532T (in 6 populations; allelic frequencies below 22.70%), but absence of V1016G. CCE gene amplifications were recorded in 8 out of 11 populations (overall frequency: 33%). Co-presence of the F1534C mutation and CCEae3a amplification was reported in 39 of the 156 samples analysed by both assays. No mutations at the CHS-1 I1043 locus were detected. Conclusions: The results indicate: (i) the suitability of larvicides DFB and Bti for Ae. albopictus control in Greece; (ii) possible incipient pyrethroid resistance due to the presence of kdr mutations; and (iii) possible reduced efficacy of OPs, in a scenario of re-introducing them for vector control. The study highlights the need for systematic resistance monitoring for developing and implementing appropriate evidence-based control programmes.

scholarly journals Bioassay and molecular monitoring of insecticide resistance status in Aedes albopictus populations from Greece, to support evidence-based vector control

2020 ◽  
Author(s):  
Sofia Balaska ◽  
Emmanouil Alexandros Fotakis ◽  
Ilias Kioulos ◽  
Linda Grigoraki ◽  
Spyridoula Mpellou ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Gene Amplification ◽  
Aedes Albopictus ◽  
Pyrethroid Resistance ◽  
Disease Outbreaks ◽  
Evidence Based ◽  
Resistance Mutations ◽  
Molecular Monitoring ◽  
Allelic Frequencies

Abstract Background: Aedes albopictus has a well-established presence in southern European countries, associated with recent disease outbreaks (e.g. Chikungunya). Development of insecticide resistance in the vector is a major concern as its control mainly relies on the use of biocides. Data on the species’ resistance status is essential for efficient and sustainable control. To date the insecticide resistance status of Ae. albopictus populations from Greece against major insecticides used in vector control remains largely unknown.Methods: We investigated the insecticide resistance status of nineteen Ae. albopictus populations from eleven regions of Greece. Bioassays were performed against diflubenzuron (DFB), B. thuringiensis var. israelensis (Bti), deltamethrin and malathion. Known insecticide resistance loci were molecularly analysed, i.e. voltage-gated sodium channel (VGSC) mutations associated with pyrethroid resistance; presence and frequency of carboxylesterases 3 (CCEae3a) and 6 (CCEae6a) gene amplification associated with organophosphate (OP) resistance and; chitin synthase-1 (CHS-1) for the possible presence of DFB resistance mutations. Results: Bioassays showed full susceptibility to DFB, Bti and deltamethrin, but resistance against the OP malathion (range of mortality: 55.30-91.40%). VGSC analysis revealed a widespread distribution of the mutations F1534C (in all populations, with allelic frequencies between 6.6% - 68.3%), and I1532T (in 6 populations; allelic frequencies below 22.70%), but absence of V1016G. CCE gene amplifications were recorded in 8 out of 11 populations (overall frequency: 33%). Co-presence of the F1534C mutation and CCEae3a amplification was reported in 39 of the 156 samples analysed by both assays. No mutations at the CHS-1 I1043 locus were detected.Conclusions: The results indicate: (i) the suitability of larvicides DFB and Bti for Ae. albopictus control in Greece, (ii) possible incipient pyrethroid resistance due to the presence of kdr mutations and (iii) possible reduced efficacy of OPs, in a scenario of re-introducing them for vector control. The study highlights the need for systematic resistance monitoring for developing and implementing appropriate evidence-based control programs.Key words: diagnostic, bioassay, arbovirus, vector control, mosquito tiger, insecticide resistance, kdr, Bti, gene amplification

scholarly journals The Effect of Sound Lure Frequency and Habitat Type on Male Aedes albopictus (Diptera: Culicidae) Capture Rates With the Male Aedes Sound Trap

2020 ◽  
Author(s):  
Tom Swan ◽  
Tanya L Russell ◽  
Thomas R Burkot ◽  
Jianyi Liu ◽  
Scott A Ritchie ◽  
...  
Keyword(s):  
Vector Control ◽  
Aedes Albopictus ◽  
Habitat Type ◽  
Evidence Based ◽  
Fine Scale ◽  
Effective Frequency ◽  
Vector Surveillance ◽  
Remote Areas ◽  
Baseline Information ◽  
Capture Rates

Abstract The global distribution of Aedes albopictus (Skuse) is rapidly expanding which has contributed to the emergence and re-emergence of dengue and chikungunya outbreaks. Improvements in vector surveillance are necessary to facilitate optimized, evidence-based vector control operations. Current trapping technology used to target Ae. albopictus and other Aedes species for vector surveillance are limited in both scale and scope, thus novel tools are required. Here, we evaluated the Male Aedes Sound Trap (MAST) for its capacity to sample male Ae. albopictus. Aims of this study were twofold: 1) to determine the most effective frequency for capturing male Ae. albopictus and 2) to investigate fine-scale variations in male Ae. albopictus abundance. MASTs which produced sound lure frequencies between 500 and 650 Hz captured significantly more male Ae. albopictus than those with sound lure frequencies set to 450 Hz. Further, the higher sound lure frequency of 700 Hz significantly reduced catches relative to 650 Hz. MASTs placed in woodland habitats captured significantly more male Ae. albopictus than MASTs placed near houses. These results provide baseline information for optimizing sound lure frequencies and placement of the MAST to sample male Ae. albopictus in remote areas.

scholarly journals Insecticide resistance in dengue vectors from hotspots in Selangor, Malaysia

2021 ◽  
Vol 15 (3) ◽  
pp. e0009205
Author(s):  
Rosilawati Rasli ◽  
Yoon Ling Cheong ◽  
M. Khairuddin Che Ibrahim ◽  
Siti Futri Farahininajua Fikri ◽  
Rusydi Najmuddin Norzali ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Vector Control ◽  
Aedes Albopictus ◽  
World Health ◽  
Dengue Vector ◽  
Organophosphate Insecticide ◽  
Potential Threat ◽  
Pyrethroid Insecticides ◽  
Dengue Vector Control

Background In Malaysia, dengue remains a top priority disease and usage of insecticides is the main method for dengue vector control. Limited baseline insecticide resistance data in dengue hotspots has prompted us to conduct this study. The present study reports the use of a map on the insecticide susceptibility status of Aedes aegypti and Aedes albopictus to provide a quick visualization and overview of the distribution of insecticide resistance. Method and results The insecticide resistance status of Aedes populations collected from 24 dengue hotspot areas from the period of December 2018 until June 2019 was proactively monitored using the World Health Organization standard protocol for adult and larval susceptibility testing was conducted, together with elucidation of the mechanisms involved in observed resistance. For resistance monitoring, susceptibility to three adulticides (permethrin, deltamethrin, and malathion) was tested, as well as susceptibility to the larvicide, temephos. Data showed significant resistance to both deltamethrin and permethrin (pyrethroid insecticides), and to malathion (organophosphate insecticide) in all sampled Aedes aegypti populations, while variable resistance patterns were found in the sampled Aedes albopictus populations. Temephos resistance was observed when larvae were tested using the diagnostic dosage of 0.012mg/L but not at the operational dosage of 1mg/L for both species. Conclusion The present study highlights evidence of a potential threat to the effectiveness of insecticides currently used in dengue vector control, and the urgent requirement for insecticide resistance management to be integrated into the National Dengue Control Program.

scholarly journals Phenotypic and molecular analysis of insecticide resistance in Aedes albopictus populations from Greece

2020 ◽  
Author(s):  
Sofia Balaska ◽  
Emmanouil Alexandros Fotakis ◽  
Ilias Kioulos ◽  
Linda Grigoraki ◽  
Spyridoula Mpellou ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Molecular Analysis ◽  
Aedes Albopictus ◽  
Pyrethroid Resistance ◽  
Disease Outbreaks ◽  
Control Methods ◽  
Resistance Mutations ◽  
Control Programs ◽  
Southern European Countries

Abstract Background: Aedes albopictus has a well-established presence in southern European countries, associated with recent disease outbreaks (e.g. Chikungunya). Development of insecticide resistance in the vector is a major concern as it’s control mainly relies on the use of biocides. Data on the specie’s resistance status is essential for efficient and sustainable control. Methods: We investigated the insecticide resistance status of several Ae. albopictus populations from Greece. Bioassays were performed against diflubenzuron (DFB), B. thuringiensis var. israelensis (Bti), deltamethrin and malathion. Molecular analysis of known insecticide resistance loci was performed, i.e. voltage-gated sodium channel (VGSC) mutations associated with pyrethroid resistance; presence and frequency of carboxylesterases 3 (CCEae3a) and 6 (CCEae6a) gene amplification associated with organophosphate (OP) resistance and; chitin synthase-1 (CHS-1) for the possible presence of DFB resistance mutations. Results: Bioassays showed full susceptibility to DFB, Bti and deltamethrin, but resistance against the OP malathion. VGSC analysis revealed a widespread distribution of mutations F1534C (in all populations, with allelic frequencies between 6.6% - 68.3%), and I1532T (in 6 populations), but absence of V1016G. CCE gene amplifications were recorded in 8 out of 11 populations. Co-presence of mutation F1534C and CCEae3a amplification was reported in a subgroup of samples. No mutations at the CHS locus I1043 were detected. Conclusions: The results indicate: (i) the suitability of larvicides DFB and Bti for Ae. albopictus control in Greece, (ii) a possible incipient pyrethroid resistance due to the presence of kdr mutations and (iii) a possible reduced efficacy of OPs, in a scenario of re-introducing them for vector control. The study highlights the need for systematic resistance monitoring for developing and implementing appropriate evidence-based control programs. Key words: diagnostic, arbovirus, mosquito tiger, insecticide resistance, vector control, Europe

scholarly journals Insecticide Susceptibility Status of Aedes albopictus in Dengue Hotspot Areas in Malaysia

2021 ◽  
Vol 14 ◽  
pp. 1-8
Author(s):  
WAN FATMA ZUHARAH ◽  
WAN FATMA ZUHARAH ◽  
Ahmad Mohiddin ◽  
Asmalia Md Lasim ◽  
Zairi Jaal ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Aedes Albopictus ◽  
Continuous Monitoring ◽  
Reference Strain ◽  
Control Program ◽  
Aedes Mosquitoes ◽  
Northern District ◽  
Vector Control Program ◽  
Susceptibility Status

The vector control program has become challenging due to the resistance problem occurs in Aedes mosquitoes. Aedes albopictus (Skuse, 1894) is the most dominant species contributing as a vector of dengue, Chikungunya and Zika viruses in Malaysia. Knowledge of the current insecticide resistance of Ae. albopictus is essential for the success of vector control program. Here, we reported the susceptibility status of Ae. albopictus collected from the dengue hotspot areas in the Northern District of Penang Island, Malaysia on three common use insecticides in vector control program. Aedes albopictus was sampled from three localities at Flat Hamna, Kampung Sungai Gelugor and Kampung Tanjung Tokong in the Northern District of Penang Island, Malaysia. The adult bioassay results suggested the Flat Hamna strain (FH) was found to develop incipient resistance after 24h exposure towards all three insecticides tested; permethrin, deltamethrin and malathion (mortality 97-87%). With 1.93 fold of Resistance Ratio 50 (RR50) values, FH strains have the highest chances to develop resistance towards permethrin. Among all insecticides tested, malathion was contributed to significantly higher KdT50 in all Ae. albopictus strains as compared to VCRU reference strain (p<0.001). Thus suggesting malathion insecticide is the least effective insecticide in our vector control program. Our finding can be used as a baseline for insecticide resistance of Ae. albopictus to improve vector control across Malaysia. Permethrin and deltamethrin are still reliable to be used in the control program, nonetheless require continuous monitoring on their susceptibility towards Ae. albopictus.

scholarly journals A Challenge for a Unique Dengue Vector Control Programme: Assessment of the Spatial Variation of Insecticide Resistance Status amongst Aedes aegypti and Aedes albopictus Populations in Gampaha District, Sri Lanka

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Rasika Dalpadado ◽  
Nayana Gunathilaka ◽  
Deepika Amarasinghe ◽  
Lahiru Udayanaga
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Vector Control ◽  
Aedes Albopictus ◽  
Rural Areas ◽  
Medical Officer ◽  
Public Health Problem ◽  
World Health ◽  
Susceptibility Status

Background. To date, dengue is considered an important public health problem in Sri Lanka. Irrational use of insecticides without evidence-based applications has primed the development of resistance in mosquito vectors. Method. The present study investigated the resistance status of Aedes aegypti and Aedes albopictus to commonly used insecticides in three selected Medical Officer of Health (MOH) areas (i.e., Attanagalla, Dompe, and Negombo) in Gampaha District, Western Province of Sri Lanka. Entomological surveys were performed using ovitraps and larval collections. Larval bioassays were carried out to determine the LC50, LC90, and LC95 and susceptibility status for organophosphate temephos, whereas adult bioassays were performed to test the 0.03% deltamethrin and 0.8% malathion susceptibility. Results. The study revealed that the temephos concentrations required to control Ae. aegypti (13.7-17.7 times) and Ae. albopictus (4.6-7.6 times) are higher than the diagnostic concentration (0.012 mg/L) proposed by the World Health Organization. The highest resistance levels were observed for both Ae. aegypti ( 14 ± 1.87 ) and Ae. albopictus ( 36 ± 1.87 ) collected from the Negombo MOH area. Therefore, the WHO recommended diagnostic concentration is no longer effective in controlling Ae. aegypti and Ae. albopictus larvae in these areas. Both the dengue vectors have evolved a high level of insecticide resistance to malathion and deltamethrin in the Gampaha District except Ae. albopictus mosquitoes in rural areas. Further, vectors in rural areas are indicated susceptible (>98%) to pyrethroids and emergence of resistance (<97%) for organophosphate insecticides. Conclusion. The results of this study warrant the vector management authorities on the proper application of insecticides and rational use in vector control. The susceptibility status of vector mosquitoes should be continuously monitored especially in dengue-endemic areas parallel to the routine surveillance programme. Further molecular studies are strongly recommended to determine the Knockdown Resistance (kdr) mutations among Aedes populations.

Developing Evidence-Based Assessment to Prevent Over- or Underidentification of Disorders for New Language Learners

2020 ◽  
Vol 5 (4) ◽  
pp. 1026-1038
Author(s):  
Sandra Levey ◽  
Li-Rong Lilly Cheng ◽  
Diana Almodovar
Keyword(s):  
Language Learners ◽  
Grade Level ◽  
Reading Skills ◽  
Language Disorder ◽  
Academic Development ◽  
Review Article ◽  
Evidence Based ◽  
Clinical Knowledge ◽  
Language And Literacy ◽  
Support Evidence

Purpose The purpose of this review article is to present certain linguistic domains to consider in the assessment of children learning a new language. Speech-language pathologists frequently face difficulty when determining if a bilingual or multilingual child possesses a true speech or language disorder. Given the increased number of new language learners across the world, clinicians must understand differences versus disorders to prevent underidentification or overidentification of a disorder. Conclusions Early identification of a true disorder has been shown to prevent language and literacy difficulties, given that children are able to achieve grade-level reading skills when given intervention. Clinical knowledge and skills are strongly required so that children receive evidence-based assessment to support their academic development. Learning Goal Readers will gain an understanding of the factors that support evidence-based assessment of bilingual and multilingual language learners.

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