scholarly journals Corrigendum to “Larvicidal Potential of Five Selected Dragonfly Nymphs in Sri Lanka over Aedes aegypti (Linnaeus) Larvae under Laboratory Settings”

2019 ◽  
Vol 2019 ◽  
pp. 1-1
Author(s):  
Chathurika Samanmali ◽  
Lahiru Udayanga ◽  
Tharaka Ranathunge ◽  
Sandun J. Perera ◽  
Menaka Hapugoda ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Dragonfly Nymphs

scholarly journals Larvicidal Potential of Five Selected Dragonfly Nymphs in Sri Lanka over Aedes aegypti (Linnaeus) Larvae under Laboratory Settings

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Chathurika Samanmali ◽  
Lahiru Udayanga ◽  
Tharaka Ranathunge ◽  
Sandun J. Perera ◽  
Menaka Hapugoda ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Statistical Significance ◽  
Pairwise Comparison ◽  
Pond Water ◽  
Predation Rate ◽  
Field Trials ◽  
Morphological Identification ◽  
Dragonfly Species ◽  
Dragonfly Nymphs

Introduction. Limitations in breeding source reduction practices, development of insecticide resistance in mosquitoes, and ill effects of chemical controlling methods on human and ecosystem health have motivated Sri Lankan authorities working for dengue control to seek for alternative, ecofriendly, and sustainable approaches for controlling of Aedes vectors, to manage dengue epidemics. The present study attempted to investigate the predation efficiency of locally available dragonfly nymphs over Aedes aegypti under laboratory conditions, aiming to evaluate the potential of using dragonflies as biocontrol agents against dengue. Methods. Nymphal stages of five locally abundant dragonfly species were collected from different stagnated water bodies in Belihuloya area. After morphological identification, a well grown individual of each species was starved for 12 hours and introduced into a glass tank containing 1L of pond water with 200 larvae (4th instar) of Aedes aegypti. Number of larvae survived in the tank was enumerated hourly up to 48 hours. In case where >75% of larvae are consumed by dragonfly nymphs, additional Ae. aegypti larvae were introduced into such tanks. Experiment was repeated for five times. Same procedure was followed with different stages of growth of the dragonfly nymphs characterized by the highest predation rate. General Linear Model followed by Tukey’s pairwise comparison was used for statistical analysis. Results. The predation rates of different dragonfly species varied significantly (p<0.05), whereby Anax indicus (110±7.14 per day) indicated the highest, followed by Pantala flavescens (54.07±5.15) and Gynacantha dravida (49.00±11.89), while Tholymis tillarga (23.47±2.48) had the lowest. Further, significant variations in the larval predation were found among different maturity stages (10–20; 25-35; and 35–45 mm in body length) of Ana. indicus (p<0.05). Regardless of statistical significance, a relatively higher larvicidal activity was observed at dusk than in dawn. Conclusion. Ana. indicus, which is characterized by the highest predation rate, and P. flavescens that has the widest geographical distribution within Sri Lanka along with a notable predation efficacy could be recommended as potential candidates for field trials in biological control of dengue outbreaks via suppression of Ae. aegypti larvae.

scholarly journals Effect of Larval Nutritional Regimes on Morphometry and Vectorial Capacity of Aedes aegypti for Dengue Transmission

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Nayana Gunathilaka ◽  
Hasini Upulika ◽  
Lahiru Udayanga ◽  
Deepika Amarasinghe
Keyword(s):  
Survival Rate ◽  
Sri Lanka ◽  
Aedes Aegypti ◽  
Adult Emergence ◽  
Bovine Liver ◽  
Vectorial Capacity ◽  
Head Width ◽  
Larval Diet ◽  
Larval Food ◽  
Emergence Rate

Background. Nutritional level in larval diet of mosquito vectors influence on life history traits and vectorial capacity (VC). Therefore, the present study was carried out to assess the effect of larval diet concentration on vector bionomic and VC of Aedes aegypti in Sri Lanka. Method. Three batches of 400 Ae. aegypti larvae (first instar) were reared under different concentrations of larval diet (6%, 8%, and 10%; Volume/Volume), which was prepared by mixing 12.5 g of tuna meal, 9.0 g of bovine liver powder, and 3.5 g of Brewer’s yeast, in 100 ml of distilled water. The effect of larval diet concentration on different morphometric and functional parameters of larvae (length and width of head, abdomen, survival rate, and pupation success), pupae (length and width of cephalothorax, survival rate, and adult emersion), adult (length and width of thorax, abdomen, survival rate, longevity, biting frequency and fecundity of adults) were examined. In addition, VC of Ae. aegypti was evaluated. The General Linear Model (GLM) was used for the statistical analysis. Results. Larval head length, head width, thoracic width, abdominal length, abdominal width, total length, and survival rate significantly increased with higher doses of larval diet (P<0.05). In case of pupae, length, and width of cephalothorax, survival rate and adult emergence rate denoted an increasing trend with the elevated larval diets. However, the variations of survival rate and adult emergence rate were statistically significant (P<0.05). In adults, all morphometric parameters (thoracic length, abdominal length, abdominal width, and wing length) significantly increased with elevating larval diets levels (except for thoracic width) along with the biting frequency, fecundity, and survival rate (P<0.05) of adult females. The VC also denoted significant variations (F4,14 = 24.048; P<0.05) with the larval diet concentration, whereby the highest VC of 196.37 was observed at 10% treatment. Conclusion. Larval food availability has a significant influence on the adult fitness and thus may affect the incidence of dengue due to variations in the VC of Ae. aegypti. Hence, this investigation highlights the requirement in accounting the environmental variation at the larval stages in order to understand transmission dynamics and control of dengue in Sri Lanka.

scholarly journals Population Dynamics and Breeding Preference of Aedes Aegypti and Ae. Albopictus Attributing to Dengue Threat in Kelaniya Medical Officer of Health Area in Sri Lanka

2021 ◽  
Author(s):  
L D Amarasinghe ◽  
P. V J. Nadeeka
Keyword(s):  
Population Dynamics ◽  
Sri Lanka ◽  
Aedes Aegypti ◽  
Medical Officer ◽  
Abundant Species ◽  
Mixed Population ◽  
Weather Factors ◽  
Dengue Transmission ◽  
Risk Areas ◽  
Indoor And Outdoor

Abstract Background Aedes aegypti and Ae. albopictus are the two species of dengue vector mosquitoes in Sri Lanka. Indoor and outdoor distribution of these species, their population dynamics and breeding preference are important factors determining the dengue transmission. Gampaha district in Sri Lanka reported to have frequent dengue epidemics from recent past, hence this study was conducted.Methods Ovitrap surveillance was conducted to determine the vector species distribution in indoor and outdoor in Kelaniya Medical Officer of Health (MOH) area of the Gampaha district. Larvae were reared in the laboratory until adults were emerged to identify species morphologically. Breeding preference of vector mosquitoes were carried out by physically observing the presence of mosquito larvae in water collected receptacles in the area. Results Aedes aegypti and Ae. albopictus were reported to distribute throughout Kelaniya MOH area as a mixed population. Ae. albopictus is the most abundant species both indoor and outdoor in Kelaniya MOH area compared to Ae. aegypti. Weather factors, rain days and wind positively correlated with Aedes population. Conclusions Aedes aegypti and Ae. albopictus are frequently present in Kelaniya MOH area as mixed population. High risk areas of the study area were identified.

Development of an Alternative Low-Cost Larval Diet for Mass Rearing of Aedes aegypti Mosquitoes In Sri Lanka

2020 ◽  
Author(s):  
Umesha Senevirathna ◽  
Lahiru Udayanga ◽  
Mangala Ganehiarachchi ◽  
Menaka Hapugoda ◽  
Tharaka Ranathunge
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Low Cost ◽  
Mass Rearing ◽  
Head Width ◽  
Larval Diet ◽  
Larval Size ◽  
Energy Agency ◽  
Developmental Parameters ◽  
Adult Fitness

Abstract Background Aedes aegypti is a major vector of arboviruses that may be controlled on an area-wide basis using novel approaches such as Sterile Insect Technique (SIT) and Incompatible Insect Technique (IIT). Larval diet is a major factor in mass-rearing of Aedes mosquitoes for SIT and IIT programs. Therefore, current study aimed to evaluate the effects of two novel diets developed from dry fish powder on growth and development of immature stages and adult fitness-related characteristics of Ae. aegypti in Sri Lanka. Method: Three batches of 250 Ae. aegypti first instar larvae were exposed to three different larval diets as, standard dry fish powder (D1), dry fish powder meal and brewer’s yeast (D2) and International Atomic Energy Agency (IAEA) reccomanded diet (D3), separately. Morphometric and developmental parameters of 4th instar larvae, pupae and adult mosquitoes reared under different dietary treatments were measured. General Linear Model (GLM) was used for statistical analysis. Results Significant diet-based variations were observed in the head length, head width, thoracic length, thoracic width, abdominal length, abdominal width and total length (F2, 87>4.811; P < 0.05) of Ae. aegypti larvae. The highest pupation success and the larval size were observed from the larvae fed with D2 diet, while the lowest was reported from D1. All adult morphometric parameters of adult male and female Ae. aegypti mosquitoes also denoted significant dietary variations, reporting the best sized adults from D2 diet (F2, 87>3.54; P < 0.05). Further, significantly higher fecundity and male longevity were also shown by the adult Ae. aegypti (F2, 6>7.897; P < 0.01) reared under diet D2. Conclusion Based on all the growth and developmental parameters, D2 diet reported the best quality adult mosquitoes similar to the IAEA recomanded diet, while being more inexpensive. Therefore, larval diet D2 could be recomaded as the ideal diet for for mass-rearing of Ae. aegypti for IIT and SIT-based vector control in Sri Lanka.

Biocontrol potential of six locally available fish species as predators of Aedes aegypti in Sri Lanka

2021 ◽  
pp. 104638
Author(s):  
Tharaka Ranathunge ◽  
P.H.D. Kusumawathie ◽  
Wimaladharma Abeyewickreme ◽  
Lahiru Udayanga ◽  
Thilan Fernando ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Fish Species ◽  
Biocontrol Potential

scholarly journals Biological Differences between Brackish and Fresh Water-Derived Aedes aegypti from Two Locations in the Jaffna Peninsula of Sri Lanka and the Implications for Arboviral Disease Transmission

PLoS ONE ◽  
2014 ◽  
Vol 9 (8) ◽  
pp. e104977 ◽  
Author(s):  
Ranjan Ramasamy ◽  
Pavilupillai J. Jude ◽  
Thabothiny Veluppillai ◽  
Thampoe Eswaramohan ◽  
Sinnathamby N. Surendran
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Fresh Water ◽  
Disease Transmission ◽  
Arboviral Disease ◽  
Biological Differences

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.

Oviposition preferences of dengue vectors; Aedes aegypti and Aedes albopictus in Sri Lanka under laboratory settings

2017 ◽  
Vol 108 (4) ◽  
pp. 442-450 ◽  
Author(s):  
N. Gunathilaka ◽  
T. Ranathunge ◽  
L. Udayanga ◽  
A. Wijegunawardena ◽  
W. Abeyewickreme
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Aedes Albopictus ◽  
Human Life ◽  
Water Source ◽  
Egg Laying ◽  
Oviposition Behaviour ◽  
Potential Threat ◽  
Female Ratio ◽  
Dengue Vectors

AbstractInvestigations on oviposition behaviour of dengue vectors are critical for effective controlling of vector breeding. Therefore, the aim of the present study was to determine the oviposition behaviour of dengue vectors, Aedes aegypti and Aedes albopictus in Sri Lanka. Batches of 1000 adult mosquitoes (1 : 1, male: female ratio) housed in rearing cages were used for each experimental setup from Ae. aegypti and Ae. albopictus. Oviposition responses with respect to the size of the ovitrap, colours of the ovitrap, water source, sodium chloride (NaCl) concentration and presence/absence of larvae were evaluated by enumerating the number of eggs laid in the ovitraps. The analysis of variance and cluster analysis were used to investigate the significance in the variations among oviposition. The number of eggs laid by both species were improved with the increasing size of ovitraps. Ae. albopictus indicated the highest mean number of eggs in 0.2% of NaCl than in the ovitraps filled with distilled water. However, the egg laying preference was reduced with increasing salinity in both species. Drain water with low dissolved oxygen (DO) level (0.43 ± 0.12 mg l−1) was the preferred water source for both species, while a significantly high oviposition rate was observed in ovitraps with larvae. Black colour ovitraps attracted the majority of gravid females, while white was least preferred. There were no significant variations among oviposition behaviours of Ae. albopictus and Ae. aegypti. The ability of these vectors to breed in waste water with low DO levels may lead them to attain wide dissemination in the natural environment, enhancing their potential threat to human life.

scholarly journals Aedes larval bionomics and implications for dengue control in the paradigmatic Jaffna peninsula, northern Sri Lanka

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Sinnathamby N. Surendran ◽  
Tibutius T. P. Jayadas ◽  
Vaikunthavasan Thiruchenthooran ◽  
Selvarajah Raveendran ◽  
Annathurai Tharsan ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Habitat Preferences ◽  
Habitat Characteristics ◽  
Coastal Zones ◽  
Source Reduction ◽  
Preimaginal Development ◽  
Preimaginal Stages ◽  
Reduction Methods ◽  
Dengue Control

Abstract Background The larval bionomics of Aedes across the Jaffna peninsula in northern Sri Lanka was investigated to obtain information needed for developing more effective larval source reduction measures to control endemic arboviral diseases. Methods The habitats of preimaginal stages of Aedes mosquitoes were surveyed, and ovitrap collections were carried out in densely populated areas of the Jaffna peninsula. Aedes larval productivities were analysed against habitat characteristics, rainfall and dengue incidence. Adults emerging from collected larvae were tested for dengue virus (DENV). Results Only Aedes aegypti, Ae. albopictus and Ae. vittatus were identified in the field habitat collections and ovitraps. Aedes aegypti was the predominant species in both the field habitat and ovitrap collections, followed by Ae. albopictus and small numbers of Ae. vittatus. Tires and open drains were the preferred field habitats for Ae. aegypti, although larval productivity was higher in discarded plastic containers. The three Aedes species differed in field habitat preferences. Concomitant presence of the three Aedes species was observed in the field habitats and ovitraps. Larval productivities were inversely correlated with the salinity of the field habitat. Rainfall in the preceding month significantly correlated with larval productivity in the field habitats. DENV serotype 2 was detected in Ae. aegypti collected from ovitraps in the city of Jaffna. High Breteau, House and Container indices of 5.1, 5.1 and 7.9%, respectively, were observed in the field habitat surveys and ovitrap indices of up to 92% were found in Jaffna city. Conclusions Aedes larval indices in populated areas of the peninsula showed a high potential for dengue epidemics. Unacceptable littering practices, failure to implement existing dengue control guidelines, vertical transmission of DENV in vector mosquitoes and preimaginal development in brackish water and open surface drains, as well as in domestic wells that provide potable water, are serious constraints to the current Aedes larval source reduction methods used to control dengue in the Jaffna peninsula. Similar shortcomings in arboviral disease control are likely present in other resource-constrained tropical coastal zones worldwide.

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