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 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

Comparison of the Effect of Insecticides on Bumble Bees (Bombus impatiens) and Mosquitoes (Aedes aegypti and Culex quinquefasciatus) by Standard Mosquito Research Methods

2020 ◽  
Author(s):  
Bethany L McGregor ◽  
Bryan V Giordano ◽  
Alfred E Runkel ◽  
Herbert N Nigg ◽  
H Lee Nigg ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Culex Quinquefasciatus ◽  
Mosquito Control ◽  
The United States ◽  
Field Trials ◽  
Bombus Impatiens ◽  
Acute Effects ◽  
Nontarget Effects ◽  
Native North American ◽  
Significant Mortality

Abstract Mosquito control districts in the United States are limited to two main classes of adulticides, pyrethroids and organophosphates, to control mosquitoes. Two adulticides used to control domestic mosquitoes are Fyfanon EW (malathion, organophosphate) and DeltaGard (deltamethrin, pyrethroid). While the effect of these pesticides on European honeybees (Apis mellifera L., Hymenoptera: Apidae) has been investigated, effects on native pollinators need additional research. The purpose of this study was to investigate the acute nontarget effects of these pesticides on Bombus impatiens Cresson (Hymenoptera: Apidae), a native North American bumble bee species, and compare these effects to wild and laboratory strains of mosquitoes (Aedes aegypti (L.) and Culex quinquefasciatus Say, Diptera: Culicidae) through field and laboratory assays. Bombus impatiens was found to be resistant to Fyfanon EW (x̅ = 6.7% mortality at 50-µg malathion per bottle) at levels that caused significant mortality to study mosquitoes (86.2 ≥ x̅ ≥ 100% mortality) in laboratory bottle bioassays. Comparatively, B. impatiens demonstrated greater mortality to DeltaGard (93.3%) at 2.5-µg deltamethrin/bottle than any mosquito colony assayed (14.1 ≥ x̅ ≥ 87.0% mortality). Only DeltaGard was tested in field applications. In the field, we observed acute effects of DeltaGard on mosquitoes and B. impatiens at 25- and 75-m distance from a truck-mounted ultra-low volume fogger, although treatment effects were not significant for B. impatiens. Additional wild-caught nontarget mortality to DeltaGard field trials was also evaluated. This study indicated that common mosquito control adulticides do cause nontarget mortality to B. impatiens but that impacts are variable depending on pesticide and further studies are needed.

scholarly journals Wolbachia strain wAu efficiently blocks arbovirus transmission in Aedes albopictus

2019 ◽  
Author(s):  
Maria Vittoria Mancini ◽  
Christie S. Herd ◽  
Thomas H. Ant ◽  
Shivan M. Murdochy ◽  
Steven P. Sinkins
Keyword(s):  
Aedes Aegypti ◽  
Aedes Albopictus ◽  
Mosquito Species ◽  
Field Trials ◽  
Asian Tiger Mosquito ◽  
Native Strain ◽  
Promising Tool ◽  
Novel Approach ◽  
Asian Tiger ◽  
Tiger Mosquito

AbstractThe global incidence of arboviral diseases transmitted by Aedes mosquitoes, including dengue, chikungunya, yellow fever, and Zika, has increased dramatically in recent decades. The release of Aedes aegypti carrying the maternally inherited symbiont Wolbachia as an intervention to control arboviruses is being trialled in several countries. However, these efforts are compromised in many endemic regions due to the co-localization of the secondary vector Aedes albopictus, the Asian tiger mosquito. Ae. albopictus has an expanding global distribution following incursions into a number of new territories. To date, only the wMel and wPip strains of Wolbachia have been reported to be transferred into and characterized in this vector. A Wolbachia strain naturally infecting Drosophila simulans, wAu, was selected for transfer into a Malaysian Ae. albopictus line to create a novel triple-strain infection. The newly generated line showed self-compatibility, moderate fitness cost and complete resistance to Zika and dengue infections.Author summaryAedes albopictus, the invasive Asian tiger mosquito, is responsible for numerous outbreaks of important viruses such as dengue and Zika in various regions of the world. The need for alterative control interventions propelled the development of a novel approach that exploits a natural insect symbiont, Wolbachia; when transferred into non-native hosts, these maternally-inherited bacteria are able to interfere with the transmission of mosquito-borne viruses, and also provide reproductive advantages to the host, offering a promising tool for self-sustaining field applications. Currently, several field trials are ongoing for the primary vector of dengue and several other arboviruses, Aedes aegypti, providing encouraging results. In this study, Ae. albopictus has been targeted for a similar approach: this mosquito species naturally carries two strains of Wolbachia. The artificial introduction of a third, non-native strain made this line less able to transmit dengue and Zika viruses and had an impact on its fitness.

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 Morphological identification keys for adults of sand flies (Diptera: Psychodidae) in Sri Lanka

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Tharaka Wijerathna ◽  
Nayana Gunathilaka
Keyword(s):  
Sri Lanka ◽  
Species Abundance ◽  
Morphological Features ◽  
Control Measures ◽  
Sand Fly ◽  
Health Staff ◽  
Morphological Identification ◽  
Sand Flies ◽  
Identification Keys ◽  
Control Programmes

Abstract Background Phlebotomine sand flies are a medically important group of insects that is responsible for the transmission of leishmaniasis. Surveillance plays a major role in vector control programmes through exploring species abundance, potential entomological risk and designing appropriate control measures. In field surveillance programmes of such nature, morphological identification of vector species is of paramount importance. However, in Sri Lanka, there is no published taxonomic key available for the identification of leishmaniasis vectors. Method Identification keys for both male and females of the sand flies recorded in Sri Lanka were developed using morphological features. Main identification features were compared with the original observation of specimens collected from surveys and the use of published literature. Photographic illustrations of morphological features are included with the intention of making the keys user-friendly for non-taxonomists. Results A total of 22 sand fly species (Diptera: Psychodidae) of the genera Phlebotomus and Sergentomyia reported in Sri Lanka from 1910 to 2019 are included in the present work. Conclusion This simplified key, along with photographs taken from specimens would be beneficial to the health staff, entomologists and research staff who deal with leishmaniasis control programmes and vector-related studies.

scholarly journals Modeling confinement and reversibility of threshold-dependent gene drive systems in spatially-explicit Aedes aegypti populations

2019 ◽  
Author(s):  
Héctor M. Sánchez C. ◽  
Jared B. Bennett ◽  
Sean L. Wu ◽  
Gordana Rašić ◽  
Omar S. Akbari ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Disease Transmission ◽  
Release Site ◽  
Field Trials ◽  
Mosquito Vector ◽  
Gene Drive ◽  
Isolated Populations ◽  
Dependent Behavior ◽  
Wide Scale ◽  
Drive Systems

AbstractBackgroundThe discovery of CRISPR-based gene editing and its application to homing-based gene drive systems has been greeted with excitement, for its potential to control mosquito-borne diseases on a wide scale, and concern, for the invasiveness and potential irreversibility of a release. Gene drive systems that display threshold-dependent behavior could potentially be used during the trial phase of this technology, or when localized control is otherwise desired, as simple models predict them to spread into partially isolated populations in a confineable manner, and to be reversible through releases of wild-type organisms. Here, we model hypothetical releases of two recently-engineered threshold-dependent gene drive systems - reciprocal chromosomal translocations and a form of toxin-antidote-based underdominance known as UDMEL - to explore their ability to be confined and remediated.ResultsWe simulate releases of Aedes aegypti, the mosquito vector of dengue, Zika and other arboviruses, in Yorkeys Knob, a suburb of Cairns, Australia, where previous biological control interventions have been undertaken on this species. We monitor spread to the neighboring suburb of Trinity Park to assess confinement. Results suggest that translocations could be introduced on a suburban scale, and remediated through releases of non-disease-transmitting male mosquitoes with release sizes on the scale of what has been previously implemented. UDMEL requires fewer releases to introduce, but more releases to remediate, including of females capable of disease transmission. Both systems are expected to be confineable to the release site; however, spillover of translocations into neighboring populations is less likely.ConclusionsOur analysis supports the use of translocations as a threshold-dependent drive system capable of spreading disease-refractory genes into Ae. aegypti populations in a confineable and reversible manner. It also highlights increased release requirements when incorporating life history and population structure into models. As the technology nears implementation, further ecological work will be essential to enhance model predictions in preparation for field trials.

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.

Clinical Breathing Mechanics Differ Based on Test and Position

2019 ◽  
Vol 28 (6) ◽  
pp. 635-639
Author(s):  
Hannah Horris ◽  
Barton E. Anderson ◽  
R. Curtis Bay ◽  
Kellie C. Huxel Bliven
Keyword(s):  
Multiple Testing ◽  
Body Position ◽  
Statistical Significance ◽  
Pairwise Comparison ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Postural Changes ◽  
Breathing Mechanics ◽  
Test Position ◽  
Cage Migration

Context: Altered diaphragm function is linked to decreased core stabilization, postural changes, and decreased function. Two clinical tests used to assess breathing are the Hi-lo and lateral rib expansion (LRE) tests. It is currently unknown how breathing classification based on these tests differ and how their results are affected by varying test positions. Objective: To compare the results of breathing tests when conducted in varying test positions. Design: Prospective cross-sectional study. Setting: University laboratory. Participants: A total of 50 healthy adults (females 31 and males 29; age 29.3 [4.1] y; height 170.0 [10.4] cm; weight70.7 [15.1] kg). Intervention(s): Hi-lo and LRE tests in supine, seated, standing, and half-kneeling body positions. All tests were recorded and later scored by a single examiner. A generalized estimating equations approach with breathing test and body position as factors was used for analysis. Pairwise comparison with Bonferroni correction was used to adjust for multiple tests. Statistical significance was set at P = .05, 2 tailed. Main Outcome Measures: Hi-lo and LRE tests were scored based on the presence or absence of abdominal excursion, LRE, and superior rib cage migration. Following scoring, results were classified as functional or dysfunctional based on observation of these criteria. Results: A significant breathing test × test position interaction (P < .01) was noted, as well as main effects for test (P < .01) and test position (P < .01). All Hi-lo test positions identified significantly more dysfunctional breathers in positions of increased stability demand (P < .01), except between standing and half-kneeling positions (P = .52). In the LRE test, all positions were similar (P > .99) except for half-kneeling, which was significantly different from all other positions (P < .01). Conclusions: The Hi-lo test and LRE tests assess different breathing mechanics. Clinicians should use these tests in combination to gain a comprehensive understanding of a person’s breathing pattern. The Hi-lo test should be administered in multiple testing positions.

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