scholarly journals Microbes increase thermal sensitivity in the mosquito Aedes aegypti, with the potential to change disease distributions

2021 ◽  
Vol 15 (7) ◽  
pp. e0009548
Author(s):  
Fhallon Ware-Gilmore ◽  
Carla M. Sgrò ◽  
Zhiyong Xi ◽  
Heverton L. C. Dutra ◽  
Matthew J. Jones ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Thermal Tolerance ◽  
Biological Control Agent ◽  
Thermal Sensitivity ◽  
Virus Transmission ◽  
Denv Infection ◽  
Control Agent ◽  
Thermal Limits ◽  
Primary Vector ◽  
Global Mean

The mosquito Aedes aegypti is the primary vector of many disease-causing viruses, including dengue (DENV), Zika, chikungunya, and yellow fever. As consequences of climate change, we expect an increase in both global mean temperatures and extreme climatic events. When temperatures fluctuate, mosquito vectors will be increasingly exposed to temperatures beyond their upper thermal limits. Here, we examine how DENV infection alters Ae. aegypti thermotolerance by using a high-throughput physiological ‘knockdown’ assay modeled on studies in Drosophila. Such laboratory measures of thermal tolerance have previously been shown to accurately predict an insect’s distribution in the field. We show that DENV infection increases thermal sensitivity, an effect that may ultimately limit the geographic range of the virus. We also show that the endosymbiotic bacterium Wolbachia pipientis, which is currently being released globally as a biological control agent, has a similar impact on thermal sensitivity in Ae. aegypti. Surprisingly, in the coinfected state, Wolbachia did not provide protection against DENV-associated effects on thermal tolerance, nor were the effects of the two infections additive. The latter suggests that the microbes may act by similar means, potentially through activation of shared immune pathways or energetic tradeoffs. Models predicting future ranges of both virus transmission and Wolbachia’s efficacy following field release may wish to consider the effects these microbes have on host survival.

scholarly journals Observations on the predatory potential of Lutzia fuscana on Aedes aegypti larvae: implications for biological control (Diptera: Culicidae)

2016 ◽  
Vol 48 (2) ◽  
pp. 137
Author(s):  
Soujita Pramanik ◽  
Sampa Banerjee ◽  
Soumyajit Banerjee ◽  
Goutam K. Saha ◽  
Gautam Aditya
Keyword(s):  
Biological Control ◽  
Aedes Aegypti ◽  
Biological Control Agent ◽  
Instar Larva ◽  
Control Agent ◽  
The Body ◽  
Larval Habitats ◽  
Larval Stages ◽  
Augmentative Release ◽  
Predatory Potential

Among the natural predators, larval stages of the mosquito <em>Lutzia fuscana (</em>Wiedemann, 1820) (Diptera: Culicidae) bear potential as a biological control agent of mosquitoes. An estimation of the predatory potential of the larva of <em>L. fuscana</em> against the larva of the dengue vector <em>Aedes aegypti</em> (Linnaeus, 1762) (Diptera: Culicidae) was made to highlight its use in vector management. Laboratory experiments revealed that the larva of<em> L</em>. <em>fuscana</em> consumes 19 to 24 <em>A. aegypti</em> larvae per day, during its tenure as IV instar larva. The consumption of <em>A. aegypti</em> larvae was proportionate to the body length (BL) and body weight (BW) of the predatory larva<em> L. fuscana</em> as depicted through the logistic regressions: y = 1 / (1 + exp(-(-2.09 + 0.35*BL))) and y = 1 / (1 + exp(-(0.4+ 0.06*BW))). While the prey consumption remained comparable among the days, the net weight gained by the <em>L</em>. <em>fuscana</em> larva showed a decreasing trend with the age. On the basis of the results, it is apparent that the larva of the mosquito <em>L. fuscana</em> can be used in the regulation of the mosquito <em>A. aegypti</em> through augmentative release, particularly, in the smaller mosquito larval habitats.

scholarly journals Field- and clinically derived estimates of Wolbachia-mediated blocking of dengue virus transmission potential in Aedes aegypti mosquitoes

2017 ◽  
Vol 115 (2) ◽  
pp. 361-366 ◽  
Author(s):  
Lauren B. Carrington ◽  
Bich Chau Nguyen Tran ◽  
Nhat Thanh Hoang Le ◽  
Tai Thi Hue Luong ◽  
Truong Thanh Nguyen ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Dengue Virus ◽  
Virus Transmission ◽  
Field Testing ◽  
Denv Infection ◽  
Ho Chi Minh City ◽  
Wild Type ◽  
Transmission Potential ◽  
Blood Meals ◽  
Increased Susceptibility

The wMel strain of Wolbachia can reduce the permissiveness of Aedes aegypti mosquitoes to disseminated arboviral infections. Here, we report that wMel-infected Ae. aegypti (Ho Chi Minh City background), when directly blood-fed on 141 viremic dengue patients, have lower dengue virus (DENV) transmission potential and have a longer extrinsic incubation period than their wild-type counterparts. The wMel-infected mosquitoes that are field-reared have even greater relative resistance to DENV infection when fed on patient-derived viremic blood meals. This is explained by an increased susceptibility of field-reared wild-type mosquitoes to infection than laboratory-reared counterparts. Collectively, these field- and clinically relevant findings support the continued careful field-testing of wMel introgression for the biocontrol of Ae. aegypti-born arboviruses.

A simple method for the detection of Leptolegnia chapmanii from infected Aedes aegypti larvae

2013 ◽  
Vol 59 (6) ◽  
pp. 425-429 ◽  
Author(s):  
Renan N. Leles ◽  
Cláudia C. López Lastra ◽  
Juan J. García ◽  
Éverton K.K. Fernandes ◽  
Christian Luz
Keyword(s):  
Aedes Aegypti ◽  
Biological Control Agent ◽  
Field Tests ◽  
Water Film ◽  
Control Agent ◽  
Significant Progress ◽  
Simple Method ◽  
Large Numbers ◽  
Simplified Method ◽  
Leptolegnia Chapmanii

Significant progress in developing Leptolegnia chapmanii as a biological control agent against mosquitoes will be accelerated by improved and simpler methods to detect and to isolate this virulent and rapidly lethal watermold from field-collected mosquito larvae. To date, however, this oomycete has remained understudied and little used. This study presents a simplified method to detect Leptolegnia in infected Aedes aegypti larvae. The development of L. chapmanii inside mosquitoes is easily monitored when pathogen-treated larvae are quasi-immobilized for an initial 48 h in the water film on plates of water agar amended with antibiotic (chloramphenicol, 0.5–1 g/L) and fungicide (thiabendazole, 4–8 g/L) and then transferred to a larger volume of water for an additional 48 h. Surprisingly, chloramphenicol stimulated oosporogenesis by L. chapmanii. The method permits processing of large numbers of A. aegypti and other culicid larvae and is useful for both obtaining new strains and also monitoring the efficacy of L. chapmanii during field tests.

Action of Metarhizium brunneum (Hypocreales: Clavicipitaceae) Against Organophosphate- and Pyrethroid-Resistant Aedes aegypti (Diptera: Culicidae) and the Synergistic Effects of Phenylthiourea

2019 ◽  
Author(s):  
Rodrigo Prado ◽  
Pãmella A Macedo-Salles ◽  
Rodrigo C Duprat ◽  
Andrea R S Baptista ◽  
Denise Feder ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Biological Control Agent ◽  
Synergistic Effects ◽  
Biological Effects ◽  
Survival Rates ◽  
Resistance Mechanisms ◽  
Control Agent ◽  
Cross Resistance ◽  
Synergistic Activity ◽  
Metarhizium Brunneum

Abstract Dengue, yellow fever, Zika, and chikungunya arboviruses are endemic in tropical countries and are transmitted by Aedes aegypti. Resistant populations of this mosquito against chemical insecticides are spreading worldwide. This study aimed to evaluate the biological effects of exposure of pesticide-sensitive Ae. aegypti larvae (Rockefeller) to conidia of the entomopathogen, Metarhizium brunneum, laboratory strains ARSEF 4556 and V275, and any synergistic activity of phenylthiourea (PTU). In addition, to investigate the nature of any cross-resistance mechanisms, these M. brunneum strains were tested against the Rockefeller larvae and two temephos- and deltamethrin-resistant wild mosquito populations from Rio de Janeiro. Treatment of Rockefeller larvae with 106 conidia/ml of ARSEF 4556 and V275 fungal strains resulted in significant decreased survival rates to 40 and 53.33%, respectively (P < 0.0001), compared with untreated controls. In contrast, exposure to 104 or 105 conidia/ml showed no such significant survival differences. However, the addition of PTU to the conidia in the bioassays significantly increased mortalities in all groups and induced a molt block. Experiments also showed no differences in Ae. aegypti mortalities between the fungal treated, wild pesticide-resistant populations and the Rockefeller sensitive strain. The results show the efficacy of M. brunneum in controlling Ae. aegypti larvae and the synergistic role of PTU in this process. Importantly, there was no indication of any cross-resistance mechanisms between Ae. aegypti sensitive or resistant to pesticides following treatment with the fungi. These results further support using M. brunneum as an alternative biological control agent against mosquito populations resistant to chemical insecticides.

scholarly journals Establishment of Wolbachia strain wAlbB in Malaysian populations of Aedes aegypti for dengue control

2019 ◽  
Author(s):  
W. A. Nazni ◽  
A. A. Hoffmann ◽  
A. Noor Afizah ◽  
Y. L. Cheong ◽  
M. V. Mancini ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Virus Transmission ◽  
Larval Rearing ◽  
Kuala Lumpur ◽  
Novel Approach ◽  
Dengue Transmission ◽  
Vector Mosquito ◽  
Primary Vector ◽  
Dengue Control ◽  
Very High

AbstractDengue has enormous health impacts globally. A novel approach to decrease dengue incidence involves the introduction of Wolbachia endosymbionts that block dengue virus transmission into populations of the primary vector mosquito, Aedes aegypti. The wMel Wolbachia strain has previously been trialed in open releases of Ae. aegypti; however the wAlbB strain has been shown to maintain higher density than wMel at high larval rearing temperatures. Releases of Ae. aegypti mosquitoes carrying wAlbB were carried out in 6 diverse sites in greater Kuala Lumpur, Malaysia, with high endemic dengue transmission. The strain was successfully established and maintained at very high population frequency at some sites, or persisted with additional releases following fluctuations at other sites. Based on passive case monitoring, reduced human dengue incidence was observed in the release sites when compared to control sites. The wAlbB strain of Wolbachia provides a promising option as a tool for dengue control, particularly in very hot climates.

scholarly journals Ascogregarina Taiwanensis Interfere in the Performance of Aedes Albopictus and in the Susceptibility of Aedes Aegypti to Temephos and Azadirachta Indica Oil

2021 ◽  
Author(s):  
Josiane Somariva Prophiro ◽  
Thiago Nunes Pereira ◽  
Joice Guilherme de Oliveira ◽  
Felipe Allan Silva da Costa ◽  
Harry Luiz Pilz Júnior ◽  
...  
Keyword(s):  
Biological Control ◽  
Aedes Aegypti ◽  
Aedes Albopictus ◽  
Azadirachta Indica ◽  
Biological Control Agent ◽  
Negative Influence ◽  
Control Agent ◽  
Chemical Insecticide ◽  
Different Types ◽  
Ascogregarina Taiwanensis

Abstract Background: Aedes albopictus and Aedes aegypti are mosquitoes commonly adapted to tropical and subtropical regions. These vectors can transmit different types of arboviruses causing a serious concern to public health. New alternatives for the vector/arboviruses control are emerging, and in this sense the protozoan Ascogregarina taiwanensis may present potential as a biological control agent against these mosquitoes. Methods: To evaluate the effects of protozoan A. taiwanensis, mosquitoes were parasitized with a solution containing oocysts and evaluated to lifetime, fertility, fecundity for Ae. albopictus and for Ae. aegypti interaction with Azadirachta indica and Temephos. Results: In this work it was possible to observe the protozoan morphology in mosquitoes Ae. albopictus, as well its negative influence on mortality, 73% and non-parasitized was 44%. The number of eggs oviposited by parasitized females of Ae. albopictus was lower (3,490) than for the non-parasitized females (5,586). In addition, the hatchability and/or viability of these eggs were also lower for the parasitized females (63%) than the non-parasitized ones (74%). For Ae. aegypti mosquitoes, a synergism between the use of A. taiwanensis associated with a chemical insecticide and a botanical insecticide was observed. The results demonstrate that when Ae. aegypti larvae was parasitized by A. taiwanensis and exposed to the oil of Az. indica or to the organophosphate Temephos present a greater mortality. Conclusion: It was notable that A. taiwanensis can be a potential for biological control and adjuvant of insecticides. We also provide important information about the maintenance of A. taiwanensis in laboratory.

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