Larval rearing temperature influences the effect of malathion on Aedes aegypti life history traits and immune responses

Muturi, Ephantus J.

doi:10.1016/j.chemosphere.2013.01.055

Cited by 16 publications

(14 citation statements)

References 34 publications

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“…tarsalis (Dodson et al 2012), temperatures between the 2 media in this experiment were similar. Although treatment with pesticides has been associated with faster growth in surviving mosquito larvae due potentially to competitive release (Muturi 2013), the lack of difference in wing size with Bti concentration here does not support this hypothesis. In addition, the significant effect of Bti on develop- Table 2.…”

Section: Discussioncontrasting

confidence: 57%

The Efficacy of the Bacillus thuringiensis israelensis Larvicide Against Culex tarsalis in Municipal Wastewater and Water from Natural Wetlands

Dawson¹,

Salice²,

Subbiah³

2019

Journal of the American Mosquito Control Association

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Water quality is a factor that is likely to interact with the activity of Bacillus thuringiensis israelensis (Bti)-based mosquito larvicides. High rates of adsorption to dense particulate matter and toxin degradation in water may be expected to reduce Bti effectiveness. Therefore, water from wastewater lagoons may serve as a protective habitat for mosquito larvae against Bti larvicides relative to natural wetlands. We conducted a study in which we exposed larvae of Culex tarsalis to various concentrations of Bti in water collected from an urban wetlands and an urban wastewater pond. We used survival analysis and a comparison of life-history characteristics to assess the effects of aquatic media on the relative efficacy of Bti and on fitness indicators. In our study, mosquitoes reared in wastewater and exposed to high (100% of minimum field application rate) and medium (50% of minimum field application rate) concentrations of Bti experienced significantly higher mortality than mosquitoes exposed to corresponding concentrations but reared in water from natural urban wetlands. In addition, females that emerged from wastewater had shorter wings than those that emerged from wetland-collected water. These effects may have been due to higher turbidity and higher ionic concentrations in wastewater than water from natural wetlands.

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Section: Discussioncontrasting

confidence: 57%

The Efficacy of the Bacillus thuringiensis israelensis Larvicide Against Culex tarsalis in Municipal Wastewater and Water from Natural Wetlands

Dawson¹,

Salice²,

Subbiah³

2019

Journal of the American Mosquito Control Association

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“…Second, detoxifying insecticides may use processes that are also involved in the immune response. For example, exposure to insecticides leads to the long-lasting expression of genes, like defensin, that are involved in the mosquito's immune responses 38 . Furthermore, several studies reported links between metabolic resistance to insecticides and immunocompetence: phenoloxidase (an enzyme that plays a central role in melanisation 27 and contributes to antibacterial defense 40 ) is more active in resistant Culex pipiens mosquitoes 41 and Plutella xylostella moths 42 than in sensitive ones, several antimicrobial peptides (AMP) are expressed more strongly in resistant Culex pipiens and Anopheles gambiae 43,44 , and nitric oxide synthase is expressed more in resistant than in sensitive Anopheles stephensi 45 .…”

Section: Discussionmentioning

confidence: 99%

Larval exposure to a pyrethroid insecticide and competition for food modulate the melanisation and antibacterial responses of adult Anopheles gambiae

Hauser

Koella

2020

Sci Rep

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the insecticides we use for agriculture and for vector control often arrive in water bodies, where mosquito larvae may be exposed to them. Not only will they then likely affect the development of the larvae, but their effects may carry over to the adults, potentially affecting their capacity at transmitting infectious diseases. Such an impact may be expected to be more severe when mosquitoes are undernourished. in this study, we investigated whether exposing larvae of the mosquito Anopheles gambiae to a sub-lethal dose of permethrin (a pyrethroid) and forcing them to compete for food would affect the immune response of the adults. We found that a low dose of permethrin increased the degree to which individually reared larvae melanised a negatively charged Sephadex bead and slowed the replication of injected Escherichia coli. However, if mosquitoes had been reared in groups of three (and thus had been forced to compete for food) permethrin had less impact on the efficacy of the immune responses. Our results show how larval stressors can affect the immune response of adults, and that the outcome of exposure to insecticides strongly depends on environmental conditions.The immune system of mosquito vectors underlies their susceptibility to parasites, and thus their ability to transmit pathogens to humans 1,2 . While the strength of their immune response has a strong genetic component 3 , it is also influenced by the environment. Adult Anopheles gambiae, for example, have a less effective melanisation response if they were undernourished as larvae 4 . Correspondingly, the ability to transmit pathogens is influenced by the environment. Examples are that vectorial competence is influenced by the bacterial microbiota the mosquitoes acquire as larvae 5 , and that the susceptibility of Aedes mosquitoes to arboviruses and of Anopheles mosquitoes to malaria parasites depend on the temperature and food conditions during larval development 6-8 .One aspect of the environment that is becoming increasingly important is the presence of insecticides. Because insecticides are used extensively in agriculture and vector control, they are often found in water of agricultural areas 9 , where mosquito larvae are exposed to them. Although their concentration is often so low that they do not kill the larvae, they affect the mosquitoes' development. In particular, their effects can carry over to adults to influence their life-history traits (reproductive success, adult longevity, sex ratio 10-13 ) and their vectorial competence for arboviruses 14,15 and malaria 16,17 .Such effects of sub-lethal doses of insecticides on vectorial competence are likely to be linked to their impact on the immune response. Indeed, exposure to insecticides affects the immune response of insects in several ways 18 : botanical insecticides 19,20 , an insect growth regulator 21 and a pyrethroid 22 decrease the activity of phenoloxidase (which is involved in the melanisation immune response) and botanical insecticides 23 , organophosphates and organochlorines 24 aff...

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“…One possible explanation for this is that bacterial clearance was assessed 24 hr after challenge, by which time the induced immune system should also be activated (Haine, Moret, Siva‐Jothy, & Rolff, 2008) and production of antimicrobial peptides upregulated. These components of the induced immune system could trade‐off with constitutive measures (Cotter, Kruuk, & Wilson, 2004; Cotter et al., 2008) or have very different thermal sensitivities to the innate components that we measured (Muturi, 2013; Muturi, Nyakeriga, & Blackshear, 2012), resulting in a reduction in the effectiveness of larval resistance. The impact of temperature on pathogen population dynamics is also likely to be important in determining the thermal sensitivity of infection.…”

Section: Discussionmentioning

confidence: 99%

Responses to a warming world: Integrating life history, immune investment, and pathogen resistance in a model insect species

Laughton

O'Connor

Knell

2017

Ecology and Evolution

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Environmental temperature has important effects on the physiology and life history of ectothermic animals, including investment in the immune system and the infectious capacity of pathogens. Numerous studies have examined individual components of these complex systems, but little is known about how they integrate when animals are exposed to different temperatures. Here, we use the Indian meal moth (Plodia interpunctella) to understand how immune investment and disease resistance react and potentially trade‐off with other life‐history traits. We recorded life‐history (development time, survival, fecundity, and body size) and immunity (hemocyte counts, phenoloxidase activity) measures and tested resistance to bacterial (E. coli) and viral (Plodia interpunctella granulosis virus) infection at five temperatures (20–30°C). While development time, lifespan, and size decreased with temperature as expected, moths exhibited different reproductive strategies in response to small changes in temperature. At cooler temperatures, oviposition rates were low but tended to increase toward the end of life, whereas warmer temperatures promoted initially high oviposition rates that rapidly declined after the first few days of adult life. Although warmer temperatures were associated with strong investment in early reproduction, there was no evidence of an associated trade‐off with immune investment. Phenoloxidase activity increased most at cooler temperatures before plateauing, while hemocyte counts increased linearly with temperature. Resistance to bacterial challenge displayed a complex pattern, whereas survival after a viral challenge increased with rearing temperature. These results demonstrate that different immune system components and different pathogens can respond in distinct ways to changes in temperature. Overall, these data highlight the scope for significant changes in immunity, disease resistance, and host–parasite population dynamics to arise from small, biologically relevant changes to environmental temperature. In light of global warming, understanding these complex interactions is vital for predicting the potential impact of insect disease vectors and crop pests on public health and food security.

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Larval rearing temperature influences the effect of malathion on Aedes aegypti life history traits and immune responses

Cited by 16 publications

References 34 publications

The Efficacy of the Bacillus thuringiensis israelensis Larvicide Against Culex tarsalis in Municipal Wastewater and Water from Natural Wetlands

The Efficacy of the Bacillus thuringiensis israelensis Larvicide Against Culex tarsalis in Municipal Wastewater and Water from Natural Wetlands

Larval exposure to a pyrethroid insecticide and competition for food modulate the melanisation and antibacterial responses of adult Anopheles gambiae

Responses to a warming world: Integrating life history, immune investment, and pathogen resistance in a model insect species

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