Patterns of phenoloxidase activity in insecticide resistant and susceptible mosquitoes differ between laboratory-selected and wild-caught individuals

Cornet, Stéphane; Gandon, Sylvain; Rivero, Ana

doi:10.1186/1756-3305-6-315

Cited by 33 publications

(41 citation statements)

References 90 publications

(112 reference statements)

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“…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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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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“…As the amount of haemolymph that can be extracted from a single fly is very limited, phenoloxidase activity was quantified from whole individual homogenates (see a similar procedure in Cornet et al, 2013). Flies were crushed individually in 80 μl of cold phosphate-buffered saline (PBS) buffer.…”

Section: Measurement Of Phenoloxidase Activitymentioning

confidence: 99%

Healthier or bigger? Trade‐off mediating male dimorphism in the black scavenger fly Sepsis thoracica (Diptera: Sepsidae)

Busso

Blanckenhorn

González‐Tokman

2017

Ecological Entomology

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1. Life history trade-offs emerge when limited resources are allocated to multiple functions of an organism. Under highly competitive conditions trade-offs can result in alternative phenotypes that differ morphologically and physiologically. Such is the case in insect species that grow under high densities, where competition for resources but also the risk of disease contagion is high, prompting important adjustments in immune response and melanic cuticular pigmentation, with consequent sacrifices in other fitness-related traits.2. In the present study, the potential trade-offs between total-and active phenoloxidase (PO), body size and body pigmentation in Sepsis thoracica black scavenger flies that show alternative male morphs differing in cuticular pigmentation, and body size were evaluated.3. As expected, small/dark (obsidian) males showed higher total-PO activity than larger/orange (amber) males. A negative relationship was found between total-PO activity and body size in females and obsidian but not amber males, suggesting that growth and immunity are more costly for the former. In contrast, density did not affect PO activity, as predicted by the density-dependent prophylaxis hypothesis, which had not been tested in dipterans before. However, rearing density did affect the body size negatively in females and amber but not obsidian males, showing that male morph is largely determined by condition-dependent plasticity rather than genes.4. This study provides good evidence that trade-offs between different life-history traits can result in alternative resource allocation strategies, even within one species. These strategies can produce strikingly different alternative phenotypes, evincing that there is not only one optimal solution to address fitness optimisation.

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“…), indicating that stressors affecting this pathway, may also have effects on vector competence (Cornet et al. ).…”

Section: Introductionmentioning

confidence: 99%

Synthetic predator cues impair immune function and make the biological pesticide Bti more lethal for vector mosquitoes

Beeck

Janssens

Stoks

2016

Ecological Applications

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The control of vector mosquitoes is one of the biggest challenges facing humankind with the use of chemical pesticides often leading to environmental impact and the evolution of resistance. Although to a lesser extent, this also holds for Bacillus thuringiensis israelensis (Bti), the most widely used biological pesticide to control mosquito populations. This raises the need for the development of integrated pest management strategies that allow the reduction of Bti concentrations without loss of the mosquito control efficiency. To this end, we tested in a laboratory experiment the combined effects of larval exposure to a sublethal Bti concentration and predation risk cues on life history and physiology of larval and adult Culex pipiens mosquitoes. Besides natural predator kairomones and prey alarm cues, we also tested synthetic kairomones of Notonecta predators. Neither Bti nor predation risk cues affected mortality, yet when both stressors were combined mortality increased on average by 133% compared to the treatment with only predation risk cues. This synergistic interaction was also present when Bti was combined with synthetic kairomones. This was further reflected in changes of the composite index of population performance, which suggested lowered per capita growth rates in mosquitoes exposed to Bti but only when Bti was combined with synthetic kairomones. Furthermore, predation risk cues shortened larval development time, reduced mass at metamorphosis in males, and had an immunosuppressive effect in larval and adult mosquitoes which may affect the mosquito vector competence. We provide the first demonstration that synthetic kairomones may generate similar effects on prey as natural kairomones. The identified immunosuppressive effect of synthetic kairomones and the novel lethal synergism type between a biological pesticide and synthetic predator kairomones provide an important proof of principle illustrating the potential of this combination for integrated mosquito control and should in a next step be evaluated under more natural conditions. It may guide novel integrated pest management programs with Bti that incorporate synthetic kairomones and thereby can reduce environmental impact and evolution of resistance creating more efficient and sustainable mosquito control.

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Patterns of phenoloxidase activity in insecticide resistant and susceptible mosquitoes differ between laboratory-selected and wild-caught individuals

Cited by 33 publications

References 90 publications

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

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

Healthier or bigger? Trade‐off mediating male dimorphism in the black scavenger fly Sepsis thoracica (Diptera: Sepsidae)

Synthetic predator cues impair immune function and make the biological pesticide Bti more lethal for vector mosquitoes

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