Daily temperature variation magnifies the toxicity of a mixture consisting of a chemical pesticide and a biopesticide in a vector mosquito

Delnat, Vienna; Tran, Tam T.; Janssens, Lizanne; Stoks, Robby

doi:10.1016/j.scitotenv.2018.12.332

Cited by 30 publications

(27 citation statements)

References 56 publications

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“…The only positive effect of CPF exposure was the increased growth rate at the high CPF concentration, which may indicate an escape response toward the terrestrial adult stage. Similar escape responses where semi-aquatic insects accelerated growth and development to avoid aquatic exposure to CPF have been documented in the study species (Delnat et al, 2019), and in other taxa such as damselfly larvae (Janssens and Stoks, 2013b) and fiddler crabs (Weis and Mantel, 1976). However, note that this increased growth rate did not occur at a low CPF concentration which can be explained on the one hand by the magnitude of the stressor not being high enough to cause this escape response or on the other hand that survival selection retained only survivors of high quality.…”

Section: Effects Of Chlorpyrifos In the Absence Of Warmingsupporting

confidence: 76%

Whether warming magnifies the toxicity of a pesticide is strongly dependent on the concentration and the null model

2019

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How global warming changes the toxicity of contaminants is a research priority at the intersection of global change biology and ecotoxicology. While many pesticides are more toxic at higher temperatures this is not always detected. We studied whether deviations from this general pattern can be explained by concentration-dependent interaction effects and by testing the interaction against the inappropriate null model. We exposed larvae of the mosquito Culex pipiens to three concentrations of the pesticide chlorpyrifos (absence, low and high) in the absence and presence of 4°C warming. Both the low and high chlorpyrifos concentration were lethal and generated negative sublethal effects: activity of acetylcholinesterase (AChE) and total fat content decreased, and oxidative damage to lipids increased, yet growth rate increased. Warming was slightly lethal, yet had positive sublethal effects: growth rate, total fat content and metabolic rate increased, and oxidative damage decreased. For four out of seven response variables the independent action model identified the expected synergistic interaction between chlorpyrifos and warming. Notably, for three variables (survival, AChE and fat content) this was strongly dependent on the chlorpyrifos concentration, and for two of these (AChE and fat content) not associated with a significant interaction in the general(ized) linear models. For survival and fat content, warming only potentiated chlorpyrifos (CPF) toxicity at the low CPF concentration, while the opposite was true for AChE. Our results highlight that taking into account concentration-dependence and appropriate null model testing is crucial to improve our understanding of the toxicity of contaminants in a warming world.

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Section: Effects Of Chlorpyrifos In the Absence Of Warmingsupporting

confidence: 76%

Whether warming magnifies the toxicity of a pesticide is strongly dependent on the concentration and the null model

2019

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“…This antagonistic interaction is in contrast with the additive effects for mortality in Culex pipiens between the organophosphate malathion and Bti (Mansour et al, 2012), and between CPF and Bti at a constant temperature of 20°C (Delnat et al, 2019). The different interaction effect between the pesticides in the study by Delnat et al (2019) compared to the current study might be explained by the following three differences: (i) a higher mean temperature was used in the current experiment (24°C instead of 20°C in the previous study) which can influence the degradation rates, (ii) a difference in the pesticide exposure regime with in the current experiment two pesticide renewals instead of only one which influences the time that both pesticides are simultaneously present, and (iii) a difference in the presence of food whereby in the current experiment ad libitum food was given thereby stimulating filter feeding which is the main uptake mechanism of Bti instead of no food in the previous study. Our finding also contrasts with the emerging view that the most common interaction type in pesticide mixtures is an additive effect (Cedergreen, 2014;Kamo and Yokomizo, 2015;Rizzati et al, 2016;Rodea-Palomares et al, 2015).…”

Section: Mortality By Pesticide Exposurementioning

confidence: 79%

Resistance to a chemical pesticide increases vulnerability to a biopesticide: Effects on direct mortality and mortality by predation

et al. 2019

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Pesticide mixtures are increasingly used to fight pest species that developed resistance to pesticides. To assess the pesticide control efficiency and to reduce ecological damage to nontarget species, it is important to quantify the effect of these mixtures and compare them with the effect of their single pesticides on pest species, non-target species and their predator-prey interactions. We studied the effects of the chemical pesticide chlorpyrifos (CPF), the biopesticide Bacillus thuringiensis israelensis (Bti) and their mixture both on the direct mortality and on the mortality by predation. We focused on larvae of a CPF-resistant and a non-resistant strain of the vector mosquito Culex quinquefasciatus and its predator, the pygmy backswimmer Plea minutissima. In the CPF-Bti mixture, both pesticides interacted antagonistically for direct mortality. Exposure to the mixture caused equal direct mortality and equal mortality by predation in both strains. As expected, exposure to CPF resulted in less direct mortality and less mortality by predation in the CPF-resistant mosquito strain compared to the non-resistant strain. Notably, Bti caused a higher mortality in the mosquito larvae of the CPF-resistant strain compared to the non-resistant strain. Furthermore, the predator killed more mosquito larvae of the resistant strain compared to the non-resistant strain when exposed before to Bti alone. These observations identify a novel cost of resistance to a chemical pesticide in terms of increased vulnerability to a biopesticide.

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“…Sin embargo, nuestros resultados demostraron que la eficiencia del (Bti) aplicado en menor concentración se vio reducido durante las primeras horas como lo menciona (Becker et al, 1992). Según estudios realizados en laboratorio demuestran que las larvas de Aedes y Culex necesitan temperaturas óptimas que oscilan entre 28 y 30 ºC para aumentar su efectividad y por lo tanto su metabolismo (Delnat et al, 2019).…”

Section: Discussionunclassified

LARVICIDAL ACTIVITY OF Bacilllus thuringiensis H-14 var. israelensis AND Beauveria bassiana ON Aedes aegypti

Rebaza-Sánchez¹,

Zavaleta-Espejo²,

Blas-Cerdán³

et al. 2020

rebiol

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En el presente trabajo se evaluó la actividad larvicida de Bacillus thuringiensis H-14 var. israelensis y Beauveria bassiana sobre larvas del III estadio de Aedes aegypti, bajo condiciones de laboratorio, además se determinó la dosis letal media (DL50) y máxima (DL90). Se realizaron los bioensayos con doce grupos experimentales y dos grupos control, con tres repeticiones, utilizando 25 larvas del III estadio de A. aegypti en 100 mL de agua destilada por cada unidad experimental. Se utilizaron seis grupos experimentales con B. thuringiensis H-14 var. israelensis, a las concentraciones de 670; 1683; 4247; 10619; 26673; 67000 esp/mL y un grupo control; obteniéndose una mortalidad del 50% a las 8 horas y del 100% a las 24 horas. Con B. bassiana se utilizaron seis grupos experimentales a las concentraciones de 4x10 8 ; 1x10 9 ; 2,5x10 9 ; 6,3x10 9 ; 1,6x10 10 ; 4x10 10 conidios/mL y un grupo control; obteniéndose una mortalidad del 50% a los 7 días y del 100% a los 9 días. Mediante la dosis letal media (LD50) y máxima (DL90) se demostró que tanto B. thuringiensis H-14 var. israelensis como B. bassiana presentan mayor mortalidad en relación directa a la concentración e inversamente al tiempo. Se concluye que B. thuringiensis H-14 var. israelensis y B. bassiana a las diferentes concentraciones utilizadas en los bioensayos, presentó una alta actividad larvicida en A. aegypti bajo condiciones de laboratorio.

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Daily temperature variation magnifies the toxicity of a mixture consisting of a chemical pesticide and a biopesticide in a vector mosquito

Cited by 30 publications

References 56 publications

Whether warming magnifies the toxicity of a pesticide is strongly dependent on the concentration and the null model

Whether warming magnifies the toxicity of a pesticide is strongly dependent on the concentration and the null model

Resistance to a chemical pesticide increases vulnerability to a biopesticide: Effects on direct mortality and mortality by predation

LARVICIDAL ACTIVITY OF Bacilllus thuringiensis H-14 var. israelensis AND Beauveria bassiana ON Aedes aegypti

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