scholarly journals Warmer temperatures reduce the vectorial capacity of malaria mosquitoes

2011 ◽  
Vol 8 (3) ◽  
pp. 465-468 ◽  
Author(s):  
Krijn P. Paaijmans ◽  
Simon Blanford ◽  
Brian H. K. Chan ◽  
Matthew B. Thomas
Keyword(s):  
Life History ◽  
Incubation Period ◽  
Vector Competence ◽  
Development Rate ◽  
Transmission Intensity ◽  
Interactive Effects ◽  
Cumulative Distribution ◽  
Parasite Development ◽  
Maximum Proportion ◽  
Malaria Mosquitoes

The development rate of parasites and pathogens within vectors typically increases with temperature. Accordingly, transmission intensity is generally assumed to be higher under warmer conditions. However, development is only one component of parasite/pathogen life history and there has been little research exploring the temperature sensitivity of other traits that contribute to transmission intensity. Here, using a rodent malaria, we show that vector competence (the maximum proportion of infectious mosquitoes, which implicitly includes parasite survival across the incubation period) tails off at higher temperatures, even though parasite development rate increases. We also show that the standard measure of the parasite incubation period (i.e. time until the first mosquitoes within a cohort become infectious following an infected blood-meal) is incomplete because parasite development follows a cumulative distribution, which itself varies with temperature. Including these effects in a simple model dramatically alters estimates of transmission intensity and reduces the optimum temperature for transmission. These results highlight the need to understand the interactive effects of environmental temperature on multiple host-disease life-history traits and challenge the assumptions of many current disease models that ignore this complexity.

scholarly journals Early life history responses and phenotypic shifts in a rare endemic plant responding to climate change

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Daniel E Winkler ◽  
Michelle Yu-Chan Lin ◽  
José Delgadillo ◽  
Kenneth J Chapin ◽  
Travis E Huxman
Keyword(s):  
Climate Change ◽  
Life History ◽  
Phenotypic Variation ◽  
Early Life ◽  
Early Life History ◽  
Interactive Effects ◽  
Endemic Plant ◽  
Cushion Plant ◽  
Rare Endemic

We studied how a rare, endemic alpine cushion plant responds to the interactive effects of warming and drought. Overall, we found that both drought and warming negatively influenced the species growth but that existing levels of phenotypic variation may be enough to at least temporarily buffer populations.

scholarly journals Molecular characterization of Plasmodium falciparum PHISTb proteins as potential targets of naturally-acquired immunity against malaria

2020 ◽  
Vol 5 ◽  
pp. 136
Author(s):  
Tony I. Isebe ◽  
Joel L. Bargul ◽  
Bonface M. Gichuki ◽  
James M. Njunge ◽  
James Tuju ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
The Gambia ◽  
Antibody Responses ◽  
Transmission Intensity ◽  
Parasite Development ◽  
Natural Immunity ◽  
Malaria Transmission Intensity ◽  
Transmission Region ◽  
Antibody Levels

Background: Plasmodium falciparum causes the deadliest form of malaria in humans. Upon infection, the host’s infected red blood cells (iRBCs) are remodelled by exported parasite proteins in order to provide a niche for parasite development and maturation. Methods: Here we analysed the role of three PHISTb proteins Pf3D7_0532400, Pf3D7_1401600, and Pf3D7_1102500 by expressing recombinant proteins and evaluated antibody responses against these proteins using immune sera from malaria-exposed individuals from Kenya and The Gambia in Africa. Results: Our findings show that children and adults from malaria-endemic regions recognized the three PHISTb proteins. Responses against the PHISTb proteins varied with malaria transmission intensity in three different geographical sites in Kenya (Siaya and Takaungu) and The Gambia (Sukuta). Antibody responses against PHISTb antigens Pf3D7_1102500 and Pf3D7_1401600 were higher in Sukuta, a low transmission region in the Gambia, as compared to Siaya, a high transmission region in western Kenya, unlike Pf3D7_0532400. Anti-PHIST responses show a negative correlation between antibody levels and malaria transmission intensity for two PHIST antigens, Pf3D7_1102500 and Pf3D7_1401600. However, we report a correlation in antibody responses between schizont extract and Pf3D7_0532400 (p=0.00582). Acquisition of anti-PHIST antibodies was correlated with exposure to malaria for PHISTb protein Pf3D7_0532400 (p=0.009) but not the other PHIST antigens Pf3D7_1102500 and Pf3D7_1401600 (p=0.507 and p=0.15, respectively, CI=95%). Children aged below 2 years had the lowest antibody levels, but the responses do not correlate with age differences. Conclusions: Collectively, these findings provide evidence of natural immunity against PHISTb antigens that varies with level of malaria exposure and underscore potential for these parasite antigens as possible serological markers to P. falciparum infection aimed at contributing to malaria control through vaccine development.

Vector survival and parasite infection: the effect of Wuchereria bancrofti on its vector Culex quinquefasciatus

Parasitology ◽  
2004 ◽  
Vol 129 (1) ◽  
pp. 43-50 ◽  
Author(s):  
K. KRISHNAMOORTHY ◽  
S. SUBRAMANIAN ◽  
G. J. VAN OORTMARSSEN ◽  
J. D. F. HABBEMA ◽  
P. K. DAS
Keyword(s):  
Incubation Period ◽  
Culex Quinquefasciatus ◽  
Geometric Mean ◽  
Wuchereria Bancrofti ◽  
Parasite Load ◽  
Infected Mosquito ◽  
Parasite Development ◽  
Mosquito Vector ◽  
Extrinsic Incubation Period ◽  
Parasite Loss

This paper investigates a cohort of 2187 laboratory reared Culex quinquefasciatus fed on 69 human volunteers, including 59 persons with different levels of Wuchereria bancrofti microfilariae and 10 without microfilaria. Mosquitoes were followed until death. Mosquito survival was analysed in relation to the level of microfilaria in the human and larval count in the dead mosquito. Vector mortality during the extrinsic incubation period (12 days post-engorgement) was significantly higher in mosquitoes fed on microfilaraemic volunteers (50%) than in those fed on amicrofilaraemics (29%). Both the percentage infected and the geometric mean parasite density was significantly higher among mosquitoes which died before 13 days (45% infected and 10 larvae per infected mosquito) than those surviving beyond 13 days (39% and 2·2), suggesting a parasite loss of more than 80% during the extrinsic incubation period. A large proportion (62%) of the mosquitoes that died during the early of phase of parasite development were infected (36% in low, 26% in medium and 90% in high human Mf-density). Survival analysis showed that the parasite load in mosquitoes and the human Mf-density for a given parasite load are independent risk factors of vector survival. Overall, the hazard of dying was found to be 11–15 times higher among mosquitoes fed on microfilaraemic volunteers than those fed on amicrofilaraemics. The hazard doubles for every increase of about 60–70 parasites in the vector. As a consequence of the parasite-induced reduction in vector survival, the transmission success of the parasite is reduced. The implication of the results on control/elimination of lymphatic filariasis using mass-drug administration is discussed.

scholarly journals Influence of Lab Adapted Natural Diet and Microbiota on Life History and Metabolic Phenotype of Drosophila melanogaster

2020 ◽  
Vol 8 (12) ◽  
pp. 1972
Author(s):  
Andrei Bombin ◽  
Owen Cunneely ◽  
Kira Eickman ◽  
Sergei Bombin ◽  
Abigail Ruesy ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Life History ◽  
Development Rate ◽  
Metabolic Phenotype ◽  
Natural Diet ◽  
Theory Of Evolution ◽  
Nutritional Conditions ◽  
Novel Approach ◽  
Survival And Development ◽  
Symbiotic Microbiota

Symbiotic microbiota can help its host to overcome nutritional challenges, which is consistent with a holobiont theory of evolution. Our project investigated the effects produced by the microbiota community, acquired from the environment and horizontal transfer, on metabolic traits related to obesity. The study applied a novel approach of raising Drosophila melanogaster, from ten wild-derived genetic lines on naturally fermented peaches, preserving genuine microbial conditions. Larvae raised on the natural and standard lab diets were significantly different in every tested phenotype. Frozen peach food provided nutritional conditions similar to the natural ones and preserved key microbial taxa necessary for survival and development. On the peach diet, the presence of parental microbiota increased the weight and development rate. Larvae raised on each tested diet formed microbial communities distinct from each other. The effect that individual microbial taxa produced on the host varied significantly with changing environmental and genetic conditions, occasionally to the degree of opposite correlations.

scholarly journals Linking thermal adaptation and life-history theory explains latitudinal patterns of voltinism

2019 ◽  
Vol 374 (1778) ◽  
pp. 20180547 ◽  
Author(s):  
Jacinta D. Kong ◽  
Ary A. Hoffmann ◽  
Michael R. Kearney
Keyword(s):  
Life History ◽  
Thermal Sensitivity ◽  
Thermal Adaptation ◽  
Thermal Response ◽  
Life Cycles ◽  
Development Rate ◽  
Latitudinal Gradients ◽  
Seasonal Temperature ◽  
Egg Development ◽  
Latitudinal Patterns

Insect life cycles are adapted to a seasonal climate by expressing alternative voltinism phenotypes—the number of generations in a year. Variation in voltinism phenotypes along latitudinal gradients may be generated by developmental traits at critical life stages, such as eggs. Both voltinism and egg development are thermally determined traits, yet independently derived models of voltinism and thermal adaptation refer to the evolution of dormancy and thermal sensitivity of development rate, respectively, as independent influences on life history. To reconcile these models and test their respective predictions, we characterized patterns of voltinism and thermal response of egg development rate along a latitudinal temperature gradient using the matchstick grasshopper genus Warramaba . We found remarkably strong variation in voltinism patterns, as well as corresponding egg dormancy patterns and thermal responses of egg development. Our results show that the switch in voltinism along the latitudinal gradient was explained by the combined predictions of the evolution of voltinism and of thermal adaptation. We suggest that latitudinal patterns in thermal responses and corresponding life histories need to consider the evolution of thermal response curves within the context of seasonal temperature cycles rather than based solely on optimality and trade-offs in performance. This article is part of the theme issue ‘Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen’.

scholarly journals Interactions with a Complex Microbiota Mediate a Trade-Off between the Host Development Rate and Heat Stress Resistance

2020 ◽  
Vol 8 (11) ◽  
pp. 1781
Author(s):  
Samuel Slowinski ◽  
Isabella Ramirez ◽  
Vivek Narayan ◽  
Medha Somayaji ◽  
Maya Para ◽  
...  
Keyword(s):  
Life History ◽  
Heat Stress ◽  
Stress Resistance ◽  
Life History Traits ◽  
Soil Microbes ◽  
Development Rate ◽  
Heat Stress Resistance ◽  
Host Life ◽  
Host Development ◽  
Resistance To Heat

Animals and plants host diverse communities of microorganisms, and these microbiotas have been shown to influence host life history traits. Much has been said about the benefits that host-associated microbiotas bestow on the host. However, life history traits often demonstrate tradeoffs among one another. Raising Caenorhabditis elegans nematodes in compost microcosms emulating their natural environment, we examined how complex microbiotas affect host life history traits. We show that soil microbes usually increase the host development rate but decrease host resistance to heat stress, suggesting that interactions with complex microbiotas may mediate a tradeoff between host development and stress resistance. What element in these interactions is responsible for these effects is yet unknown, but experiments with live versus dead bacteria suggest that such effects may depend on bacterially provided signals.

scholarly journals Relevant microclimate for determining the development rate of malaria mosquitoes and possible implications of climate change

2010 ◽  
Vol 9 (1) ◽  
Author(s):  
Krijn P Paaijmans ◽  
Susan S Imbahale ◽  
Matthew B Thomas ◽  
Willem Takken
Keyword(s):  
Climate Change ◽  
Development Rate ◽  
Malaria Mosquitoes

scholarly journals Molecular characterization of Plasmodium falciparum PHISTb proteins as potential targets of naturally-acquired immunity against malaria

2021 ◽  
Vol 5 ◽  
pp. 136
Author(s):  
Tony I. Isebe ◽  
Joel L. Bargul ◽  
Bonface M. Gichuki ◽  
James M. Njunge ◽  
James Tuju ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
Negative Correlation ◽  
The Gambia ◽  
Antibody Responses ◽  
Transmission Intensity ◽  
Parasite Development ◽  
Malaria Transmission Intensity ◽  
Transmission Region ◽  
Antibody Levels

Background: Plasmodium falciparum causes the deadliest form of malaria in humans. Upon infection, the host’s infected red blood cells (iRBCs) are remodelled by exported parasite proteins to provide a niche for parasite development and maturation. Methods: Here we analysed the role of three PHISTb proteins Pf3D7_0532400, Pf3D7_1401600, and Pf3D7_1102500 by expressing recombinant proteins and evaluated antibody responses against these proteins using immune sera from malaria-exposed individuals from Kenya and The Gambia in Africa. Results: Children and adults from malaria-endemic regions recognized the three PHISTb proteins. Responses against PHISTb proteins varied with malaria transmission intensity in three different geographical sites in Kenya (Siaya and Takaungu) and The Gambia (Sukuta). Antibody responses against PHISTb antigens Pf3D7_1102500 and Pf3D7_1401600 were higher in Sukuta, a low transmission region in Gambia, compared to Siaya, a high transmission region in western Kenya, unlike Pf3D7_0532400. Anti-PHIST responses indicate negative correlation between antibody levels and malaria transmission intensity for Pf3D7_1102500 and Pf3D7_1401600. We report a correlation in antibody responses between schizont and gametocyte extract, but this is not statistically significant (cor=0.102, p=0.2851, CI=95%) and, Pf3D7_0532400 (cor=0.11, p=0.249, CI=95%) and Pf3D7_1401600 (cor=0.02, p=0.7968, CI=95%). We report a negative correlation in antibody responses between schizont and Pf3D7_1102500 (cor=-0.008, p=0.9348, CI=95%). There is a correlation between gametocyte extract and Pf3D7_1401600 (cor=-0.0402, p=0.6735, CI=95%), Pf3D7_1102500 (cor=0.0758, p=0.4271, CI=95%) and Pf3D7_0532400 (cor=0.155, p=0.1028, CI=95%). Acquisition of anti-PHIST antibodies correlates with exposure to malaria for Pf3D7_0532400 (p=0.009) but not Pf3D7_1102500 and Pf3D7_1401600 (p=0.507 and p=0.15, respectively, CI=95%). Children aged below 2 years had the lowest antibody levels which do not correlate with age differences. Conclusions: Collectively, these findings provide evidence of natural immunity against PHISTb antigens that varies with level of malaria exposure and underscore their potential as possible serological markers to P. falciparum infection aimed at contributing to malaria control through vaccine development.

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