The growth and production of adult mosquitoes from the aquatic larval habitats is constrained by conversion of refractile organic material into ingestible and digestible microbial biomass. Rates of conversion of organic matter into microbial biomass are tempered by the quality of particulate substrates that is manifested in dual roles of inhibition and stimulation of microbial and larval growth. Our long-term goal is to delineate the biological basis for and constraints on mosquito production, to identify the efficiency of utilization of these resources, and to elaborate a realistic model of larval growth. We have identified the tree hole ecosystem for study, harboring the species Ochlerotatus triseriatus, Ochlerotatus japonicus, and Culex pipiens, two vectors of human pathogens and one an exotic invader. Research approaches include an axenic (germ-free) experimental system into which individual food sources including microorganisms can be provisioned;stable isotopic analyses (13C/12C;15N/14N) to track larval foods to their sources;molecular analyses of microbial community structure;a functional gene array analysis of microbial genes encoding enzymes involved in large biomolecule degradation, including xylanases, cellulases, and chitinases;and microcosm and naturalistic experiments in which microbial biomass and metabolic activity relative to larval growth are quantified. A growth model is proposed in which developmental time to, and mass at, metamorphosis (i.e., pupation) are postulated to be flexible life history traits whose minima are nutritionally and genetically constrained into a pupation window defining body size and affecting adult survivorship;both are key fitness parameters and both important components of vectorial capacity. Experiments will delineate relationships among them, and reveal environmental and genetic components contributing to their variation. The current understanding of larval growth rates requires conversion efficiencies (mg food assimilated per mg food ingested) far higher than observed, thus we will iteratively test growth responses relative to natural microbial food sources of various qualities, fit observed growth data to models, and revise conversion efficiency estimates accordingly. The three mosquito species sharing the same larval habitat and resources will be compared to assess growth rates under conditions of intense intra- and interspecific competition, both to make predictions of competitive outcomes and potential for ecological displacement, and to quantify comparative efficiency of utilization of larval foods. Manipulation of the Flavobacterium component of the microbial community a dominant member with molecular genetic tools to express genes encoding proteins having larval toxin and growth inhibiting properties will be conducted, including cry toxin genes from Bacillus, and chitinases.

Public Health Relevance

Mosquitoes are responsible for transmission of large number of human pathogens, including those causing malaria, filariasis, and arboviral infections. Abundance and longevity of adult, female mosquitoes (the blood feeding and pathogen transmitting stage) are dependent upon the nutritional and other factors operating in the larval environment, the constraints of which are the focus of the research here.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37AI021884-27
Application #
8299130
Study Section
Vector Biology Study Section (VB)
Program Officer
Costero, Adriana
Project Start
1984-12-01
Project End
2013-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
27
Fiscal Year
2012
Total Cost
$366,074
Indirect Cost
$121,049
Name
Michigan State University
Department
Microbiology/Immun/Virology
Type
Schools of Arts and Sciences
DUNS #
193247145
City
East Lansing
State
MI
Country
United States
Zip Code
48824
Norman, B C; Walker, E D (2018) Conditioning of Leaf Detritus Modulates Density-Dependent Growth of Aedes triseriatus Larvae (Diptera: Culicidae). J Med Entomol 55:342-350
Chen, Shicheng; Blom, Jochen; Loch, Thomas P et al. (2017) The Emerging Fish Pathogen Flavobacterium spartansii Isolated from Chinook Salmon: Comparative Genome Analysis and Molecular Manipulation. Front Microbiol 8:2339
Grode, Ari; Chen, Shicheng; Walker, Edward D et al. (2017) Onion Thrips (Thysanoptera: Thripidae) Feeding Promotes Infection By Pantoea ananatis in Onion. J Econ Entomol 110:2301-2307
Duguma, Dagne; Kaufman, Michael G; Simas Domingos, Arthur B (2017) Aquatic microfauna alter larval food resources and affect development and biomass of West Nile and Saint Louis encephalitis vector Culex nigripalpus (Diptera: Culicidae). Ecol Evol 7:3507-3519
Chen, Shicheng; Blom, Jochen; Walker, Edward D (2017) Genomic, Physiologic, and Symbiotic Characterization of Serratia marcescens Strains Isolated from the Mosquito Anopheles stephensi. Front Microbiol 8:1483
Yee, Donald A; Kaufman, Michael G; Ezeakacha, Nnaemeka F (2016) Correction: How Diverse Detrital Environments Influence Nutrient Stoichiometry between Males and Females of the Co-Occurring Container Mosquitoes Aedes albopictus, Ae. aegypti, and Culex quinquefasciatus. PLoS One 11:e0144867
Chen, Shicheng; Zhao, Jiangchao; Joshi, Deepak et al. (2016) Persistent Infection by Wolbachia wAlbB Has No Effect on Composition of the Gut Microbiota in Adult Female Anopheles stephensi. Front Microbiol 7:1485
Walker, Edward D (2016) Toxicity of Sulfide and Ammonium to Aedes triseriatus Larvae (Diptera: Culicidae) in Water-Filled Tree Holes and Tires. J Med Entomol 53:577-583
Chen, Shicheng; Soehnlen, Marty; Walker, Edward D (2016) Genome Sequence of Elizabethkingia meningoseptica EM1, Isolated from a Patient with a Bloodstream Infection. Genome Announc 4:
Mendoza, Leonel; Taylor, John W; Walker, Edward D et al. (2016) Description of three novel Lagenidium (Oomycota) species causing infection in mammals. Rev Iberoam Micol 33:83-91

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