Mosquito feeding and fitness: An exploration of mosquito diets and feeding behaviors that impact mosquito fitness, with applications for mosquito mass rearing and control
Open Access
- Author:
- Ohm, Johanna Ruth
- Graduate Program:
- Biology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 13, 2018
- Committee Members:
- Andrew Fraser Read, Dissertation Advisor/Co-Advisor
James Harold Marden, Committee Chair/Co-Chair
Matthew Brian Thomas, Committee Member
Thomas Charles Baker, Committee Member
Gregory Ray Ziegler, Outside Member - Keywords:
- mosquito
malaria
artificial diet
Aedes aegypti
Aedes albopictus
Anopheles stephensi
Aedes
Anopheles
parasite manipulation
blood feeding
Galleria mellonella
wax moth
sickness behavior
fitness
insecticides
mosquito control
insect - Abstract:
- Mosquito feeding behavior is a key determinant of mosquito-borne disease transmission. The number of infectious bites an infected mosquito takes, the proportion of mosquitoes feeding on humans as opposed to other food sources, and the effects food-choice has on mosquito survival and fecundity, all contribute to sustained transmission of diseases such as dengue, malaria, and yellow fever. My doctoral dissertation work has aimed to evaluate how certain feeding behaviors of adult mosquitoes may impact disease transmission and to explore the fitness consequences that both feeding behaviors and replacement of blood with artificial diets have on adult mosquitoes. Understanding mosquito fitness is becoming increasingly important for mosquito-borne disease control as vector control programs veer away from using insecticides to implement novel alternatives. Some of these alternatives include the use of biocontrol agents to infect mosquitoes and block their ability to transmit disease, and the use of genetic engineering to create mosquitoes that are more resistant to infection. Insecticides don’t require an understanding of mosquito fitness to implement, but release programs that rely on released mosquitoes to spread and out-compete wild populations rely on mosquito fitness to be successful. Additionally, mosquito fitness is important to understand how to manage resistance to interventions when they evolve. The evolution of insecticide-resistance in mosquito populations has threatened the long- term sustainability of using insecticides for mosquito control, forcing new considerations of how to manage the spread of resistance and to consider alternatives that require understanding mosquito fitness for spread. Fitness is difficult to estimate for any organism. In Chapter 2, I evaluate how life history traits of mosquitoes relate to a holistic estimate of mosquito fitness, the intrinsic rate of increase, and suggest ways to better capture mosquito fitness in the lab that may have predictive value in the field. I found that measuring early life history traits, as predicted by life history theory, do a better job of estimating mosquito fitness than late life traits, such as late life reproduction. Importantly, juvenile traits, which are very rarely measured in the literature on mosquito life history, impact mosquito fitness in such a way that even when mosquito control interventions target adult mosquitoes, background vital rates in the juvenile stage can impact the rate of resistance emergence and spread. These results also have implications for predicting the spread of mosquitoes that are transinfected with Wolbachia or genetically modified to be resistant to infections, my results emphasize that the impacts these interventions have on juvenile traits will be the most relevant metrics for predicting mosquito fitness and the evolution of resistance. In Chapter 3, I explore how feeding behaviors affect mosquito fitness by empirically testing how altered timing of blood feeding behavior impacts mosquito intrinsic rate of increase, demonstrating that delayed feeding behaviors that occur with malaria infection in Anopheles are costly to mosquito fitness, but potentially beneficial to parasites (Chapter 3). In Chapter 4, I explore the fitness consequences of artificial diets to replace blood meals for mosquitoes intended for release in vector control programs. I found that an artificial diet based on insect hemolymph from soft bodied insect larvae can be used to stably rear mosquito populations for multiple generations in the laboratory. This is the first demonstration of a non-vertebrate based blood meal replacement to rear mosquitoes for multiple generations. This finding leads to interesting questions about the evolution of mosquito blood feeding, the potential ecology of mosquito interactions with other insects in the field, and the nutritional requirements for egg laying that may be met by alternative food sources beyond blood. I discuss these and other implications of this work in Chapter 4. I integrate Chapters 2-4 in a general discussion of how mosquito feeding behaviors impact mosquito fitness and implications for improving vector control in Chapter 5.