Research

Research in the Harrington lab focuses on mosquito vector ecology, biology, and behavior. Our goal is to understand basic (and often overlooked) aspects of mosquito biology in order to identify new targets for controlling mosquitoes and reducing transmission of vector-borne diseases. We examine long-standing questions in the field of vector biology from broad and, sometimes unconventional, angles. Research in the Harrington lab focuses on the most dangerous mosquito vectors impacting human health today; those that transmit dengue, yellow fever and West Nile viruses and those that transmit malaria parasites. We use a combined approach to studying disease vectors that includes biochemical and proteomics tools as well as conducting classical field studies. This approach allows us to validate laboratory findings in epidemiologically-relevant field settings leading to more meaningful research outcomes.

Male and female mosquitoes in copula (photo by C. Walcott)

Mosquito mating biology

This critically understudied area is important for the understanding of vector borne disease transmission and control. Our work has recently shed light on the sophisticated interactions of male and female mosquitoes. We have focused our efforts on mating behavior and mating physiology.

Mating behavior

With the help of a talented group of graduate students, postdocs, and colleagues, as well as funding from Bill and Melinda Gates foundation/FNIH, CDC and NIH, we have made significant breakthroughs in understanding the mosquito mating system. For example, we have identified several components of male fitness that are important in male mating success and likely critical for male mating competition in genetic vector control programs (Polawat and Harrington 2007, Ponlawat and Harrington 2009, Helinski and Harrington 2011). Recently, we made progress with longstanding questions about female mating frequency, sperm utilization and conditions which may lead to polyandry (Helinski et al. 2012). In addition, we discovered a new pre-copulatory phenomenon which we termed “harmonic convergence”. We have now demonstrated this behavior, where male and female mosquitoes actively alter their flight tones prior to mating so they match at harmonic frequencies, in the dengue vector, Ae. aegypti (Cator et al. 2009; Cator et al. 2011) and the malaria vector, An. gambiae (Cator et al. 2010). This phenomenon is likely to be common across the mosquito taxa. The exact function of harmonic convergence is not clear, but it is probably a component of mate assessment. We find that successful convergence between pairs of Ae. aegypti significantly predicts the formation of a successful copula (Cator and Harrington, 2011). In another study with the malaria vector, An. gambiae, we used computer generated acoustic playback to determine the effect of flight tone frequency (which is correlated with an important fitness component- body size) on harmonic convergence interactions (Cator et al. 2010). We found that males and females altered components of convergence behavior depending on the body size of a perceived potential mate. Further work in the Harrington lab demonstrates an association between harmonic convergence and increased mating success in sons. In addition, we’ve demonstrated that harmonic convergence is a heritable trait (Cator and Harrington, 2011).

Watch a video of mating rejection and acceptance behaviors (video by L. Cator).
Listen to a male-alone and female-alone as they paired-flight (audio file by L. Cator).

Male accessory gland proteins

In collaboration with Professor Mariana Wolfner and support from NIH and Hatch, we are investigating the identification and function of male seminal fluid proteins (sfps) in mosquitoes. While sfps have been recognized and studied in other insects, no work had been undertaken to determine if they existed in mosquitoes. The existence and potential function of these proteins was an important question because they may provide targets or pathways that can be manipulated to reduce pathogen transmission by blood-feeding arthropods. We began this line of investigation with a bioinformatics and proteomic based study and identified 63 putative sfps in Ae. aegypti (Sirot et al. 2008). In a second study we used a novel “reverse isotope labeling” approach to track and determine transfer of sfps from males to females. With this approach we identified 93 male-derived Sfps and 52 predicted sperm proteins that are transferred to females during mating (Sirot et al. 2011). The Sfp protein classes we detected suggest intriguing and potentially critical roles of male sfps on females including protein activation/ inactivation, induction of host seeking and blood feeding, sperm utilization, and ecdysteroidogenesis.

Potential influences of seminal fluid proteins on signaling pathway linking blood intake with yolk accumulation. Dashed arrows indicate known signaling pathways within the blood-fed female. Solid arrows indicate potential influences of seminal fluid proteins on these signaling pathways (for simplicity, the female is depicted as feeding and mating simultaneously). Illustration by A. Yori.

Genetically modified mosquitoes for vector/disease control

Through a large collaborative Gates funded project, the Harrington lab developed methods for assessing male fitness and measuring fitness differences in genetically modified males (Polawat and Harrington 2007, Ponlawat and Harrington 2009, Helinski and Harrington 2011 Koenraadt et al. 2010,Facchinelli et al. 2011). We also contributed to development of guidelines for field-cage studies of GMM and for working with communities in potential release areas (Lavery et al. 2008, 2010, Benedict et al. 2008).

Mosquito ecology

The Harrington laboratory continues to study aspects of mosquito survival (Harri

Harrington evaluating dengue vector populations with colleagues at a field site in Mexico.ngton et al. 2008a) dispersal (Harrington et al. 2005), oviposition (Harrington et al. 2008b) and human blood feeding patterns (Harrington et al. 2001, Ponlawat and Harrington 2005, Scott et al. 2006, Chaves et al. 2010) and the impact of host defensive behavior on mosquito feeding success (Darbro and Harrington 2007).Invasive Aedes albopictus biology

Our research on the biology and ecology of the Asian tiger mosquito has demonstrated

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