Effects of temperature on mosquito-host-pathogen interactions 

Our lab focuses on studying the effects of temperature, and by extension climate change on:

(1) the physiology and behavior of disease vector insects,

(2) the vector-host-pathogen interactions and

(3) the disease vector insects’ ability to invade new areas

We rely on a multidisciplinary and integrative approach, combining genetics, behavioral analyses, field observations and we work with different mosquito species along with kissing bugs and tsetse flies.

The results from these projects will help to get a better understanding of disease vector insects’ biology, physiology and neuroethology and will lay the groundwork for the development of new control tools targeting their thermo-sensory system.

Olfactory neurobiology and behavior of mosquitoes (Post-doc work)

     During my post-doc in Jeffrey Riffell's lab, I investigated several aspects of mosquitoes' interactions with their environment. In particular,I focus on mosquito learning abilities, pollination ecology and thermal biology.

Project 1: Olfactory Processing of Plant Odors in Mosquitoes 

 

     Moquitoes are not only blood-feeders but they also use carbohydrates from plants to sustain their basal metabolism. In nature, sugars are found in ripe fruits and flower nectar. During their visitation of flowers, mosquitoes can transfer pollen to another flower and pollinate them. It is the case for the beautiful Platanthera obtusata (on right), a small and rare orchid. 

     For this project, I study the snow mosquitoes species complex that are present in Washington State and that are the primary pollinators of this orchid species. We use chemical ecology approaches, electrophysiology and behavioral assays to understand what make mosquitoes attracted to these plants.

Project 2: Temperature Effect on Olfactory Processing in mosquitoes

     In order to obtain a blood meal, disease vector insects need to accurately identify and locate mobile vertebrate hosts using a wide range of cues, in particular olfactory signals, which are key mediator of the vector-host interaction. While the physiological processes regulating food-seeking behavior have been well studied in these insects, comparatively less is understood about how environmental temperature might affect the performance of their sensory system. 

     l thus aim at contributing closing the knowledge gaps in our understanding of thermal sensitivity in disease vector mosquitoes.

Project 3: Olfactory Learning and Memory in Aedes aegypti Mosquitoes

 

     Mosquitoes are able to learn and retain olfactory information in an appetitive context when an odor is paired with the presentation of a reward such as a blood-meal.

     In collaboration with Dr. Clément Vinauger, another post-doctoral researcher in the Riffell lab, I seek to dive deeper into the understanding of the fine underlying processes implicated in learning and memory in mosquitoes.

     For this project, we use behavioral assays, develop molecular tools as well as electroghysiological techniques to assess their learning abilities (Vinauger, Lahondère et al., 2017).

Thermal stress associated with feeding in haematophagous insects (PhD work)

     In their environment, insects are submitted to thermal fluctuations and have developed a suite of responses, both physiological and behavioral, to minimize the deleterious consequences that high temperature might cause. Some species even actively regulate their internal temperature independently of the environmental temperature (i.e. thermoregulation). If these insects can overcome the thermal constraints imposed by their environment, those that feed on warm-blooded vertebrate hosts have no choice but to experience a thermal stress at each feeding event.

    The main objective of my PhD in Claudio Lazzari's lab consisted in understanding how haematophagous disease vector insects manage the thermal stress associated with the massive heat flow generated by the ingestion of blood. Using complementary techniques such as real-time infrared thermography during blood-feeding, anatomical and morphological analysis as well as physiological manipulations, I specifically sought to answer three questions:

 

     (1) How do they manage to withstand the blood-meal temperature?

     (2) Do they rely on thermoregulatory strategies to minimize thermal stress risks?

     (3) If so, what are the specific mechanisms involved (e.g. physiological, morphological and behavioral)?

           

       For this project, I worked with triatomine bugs (Rhodnius prolixus), mosquitoes (Aedes aegypti, Anopheles stephensi, Anopheles gambiae) and tsetse flies (Glossina morsitans morsitans). These insects are vectors of the causative agents of several diseases such as Chagas disease, malaria, yellow fever or sleeping sickness. A better knowledge of their thermal biology may have important epidemiological consequences for humans.

 

     This work showed that they have indeed developed different highly sophisticated thermoregulation strategies such as evaporative cooling of droplets of fluids in mosquitoes (Lahondere and Lazzari, 2012, 2013) or specific hemolymph circulation patterns in triatomine bugs (Lahondere et al., 2017) that protect them from overheating and potential death. Tsetse flies seem to have a higher thermotolerance as thermoregulation processes has not been evinced in the species we studied (Lahondere and Lazzari, 2015). 

elife-26107-fig7-v2

elife-26107-fig7-v2

3-D model of the heat exchange that occurs in the head of kissing bugs during blood-feeding. This thermoregulatory process allows the insect to cool down the warm ingested blood before it reaches the abdomen

Tsetse fly during feeding thermogram

Tsetse fly during feeding thermogram

Thermographic view of a tsetse fly (Glossina morsitans morsitans) during feeding on an artificial feeder

Adults of Rhodnius prolixus

Adults of Rhodnius prolixus

Female on the right / Male on the left

Anopheles evaporative cooling

Anopheles evaporative cooling

Thermographic image of Anopheles stephensi during feeding on an anesthetized mouse (Mean skin Thost = 32°C). Note the drop of excreted fluid used to cool down its abdomen and avoid overheating during blood intake

Rhodnius prolixus during feeding

Rhodnius prolixus during feeding

Wingless Rhodnius prolixus during feeding on an artificial transparent meal to highlight its heart mouvements through the thorax wall

Anopheles stephensi

Anopheles stephensi

A mosquito takes a blood meal on my arm

Thermographic experiment

Thermographic experiment

One of the first thermographic experiment we realized on mosquitoes - Pasteur Institut, Paris, France

Anopheles stephensi

Anopheles stephensi