PipPop: The Culex pipiens POPulation Genomics Project

The northern house mosquito, Culex pipiens, is a major vector of diseases such as West Nile Virus and lymphatic filariasis. It is found in temperate regions across the world. Culex pipiens includes at least two morphologically indistinguishable forms, Culex pipiens form pipiens and Culex pipiens form molestus. Despite their morphological similarity, the two forms exhibit striking ecological and behavioral differences. Form pipiens is cold-adapted, requires a blood meal to lay eggs, and primarily bites birds. Form molestus is warm-adapted, can lay its first clutch without a blood meal, and, at least in some places, primarily bites mammals. Intriguingly, molestus can also exist alongside pipiens in the colder northern latitudes of Europe and North America, where it lives exclusively below ground in urban subway systems and basements. A distinct subspecies, Culex pipiens pallens occurs in parts of East Asia. We know very little about how these taxa arose and dispersed across the world.

We have launched the Culex pipiens Population Genomics Project (PipPop) to better understand the evolutionary history of this interesting species and important disease vector.  Our goal is to conduct whole genome sequencing and analysis on 1000+ individuals from 39 target regions across the global range of the species (see map).

We are reaching out to the larger Culex research community to ask for collaborators willing to contribute samples. All participants will be included as authors on the flagship paper resulting from this work, will have immediate access to data from their samples if desired, and will be invited to provide input on analysis and interpretation of data.

We are looking for…

    • Both above ground and below ground forms
    • Up to 50 individuals from any given population
    • Intact mosquitoes collected within the past 5 years
    • Sibling species Cx. quinquefasciatus (and pipiens-quinquefasciatus hybrids) from the contact zone

We need your help!  Please see Frequently Asked Questions & Answers below for more information and contact us if you might be willing to collaborate by contributing samples. We are happy to provide more details. Also see this PROJECT FLYER and METADATA FORM.

Yuki Haba ( yhaba at princeton dot edu)
PhD student
Lindy McBride ( csm7 at princeton dot edu)
Assistant Professor

Frequently Asked Questions & Answers

What is the overall scope of the project? We intend to sequence 1000+ individuals from across the full range of the species, with denser sampling in the native range of the species than in the introduced range.

How many populations will you sample per zone on the map? We plan to sequence mosquitoes from 2-10 populations per zone: including above ground, below ground, urban, and rural populations where possible. We can’t guarantee that we will sequence mosquitoes from every single population sent to us. However, all contributors will be considered collaborators regardless.

What kind of samples are you looking for?

20-50 individuals per population (taken from multiple sites). We ask for up to 50 mosquitoes per population – ideally coming from multiple collection sites within the general area. We will start by sequencing only ~5 individuals per population, so fewer individuals can still be useful. However, the additional samples provide (1) back-up in case not all individuals are pipiens and/or yield high quality DNA, and (2) options for expansion and targeted follow-up based on preliminary results.

Both females and males. We prefer an approximately equal number of males and females, but understand that many trapping methods are biased towards females.

Adults preferred, larvae also OK. We prefer mosquitoes collected as adults since we want to sequence unrelated individuals, and those collected as larvae from the same water source may include siblings. However, larvae collected from dense populations or multiple water sources are fine. Please be sure to keep larvae from different pools in separate tubes.

Recently collected. We request samples collected as recently as possibly – ideally in 2017 or 2018, but up to 5 years old is OK. We may also accept samples over 5 years old if they come from locations/habitats that are difficult to sample (e.g. Africa, Middle East, or underground habitats).

Field collected individuals only (except underground molestus populations). We will only be sequencing field-collected individuals. The one exception is underground populations of Cx. pipiens form molestus. In this case, since field collection is so sporadic, we would love to supplement field collections with colony samples.

How should samples be preserved and shipped? We prefer samples preserved in 95-100% ethanol or dried on silica gel since the DNA will be stable during shipping at room temperature. Frozen samples can be transferred to 95-100% ethanol before shipping. Please use an ethanol resistant pen for labeling and let us know when you are ready to ship so that we can send a pre-paid waybill.

How can I provide metadata – including GPS coordinates – with my collections? All contributors must submit a completed METADATA FORM with their samples. Please download this using the link. We will need at least the following mandatory information with each sample: Collection year/month/day, Latitude/longitude, Country, Region, Site description, Trapping method, Trapping bait, Life Stage, Sex, Preliminary species ID and method of identification.

By when do we need samples? Sample assembly will continue through at least July 2019. However, we will start sequencing immediately and would love to receive samples as soon as possible.

Are you interested in Culex quinquefasciatus? We plan to sequence a small number of individuals from related species that hybridize with Cx. pipiens (and thus may contribute to genetic variation within pipiens populations). One obvious example is Cx. quinquefasciatus. If you have quinqs or pip-quinqs hybrids in your area, we would love to get them as well as ‘pure’ pipiens.

How can we provide input during analysis? No input is required, but we very much welcome input if you have any. We tentatively foresee sending out preliminary analyses for comment by all collaborators at least twice during the analysis stage. Collaborators are also welcome to use the data for their own separate analyses, assuming they do not overlap with the primary study goals.