Other West Nile Vectors

Tue Aug 12 17:53:43 EDT 2003

Thanks for the note. I was involved in identifying one of the vectors of
infection of HIV in the third world ...eg.prostitutes... In cultures with
arranged marriages -men seldom -"bother" their wives oddly out of "respect"
and go to prostitutes thus the montrous spred of HIV in the Third World. I
had this presented at a WHO conference back in 1996.

This disscusion of West Nile reminds me of our first attempts to brainstorm
where all this infection was coming from.

Since the Virus "explodes" in reported infection in August is it not
possible that the new hatchlings of birds are the source of infection. As
they spread from the nest to new hunting grounds they infect new mosquitoes
and thus a huge rise in infection??

Just thinking aloud, but I feed birds and a few bird parents produce lots of
offspring.

Also, Cabbage white population have been very low this year, so I doubt they
have spread the disease.

Aslo, Is the disease active and infectious  in bird droppings? Its pretty
corrosive --as any one who has ever cleaned a chicken coop knows.

Good luck! Sounds like you are really working at this!
Best,
Lili
Dr. Lili Pintea-Reed, PhD

----- Original Message -----
From: Bob Augustine <raugustine at tms-hq.com>
To: <gochfeld at eohsi.rutgers.edu>
Cc: <pinteareed at madbbs.com>; <viceroy at gate.net>; <agrkovich at tmpeng.com>;
<janature at compusmart.ab.ca>; <nck6 at cdc.gov>; <pbright at abcbirds.org>;
<tjwalker at ifas.ufl.edu>; <esaito at usgs.gov>; <marrap at si.edu>
Sent: Tuesday, August 12, 2003 3:29 PM
Subject: Cabbage Whites

Thank you for posting my suggestions to the Leps-L list etc. The feedback
will help prove or
disprove the hypothesis.

As for the gap in our knowledge of "rapid spread," I agree that certainly
there may be lags
associated with viral development and/or surveillance. I find it very
strange that months can go by
with no human infections (before July the CDC national map was entirely
blank) then all of a
sudden in August there's this big explosion. If it had to do with heat, it
would show up earlier in
the South. After all, mosquitoes only live about 2 weeks.

I had never thought of Cabbage Whites as having any migratory inclinations
until I read Dr.
Walker's paper. I had some correspondence with him in 2000 concerning
migration of the
Cloudless Giant Sulfur, Phoebis sennae.(*posted below) [For years I had
noted large numbers of this species
along the coast, always heading south. None of the regional guides listed
the species as breeding
(or even occurring) in the NE. What books did refer to the species said it
flew north in summer,
but I couldn't find anyone who'd seen one going north. Ultimately, a few
years ago, breeding was
confirmed at many NE sites.] He reported to me one paper he had written on
it, which I then read
("Migrating Lepidoptera: Are Butterflies Better Than Moths?"). I also
discovered in the
references another paper of relevance ( He also indicated he had two more
papers on the subject
in preparation. I inquired last month if these were now done, and he replied
that one was. That is
the paper in which I discovered that Cabbage Whites do sometimes migrate. Of
course I couldn't
know if it was a strictly local phenomenon, restricted to Florida, but I
couldn't see any reason to
suppose that it was either. Before that, I had no reasonable candidate for a
WNV vector among
butterflies. All northward migratory species were either too uncommon or too
restricted in range
(e.g. Eurema lisa, Nathalis iole). There is still the possibility that moths
are vectors. Of the 11,000
species of North American Lepidoptera, 10,000 are moths. But moths are so
much less well
known than butterflies. Where would one start? I would start with the
noctuid, Spodoptera frugiperda, because
Dr. Walker's paper mentioned a suitable dispersion of that species (albeit
in Sept.).

I also recently learned of massive northbound late spring flights of
dragonflies, previously
unknown to me (The autumn southbound flights I have known of for some time).
Dragonflies, of
course, at all stages of their lives, eat mosquitoes. Still that phenomenon
seemed too rarely
reported to qualify. What I felt was needed was something that moved rapidly
in the appropriate
direction (north) at the appropriate time (late spring-summer) in large
numbers.

There are other possibilities: Perhaps birds carry it south in the fall
along the Atlantic coast and
then north up the Mississippi in the spring (as a number of migratory birds
follow that route), but
one then also has to postulate some delaying factor, because this spring
movement is entirely over
by mid-June. Or it was carried to the Midwest in the previous (2001) fall by
migrants heading
SW. But why should the virus remain entirely inactive all winter and spring
until all of a sudden,
everywhere at once it seems, it breaks out at the end of July? In Kentucky
in 2002, bird cases
came first, then mosquitoes and people 2 weeks later, followed by horses
after another 2
weeks-as though the mosquitoes had gotten it from birds and then passed it
on to people. Why
weren't the mosquitoes first?

I think the rapid change of focus from the Gulf coast to the upper Midwest
in 2002 needs a better
explanation than those proposed so far. Now we have the Colorado focus to
figure out. Sure it
blossoms whenever it hits a new, previously unexposed population, but is
that all there is to it?
Why the timing? I can accept that birds may spread it southward in the
fall-although this may be
incorrect, despite its plausibility (I would point out there were no cases
last year in Cape May
County, which funnels birds from farther north and where mosquitoes abound.
If birds are
carrying it, why isn't that a hotspot?) I do not wish to "blame" butterflies
or any other animal
group. It's just that too often we too easily adopt as gospel the first
plausibility that comes along
without the requisite proof. Certainly it has been adequately proven that
birds do carry WNV, but
that does not mean there are not other significant vectors.

I seem to recall that in the tropics many Pierids feed at mudholes and bird
droppings, but maybe I
am wrong. That is what I came up with in trying to explain how the Cabbage
Whites might pick
up the virus. Hopefully, those more knowledgeable can suggest other
possibilities. (I would point
out in response to Lili Pintea-Reed that bird droppings are not "dried out"
when fresh, and that's
when insects visit them.)

The idea of people as a vector is intriguing too. When I first saw the case
distribution in 2001 my
first reaction was that this looked more like the movement patterns of
humans than birds. In
particular, I thought of all those New Yorkers who go to Florida for the
winter. They don't stop
in SC and GA and neither did the WNV-or was that just an artifact of poorer
surveillance in
those states? Moreover, one must think not so much of humans but of their
conveyances. Trains
and trucks travel all over, but primarily along these routes also, carrying
all sorts of products and
produce.
----------------------------------------------------------------------------
--------------------------
At 02:38 PM 9/8/00 -0400, you wrote:

>Richard Worth suggested I seek your comments.
>

I've been interested in P. sennae migrations for more than 40 years.  What
I have published on them can be downloaded from my home page
(http://csssrvr.entnem.ufl.edu/~walker/tjwbib/walker.htm) under
publications.  I am currently working on two more articles.

If you want me to send reprints, give me your postal address.

(What follows is my original e-mail to Dr. Walker with his comments in
reply.)

>The Mystery of the Cloudless Giant Sulphurs (Phoebis sennae)
>
>Has anyone reported Cloudless Giant Sulphurs heading north? I have
>contended for years that their movement is southbound only, contrary to
>most books, and I have yet to meet anyone who has actually seen one
>definitely going north.
>
>Even if one PS was seen in Washington heading north, it may have been
>doing so merely to follow a bend in the river or an attractive scent and
>may not have continued in that direction once it was beyond the observer s
>view. Moreover, to create the sort of southbound flows that have been seen
>many, many, sulphurs not one or two would have to have moved north. There
>is no evidence whatsoever of any such movement ever taking place around
>here (Washington). Most authors of lepidoptera literature covering the
>middle Atlantic states omit the species altogether.

I suspect, as you do, that the occasional reports of northward migrations
of cloudless sulphurs along the upper Atlantic coast are maladaptive (they
can't survive northern winters).  As you note, cloudless sulphurs are not
regular breeders in the middle Atlantic states.  This is perhaps because
those that migrate northward in spring from their overwintering areas fly
mostly northwestward (the reverse of their fall migration).

>The reports from Folly Island, SC (near Charleston) from 1978-1980 (Aug.
>24-Oct. 9) of as many as 125-323/5 minutes going NE are intriguing. At
>that location, NE is exactly the direction of the coastline as far as Cape
>Hatteras, NC. One wonders what happened when they got that far. If it
>weren t for the reports from Florida, I d be tempted to say perhaps they
>flew on out to sea NE from Hatteras. Where did they go? That s the kind of
>flight we should have witnessed every summer that was followed by a big
>southbound flight. (Could such a movement at such dates be responsible for
>new broods heading south so soon afterward?) Where did the Florida
>butterflies go?
>
>I recall seeing similar numbers of these "flying Post-it Notes" streaming
>off from Point Lookout, MD toward Cape Charles on peninsular Virginia (I
>ve no doubt some stopped in at Smith Island, but I ll bet they moved on
>from there as in Florida, heading SSE) on 10 Oct. 1987 across many more
>miles of open water than the easier trip to the more southerly, nearby
>west shore of the Chesapeake Bay in Virginia. Until that point, I had
>believed the species or at least its movements were all coastal. But Point
>Lookout is many (about 50) miles inland, and there were more there than at
>coastal locations of similar latitude such as Chincoteague and Ocean City.
>Clearly, they were coming from somewhere inland.

Interestingly on a transect from near Fernandino Beach, Florida, to
Valdosta, Georgia, along which J. J. Whitesell and I studied fall
migrations for several years, CS seemed to avoid the coast.  At least their
numbers were very low near the coast compared to inland even though an
extrapolation of their general south eastward or south south eastward
movements in SE US would have taken them to the coast, where they would
have presumably formed a river of butterflies going south along the coast
(and perhaps a creek of misguided butterflies going north along the coast).

>I saw a similar flight at Point Lookout in 1998 and traced it all the way
>back to Route 50, the main E-W route between Washington and Annapolis
>mostly following the Patuxent River. Some were seen even further north.
>That year eggs and caterpillars of PS were found at Cape May and elsewhere.
>

Do you see numbers of CS around Washington every year or only occasional
years?  When do you first see CS in years that you see them?

>Where do all these butterflies go? Not so many years ago we were asking
>that about Monarchs, and the question turned out to have a surprising
answer.
>
>The little research I ve done on this intrigues me further. Did you know
>that a number of related species also have northward movements like those
>alleged to occur with Phoebis sennae? The final paragraphs in the species
>accounts of the (1981) Audubon Society Field Guide to North American
>Butterflies make for some fascinating reading (emphasis added):
>
>"Like the White Angled Sulphur [Anteos clorinde], this high-flying species
>[Yellow Angled Sulphur Anteos maerula] engages in northern emigrations
>that occasionally send some into the United States."
>
>"Statira [Aphrissa statira], along with some species of Phoebis, takes
>part in immense flights out to sea from South America. Unlike the
>Cloudless Giant Sulphur, Statira exhibits no such mass movements in North
>America, and in fact is considered rather an uncommon resident species."
>
>"Bursting out of Texas, Lyside [Kricogonia lyside] often invades the
>Arkansas Valley and other watersheds of the western Great Plains."
>
>"Although fairly common far north in late summer, the Little Yellow
>[Eurema lisa] cannot survive temperate or northern winters. The species
>refills the Northeast and Midwest every year with fresh immigrants, which
>furnish 1 or 2 more broods before the autumn chill kills them. Vast
>numbers of Little Yellows emigrate to the Caribbean and Atlantic. Columbus
>is supposed to have witnessed from the decks of the Santa Maria one such
>mass movement, probably consisting of this species or the Cloudless Giant
>Sulphur." (One might reflect on the changes to the flora of eastern North
>America since 1492.)

This species flies south in fall in Gainesville FL and north in spring.

>"This sulphur [Sleepy Orange Eurema nicippe] cannot withstand cold winters
>yet annually penetrates the northern latitudes a characteristic of many
>North American butterflies...Northern individuals are usually more
>dispersed, and may turn up in surprising places well up a Colorado canyon,
>for example, or along a Great Lakes shoreline."

This species flies north in Gainesville in the fall.  Perhaps it
overwinters better in cooler climates?

>"Each year, if conditions are favorable in the South, cadres of Dwarf
>Yellows [Nathalis iole] advance northward from Mexico and the southwestern
>desert, reaching as far as interior Canada. Recently, a much less frequent
>or obvious emigration to the Northwest and the Northeast has been
>detected, recorded many years and miles apart, but always along major
>river courses such as the Snake and the Shenandoah. Whether individuals
>travel great distances themselves, or leapfrog northward through
>successive broods is not yet clear. Unable to withstand the frosts of
>winter, the Dwarf reenacts its invasion of the North each year, only to
>perish with the coming of autumn."
>
>However, the account for Phoebis sennae conflicts with my personal
experience:
>
>"Summer movements bring this sulphur to states far north of its winter
>range, and autumn emigrations greatly reinforce its northern numbers,
>sometimes introducing millions to relatively small areas. This butterfly s
>appearance in the Rockies or New York is a real event. Yet all of these
>northern emigrants die without returning south; the function of the
>emigration is not really known.

Like you, I suspect this migration has no more function than monarchs
arriving in England (from North America) or desert locusts arriving in the
West Indies (from Africa).

The reason the migration is recorded is because cloudless sulphurs are so
rare in the northeast and so conspicuous when they migrate there.

>The Tailed Giant Sulphur (P. neocypris) somewhat resembles the Cloudless,
>but it is larger and bears stout, turned-in tails on the hindwings. It
>emigrates seaward in great numbers, yet is rarely encountered north of
Mexico."
>
>We have here a genuine mystery. The recorded natural history of this
>species seems to contain errors or at least needs updating. Perhaps
>sometime in this century field observers will get involved enough to solve
>it. Bob Augustine raugustine at tms-hq.com

Cheers,
Tom

==========================================================================
Thomas J. Walker
Department of Entomology & Nematology
University of Florida, PO Box 110620, Gainesville, FL 32611-0620
E-mail: tjw at gnv.ifas.ufl.edu         FAX: (352)392-0190
Web: http://csssrvr.entnem.ufl.edu/~walker/tjwbib/walker.htm
==========================================================================

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