Is spraying for mosquitoes in April warranted?

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barbara.katzenberg

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Apr 25, 2021, 9:26:26 AM4/25/21
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Hello all: I have watched the announcements over the years for planned spraying in swamps for mosquitoes. This year we saw on our website "The East Middlesex Mosquito Control Project will be using a helicopter to spray an application of Bti (Bacillus thuringiensis var. israelensis) to control mosquito larvae over large wetlands in Lexington between April 19-30. Wetlands currently being evaluated include Tophet Swamp, Hayden Woods, Great Meadows, the Meagherville Conservation area and the upper Vine Brook area. The Bti will be applied in a granular formulation by a helicopter flying low directly over the wetlands."

I understand there is a concern for mosquito-borne illnesses that should be taken seriously.  But, we also know that some human-centered goals can have unintended effects on other species. To that end, I wrote to the organization of noted environmentalist and recent Cary Memorial lecturer, Doug Tallamy,  to get his point of view on whether this practice is as harmless as it is purported to be.  Dr. Tallamy responded as follows: 

Three things. 1) April is way too early to be treating for mosquito populations. Populations are at their lowest point in April.
2) Mosquitos do not need to be treated in permanent bodies of water. Natural predators of larvae, and there are many, do an excellent job when water bodies are permanent. Mosquitoes do well in temporary bodies of water where predator populations cannot persist.
3) Be aware the BTi kills all species of aquatic Diptera, not just mosquitos

I'm not sure whether a swamp has predators for mosquito larvae, but I would think so.  I think we should learn more about this practice, and ascertain whether everything is being done to minimize unintended consequences to other species. 

Barbara Katzenberg
TMM, Precinct 2


Meg Muckenhoupt

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Apr 25, 2021, 11:39:34 AM4/25/21
to barbara.katzenberg, LexTMMA
Have you contacted the East Middlesex Mosquito Control Project to ask them why they are spraying now?

In Massachusetts, birds are reservoirs for Eastern Equine Encephalitis - which has a case mortality rate of 33%.  The spraying may have to do with preventing early infection of and by migrating birds, reducing the probability that the virus will spread via mosquitoes that bite both birds and mammals. 

Vector-host interactions and epizootiology of eastern equine encephalitis virus in Massachusetts

Meg Muckenhoupt
Pct 1

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barbara.katzenberg

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Apr 25, 2021, 12:57:22 PM4/25/21
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Thanks for the reply, Meg.  I have not contacted them yet--wanted to hear what others had to say about it.  There are always going to be some tradeoffs in any initiative and I don't minimize the seriousness of Eastern Equine Encephalitis when it occurs.  That said, it is quite rare.   I'm sure Bti biologists have made an effort to take possible side-effects into account, but some of the knowledge around species extinction (particularly of insects) is only recently becoming known.    People can minimize mosquito breeding in their own yards through known methods and protect themselves when visiting conservation lands via their clothing, or wearing insect repellant.   Dr. Tallamy writes in addition " Unfortunately, mosquito larvae are the main source of food for aquatic predators like dragonflies and damselflies, Backswimmers, predaceous diving beetles, etc. One big mosquito breeding site that is often overlooked are street drains."   I'd be interested to know whether storm drains are a breeding ground for mosquitoes in our area and whether any effort has been made to control them there, as this would presumably would affect fewer species and might be more relevant to what happens in our neighborhoods. 

Barbara Katzenberg
Precinct 2


eric.mi...@verizon.net

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Apr 25, 2021, 1:31:01 PM4/25/21
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Barbara,

 

I have lived on a street that abuts the Great Meadow for 15 years. While I do not know the science behind this mosquito control program, I can tell you that:

 

  1. It has always been done at this time of year;
  2. It is highly effective in keeping the mosquito population to a tolerable level throughout the spring and summer;
  3. Based on my many walks through the Meadows, the diversity and size of both the bird and frog population does not seem to suffer from this control program.

 

I ask that you do not meddle with this effective program. We in Lexington have been luck to have minimum levels of EEE and West Nile cases. If this program we to become ineffective I fear that my family, my neighbors families, and the many people who walk Lexington’s open spaces will be at risk.

 

Eric Michelson

Precinct 1

Dinesh Patel MD

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Apr 25, 2021, 1:58:19 PM4/25/21
to eric.mi...@verizon.net, LexTMMA
Eric and all 
Do you or others know if they spray in Willards wood — there is small pond and stream which may harbor mosquitos ?? 
I am sure the town health department puts their input into details but just wonder if Willards wood is part of this prophylactic preventive action
Thanks 
Dinesh
Precinct 6 tm 


Sent from my iPhone

On Apr 25, 2021, at 1:31 PM, eric.michelson via LexTMMA <lex...@googlegroups.com> wrote:



barbara.katzenberg

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Apr 27, 2021, 8:11:09 AM4/27/21
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Here is what I have learned so far from the Eastern Middlesex Mosquito Control Commission: "For determining which wetlands will have Bti applied, a technician visits each wetland and takes a minimum of 30 water samples. If larvae aren't present or there aren't very many larvae, Bti won't be applied. The Bti bacteria dies quickly, so if there aren't mosquito larvae present at the time of the application, we don't want to apply to product. The Bti will affect all mosquito larvae that are in the water at the time of the application, both vector species and non-vector species. Bti is only affecting mosquito larvae and other closely related diptera. The same process that we're using during 2021 was also used in 2020. During 2020, Tophet Swamp and Arlington's Great Meadows had Bti applied. These are also the areas scheduled for 2021."  (emphasis mine).

 So, I was happy to see that they were using data and being selective in this phase of the operation.  I also wrote a similar question to the Lexington Conservation Land Stewards (of which I am one) and was provided some additional documentation on the practices around mosquito control  in MA which I will be reading and will share any interesting findings.  The most detailed appears to be this one ( https://www.mass.gov/doc/massachusetts-emergency-operations-response-plan-for-mosquito-borne-illness-0/download)

Barbara Katzenberg
TMM Precinct 2


Dinesh Patel MD

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Apr 27, 2021, 8:40:44 AM4/27/21
to barbara.katzenberg, Lex-TMMA Town Meeting Members, precinct 6 Town Meeting Members
Thank you Barbara 
Great information 
My question is the same 
 Willrads wood area 
Lexington Conservation Land Stewards. Commission — can they tell us --precinct 6 area residents as well as those who visit Willards wood about what 
 Eastern Middlesex Mosquito Control Commission is planning to do
There is small pond as well as small stream---breeding  ground for mosquito. Do not know but can Lexington Conservation Land Stewards. Commission find out and if needed institute what is best for health welfare and safety 
They may be doing it but do not know 
Appreciate your volunteering work for us 

Thanks 
 Dinesh Patel
Precinct 6 tm
 

barbara.katzenberg

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Apr 27, 2021, 9:03:45 AM4/27/21
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Dinesh, from what I learned they are not doing any spraying this spring (really dropping of Bti pellets) in any wetland other than Tophet Swamp or Arlington Great Meadows.  My understanding is that later in the year if there is a bad infestation and the mosquitoes are shown to be carrying diseases that put humans at risk, they could do locale-specific killing of the mosquito adults.  Because this practice of pesticide spraying is much less specific, killing butterflies, bees, and other desirable species, my understanding is this is only done if it has been determined there are mosquitoes carrying disease (EEE, West Nile Virus). I will continue to post as I learn more.

Barbara Katzenberg
Precinct 2, TMM


barbara.katzenberg

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Apr 30, 2021, 11:42:05 AM4/30/21
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Here are some additional info:
  • There is a very high bar to be reached if there is going to be pesticide spraying for adult mosquitoes, because of the known risk of secondary commercial and ecological side effects.  In 2020 in MA this was only done in Bristol/Plymouth counties
  • From Brian Farley, Superintendent of the East Middlesex Mosquito Control project: "... we never spray for adult mosquitoes in Lexington, it's not part of Lexington's mosquito and vector control program. For EEE emergency spraying, I'm not aware of the state ever including Lexington in that operation, and this is due to the lack of correct wetland habitat for EEE vectors. It would be highly unusual to find EEE inside of Route 128."
  • There is a Public Listening Session" this coming Monday from 11-1 for a state task force called "Mosquito Control for the Twenty-First Century."  I'm going to attend, let me know if you want more info about how to attend.  
  • They requested public comments in advance of the meeting and I sent in the following: " In reviewing current practices, it appears that even when there have been no recent documented cases of mosquito-borne diseases in an area, it is standard practice to lower the number of mosquitoes by killing larvae in wetlands.  The use of Bti, while non-toxic for humans, does affect other insects and has unknown effects on overall biodiversity in the areas where it is applied. Mosquitoes and other aquatic Diptera killed by Bti are food for birds, bats, and amphibians. During an era of mass extinction of animal species, I believe we should examine the effects larvicide practice has on overall biodiversity and review whether it could be done in a more limited fashion without putting humans at risk."
Barbara Katzenberg
Precinct 2, TMM

Meg Muckenhoupt

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Apr 30, 2021, 12:13:08 PM4/30/21
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There was a West Nile case in Cambridge last year.
The Cambridge man was exposed in Middlesex County.

Oakes Plimpton, who contracted West Nile virus five years ago in Arlington, talked about his experience in the local newspaper. 

Meg Muckenhoupt
Pct 1

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