What good are mosquitoes?

An article in the July 21 online edition of Nature magazine posed researchers the question, "Would it be a good thing if all mosquitoes were eradicated from the earth?"  I've often been posed a similar question in slightly different form, namely, "What good are mosquitoes (or ticks, or chiggers)?"

Aside from the purely speculative question that Nature asked (we couldn't get rid of all the mosquitoes in the world in a thousand years if we tried), perhaps a more realistic question would be, "If we could get rid of even one mosquito species, should we?"

Humans have been sadly effective in causing the extinction of species from the dodo bird to innumerable beetles and butterflies and other creatures.  Most of the time it is accidental, or through neglect.  Habitat destruction is probably the number one cause of species elimination.

Now, through the power of biotechnology it may be possible to cause the deliberate extinction of certain species.  So, if we had the power, should we do it?  There are powerful arguments on both sides.  Some scientists have argued that if we could destroy all the species of Anopheles and Aedes mosquitoes, for example, the world would be a better place and millions of lives would be saved. 

As the writer in Nature points out, there are many species which appear to be pests to us humans, but which hold together important strands in the web of life.  We humans have never been very good at predicting what would happen when you pull one of those threads.  Eliminating all species of no-see-um flies (a family known for its painful bite and transmission of certain viruses, protozoa and filarial worms), for example, would include elimination of a species of these flies that pollinate the cacao tree. As the Nature article threateningly proposes, "Imagine a world without chocolate!"


I am still unsure that we should deliberately cause the extinction of all mosquitoes. And I suspect I'm not alone in feeling this way about insects.  I wonder what PMPs would say if someone come up with a practical proposal to cause the extinction of German cockroaches?  I'll bet there are more cockroach lovers out there than anyone realizes.

Good news for BASF

In a recent post I noted that fipronil, the active ingredient in Termidor and other products sold or licensed by BASF Corporation, was about to go off patent.  In today's article by Dan Moreland of PCT it is reported that the judge has set a July 2011 court date, effectively buying BASF some breathing room for its patent.

We'll just have to wait another year or more to see whatever big waves will take place in the termite control business when generic fipronil hits the market.

Disinfectants as pesticides

Pest management professionals typically don't have to worry a lot about disinfectants.  Application of disinfectants is generally not part of the PMP's responsibilities; and in general the use of disinfectants is exempted from Texas (and most other states') pest control laws and regulations.  This makes sense, because daycare workers wiping down countertops, and nurses disinfecting hospital rooms and equipment, would otherwise have to have pest control licenses.

Nevertheless, questions about disinfectants frequently come up in discussion with the public.  Just the other day we were asked for input about the availability of "green" disinfectants for a public health clinic.  My school IPM colleague, Janet Hurley, provided a couple of excellent web links that I thought I would pass on in case you have an interest in learning more about the regulatory and scientific background of disinfectants.

If a customer asked, could you tell the difference between a sanitizer and a disinfectant?  Did you know that disinfectants don't kill all microorganisms?  It takes a sterilant to do that.  Sterilization processes typically rely on creating harsh physical or chemical conditions that kill all microorganisms, including tough bacterial spores and viruses.  To get a better understanding of these distinctions, Wikipedia provides an excellent introduction to disinfectants and related products.  The Wikipedia writers summarize the quandary of finding the ideal disinfectant well:

A perfect disinfectant would.. offer complete and full sterilization, without harming other forms of life, be inexpensive, and non-corrosive. Unfortunately, ideal disinfectants do not exist. Most disinfectants are also, by nature, potentially harmful (even toxic) to humans or animals. 

One of the things I learned from this article was that many household disinfectants contain Bitrex, an ingredient familiar to many of us in the pest control industry.  Bitrex is added to many rodenticides to make them highly distasteful to most pets and to humans.

The article explains why bleach remains one of the most cost-effective and efficient disinfectants.  But did you know that it's critical to never mix different kinds of indoor disinfectants, as many of them can interact and produce toxic byproducts?  Bleach, especially, should never be mixed with ammonia as it produces highly toxic ammonium chloride gas.  When using a bleach solution to clean areas that have been contaminated with pet or rodent urine one should always clean the surfaces with soapy water first to remove the ammonia components that might react with the bleach.


The Centers for Disease Control and Prevention (CDC) also maintains a site on the subject of disinfectants.  The focus of this article is on the regulatory framework affecting disinfectants and sterilants.  Lest we forget that germs are pests too, all disinfectants must be registered as pesticides with the U.S. EPA.  Look at the label of a bactericide product and you'll notice the EPA registration number, signal words, and precautionary statements similar to what we see on insecticide labels.


While the idea of using green cleaning products is good in many ways, we should not kid ourselves that there is always a perfectly safe way to do everything.  Most green cleaning products do not kill a wide variety of bacteria and cannot disinfect well, or sterilize.  However regular cleaning, good housekeeping and effective pest control can reduce the need for disinfectants by maintaining conditions that are not conducive to bacterial survival and multiplication.  And this is the best solution of all.

Seed bugs common in many areas

One of the occasional invaders of structures that we see in Texas is actually a family of insects called the seed bugs (Order Hemiptera: Family Lygaeidae).  There are some beautiful little insects in this group (see the picture to the right, taken by entomologist Mike Quinn on Bugguide.net, of a species called Pseudopamera aurivilliana), most of which are overlooked by the casual insect observer because they stay in the fields and roadsides and feed only on, well, seeds.

Seed feeders don't hurt the plants they feed on, but they do reduce seed production.  Lygaeid bugs are just another part of the natural balance helping keep plant populations from getting out of hand.  

Some years we see high populations of a variety of these seed bugs, and this seems to be one of these years.  Entomologists from El Paso, Uvalde and other parts of south Texas are reporting invasions of false chinch bug, another type of Lygaeid this summer.

I recently had pictures of what appear to be Pseudopamera submitted by James Kiening (Bugmobile) through Martyn Hafley (Estes, Inc.).  The insects were clustered on what appeared to be building siding.  Also, John Stewart (Commercial Pest Control, Dallas) sent in samples of Ozophora picturata (see picture to right) that was clustering by the thousands outside a home in Dallas a couple of weeks ago (30 June). 

While interesting and useful to document the species that enter buildings, the bottom line for a customer with a Lygaeid infestation is that these are outdoor-living insects.  They show up only accidentally inside buildings (once they get indoors they have nowhere to go and nothing to eat).  If they enter a home or business it will be a temporary nuisance.  They will not reproduce or set up shop indoors.  If significant numbers show up indoors it's probably an indication of the need to seal windows, doors, air vents, etc.  Also take a look at outdoor lighting to see if unnecessary lights are being left on all night, especially lights shining on doors, windows or sides of the structure. 

P.S., I'm told by Ed Riley of the entomology museum at Texas A&M University that the Hemipteran family Lygaeidae is being split into multiple families by the meddling DNA-obsessed taxonomists.  I was encouraged to know that even he didn't recall the new families for these little guys, so we just agreed to keep calling them all Lygaeids until we're arrested by the entomology police.

The most common mosquito-borne encephalitis

I think that one of the most awesome things our industry does is protect people from disease that can literally destroy a life.  It is also a weighty responsibility when we stand between a customer and the threat of disease.  Numerous pests that are controlled by our industry have the potential for causing disease in humans.  Consider a few examples:

• Rodents are implicated in 55 human diseases.  In Texas, murine typhus is on the increase with nearly 3/4 of all U.S. cases in the southern part of our state.  
• Over 100 pathogens have been associated with house flies, including Campylobacter and the deadly E. coli O157:H7, and possiby community-acquired MRSA.
• Although it's been hard to connect cockroaches with outbreaks of human disease, the German cockroach has been shown to be a carrier of at least 60 species of bacteria, fungi, molds, helminths, protozoans and viruses.  
• Cockroaches have also been implicated in causing asthma, especially in pre-school aged children.  In older people, definitive evidence shows that cockroach allergens exacerbate asthma.
• Mosquitoes may be the worst, with their frequent association with virus transmission, heartworm (in dogs) and other disease. 

The Centers for Disease Control and Prevention recently published the annual report on West Nile virus for 2009.  Since its introduction into the United States in 1999, West Nile virus (WNV) has become the leading cause of arthropod-borne viral encephalitis in the country. The good news is that the number of WNV cases continued to decline this year, with 38 states (and the District of Columbia) reporting 720 cases (down from 1356 cases last year, and a high of 4156 cases in 2002). The bad news is that Texas continues to lead the country (with nearly a quarter of all cases) in reported neuro-invasive cases of WNV.  The term "neuroinvasive" refers to severe cases of the disease that affect a person’s nervous system. These include encephalitis (an inflammation of the brain), meningitis (an inflammation of the membrane around the brain and the spinal cord) and acute flaccid paralysis (an inflammation of the spinal cord that can cause a sudden onset of weakness in the limbs and/or breathing muscles).  None of this is something you want to get. 

I've discussed WNV before in this blog, partly because we have had a number of cases in my Dallas community, but also because WNV is typical of many mosquito borne diseases which pop up periodically in the U.S.  I am convinced that our industry can and should be doing more for the public with regard to mosquito control.  Although most mosquito control is (appropriately) conducted by county and city health departments or mosquito control districts, PMPs can play an important role in the fight against mosquito-borne disease.  Here some of my thoughts on how you can help.

• Train your technicians to be on the lookout for mosquito breeding sites when conducting inspections of residential accounts.  No one thinks their backyard is the one breeding mosquitoes.  It's always the next-door neighbor or the creek down the street.  In one study done by the Dallas County health department a few years ago, 25% of the folks who called the health department to complain about mosquitoes had mosquitoes breeding in their own backyard.  I know from experience that it's easy to forget to turn over the wheelbarrow or put away the kids' toys before rain or irrigation water can sit and breed mosquitoes.  Having an extra set of trained eyes looking over the yard every month can make a significant difference.
• Educate your customers about mosquito control.  How to recognize and report problems, explaining the importance of repellents, and reports on the local mosquito situation in your community(maybe through a newsletter, your website, or monthly bill inserts) can be a much-appreciated service and increase your value to your customer.  A lot of people forget about mosquitoes after the spring tides of floodwater mosquitoes ebb, but now as the summer heats up the risk of mosquito-borne disease actually increases.
• Consider including mosquito control among your summertime pest control services.  In addition to backyard fogging prior to outdoor events, residual sprays applied to mosquito resting sites (via sprayer or backpack ULV blower) can be very effective.  Of course larvaciding in some locations can be helpful also.
• Refer your customers to the Mosquito Safari website for more information about mosquito control and how to find mosquito breeding sites in their own backyards.