The bizarre life of a parasite

I received an unusual sample last week that nicely illustrated the lengths some organisms go to survive.  A woman was puzzled by a number of hard flaky objects that mysteriously appeared in her bed sheets. The accompanying image shows the sample under 6X magnification.  The objects were hard, but crushable and 2-3 mm in length.

It's not uncommon for people to find objects presumed to be droppings or some other evidence of insect presence in a home.  Rodent droppings, American cockroach, silverfish and other insect droppings are not unusual to find indoors.  In addition, carpenter ants have the interesting habit of tossing insulation and other debris, along with dead insects and insect fragments, out of their nests.  Most often carpenter ant "frass" is found in windows and doorways, where carpenter ant "kick-holes" (garbage shoots) are commonly located.

My sample was none of these, however.  My first task was to determine whether the client had a dog or cat.  A quick phone call confirmed that the family had no cats, but did have a dog which frequently slept on the bed.

This answer clinched the diagnosis of "tapeworm proglottids". The dog tapeworm, Dipylidium caninum, lives and feeds as a parasite in the intestinal tract of dogs, cats and (rarely) humans.  These worms are long and flat and may reach lengths of up to 12 inches. The body of the tapeworm consists of segments called proglottids. As a tapeworm matures, the oldest proglottid segments detach from the main body of the tapeworm and wriggle from the anus of the infected animal. These fresh tapeworm segments move with a stretching and shrinking motion.  They are opaque or pinkish white, flat and rectangular, and initially can move short distances.  Eventually they dry into 1/16 inch-long, rice-shaped sacs as seen in the image.  These sacs contain viable tapeworm eggs, and are often seen attached to the hairs around the pets's anus, in feces, or in areas where the pet sleeps (in this case a human bed).

Here's where things get really bizarre.  Fleas are essential to the life cycle of the dog tapeworm.  Tapeworms use fleas to disperse from one host to another.

Flea larva. © M. Merchant.

Flea larvae are the least frequently seen life stage of the flea, but are always present in the soil (outdoors), flooring, carpet or pet bedding of an infested home.  Normally flea larvae scavenge unnoticed around pet loafing areas for the dried blood that always flakes off the fur and skin of a flea-infested host.  Since flea proglottids are likely to drop into these same locations, it's not uncommon for flea larvae to encounter and feed on them. Once a proglottid is nibbled on by a flea larva, the ingested tapeworm eggs hatch inside the flea's body.  In this way the flea larva (and eventually the adult flea) becomes infested with a life stage of the tapeworm that is capable of infecting warm-blooded hosts.

A cat or dog subsequently becomes infected with tapeworms when they ingest these infested fleas during grooming. Once released into the pet's digestive tract, the tapeworms begin to grow into mature adults that help themselves to a share of the unwitting pet's diet.

Finding tapeworm proglottids in a home does not indicate a threat to people (though small children have been known to become infested when they pick up and eat fleas!), but they are an indication of a tapeworm-infested pet. If you find tapeworm eggs in a home, recommend to the homeowner to take their pest to the vet for treatment with anti-parasite drugs.

The dog tapeworm has got to be one of the most unusual pest life cycles encountered in the indoor environment.  For more information about fleas and tapeworms see our online publication, Controlling Fleas.

Texas A&M Workshop to offer ACE prep class this year

The Texas Pest Control Association, Texas AgriLife Extension, and the Texas A&M University Department of Entomology will be hosting the 65th annual pest control workshop in Bryan, TX on January 12-14, 2011. If you've never been before, this conference is designed for both the newly certified applicator and those who have been in the business for years. The focus is on providing you with the latest research-based information about the science of pest control.

The workshop includes two full days of continuing education credits (Wednesday and Thursday) and three short courses on Friday.  Topics of the three short courses include pest control in commercial food establishments, termite biology and control, and fumigation. Participants can choose one course and receive up to three additional CEUs. Be sure to sign up early as space is limited to the first 100 people. School IPM even gets its own track at the A&M workshop.  On Thursday, one concurrent session track is designed for IPM Coordinators and individuals interested in school IPM topics.

In addition to the regular program, the ACE (Associate Certified Entomologist) exam prep course will be offered for the first time at the A&M workshop.  The prep class is a popular way to get motivated to finally take that ACE exam you've been promising yourself to take.  If you are experienced, and think you know your stuff when it comes to entomology, check us out. The ACE certification program does not require a degree in entomology, but seven verifiable years in pest control and willingness to subscribe to the ACE code of ethics.  Sponsored by the Entomological Society of America, ACE certification is another assurance for your customers that you know your profession well.

Dr. Bob Davis, BASF Corporation, and I will present the prep class on Wednesday, from 10:15 am to 5 pm.  In addition, if you want to take the ACE exam, it will be offered the following day, Thursday, January 13, from 8 am to 12 pm.  Anyone wanting to test must apply at least 30 days in advance by completing an online application at the Entomological Society of America (ESA). You do not have to pre-qualify to take the course without the exam. The course is also good for one General-Other, one General-IPM, one Pest, and one Termite CEU, as well as 4 technician credit hours. There is an additional charge through ESA to apply and take the exam; and anyone wanting to sit in on the class or take the exam must be registered for the workshop.  For more information about the ACE program and how to apply, go to the ESA ACE website.

If you're interested in registering for the workshop, call (979) 845-5855 or check out the website at http://pcoconference.tamu.edu

Bed bug sniffing dogs not perfect

From New York Times story.  11/11/2010

One of the most popular tactics in the world of bed bug IPM has got to be bed bug sniffing dogs.  Let's face it, a PMP with a worried face and a flashlight can't hold a candle to a cute pup with mysterious powers to sniff out bed bugs where they hide.  The problem, we are learning, is that bed bug sniffing dogs are fallible.

A New York Times article published last week details a number of cases where dogs gave "false positives"--that is they detected bed bugs when they didn't appear to be there.  According to the story, one couple paid $3,500 in extermination fees after a dog indicated there were bedbugs throughout their home. After throwing out a bed and 40 garbage bags full of clothes and baby toys, the customer continued to get bites.  Another pest control company couldn't detect any bed bugs, and eventually the problem was traced to a rodent mite infestation. 

While not a scientific evaluation of doggie abilities to sniff out pests, the story points out some nagging concerns about dogs and pest control. 

Assuming dogs can be trained to accurately and consistently sniff out bed bugs, many factors can influence the effectiveness of a dog team.  I say team, because a detector dog service is a team of animal and handler.  If the dog is poorly trained, or training is not reinforced on a daily basis, or a handler is not used to a dog (or vice versa), nearly everyone admits that reliability will suffer. 

Dogs were popular in some markets 10-15 years ago as termite detectors, but few companies seem to employ them today.  I suspect that the high cost of maintaining dogs and retaining handlers were the principal factors leading to the demise of termite beagles (though the U.S. Animal and Plant Health Inspection Service still employs contraband-sniffing dogs at international airports--and sniffing dogs are used in many other venues).  Perhaps the termite market wasn't robust enough to sustain termite-sniffing dogs.  It's yet to be seen whether bed bug sniffing dogs will have greater success.

If these dogs are going to make it, a credible certification program is sorely needed, as pointed out in the Times Article.  The stakes are very high, because a handler who suggests a room is infested when it's not stands to cost the customer a bunch of money.  And let's not forget the potential for fraud with unscrupulous handlers trying to drum up money to treat apartments or hotel rooms that don't need treatment.  It seems to me that this is one very good reason for pest control companies to keep their financial distance from canine detection services.

The key to developing effective IPM programs for bed bugs, I believe, is good monitoring and detection techniques.  Pitfall traps, pheromone and carbon dioxide traps, skilled inspectors, and sticky cards will undoubtedly be around for awhile.  But only time will tell whether bed bug dogs will find an honored place among the bloodhound, drug and bomb sniffing honor roll of service dogs.

Loss for Texas pest control

Any of you who knew Jeff Seabrook will be sorry to hear that he lost his battle with cancer yesterday.  According to a TPCA email today, there will be a memorial service for Jeff at Dalton Funeral Home in Lewisville, TX (972-436-6511) this Saturday, November 13, from 2-5 PM.

Jeff was one of the great personalities produced by the pest control industry in Texas.  I first met Jeff when he worked for ICI Americas, but he had worked as many capacities in the industry that one can.  He always had a story, or a gadget, for every occasion.  I will be forever grateful for his invite to go on a fishing trip many years ago in Costa Rica... a trip I'll never forget.

In recent years Jeff and his wife Diane moved to the Davis Mountains area where he reveled in the scenery and wildlife.  If you are a Facebook follower, consider taking a minute to write a note on his Wall.

Wind turbine woes

Wind turbine near Abilene, TX.  NY Times photo.

When does urban entomology have nothing to do with houses or cities?  Perhaps no better example can be found than the recent email received by my colleague  Dr. Chris Sansone.  He was contacted concerning a wasp problem by the supervisor for a company that provides maintenance services for wind turbines.

If you haven't traveled recently to west Texas, or the corn fields of Iowa or Minnesota you may have missed the sprouting of thousands of towering wind turbines on the vast, windy plains of America.  The size and scope of these wind farms is truly amazing, providing a reported 4.5% of Texas' energy.

Apparently 2010 has been a banner year in many areas for paper wasps. Paper wasps, genus Polistes, are the most common of the social wasps around the state, with nests easily found around most homes and buildings.  Polistes wasps are predators on caterpillars and other insects, and build umbrella-shaped paper nests under tree branches, under eaves of buildings and in windows.

Paper wasps around the entrance to a wind turbine. 
Photo courtesy Aaron Foster.

Most Texans learn sooner or later to respect paper wasps for their powerful sting and their willingness to defend their nests with joint attacks on intruders.  No wonder then that maintenance crews of wind turbines get a little skittish when wasps gather at turbine doors at the ground, inside the tower and, even worse, at 300 feet around the generator housing (nacelle).  Imagine being at the top of one of those towers and getting a face full of wasps!

This phenomenon should not surprise pest management professionals who have observed paper wasp behavior over the years.  Each fall, we see paper wasps abandon their barren nests to seek shelter for the winter.  These overwintering wasps are queens, and they are especially drawn toward structures, especially tall structures in their search for overwintering quarters.  Tall buildings, chimneys and towers are common points of congregation for paper wasps during the months of October and November in Texas.

This behavior explains the high frequency of complaints by office workers (and homeowners) of wasps in buildings during late fall, winter and the early spring months.  Once inside the attic, or false ceilings, of buildings, paper wasps will move around, especially during periods of warmer weather.  These same wasps frequently find their way into living and working quarters, to the dismay of people.  The good news, however, is that without a nest to defend, these wasps have little fight in them.  Therefore, there is little risk of being stung by wasps at this time.

Wind turbine crews aren't the only high fliers worrying about wasps.  Communications tower workers, construction workers and even NASA launch pad workers have discovered the fondness of paper wasps for high places.  When encountering wasps in such locations I have no doubt that the best course of action is to keep calm, wear clothing that can be buttoned tight and try your best to ignore the critters.  Of course you're not getting me up there to test the theory.