Wednesday, March 16, 2016

Controlling fire ants in gardens

Fire ant carrying bait back to the nest.  Baits do not have to be
applied directly to a garden to control fire ants living inside a
vegetable garden.  USDA image courtesy Bugwood.
One of the common questions about fire ants concerns control within vegetable gardens. This is an especially common question directed to licensed applicators who work for school districts with school gardens.  It also may be an issue for PMPs servicing residential accounts with home gardens.

A standard, low-risk treatment on commercial, residential and school properties is use of a fire ant bait; however many of the most commonly used baits do not allow direct use in vegetable gardens. Fortunately, there is a work-around.

In most cases the simplest way to get fire ants out of a small- to medium-sized garden is to apply a fast acting fire ant bait around the outside garden perimeter.  This should be a legal application for all fire ant baits (check your label to be sure), and since fire ants do not pay much attention to garden edges, the garden infesting ants will readily pick up bait from the surrounding ground.  Yes the bait does end up inside the garden anyway, but only inside the fire ant nests, where there is no risk of it contaminating leafy vegetables.

For larger gardens or cropland where perimeter treatments might be less effective, several fire ant baits are legal for use.  Spinosad and abamectin-containing baits generally allow garden application (e.g., Clinch®, Fertilome® Come and Get It, and Payback®).  In addition, Extinguish® (but not Extinguish® Plus) fire ant bait containing methoprene has a label that allows use on cropland. However Extinguish is too slow for most gardeners, requiring approximately two months for maximum control.

In addition to baits, mounds can be treated directly with any of several mound drenches labeled for use in gardens.  The eXtension website contains recommendations for a two-step (bait and mound treatment) approach to fire ant control in both conventional and organic vegetable gardens.

Appreciation to Dr. Paul Nester (Texas A&M AgriLife) for supplying some of the information used in this post.

Tuesday, March 15, 2016

Do carpet beetles "sting"?

Varied carpet beetle larva.  The tufts of hair on the final tail
segments (right) are barbed and have been associated
with dermatitis and gastrointestinal upset in some people.
Dermestid beetles (Coleoptera: Dermestidae) are among the most common indoor pests throughout the United States.  The principal damage caused by these beetles occurs when they feed on stored products containing animal protein, such as woolen sweaters, rugs, silks, furs and feathers.  Also products containing dried dairy and grain based foods may be attacked. Outdoors, dermestid beetles may feed on dead animals or may scavenge in bird and other animal nests.

What's less known about these beetles is that they occasionally make people sick. I was reminded of this today after being asked whether carpet beetles could bite from two email correspondents.  Now it's true that carpet beetles do not bite, but they can affect people in other ways.

Small hairs called hastisetae are found on the larvae of some dermestid beetles, especially in the genera Anthrenus (carpet beetles) and Trogoderma (warehouse beetles).  These hairs can cause urticaria, dermatitis, vasculitis, lymphadenopathy, and allergic rhinitis in sensitive persons, as illustrated by a recent paper in Pediatric Dermatology from Kara Hoverson and colleagues.

Multiple beetle-caused, excoriated lesions on the
face of a 2-year-old girl. From Hoverson et. al. 2015.
In this paper a two-year old girl experienced skin eruptions on her feet, face and hands.  Subsequently, a few carpet beetles were found in the patient's stuffed animals, mattresses, drawers, baseboards and nightstands, according to the article.  Pesticide applications alone were ineffective in stopping the lesions; but after thorough vacuuming, carpet steam cleaning, and discarding of old bedding and linens, along with physician prescribed ointment treatments, the lesions improved by 70%-80%.  By two weeks after treatment, all lesions were healing. The mother had only a few lesions and the father, who traveled extensively, had none.

An adjoining apartment was found to be even more heavily infested, possibly the original source of the problem.  Occupants of that unit were not bothered by the beetles and refused treatment. Dermestid beetles found in the apartment included larder beetles (Dermestes lardarius), beetles in the genus Anthrenus (carpet beetles) and the genus Attagenus (furniture beetles).

Such hypersensitive reactions are not new to the medical literature.  The Pennsylvania State University published a fact sheet on carpet beetle dermatitis that summarizes reports from 1948 concerning several case histories.  In addition, carpet beetle larvae can cause gastrointestinal upset if swallowed, for example in infested milk, cereal or grain products.

All this does not make carpet beetles an especially alarming indoor pest. Dermestid beetles are very common in homes, especially in the South.  Yet, reports of hypersensitive reactions to contact with carpet beetles are rare in the medical literature. Even when beetles are present in a home, direct contact with humans is not common. And finding a few carpet beetles in a home does not necessarily mean that they are automatically the cause of skin lesions.  Nevertheless, customer reports of "bites" or lesions should be investigated when carpet beetles are apparent.

Complicating matters further, carpet beetles are, not surprisingly, often collected from apartments of people with suspected delusions of parasitosis. This can make diagnosis of such a condition more difficult, because it may require ruling out beetle-related dermatitis as a cause of suspected bites or skin irritation.

Delusions of parasitosis, however, normally involve unreasonably high levels of stress and irrational response to perceived pest problems, beyond what would be considered a normal response to a minor or undetectable pest infestation. PMPs who encounter mystery bug cases where carpet beetles are present, should recommend a thorough (HEPA) vacuuming of furniture and other likely sources of infestation, including cleaning of bed linens.  In addition a thorough inspection should be made for possible sources of a beetle infestation, including use of sticky traps.

I have carpet beetles in my home, but this information will not change the way I view these persistent insects. When I see a carpet beetle my first concern is for any expensive sweaters stored in our closets.  Good housekeeping will keep most carpet beetle populations at acceptably low levels in most homes.  

The annual crane fly invasion

The long-legged crane flies are one of our early
harbingers of spring. Like all flies, crane flies
have only two functional wings--though the
remnants of the second set of wings, borne by most
insects, are visible here as small knobby structures
behind the flying wings.
While concern about mosquitoes floats ominously over the digital airwaves this month, annual flying hosts of crane flies quietly fill the real air over cities and fields throughout Texas.  Crane flies are most apparent each year in our state during the late winter/early spring.  I think of them as one of the first signs that spring is nearly upon us.

The crane fly family is one  of the most diverse families of true flies.  There are over 1500 different kinds found in North America.

The common name "mosquito hawk" is sometimes given to these flies; however the name usually comes with the belief that these insects are predators, perhaps on mosquitoes. Nothing could be further from the truth. Crane flies are among the gentlest of insects.  Some are nectar feeders, sipping sweet sugars from plants and possibly helping out a little with pollination in the process. Other species lack mouth parts entirely.  Instead, the adults of these species live out their short lives relying on fat reserves built up during their underground larval stage.

Crane fly larvae are rarely seen by all but the most dedicated (nerdy?) naturalists.  These long, legless, worm-like creatures may be found in many types of moist soil, sandy areas along streams, rotting vegetation, mosses, or even feeding on organic matter in the nests of birds and mammals.  Very few are considered pests, though the European leatherjacket can be a pest of turfgrass.

Your customers may be seeing crane flies and thinking that the mosquitoes are coming out larger and earlier every year.  But crane flies are generally active before our pest mosquitoes. They can be distinguished from mosquitoes by their generally larger size; but also by their wings, which lack the scales found on mosquito wings. Close examination of the thorax with a hand lens will also show a V-shaped suture just behind the wings.  

So what is good about crane flies?  They are undoubtedly greatly appreciated by hungry birds at this time of year, as well as smaller mammals, fish, spiders and predatory insects.

There is no practical control for crane flies since they emerge from a variety of breeding sites and fly into backyards regardless of pest control measures.  Instead, perhaps we should encourage our customers to "enjoy" crane flies while they last.

Some of your customers may think more kindly of these gentle and harmless insects when they learn that they only have love on their tiny minds.  The sole activity and goal of the adult crane fly is to find a mate and, for the females, to lay eggs for next spring's crop of flies. And who wants to get in the way of love?

Friday, March 11, 2016

Zika Updates

Things have happened so quickly on the Zika virus front over the past three months, I thought a short update might be in order.  You may recall a post I wrote in December warning about a need to brace ourselves for what might possibly be a big year for the new Zika phenomenon.  As my wife might say, "Well, at least you were right this once."  A quick peak at Google Trends surely bears this out.  The following graph shows the relative number of times people on the Internet used the search term "Zika" in recent years:

Much of the excitement about Zika virus, of course, has centered around the possibility, insisted on by many Brazilian public health officials, that there is a connection between Zika infection and a condition in newbornes called microcephaly.  Since the initial reports, there has been some pretty wild speculation about whether Zika really is the cause of the condition.  One was a blog posted on Reddit, a "social networking newsite" that bills itself as "the front page of the Internet".  The post speculated that the real reason there had been no previous connection between microcephaly and Zika was that the microcephaly in Brazil was actually linked to experiments with genetically modified mosquitoes in some parts of the country where microcephaly was rampant. Many people have since discredited the logic behind this conspiracy theory.  But expect this idea to float around the Internet for a long time anyway--that's what conspiracy theories do.

Another theory posted online claimed that the real reason for microcephaly increases in Brazil is a pest control insecticide being used in the drinking water of Zika outbreak zones.  The insecticide was pyriproxifen, which we in the pest control industry use under the trade names Nylar® and Archer® flea and roach sprays. The anti-GMO group blaming pyriproxyfen claims that the association between microcephaly and areas where pyriproxyfen is used "is not a coincidence." Like the genetically modified mosquito claim, this group also asserted that so far, there have been no cases of microcephaly reported in other countries affected by Zika. While microcephaly does not (yet) seem to be as prevalent in some Zika areas, like Colombia, this claim is not strictly true. Higher rates of central nervous system malformations were also found in French Polynesia following the Zika outbreak there in 2014.  In addition, there is no scientific evidence of any connection between pyriproxyfen and brain abnormalities, and officials in Brazil point out that some areas that do not use pyriproxyfen to treat mosquitoes still have seen increases in microcephaly.  Pyriproxyfen, by the way, is an insect growth regulator that is one of the lowest toxicity treatments (LD50 greater than 5000 mg/Kg) available for fleas, cockroaches and other pests. The EPA does not consider it an endocrine disruptor, and it is not considered a carcinogen.

On the scientific side, last week an article was posted in the New England Journal of Medicine (a much more reliable source than social networking news sites) that provides some of the strongest evidence yet for a link between Zika and microcephaly.  Fetuses from 42 women with evidence of Zika infection during gestation were examined.  Preliminary analysis of ultrasound examination of these fetuses showed 29% (!) occurrence of microcephaly in infected women compared to 0% in 17 non Zika infected women.  The authors concluded that "despite mild clinical symptoms, ZIKV infection during pregnancy appears to be associated with grave outcomes, including fetal death, placental insufficiency, fetal growth restriction, and [central nervous system] CNS injury."

If research continues to show similar associations between Zika infection and microcephaly the stakes are surely raised this summer with thousands of expected travelers coming back into the U.S. from Zika zones, including the Olympic venues in Brazil.  All the more reason for all of us to be aware of travel safety recommendations by the CDC.

For our part, Texas A&M is also ramping up its educational efforts this summer with launch of a new website to collect information pertaining to ways to prevent Zika.  The bottom line of all the current news, however, is that there is currently no way to prevent getting the disease from an infected mosquito other than by avoiding mosquito bites.  And pest control is an important part of that equation.  So take the time to learn more about the Aedes mosquitoes that carry Zika, and consider how you might respond to the concerns that are sure to be around this summer.