“WHAT’S HAPPENING

“WHAT’S HAPPENING?”

University of Tennessee - Agricultural Extension Service

Entomology & Plant Pathology - EPP #60

Volume No. 10 - July 23, 2004

Squash Beetle and Mexican Bean Beetle

Frank A. Hale

The coccinellid or ladybird beetles are primarily predaceous and thus considered beneficial insects. There are two plant feeding species in this beetle family and they can both be found in Tennessee vegetable crops. They are also the only large ladybird beetles that are covered with short fine hairs.

We have received samples of the squash beetle during the last week or so. Although they are said to be common, many have never seen them on their plants. The adult of the squash beetle is 11/32 inch long with a yellowish-brown legs and body. It has four small spots on the prothorax (area directly behind the head) and 12-14 (some spots are close together and two look like one) different size larger spots on the elytra (wing covers). The larvae of both the squash beetle and the Mexican bean beetle are yellow and covered with forked spines. Both the larvae and adults are plant feeders. Squash beetles primarily skeletonize the foliage of cucurbits but are also known to feed on the blossoms and pods of lima beans and cowpeas, on lima bean foliage, and on corn silks.

Mexican bean beetle adults are yellowish to copper red with 16 spots on the elytra. The eggs are laid in a cluster and are yellow. It is the most injurious pest of beans (lima, snap, pole, kidney etc.). It can also attack cowpea, soybean, clover, alfalfa and some leguminous weeds. They feed on the underside of the leaf between the veins. The tissue that is left turns brown and the skeletonized leaves can give the field a burnt cast. This pest can also feed on the pods and stems and in severe infestations some of the plants can die before the crop is produced. The adults migrate to ditches, fence rows and brushy areas later in August or September to overwinter under plant debris. The adults start to emerge to feed on newly emerged seedlings in the spring.

Decapitating Flies Found Hovering Over East Tennessee Fire Ant Mounds

Karen Vail, Pat Parkman and Tahir Rashid

Decapitating phorid flies, parasitoids of imported fire ants (IFAs), have been discovered attacking IFAs in East Tennessee. The flies, Pseudacteon curvatus, were released near Cleveland (Bradley Co.) and Madisonville (Monroe Co.) in April 2000 by UT faculty cooperating with the USDA ARS, USDA APHIS and TDA. Periodic sampling over the next year or so revealed no flies were established and the project was abandoned. Subsequent releases were made by Jason Oliver of TSU in Franklin Co. and were soon deemed successful.

The fly could be the subject of a horror movie. It lays its eggs in the thorax of a fire ant. After hatching, the fly larva migrates to the head of the ant where it releases an enzyme that causes the ant’s head to fall off. The fly completes its development in the decapitated head.

This year the FARET (Fire Ant Research and Education Team) planned to release phorids on hybrid fire ants in East Tennessee. Thanks to persistent work by Ray Burden, Hamilton County Extension Agent, a suitable site was located near the Hamilton County office. Ants were collected from this site, sent to Gainesville, FL to be parasitized by flies in the laboratory, then shipped back for release. On the day of the release, Jason Oliver and other FARET members discovered phorid flies were already present at the release site. Subsequent searches in East Tennessee have revealed P. curvatus attacking IFAs from Chattanooga to Cleveland, and to the Ocoee dam northward to Madsonville. We will continue to survey the state for the presence of the fly. We believe the flies we have found during these recent searches are a result of the releases made in 2000 (or, at least, one of the releases).

If county agents are interested in helping in this endeavor, please contact Karen Vail (kvail@utk.edu) or Pat Parkman (jparkman@utk.edu) at (865) 974-7138. While we don’t expect one species of phorid to limit the spread and growth of fire ant mounds, getting it established is a first step in what we hope is a permanent solution to suppressing IFA populations in Tennessee and the southeast US.

Mosquitoes Waiting Outside Your Door?

Karen M. Vail

If you’re like me, the mosquitoes seem to be resting in nearby vegetation waiting to zoom in as soon as my backdoor opens. Rains early in the season have left a bounty of mosquitoes. While the chances of Tennesseans contracting West Nile Virus and other mosquito-borne viruses are slight, mosquitoes are still a nuisance and can reduce people’s participation in outdoor activities. There is no easy solution. Countless products will claim ease of use and effectiveness, but few have appreciable value in lessening the annoyance and incidence of bites. Unlike most insects encountered around homes, mosquitoes are pervasive outdoor pests and there are limits to what can be done to minimize their abundance. Options for homeowners are listed below.

Eliminate Larval Sites – Mosquitoes need quiet, non-flowing water for their development. Eliminating sources of standing water, such as swamps and ditches, may require community-wide effort and will require permits from Tennessee Wildlife Resource Agency (TWRA). Nonetheless, homeowners can take steps to prevent mosquitoes from breeding on their property:

1. Dispose of old tires, buckets, aluminum cans, plastic sheeting or other refuse that can hold water. Empty accumulated water from trashcans, boats, wheelbarrows, pet dishes, and flowerpot bottoms, and if possible turn them over when not in use.

2. Clean debris from rain gutters and unclog obstructed down spouts. Clogged or damaged rain gutters are one of the most overlooked mosquito breeding sites around homes.

3. Change water in birdbaths and wading pools at least once a week, and keep swimming pools clean, chlorinated or covered when not in use. Ornamental pools can be aerated or stocked with mosquito-eating fish. Aeration and water movement helps because mosquitoes prefer quiet, non-flowing water for egg laying and development.

4. Fill or drain ditches, swampy areas, and other soil depressions and remove, drain or fill tree holes and stumps with mortar or sand to prevent water accumulation. Before modifying any wetlands, contact your local TWRA representative. Eliminate standing water and seepage around animal watering troughs, cisterns, and septic tanks. Be sure cistern screens are intact and access covers fit tightly.

5. Water landscape to allow water to drain.

Larval Control - Use of a mosquito larvicide may be beneficial when it is impractical to eliminate a breeding site. Larvicides are insecticides used to control immature mosquitoes before they have a chance to develop into biting adults. Larval mosquitoes are confined to water making them easier to locate than the adults. Most larvicides sold to homeowners contain either the ingredient methoprene, or the bacterium Bacillus thuringiensis israelensis (Bti). Neither active ingredient is harmful to fish, waterfowl, pets or humans when used according to label directions.

Many products and formulations containing methoprene (e.g., Altosid®) and Bti (e.g., Bactimos®, Vectobac®) are used by mosquito abatement agencies and other professionals. Homeowners can purchase the methoprene-based larvicide, PreStrike™ in hardware, discount, and some pet stores. PreStrike is formulated as a granule and comes in a shaker bottle. Various products containing the mosquito- specific bacterium, Bti, are also sold to homeowners. Mosquito Dunks® , for example, can be found at hardware and discount stores.

Another method of larval control has been around for a few years, but most folks are unaware of this method discovered by a young boy, Michael Nyber, preparing a science fair project. The LarvaSonic^{TM (}http://www.larvasonic.com/^{)

kills larvae by using sound . Sound energy is transmitted into water and causes

the mosquito larval air bladder to absorb the energy and rupture the membrane

which causes bubble(s) to form that injure internal organs and cause immediate

death of the larva.}

^{Adult Control}^{- Adult mosquitoes prefer to rest in moist, quiet,

shaded areas such as dense vegetation during the daytime. Consequently,

homeowners should remove tall weeds and overgrown vegetation from their yards.

To further reduce intolerable levels of biting adult mosquitoes, insecticides

can be applied to shrubs, hedges and other shaded areas, such as under decks

and along foundations. Lawn and garden insecticides containing pyrethroids

(e.g., permethrin, Ortho Mosquito B Gone or Spectracide Mosquito Stop;

cyfluthrin, Bayer Advanced Powerforce Mosquito Killer; lambda cyhalothrin,

Spectracide Triazicide), are effective but will need to be periodically

reapplied. For such applications, some homeowners may wish to enlist the

services of a professional pest control firm.}

^Exclusion^{- Mosquitoes can be kept out of homes by securely

screening windows, doors and porches.

The occasional mosquito found indoors can be eliminated with a fly

swatter. Aerosol-type insecticides labeled for mosquitoes, gnats, and other

flying insects seldom provide much relief at the dosages applied by

householders.}

^{Topically-Applied Repellents}^{- Repellents will help prevent bites when spending

time outdoors. The most effective

mosquito repellents contain the active ingredient diethyl toluamide

(DEET). Higher percentages of DEET in

the ingredients provide longer protection.

The American Academy of Pediatrics (AAP) Committee on Environmental

Health has recently updated their recommendation for use of DEET products on children,

citing: ‘Insect repellents containing DEET (N,N-diethyl-m-toluamide, also known

as N,N-diethyl-3-methylbenzamide) with a concentration of 10% appear to be as

safe as products with a concentration of 30% when used according to the

directions on the product labels.’ (CDC 2004 http://www.cdc.gov/ncidod/dvbid/westnile/qa/insect_repellent.htm)

.}

^{Non-DEET containing repellents (e.g. Avon Skin-

So-Soft7, citronella) may provide some relief, but to a lesser degree and for

shorter duration than DEET- containing products. It is often desirable to apply insect

repellent on outer clothing as well as the skin. Always read and follow directions on the

container. Mosquito repellent should not

be applied to the hands of young children, and treated skin should be washed

with soap and water after returning indoors.}

^{Other Control Possibilities}^{- Many consumer products claim to attract, repel,

capture or kill mosquitoes. Most of these devices do not appreciably reduce

mosquito abundance or incidence of bites, or else their claims are unproven.

Electrocuting devices or "bug zappers" using ultraviolet light as an

attractant are generally ineffective in reducing outdoor populations of

mosquitoes and their biting activity. Studies indicate that mosquitoes make up

only a tiny percentage of the insects captured in such traps. The majority are

moths, beetles and other harmless night flying insects.}

^{Other types of mosquito traps utilize carbon dioxide,

warmth, light, and various chemicals (e.g., octenol) as attractants and claim

to capture tremendous numbers of adult mosquitoes. Such devices can be quite expensive. Excerpts from The American Mosquito Control

Association’s (}http://www.mosquito.org/trapqueries.php^{)

position paper on mosquito traps are listed below:}

^{The advertising claims for acre-wide control maybe

somewhat overstated, in most cases being based upon best case extrapolations

from captures of released mosquitoes made inside screened enclosures. To be

sure, it would be very difficult for the manufacturers to conduct controlled

studies yielding reliable, statistically significant data with natural

occurring mosquito populations due to confounding variables largely beyond the

control of the researcher. Meaningful, repeatable data capture requires

stability in these factors, generally over a period of years –– extremely

difficult to obtain in nature. In fact, Mosquito Control Districts using

different types of traps in survey operations often experience large variations

in mosquito trap counts among traps as well as by location, trap height, and

time of season.}

^{Nonetheless, these devices will, indeed, trap and kill

measurable numbers of mosquitoes. Whether this will produce a noticeable

reduction in the mosquito population in your case will depend upon a number of

factors, e.g. your tolerance level, absolute mosquito population size,

proximity, size and type of breeding habitat producing re-infestation, wind

velocity and direction, and species of mosquito present, among many other

things. Depending upon their placement, wind direction, and trapping

efficiency, traps may actually draw more mosquitoes into your area than they

can possibly catch. Thus, the homeowner must still use repellents and practice

source reduction methods as adjuncts to realize any measure of relief.}^...

^{Please be cautioned against putting too much faith in

traps as your sole means of control. These traps represent an evolving

technology that is a most welcome addition to our mosquito control

armamentarium. Their potential is great, but shouldn't be overestimated.}

^{Citronella oil does have mosquito-repelling

properties, and the scented candles can provide some protection. For maximum

effect, use multiple candles placed close (within a few feet) of where people

are sitting. A single candle located at the center or edge of a picnic blanket

probably won't provide much benefit other than atmosphere. Mosquito-repellent

plants, garlic, and other oft-advertised botanical products generally are

ineffective.}

^{Bats and certain types of birds (e.g., purple martins)

are often cited as effective natural agents for managing outdoor mosquitoes.

Conservation groups and nature magazines often suggest building bat and

birdhouses on one's property to promote nesting and to protect against

mosquitoes. Although insectivorous bats and birds do eat mosquitoes, they make

up only a very small portion of their natural diet. Much like the mechanical

"bug zappers," bats and birds capture all manner of other flying

insects also. Efforts to colonize and conserve these animals should not be done

with the primary intent of diminishing biting mosquitoes. When it comes to

managing mosquitoes, a good rule of thumb is if the approach or device sounds

too good to be true — it probably is.}

^{Modified from:}

^{Anonymous. 2004. CDC Questions and Answers - Insect

Repellent Use and Safety}

⁽http://www.cdc.gov/ncidod/dvbid/westnile/qa/insect_repellent.htm⁾

^{Potter, M. 2004. Mosquito Relief for Homeowners.

Kentucky Pest News Vol. 1027 June 28, 2004, Kentucky Cooperative

Extension Service (}www.uky.edu/Agriculture/kpn/kpnhome.htm⁾

^{Floore, T. 2004. Mosquito Information. Public Health

Entomology Research & Education Center Florida Agricultural &

Mechanical University. Updated 06-16-04. In the American Mosquito Control

Association Information on Mosquitoes. (}http://www.mosquito.org/info.php⁾

^{Anonymous, The American Mosquito Control

Association. 2003. A Primer on Mosquito

Traps. (}http://www.mosquito.org/trapqueries.php⁾

^{Do Mosquito Abatement Districts Based on Adulticiding

As the Only Control Source Provide Effective Control?}

^Kar^{en Vail, Reid Gerhardt and Carl Jones}

^{We are starting to receive inquiries regarding the

initiation of mosquito control abatement programs in Tennessee. Kristy Gottfried, former Medical Entomologist

for the TN Dept of Health, addressed last year the issues surrounding mosquito

control abatement districts at a meeting for County Directors. This address can be found at}http://eppserver.ag.utk.edu/images/Vail/TNDOH_Co_Dirs_Mtng.pdf^.

^{Kristy dispels some myths about these programs as well

as informs the reader of accepted methodology.

The IPM approach to managing mosquitoes is provided. A great deal of

this article addresses the reasons that adulticiding as the only control source

is ineffective. Unfortunately, county personnel often receive pressure from

their clientele and hence their administrative supervisors to initiate such a

program.}

^{In this article, IPM is defined as follows:}

^{Integrated Pest Management (IPM) or sometimes called

Integrated Mosquito Management (IMM) as it pertains to organized mosquito

control is defined as: A sustainable approach to managing mosquitoes by

selecting the best combination of control strategies (mosquito surveillance,

source reduction/prevention, larviciding, biological control, public education

and adulticiding (only when and if necessary)) in a way that prevents

unacceptable levels of mosquitoes by the most economical means and with the

least possible hazard to people, property, and the environment.}

^{Listed below are a few points from the Gottfried

(2003) article, but please read the entire article to get a more thorough

explanation of why limited control will occur if the mosquito control program

consists of just adulticiding.}

^{1. The bottom line is that the application of

adulticides without regular mosquito surveillance (knowledge of the target

species) may look pleasing to the average citizen, however, it is ineffective

and can potentially lead to serious consequences.}

^{2. Adulticides

are designed to break down fast in the environment; there are NO residual

effects of the product.}

^{3. Adulticides

will only kill flying adult mosquitoes that are in the area at the time of

application and may supply short-term relief (3-4 days).}

^{4. Overuse and

non-regulated use of chemical products used for adulticiding or larviciding

have the potential to increase the resistant individuals in a population.}

^{5. There are

non-chemical strategies available for use in many situations and the EPA

recommends considering using these methods as part of an overall pest

management strategy, IPM. Therefore, adulticides play only a small part in the

overall mosquito control program.}

^{IF A REGION IS GOING TO INVEST LOCAL FUNDS INTO A

MOSQUITO ABATEMENT PROGRAM-THEN THE PROGRAM SHOULD BE FUNDED SUFFICIENTLY TO

ENSURE COMPLIANCE WITH PROFESSIONALLY ACCEPTED MOSQUITO CONTROL STANDARDS.}

^{Want more information why adulticiding is

ineffective?}^{Adulticiding with a ULV sprayer is dependant on wind

speed, wind direction and mosquito activity patterns. To think that a mosquito that is active

during daylight hours will be killed in its nighttime resting site in the

bushes out of the wind behind the house is usually wrong. The same is true of crepuscular species

during daylight hours. Our vector and

pest species are a combination of both daytime and crepuscular feeders. Studies in major cities have shown that the

standing crop of mosquitoes is little affected by weekly or biweekly sprays

because surveillance shows populations back to the original level within three

days.}

^{If after reading the Gottfried article, you believe

your county has the substantial funding needed to conduct a complete mosquito

abatement program, the following certification or licensing is needed.}

^{If the county would like to initiate a program, they

must have someone certified in category 8 to apply pesticides for mosquito

control on public lands and waters.}

^{If the county would like to hire someone to perform

this duty, this would require the commercial applicator to be certified in

category 8 and working under the supervising of someone licensed in PHM (Public

Health Control - Mosquito). There are

only a small number of PMPs that are licensed in PHM in Tennessee.}

^{The Category 8: Public Health Control

certification manual and PHM: Public Health Control - Mosquito licensing

manual and manual ordering information can be found at}http://eppserver.ag.utk.edu/psep/secondlevel/materials.htm^{. These are new manuals and the associated exams for these categories are

extremely difficult; however The University of Tennessee Extension does offer

training for this licensing exam (}http://eppserver.ag.utk.edu/psep/secondlevel/info/F818B.pdf^).

^{For people who are serious about mosquito control techniques,

the Florida Mosquito Control Handbook (newly revised) has a wealth of

information. The American Mosquito Control Association list links of Mosquito

Control Districts throughout the US (}http://www.mosquito.org/links.php)^{,

including Florida and New Jersey, should you need further advice from folks

already conducting abatement programs and examples of professionally accepted

mosquito control standards.}