Insect Control Test

Poseidon Sciences R&D conducts efficacy testing on a wide range of insect pests:

A. Mosquitoes

About Culex quinquefasciatus

Commonly known as the southern house mosquito Culex quinquefasciatus Say is a medium-sized brown mosquito found widely in tropical regions and subtropical areas.   This species is found throughout Florida and as far north as Virginia and Iowa and as far west as California. C. quinquefasciatus also breeds with the common house mosquito, C. pipiens.  This hybridization results in a far larger range of territory.  C. quinquefasciatus is an opportunistic blood feeder and a vector of many of pathogens, several of which affect humans.

The Insect Laboratory of Poseidon Sciences (Philippines) maintains a breeding facility for C. quinquefasciatus for research and development.  Because this species is ubiquitous throughout the world, Poseidon Sciences have chosen this species as the primary model to study the effects of insect repellents.

World distribution of the southern house mosquito, Culex quinquefasciatus Say. Illustration by Stephanie Hill, University of Florida.

1. Arm-in-Cage Repellent Test

Most economical test is to run a conventional arm-in-cage test. Here the product is applied on the arm and then inserted into a cage containing unfed mosquitoes. We normally use Culex quinquefasciatus, which is a universal nuisance mosquito. Our Insect Control Station is located in Panay Island, Philippines. Studies using malarial mosquitoes are normally undertaken at our Tanzanian facility.

We follow the US EPA Guidelines for product evaluation of repellent products (see the References Section below). However, we are not an EPA certified lab and only support the product substantiation of experimental formulations by companies during the product development / testing phase.

We normally conduct the following testing paradigm. Here you may add up to 2 more test groups using the same positive and negative controls.

1. CONTROL (untreated or vehicle with no repellent)

2. EXPERIMENTAL PRODUCT (You may add up to 2 other additional products to test using the same negative control and positive control)

3. POSITIVE CONTROL (commercially comparable product at project sponsor’s choice as test reference; provided by the project sponsor)

OBSERVATION CRITERIA:

Determination of the Protection Time, i.e., the period of time elapsed after exposure of the arm in the cage and the first confirmed bite of the mosquito. The Protection time signals that the product had already reached its maximum period of protection against mosquito bite.

Timeline to completion is 3 weeks from receipt of samples and pre-payment of the study. You can ship your samples when you are ready and will send you the shipping instructions.

 2. Field Testing of Mosquito Repellents

All field test protocols follow the US EPA and ASTM Guidelines.

Poseidon Sciences R&D Station maintains areas with high densities of daytime biting mosquitoes (Aedes aegyptii) and nighttime biting mosquitoes or the common house mosquito (Culex quinquefasciatus).  Lotions and creams, sprays and area wide protection repellents (such as patches) can be tested.  Because oif safety concerns due to dengue fever carried by Aedes, all field tests are conducted beginning at 4:00 PM so that subjects are exposed only to Culex mosquitoes.

Typically, human volunteers are spaced at least two (2) meters apart in the testing area and allowed to move around provided they maintain distance of 2 meters from the next subject.  Walking, sitting, reading and other activities actually enhance attraction of female mosquitoes.  Protection time is calculated from the time the subject uses the repellent product to the time of the first confirmed bite.  Further confirmation is by noting the time of the second bite.  A research technician monitors the field testing at all times and records the data.

Field tests tend to be difficult since environmental conditions, such as wind velocity, temperature, rainfall and other factors may affect biting activity.  While field conditions tend to vary from time to time, all field trials are conducted only during optimum conditions of no rain and moderate wind. 

Both sides of the freshwater creek have high density of Culex mosquitoes.

3. Insect Repellent Candles

There has been a proliferation of candles with claims of mosquito protection. However, objective data on the performance of such products are often lacking. Human tests conducted during the biting period of mosquitoes in an outdoor setting are the most objective method of testing candle repellent performance. But, when in the process of developing optimum formulation, human testing can be expensive and time consuming. For this reason, scientists at Poseidon have developed a convenient screening method to show the performance of experimental candle formulations.

This same method may also be used in area wide protection products, such as repellent patches.

To learn more about this testing paradigm, please read our Technical Insights

Forms_Candle_test_method_repellents_mosquitoes_Culex.pdf (poseidonsciences.com)

Type of results in a candle test

 4. Tests on repellent impregnated fabrics

Impregnating textile materials with repellents is a growing market for military and outdoor activities where mosquitoes and other biting insects are often encountered.  Validation of the efficacy and estimation of the performance life of repellents impregnated into textile materials can be validated through arm-in-cage testing or actual field testing.

B.  Common Housefly

The common house fly (Musca domestica) is a nuisance pest found practically all over the world.  Repellents typically are area wide sprays to keep the species away from work/living spaces and away from food.  Efficacy testing is normally conducted in laboratory setting and/or under field conditions

Laboratory test.  Environmental factors could affect the rate of housefly landing in the open environment. This laboratory test is designed to limit or reduce some environmental factors like wind, noise, temperature, sunlight, etc. which, may affect the intensity of housefly landing on bait food.  Houseflies were bred in the insectary under ambient light and room temperature conditions. The adult house flies were transferred by net and placed inside a net covered cage (0.5 m x0.5 m x 0.5 m). They were brought to the laboratory and acclimatized for 3 hours. About 2 grams of boiled meat (chicken) as bait was placed in 10 cm ceramic plates. The bait is sprayed with the test product for only 1 second which was adequate to fully cover the bait with the product. The treated bait is then placed inside the cage with 30 houseflies after waiting 2 minutes for the vehicle to vaporize.

Data gathering is also based on determination of the Protection Time, i.e., the time it took from the placement of the bait to the time the first housefly landed on the bait. The time is noted when the examiner saw the fly remaining on the surface and eating the bait.

Below is an example of a typical test result.

Field test.  Typically, field tests are conducted in an area with high density of houseflies such as wet markets and slaughterhouse.  Procedure is the same as in the laboratory testing except that the bait is placed in an open environment.

C.  Sandfly

Phlebotomine sand flies are tiny (>3 mm in length), densely haired flies found throughout the world’s tropical and subtropical regions. The female sand fly lays its eggs inside cracks in house walls, in rubbish, ruined buildings and in sandy or savannah areas where heat, humidity and organic matter are available to promote their growth. Because a female sand fly can lay millions of eggs and because insect resistance to pesticides is increasing, eradication of sand flies to date has met with little success.

Since complete elimination of sand fly populations is highly unlikely, the prevention of transmission of leishmaniasis will depend on combination of ways to avoid contact with sand flies. This will include use of effective repellents, avoiding areas where there are sand flies, use of bed nets / protective clothing and area protection from sand fly entry. The most practical and least restrictive approach will be the use of repellents. However, conventional repellents, including DEET, had proven to be mildly effective in preventing sand flies from biting. The effectiveness is further affected by other environmental conditions–heat and wind action–that greatly diminish efficacy.

To Learn more about our sand fly R&D, please see the link here:

Sandflies_leishmaniasis_kala-azar_army_repellent.pdf (poseidonsciences.com)

Poseidon Sciences maintains a biological station in the island of Panay, Philippines.  Test site for field studies is a sandy beach area bordered by thorn bushes.  The photographs below describe the terrain.

The site is inhabited by transient fishermen who use the beach to dock their fishing boats.  Sand flies are endemic and readily bite the exposed arms, legs and face upon setting foot on this beach.  Biting activity is highest during the morning and late afternoon.  Rainy days have lesser biting activity.  Bites are numerous and quite painful as shown in the photographs below.  In most volunteers, the bite is followed by itching sensations that last for hours.  For some who are more sensitive, it leads to skin ulcers (cutaneous leishmaniasis).

The field tests are conducted using method described in ASTM E939-94 (reapproved 2000) entitled “Standard Test Method of Field Testing Topical Applications of Compounds as Repellents for Medically Important and Pest Arthropods (Including Insects, Ticks, and Mites.”

The research scientist recorded the time of application of the test sample and observed sand fly landing.  The volunteer indicated that a confirmed bite had occurred and the investigator confirmed by visual examination of the legs that a bite had indeed occurred.

The Protection Time was recorded for each individual.  Protection Time is the period that had elapsed from the time of application of the spray and the time for the first confirmed bite, indicating that the test product had reached its limit of protection from sand flies. 

An example of a sand fly field test on human volunteers is shown below

D.  Pharaoh Ants

Repellent tests against pharaoh ants (Monomonium pharaohnis) is conducted as a field test within Poseidon Sciences field test sites.  Pesticides are not used within and adjacent areas of the site to maintain endemic populations of insects, plants and aquatic organisms.  Pharaoh ants are part of natural environment and easily attracted by a wide variety of food attractants.

The food attractant (2g of fish) was placed inside a shallow open plastic dish container.  The container was then placed on top of the wooden structure as shown in the picture below.  The 1  inch x 1 inch x 3 ft long “gemelina” wood (similar to pine wood) is set upright on a holder at the base.  Within 24 hours, ants will establish a trail from the ground up the long piece of wood to the attractant.

A 1 cm wide masking tape was used
to delineate a 1 cm area around the
wood where the test products are
applied. A total of 1 ml of each
formulation was applied directly
with a paint brush.

The protection time was determined as the time elapsed after application of the test material and the first confirmed crossing of pharaoh ants over the applied area.

See the typical results of a screening of potential ant repellent products below

References

The following Guidelines are used in the performance of our testing operations.

If you might have questions or need additional information, please send email to: jrmatias@poseidonsciences.com or poseidonnova@aol.com