We thank Molly Stedfast for dilution and pesticide formulation assistance. We also thank Troy Anderson for probit analysis guidance and Zachary Adelman for assistance with experimental design. This research was partly supported by an Entomological Foundation award and by Virginia Pest Management scholarship funds.

NOTE: This protocol includes two insecticide assays for separately treating bed bug eggs and first instars. Both protocols were conducted using the same insecticides, however, the protocols had to be adapted to ensure insecticide exposure and to easily manipulate the specimens.
1. Egg Dipping Insecticide Assay
<ol>
	<li>Pull mated, well-fed adult female bed bugs from a colony and place the females (5-10) into a Petri dish with filter paper. Have at least ten replicates to ensure that there w...

<ol>
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K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Bed Bug Handbook: The Complete Guide to Bed Bugs and Their Control. , (2007).</li><li>Toloza, A. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+patterns+of+insecticide+resistance+in+eggs+and+first+instars+of+Triatoma+infestans+(Hemiptera:+Reduviidae)+from+Argentina+and+Bolivia.">Differential patterns of insecticide resistance in eggs and first instars of Triatoma infestans (Hemiptera: Reduviidae) from Argentina and Bolivia.</a> J. Med. Entomol. 45, 421-426 (2008).</li><li>Cueto, G. M., Zerba, E. N., Picollo, M. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+of+pyrethroid+resistance+in+eggs+of+Pediculus+humanus+capitis+(Phthiraptera:+Pediculidae)+from+Argentina.">Evidence of pyrethroid resistance in eggs of Pediculus humanus capitis (Phthiraptera: Pediculidae) from Argentina.</a> J. Med. Entomol. 45, 693-697 (2008).</li><li>Ho, S. H., Goh, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deltamethrin+as+a+potential+ovicidal+pyrethroid+against+Plutella+xylostella+L.">Deltamethrin as a potential ovicidal pyrethroid against Plutella xylostella L.</a> Toxicol. let. 22, 161-164 (1984).</li><li>Bell, C. H., Hole, B. D., Evans, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+occurrence+of+resistance+to+phosphine+in+adult+and+egg+stages+of+strains+of+Rhyzopertha+dominica+(F.)(Coleoptera:+Bostrichidae).">The occurrence of resistance to phosphine in adult and egg stages of strains of Rhyzopertha dominica (F.)(Coleoptera: Bostrichidae).</a> J. Stored Prod. Res. 13, 91-94 (1977).</li><li>Campbell, B. E., Miller, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insecticide+Resistance+in+Eggs+and+First+Instars+of+the+Bed+Bug,+Cimex+lectularius+(Hemiptera:+Cimicidae).">Insecticide Resistance in Eggs and First Instars of the Bed Bug, Cimex lectularius (Hemiptera: Cimicidae).</a> Insects. 6, 122-132 (2015).</li><li>Price, L. A., Mills, K. 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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> PoloPlus: Probit and Logit Analysis User's Guide. , (2003).</li><li>Montes, C., Cuadrillero, C., Vilella, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maintenance+of+a+laboratory+colony+of+Cimex+lectularius+(Hemiptera:+Cimicidae)+using+an+artificial+feeding+technique.">Maintenance of a laboratory colony of Cimex lectularius (Hemiptera: Cimicidae) using an artificial feeding technique.</a> J. Med. Entomol. 39, 675-679 (2002).</li><li>Brogdon, W. G., McAllister, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simplification+of+adult+mosquito+bioassays+through+use+of+time-mortality+determinations+in+glass+bottles.">Simplification of adult mosquito bioassays through use of time-mortality determinations in glass bottles.</a> J. Am. Mosq. Control. Assoc. 14, 159-164 (1998).</li><li>Katarzyna, K., Saddler, A., Koella, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+age+and+larval+nutrition+on+phenotypic+expression+of+insecticide-resistance+in+Anopheles+mosquitoes.">Effects of age and larval nutrition on phenotypic expression of insecticide-resistance in Anopheles mosquitoes.</a> PLoS One. 8 (3), (2013).</li><li>Outram, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+affecting+the+resistance+of+insect+eggs+to+sulphuryl+fluoride-II:+the+distribution+of+sulphuryl-35+S+fluoride+in+insect+eggs+after+fumigation.">Factors affecting the resistance of insect eggs to sulphuryl fluoride-II: the distribution of sulphuryl-35 S fluoride in insect eggs after fumigation.</a> J. Stored. Prod. Res. 3, 353-358 (1967).</li></ol>

The authors have nothing to disclose.

A critical step in this assay is to ensure that no eggs that are removed from a surface are damaged prior to the assay. Many insects cement their eggs to a substrate, therefore, a preliminary test may be needed to ensure that removal does not cause mortality. This test can be conducted with several replications of a treated group (bed bugs removed from filter paper) compared to a control group (bed bugs not removed). Similar low rates of mortality (or no mortality) between the treated and control group will ensure that ...

Bed bugs are a significant urban pest that can cause blood loss, skin irritations, sleeplessness, depression, and anxiety in their human hosts 1,2,3,4,5,6. The costs of eliminating and controlling bed bugs are high and often times require multiple visits to a home by a pest control company7. Multiple visits are usually required because of the cryptic behavior of bed bugs and the difficulties associated with killing them. In particular, bed bug eggs are difficult to control because of their small size and the protection of the embryo by the eggshell.
Currently, a common practice for many pest control companies throughout the United States is to treat a home for bed bugs using a chemical insecticide. It is well known that the eggs are difficult to control, so many companies have implemented a two-week time frame for re-treatments8. This allows bed bug eggs enough time to hatch, so that the first instar will emerge and purportedly be easier to kill with insecticides. However, there is a dearth in studies evaluating the efficacy of liquid insecticides against bed bug eggs and first instars.
Insect eggs have been documented to be the most difficult life stage to control in urban insect pests, other than bed bugs, in addition to many agricultural pests. Most of these difficulties have been attributed to the eggshell, while a few studies have reported insecticide resistance. Resistance in the egg stage has been documented in Triatoma infestans9, Pediculus humanus capitis10, Plutella xylostella11, Rhyzopertha dominica12, Cimex lectularius13, and multiple stored product beetles (i.e. Oryzaephilus surinamensis, Tribolium castaneum, Cryptolestes ferrugineus and Rhyzopertha dominica).14The development of resistance in the egg stage and immature stages, as well as complications associated with insecticide penetration through the eggshell, necessitates the need for insecticide efficacy bioassays against these life stages.
This protocol provides a step-by-step procedure for determining the efficacy of insecticides in the egg and first instar stage of common bed bugs, Cimex lectularius. Both of these protocols are concentration-response assays to allow quantification of LC50 values. Concentration-response assays are commonly used for toxicological studies, however this protocol has been adapted for easily treating groups of bed bug eggs and first instars. These assays can be adapted for various insect species&#39; eggs and immature life stages.

<table border="0" cellpadding="0" cellspacing="0" width="1067">
	<tbody>
		<tr>
			<td>Petri dishes</td>
			<td>Fisher Scientific Inc.</td>
			<td>08-757-105</td>
			<td>Plastic</td>
		</tr>
		<tr>
			<td>Filter paper</td>
			<td>Whatman</td>
			<td>1001-042</td>
			<td></td>
		</tr>
		<tr>
			<td>Featherweight forceps</td>
			<td>Fisher Scientific Inc.</td>
			<td align="right">4750</td>
			<td></td>
		</tr>
		<tr>
			<td>Temprid SC (imidacloprid/bifenthrin)</td>
			<td>Bayer CropScience</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Transport GHP (acetamiprid/bifenthrin)</td>
			<td>FMC Corp.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge tube</td>
			<td></td>
			<td>06-443-18</td>
			<td>50 mL; flat-top threaded</td>
		</tr>
		<tr>
			<td>Fine mesh</td>
			<td></td>
			<td>7250C</td>
			<td></td>
		</tr>
		<tr>
			<td>KimWipe</td>
			<td></td>
			<td>06-666A</td>
			<td>11 cm X 21 cm</td>
		</tr>
		<tr>
			<td>Small paint brush</td>
			<td></td>
			<td></td>
			<td>Any small paint brush</td>
		</tr>
		<tr>
			<td>Hardboard panels</td>
			<td></td>
			<td></td>
			<td>Composite wood or tile would be sufficient from a home improvement store</td>
		</tr>
		<tr>
			<td>Metal weights</td>
			<td></td>
			<td></td>
			<td>Any type of metal screw that will hold the weight of the Petri dish down onto a surface</td>
		</tr>
	</tbody>
</table>

a method for evaluating insecticide efficacy against bed bug, cimex lectularius, eggs and first instars

Standard toxicity evaluations of insecticides against insect pests are primarily conducted on adult insects. Evaluations are based on a dose-response or concentration-response curve, where mortality increases as the dose or concentration of an insecticide is increased. Standard lethal concentration (LC50) and lethal dose (LD50) tests that result in 50% mortality of a test population can be challenging for evaluating toxicity of insecticides against non-adult insect life stages, such as eggs and early instar or nymphal stages. However, this information is essential for understanding insecticide efficacy in all bed bug life stages, which affects control and treatment efforts. This protocol uses a standard dipping bioassay modified for bed bug eggs and a contact insecticidal assay for treating nymphal first instars. These assays produce a concentration-response curve to further quantify LC50 values for insecticide evaluations.

The eggs were dipped into 5 different concentrations of imidacloprid/ &#946;-cyfluthrin (&#181;L/mL). The first instars were placed onto treated surfaces of five different concentrations of imidacloprid/&#946;-cyfluthrin (Figure 2).
We used three different populations of C. lectularius: Harlan, Richmond, and Epic Center (Table 1). The Harlan strain is susceptible to pyrethr...

Watch this Scientific Journal Video about A Method for Evaluating Insecticide Efficacy against Bed Bug,  Cimex lectularius, Eggs and First Instars at JoVE.com

A Method for Evaluating Insecticide Efficacy against Bed Bug,  Cimex lectularius, Eggs and First Instars

Insecticide evaluations are often targeted against adult insects, rather than immature stages. Here, we present a protocol for evaluating insecticides against bed bug eggs with a comparison to the first nymphal bed bug stage. These protocols could be adjusted for other insects to evaluate insecticide efficacy in non-adult life stages.

A Method for Evaluating Insecticide Efficacy against Bed Bug, Cimex lectularius, Eggs and First Instars

Standard toxicity evaluations of insecticides against insect pests are primarily conducted on adult insects. Evaluations are based on a dose-response or ...

The overall goal of this experiment is to assess the effectiveness of insecticides in killing bed bug eggs and first instars. This method can help answer key questions in the entomology field, such as the effects of toxicological assays on bed bug eggs and small nymphs. The main advantage of this technique is that it is designed for treating a difficult insect life stage with insecticides, particularly the egg stage.To begin the experiment, pull five to 10 mated well-fed adult female bed bugs from a colony and place the females into a Petri dish with filter paper. Prepare 10 replicates to ensure there will be enough eggs for the insecticide assay. Check the dishes every day to see if the females have laid eggs.Once the females have laid eggs, take the females out of the Petri dish and put them into new Petri dishes with a new filter paper daily. Record the data on the old and new Petri dishes. Allow the eggs to age four to five days before starting the assay.Once the eggs have aged appropriately, remove the bed bug eggs gently from the filter papers using soft-tip forceps. Gently scrape the bottom of the egg attached to the filter paper using the forceps and then gently grab the egg without applying too much pressure to avoid tossing the bed bug eggs. Place the removed bed bug eggs into their respective groups inside the plastic Petri dishes.Rub the bottom of each Petri dish on the outside with a fabric softener sheet to limit static electricity from flinging bed bug eggs. Next, prepare serial dilutions of insecticides to get a range of five different concentrations and a control solution with tap water only each to a volume of 20 mL. Take 50 mL centrifuge tubes precut at the mL line and then cut fine mesh into squares large enough to fit into the cap.Screw the mesh tightly eliminating any bumps into the centrifuge tubes using the centrifuge tube cap. Next, using a paintbrush, place a group of bed bug eggs onto the mesh inside of a centrifuge tube. Dip the group of bed bug eggs inside of the cut centrifuge tube into an insecticide concentration for five seconds.Remove the centrifuge tube out of the insecticide solution. Place the centrifuge tube directly onto the laboritory tissue to dry the mesh with the eggs inside. After drying, remove the group of eggs out of the centrifuge tube using a small fine-bristled paint brush and place them into a clean Petri dish with a clean filter paper.Record the egg mortality for 14 days to ensure all eggs have had sufficient time to hatch. Correct for mortality in the control treatment using Abbott's formula. Insert recorded mortality with the corresponding concentrations into the analysis software to calculate LC50 values.Separate a group of five adult male and five adult female bed bugs fed the previous day and place them into a Petri dish with filter paper. Allow the adult bed bugs to mate and lay eggs for eight days. Next remove the adults from the Petri dishes and allow the eggs to hatch into first instars within the Petri dishes.Collect the unfed first instars of the same age using a paintbrush, then place them into new clean Petri dishes until the insecticide assay. Pipet 150 microliter aliquots of each of five previous prepared dilutions of insecticide and water for the control group onto individual filter papers. Evenly distribute the insecticide by applying droplets around the entire edge and center of the filter paper.Place the treated filter papers individually on top of individual hardboard panels. Release groups of first instars onto the individual filter papers while still wet with insecticide and cover the first instars with the bottom of a Petri dish inverted and place a weight on top of the Petri dish to prevent the first instar bed bugs from escaping. Record the mortality of first instar bed bugs after 24 hours of exposure to all insecticide concentrations.Correct for mortality in the control treatment using Abbott's formula. Insert the recorded mortality and concentrations into the analysis software to calculate LC50 values. The percent response or mortality of Harlin strain bed bug eggs to five different concentrations of metocloprid beta-cyfluthrin increased as the dose increased.Mortality reached 100%at the highest concentration tested. After watching this video, you should have a better understanding of how to evaluate insecticide efficacy against bed bug eggs and first instars.

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11.2K vues.  University of Florida. The overall goal of this experiment is to assess the effectiveness of insecticides in killing bed bug eggs and first instars. This method can help answer key questions in the entomology field, such as the effects of toxicological assays on bed bug eggs and small nymphs. The main advantage of this technique is that it is designed for treating a difficult insect life stage with insecticides, particularly the egg stage.To begin the experiment, pull five to 10 mated well-fed adult female b...