We would like to thank Cotton Incorporated State Support Program #08-317MO, USDA/CSREES SR-IPM Grant 2009-34103-20018 and Landis International for funding research pertaining to this publication.

<ol>
	<li>Yu, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Toxicology and Biochemistry of Insecticides. , (2008).</li><li>Pimentel, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Environmental+and+Economic+Costs+of+the+Application+of+Pesticides+Primarily+in+the+United+States.">Environmental and Economic Costs of the Application of Pesticides Primarily in the United States.</a> Environ. Dev. Sustain. 7, 229-252 (2005).</li><li>Plapp, F. W., McWhorter, G. M., Vance, W. H., H, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+for+pyrethroid+resistance+in+the+tobacco+budworm+in+Texas-1986.">Monitoring for pyrethroid resistance in the tobacco budworm in Texas-1986.</a> Proceedings Beltwide Cotton Production Research Conferences. , (1987).</li><li>Prabhaker, N., Toscano, N. C., Henneberry, T. J., Castle, S. J., Weddle, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+two+bioassay+techniques+for+resistance+monitoring+of+silverleaf+whitefly+(Homoptera:+Aleyrodidae)+in+California.">Assessment of two bioassay techniques for resistance monitoring of silverleaf whitefly (Homoptera: Aleyrodidae) in California.</a> J. Econ. Entomol. 89, 805-815 (1996).</li><li>Sivasupramaniam, S., Johnson, S., Watson, T. F., Osman, A. A., Jassim, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=glass-vial+technique+for+monitoring+tolerance+of+Bemisia+argentifolii+(Homoptera:+Aleyrodidae)+to+selected+insecticides+in+Arizona.">glass-vial technique for monitoring tolerance of Bemisia argentifolii (Homoptera: Aleyrodidae) to selected insecticides in Arizona.</a> J. Econ. Entomol. 90, 66-74 (1997).</li><li>Shean, B., Cranshaw, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+susceptibilities+of+green+peach+aphid+(Homoptera:+Aphididae)+and+two+endoparasitoids+(Hymenopera:+Encyrtidae+and+Braconidae)+to+pesticides.">Differential susceptibilities of green peach aphid (Homoptera: Aphididae) and two endoparasitoids (Hymenopera: Encyrtidae and Braconidae) to pesticides.</a> J. Econ. Entomol. 84, 844-850 (1991).</li><li>Willrich, M. M., Leonard, B. R., Cook, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laboratory+and+field+evaluations+of+insecticide+toxicity+to+stink+bugs+(Heteroptera+Pentatomidae).">Laboratory and field evaluations of insecticide toxicity to stink bugs (Heteroptera Pentatomidae).</a> J. Cotton Sci. 7, 156-163 (2003).</li><li>Snodgrass, G. L., Adamczyk, J., Gore, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicity+of+insecticides+in+a+glass-vial+bioassay+to+adult+brown,+green,+and+southern+green+stink+bugs+(Heteroptera:+Pentatomidae).">Toxicity of insecticides in a glass-vial bioassay to adult brown, green, and southern green stink bugs (Heteroptera: Pentatomidae).</a> J. Econ. Entomol. 98, 177-181 (2005).</li><li>Nielsen, A. L., Shearer, P. W., Hamilton, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicity+of+insecticides+to+Halyomorpha+halys+(Hemiptera:+Pentatomidae)+using+glass-vial+bioassays.">Toxicity of insecticides to Halyomorpha halys (Hemiptera: Pentatomidae) using glass-vial bioassays.</a> J. Econ. Entomol. 101, 1439-1442 (2008).</li><li>Dennehy, T. J., Russell, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Susceptibility+of+Lygus+bug+populations+in+Arizona+to+acephate+(Orthene)+and+bifenthrin+(Capture)+with+related+contrasts+of+other+insecticides.">Susceptibility of Lygus bug populations in Arizona to acephate (Orthene) and bifenthrin (Capture) with related contrasts of other insecticides.</a> Proceedings Beltwide Cotton Conferences. , (1996).</li><li>Snodgrass, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glass-vial+bioassay+to+estimate+insecticide+resistance+in+adult+tarnished+plant+bugs.">Glass-vial bioassay to estimate insecticide resistance in adult tarnished plant bugs.</a> Heteroptera: Miridae). J. Econ. Entomol. 89, 1053-1059 (1996).</li><li>Snoddgrass, G. L., Scott, W. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+discriminating-dose+bioassay+for+detecting+pyrethroid+resistance+in+tarnished+plant+bug+(+Heteroptera:+Miridae)+populations.">A discriminating-dose bioassay for detecting pyrethroid resistance in tarnished plant bug ( Heteroptera: Miridae) populations.</a> Southwest. Entomol. 24, 301-307 (1999).</li><li>Lopez, J. D., Hoffman, W. C., Latheef, M. A., Fritz, B. K., Martin, D. E., Lan, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+vial+bioassay+of+insecticidal+toxicity+against+cotton+fleahopper,+Pseudatomoscelis+seriatus+(Hemiptera:+Miridae).">Adult vial bioassay of insecticidal toxicity against cotton fleahopper, Pseudatomoscelis seriatus (Hemiptera: Miridae).</a> J. Pest. Sci.. 33, 261-265 (2008).</li><li>Lopez, J. D., Hoffman, W. C., Latheef, M. A., Fritz, B. K., Martin, D. E., Lan, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+toxicity+of+selected+insecticides+against+thrips+on+cotton+in+laboratory+bioassays.">Evaluation of toxicity of selected insecticides against thrips on cotton in laboratory bioassays.</a> J. Cotton Sci. 12, 188-194 (2008).</li><li>Smith, T. P., Hammond, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+susceptibility+of+sweetpotato+weevil+(Coleoptera:+Brentidae)+to+selected+insecticides.">Comparative susceptibility of sweetpotato weevil (Coleoptera: Brentidae) to selected insecticides.</a> J. Econ. Entomol. 99, 2024-2029 (2006).</li><li>Kanga, L. H. B., Wall, M. L., Plapp, F. W., Gardiner, E. M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pyrethroid+resistance+in+field-collected+boll+weevils+from+southeast+Arkansas+in+1994.">Pyrethroid resistance in field-collected boll weevils from southeast Arkansas in 1994.</a> Southwest. Entomol. 20, 247-253 (1995).</li><li>Bayoun, I. M., Plapp, F. W. J. r., Gilstrap, F. E., Michels, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicity+of+selected+insecticides+to+Diuraphis+noxia+(Homoptera:+Aphidiae)+and+its+natural+enemies.">Toxicity of selected insecticides to Diuraphis noxia (Homoptera: Aphidiae) and its natural enemies.</a> J. Econ. Entomol. 88, 1177-1185 (1995).</li><li>Smith, T. R., Cave, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pesticide+susceptibility+of+Cybocephalus+nipponoicus+and+Rhyzobius+Iophanthae+(Coleoptera+Cybocephalidae,+Coccinellidae).">Pesticide susceptibility of Cybocephalus nipponoicus and Rhyzobius Iophanthae (Coleoptera Cybocephalidae, Coccinellidae).</a> Fla. Entomol. 89, 502-507 (2006).</li><li>Sukontason, K., Olson, J. K., Hartberg, W. K., Duhrkopf, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organophosphate+and+pyrethroid+susceptibilities+of+Culex+salinarius+adults+from+Texas+and+New+Jersey.">Organophosphate and pyrethroid susceptibilities of Culex salinarius adults from Texas and New Jersey.</a> J Am. Mosquito Contr. 14, 477-480 (1998).</li><li>Kanga, L. H. B., Plapp, F. W. J. r., Wall, M. L., Elzen, G. W., Lopez, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+for+resistance+to+organophosphorus,+carbamate,+and+pyrethroid+insecticides+in+the+oriental+fruit+moth+(Lepidoptera:+Torticidae).">Monitoring for resistance to organophosphorus, carbamate, and pyrethroid insecticides in the oriental fruit moth (Lepidoptera: Torticidae).</a> Canadian Entomol. , 131-441 (1999).</li><li>Plapp, F. W., Jackman, J. A., Campanhola, C., Frisbie, R. E., Graves, J. B., Luttrell, R. G., Kitten, W. F., Wall, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+and+management+of+pyrethroid+resistance+in+the+tobacco+budworm+(Lepidoptera:+Noctuidae)+in+Texas,+Mississippi,+Louisiana,+Arkansas,+and+Oklahoma.">Monitoring and management of pyrethroid resistance in the tobacco budworm (Lepidoptera: Noctuidae) in Texas, Mississippi, Louisiana, Arkansas, and Oklahoma.</a> J. Econ. Entomol. 83, 335-341 (1990).</li><li>Mink, J. S., Boethel, D. J., Leonard, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+permethrin+resistance+in+soybean+looper+(Lepidoptera:+Noctuidae)+adults.">Monitoring permethrin resistance in soybean looper (Lepidoptera: Noctuidae) adults.</a> J. Entomol. Sci. 28, 43-50 (1993).</li><li>Cook, D. R., Leonard, B. R., Gore, J., Temple, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Baseline+responses+of+bollworm,+Heliocoverpa+zea+(Boddie),+and+tobacco+budworm,+Heliothis+virescens+(F.),+to+indoxcarb+and+pyridalyl.">Baseline responses of bollworm, Heliocoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), to indoxcarb and pyridalyl.</a> J. Agricul. Urban Entomol. 22, 99-109 (2005).</li><li>Temple, J. H., Pommireddy, P. L., Cook, D. R., Ma&#231;on, P., Leonard, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arthopod+management:+Susceptibility+of+selected+lepidopteran+to+pests+Rynaxypyr,+a+novel+insecticide.">Arthopod management: Susceptibility of selected lepidopteran to pests Rynaxypyr, a novel insecticide.</a> J. Cotton Sci. 13, 23-31 (2009).</li><li>Plapp, F. W., Vinson, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+toxicities+of+some+insecticides+to+the+tobacco+budworm+and+its+ichneumonid+parasite,+Campoletis+sonorensis.">Comparative toxicities of some insecticides to the tobacco budworm and its ichneumonid parasite, Campoletis sonorensis.</a> Environ. Entomol. 6, 381-384 (1977).</li><li>Xu, J., Shelton, A. M., Cheng, X. i. a. N. i. a. n. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variation+in+susceptibility+of+Diadegma+insulare+(Hymenoptera:+Ichneumonidae)+to+permethrin.">Variation in susceptibility of Diadegma insulare (Hymenoptera: Ichneumonidae) to permethrin.</a> J. Econ. Entomol. 94, 541-546 (2001).</li><li>Snodgrass, G. L., Scott, W. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Seasonal+changes+in+pyrethroid+resistance+in+tarnished+plant+bug+(Heteroptera:+Miridae)+populations+during+a+three+year+period+in+the+delta+area+of+Arkansas,+Louisiana+and+Mississippi.">Seasonal changes in pyrethroid resistance in tarnished plant bug (Heteroptera: Miridae) populations during a three year period in the delta area of Arkansas, Louisiana and Mississippi.</a> J. Econ. Entomol. 93, 441-446 (2000).</li><li>Miller, A. L. E., Way, M. O., Bernhardt, J., Stout, M. J., Tindall, K. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-state+resistance+monitoring+of+rice+stink+bug+with+a+new+and+old+insecticide.">Multi-state resistance monitoring of rice stink bug with a new and old insecticide.</a> , (2010).</li><li>Abbott, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+computing+the+effectiveness+of+an+insecticide.">A method for computing the effectiveness of an insecticide.</a> J. Econ. Entomol. 18, 265-267 (1925).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> User's Manual version 8.0. , (2002).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> A user's guide to Probitor Logit analysis. , (2002).</li><li>Preisler, H. K., Robertson, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Pesticide bioassays with arthropods. , (1992).</li><li>Hollingsworth, R. G., Steinkraus, D. C., Tugwell, N. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Responses+of+Arkansas+population+of+tarnished+plant+bugs+(Heteroptera:+Miridae)+to+insecticides,+and+tolerance+differences+between+nymphs+and+adults.">Responses of Arkansas population of tarnished plant bugs (Heteroptera: Miridae) to insecticides, and tolerance differences between nymphs and adults.</a> J. Econ. Entomol. 90, 21-26 (1997).</li></ol>

No conflicts of interest declared.

The LC50 value can be used to establish as baseline susceptibility of a target population(s). The value of this data can be in future monitoring surveys or for the immediate purpose of comparing the current results to that of a previously determined LC50 to determine the susceptibility of the target population has shifted. Actual LC50 values can be compared among populations by examining the 95% confidence intervals; if the upper and lower limits do not overlap, then it is likely that the population has experienced a significant change in susceptibility and in some situations is an indication of resistance33. The LC50s can also be used to examine seasonal changes in insecticide esusceptibilitye28, or compare responses among species or insecticide AI s. Considerable work has also use these data to compare responses between males and females10 or between adults and immature stages,10,34. Sometimes confidence intervals are wide or not able to be calculated. To gain tighter confidence intervals conduct the bioassay with more insects and/or more concentrations.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">	
		
		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>50-100 ml glass beaker </td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Volumetric flask with stoppers (can use the amber colored flasks for light sensitive pesticides such as pyrethroids)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>20ml glass scintillation vials with un-lined lids</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>A method for color coating vials (paint or markers)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Acetone</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Commercial hotdog roller (heat element disconnected)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>2 wash bottles (one modified such that the opening is large for fast delivery of the liquid and one so that the spout opening is small for slow delivery of the liquids)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Small weigh boat (make sure all plastic materials acetone safe)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Access to a balance with 0.001g readability or a higher precision.</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Parafilm M</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Repeater pipettor</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Appropriate tips</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Glass pipettes that fit in the volumetric flask.</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Hood (used to remove the acetone smell)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>A place to store insecticide solutions and vials [refrigerator (solutions), dark room or freezer depending on the chemical (vials)]</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

bioassays for monitoring insecticide resistance

Pest resistance to pesticides is an increasing problem because pesticides are an integral part of high-yielding production agriculture. When few products are labeled for an individual pest within a particular crop system, chemical control options are limited. Therefore, the same product(s) are used repeatedly and continual selection pressure is placed on the target pest. There are both financial and environmental costs associated with the development of resistant populations. The cost of pesticide resistance has been estimated at approximately $ 1.5 billion annually in the United States. This paper will describe protocols, currently used to monitor arthropod (specifically insects) populations for the development of resistance. The adult vial test is used to measure the toxicity to contact insecticides and a modification of this test is used for plant-systemic insecticides. In these bioassays, insects are exposed to technical grade insecticide and responses (mortality) recorded at a specific post-exposure interval. The mortality data are subjected to Log Dose probit analysis to generate estimates of a lethal concentration that provides mortality to 50% (LC50) of the target populations and a series of confidence limits (CL's) as estimates of data variability. When these data are collected for a range of insecticide-susceptible populations, the LC50 can be used as baseline data for future monitoring purposes. After populations have been exposed to products, the results can be compared to a previously determined LC50 using the same methodology.

Watch this Scientific Journal Video about Bioassays for Monitoring Insecticide Resistance at JoVE.com

Bioassays for Monitoring Insecticide Resistance

This manuscript demonstrates and discusses techniques used to survey pesticide susceptibility and detect resistance to contact and systemic pesticides in arthropod pests.

Pest resistance to pesticides is an increasing problem because pesticides are an integral part of high-yielding production agriculture. When few products ...

bioassays-for-monitoring-insecticide-resistance

Research

JoVE Journal

Biology

33.1K vistas.  University of Missouri, Delta Research Center. Este manuscrito demuestra y discute las técnicas utilizadas para estudiar la susceptibilidad de pesticidas y detectar la resistencia a los pesticidas de contacto y sistémicos en las plagas de artrópodos.

Video: Bioassays for Monitoring Insecticide Resistance

Choice and No-Choice Assays for Testing the Resistance of A. thaliana to Chewing Insects

Larvae of the small white cabbage butterfly are a pest in agricultural settings. This caterpillar species feeds from plants in the cabbage family, which include many crops such as cabbage, broccoli, Brussel sprouts etc. Rearing of the insects takes place on cabbage plants in the greenhouse. At least two cages are needed for the rearing of Pieris rapae. One for the larvae and the other to contain the adults, the butterflies. In order to investigate the role of plant hormones and toxic plant chemicals in resistance to this insect pest, we demonstrate two experiments. First, determination of the role of jasmonic acid (JA - a plant hormone often indicated in resistance to insects) in resistance to the chewing insect Pieris rapae. Caterpillar growth can be compared on wild-type and mutant plants impaired in production of JA. This experiment is considered "No Choice", because larvae are forced to subsist on a single plant which synthesizes or is deficient in JA. Second, we demonstrate an experiment that investigates the role of glucosinolates, which are used as oviposition (egg-laying) signals. Here, we use WT and mutant Arabidopsis impaired in glucosinolate production in a "Choice" experiment in which female butterflies are allowed to choose to lay their eggs on plants of either genotype. This video demonstrates the experimental setup for both assays as well as representative results.

Plant resistance to chewing insect herbivores can be tested in several ways. Here, we demonstrate how to set-up a choice and a no-choice experiment with the model plant Arabidopsis thaliana to identify resistance against the pest species Pieris rapae.

Larvae of the small white cabbage butterfly are a pest in agricultural settings. This caterpillar species feeds from plants in the cabbage family, which ...

Monitoring Heart Function in Larval Drosophila melanogaster for Physiological Studies

We present various methods to record cardiac function in the larval Drosophila. The approaches allow heart rate to be measured in unrestrained and restrained whole larvae. For direct control of the environment around the heart another approach utilizes the dissected larvae and removal of the internal organs in order to bathe the heart in desired compounds. The exposed heart also allows membrane potentials to be monitored which can give insight of the ionic currents generated by the myocytes and for electrical conduction along the heart tube. These approaches have various advantages and disadvantages for future experiments that are discussed. The larval heart preparation provides an additional model besides the Drosophila skeletal NMJ to investigate the role of intracellular calcium regulation on cellular function. Learning more about the underlying ionic currents that shape the action potentials in myocytes in various species, one can hope to get a handle on the known ionic dysfunctions associated to specific genes responsible for various diseases in mammals.

Monitoring Heart Function in Larval Drosophila melanogaster for Physiological Studies

We present various ways to monitor heart function in the larva of Drosophila for assessing questions dealing with the function of gap junctions, ion channel mutations, modulation of pacemaker activity and pharmacological studies.

We present various methods to record cardiac function in the larval Drosophila. The approaches allow heart rate to be measured in unrestrained  and  ...

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example

Plants can resist herbivore damage through three broad mechanisms: antixenosis, antibiosis and tolerance1. Antixenosis is the degree to which the plant is avoided when the herbivore is able to select other plants2. Antibiosis is the degree to which the plant affects the fitness of the herbivore feeding on it1.Tolerance is the degree to which the plant can withstand or repair damage caused by the herbivore, without compromising the herbivore's growth and reproduction1. The durability of herbivore resistance in an agricultural setting depends to a great extent on the resistance mechanism favored during crop breeding efforts3.
We demonstrate a no-choice experiment designed to estimate the relative contributions of antibiosis and tolerance to spittlebug resistance in Brachiaria spp. Several species of African grasses of the genus Brachiaria are valuable forage and pasture plants in the Neotropics, but they can be severely challenged by several native species of spittlebugs (Hemiptera: Cercopidae)4.To assess their resistance to spittlebugs, plants are vegetatively-propagated by stem cuttings and allowed to grow for approximately one month, allowing the growth of superficial roots on which spittlebugs can feed. At that point, each test plant is individually challenged with six spittlebug eggs near hatching. Infestations are allowed to progress for one month before evaluating plant damage and insect survival. Scoring plant damage provides an estimate of tolerance while scoring insect survival provides an estimate of antibiosis. This protocol has facilitated our plant breeding objective to enhance spittlebug resistance in commercial brachiariagrases5.

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example

This video explains mechanisms of host plant resistance to herbivory and demonstrates a no-choice test that estimates the relative contributions of antibiosis and tolerance to spittlebug resistance in Brachiaria spp.

Plants can resist herbivore damage through three broad mechanisms: antixenosis, antibiosis and tolerance1. Antixenosis is the degree to which the plant is ...

Long-term Lethal Toxicity Test with the Crustacean Artemia franciscana

Our research activities target the use of biological methods for the evaluation of environmental quality, with particular reference to saltwater/brackish water and sediment. The choice of biological indicators must be based on reliable scientific knowledge and, possibly, on the availability of standardized procedures. In this article, we present a standardized protocol that used the marine crustacean Artemia to evaluate the toxicity of chemicals and/or of marine environmental matrices. Scientists propose that the brine shrimp (Artemia) is a suitable candidate for the development of a standard bioassay for worldwide utilization. A number of papers have been published on the toxic effects of various chemicals and toxicants on brine shrimp (Artemia). The major advantage of this crustacean for toxicity studies is the overall availability of the dry cysts; these can be immediately used in testing and difficult cultivation is not demanded1,2. Cyst-based toxicity assays are cheap, continuously available, simple and reliable and are thus an important answer to routine needs of toxicity screening, for industrial monitoring requirements or for regulatory purposes3. The proposed method involves the mortality as an endpoint. The numbers of survivors were counted and percentage of deaths were calculated. Larvae were considered dead if they did not exhibit any internal or external movement during several seconds of observation4. This procedure was standardized testing a reference substance (Sodium Dodecyl Sulfate); some results are reported in this work. This article accompanies a video that describes the performance of procedural toxicity testing, showing all the steps related to the protocol.

Long-term Lethal Toxicity Test with the Crustacean Artemia franciscana

This study concerns the development and standardization of a valuable methodological protocol to determine long-term (14 days) lethal toxicity exerted by chemical substances, industrial wastewater or sewage and liquid environmental samples on the saltwater crustacean, Artemia franciscana.

Our research activities target the use of biological methods for the evaluation of environmental quality, with particular reference to saltwater/brackish ...

RNA Secondary Structure Prediction Using High-throughput SHAPE

Understanding the function of RNA involved in biological processes requires a thorough knowledge of RNA structure. Toward this end, the methodology dubbed "high-throughput selective 2' hydroxyl acylation analyzed by primer extension", or SHAPE, allows prediction of RNA secondary structure with single nucleotide resolution. This approach utilizes chemical probing agents that preferentially acylate single stranded or flexible regions of RNA in aqueous solution. Sites of chemical modification are detected by reverse transcription of the modified RNA, and the products of this reaction are fractionated by automated capillary electrophoresis (CE). Since reverse transcriptase pauses at those RNA nucleotides modified by the SHAPE reagents, the resulting cDNA library indirectly maps those ribonucleotides that are single stranded in the context of the folded RNA. Using ShapeFinder software, the electropherograms produced by automated CE are processed and converted into nucleotide reactivity tables that are themselves converted into pseudo-energy constraints used in the RNAStructure (v5.3) prediction algorithm. The two-dimensional RNA structures obtained by combining SHAPE probing with in silico RNA secondary structure prediction have been found to be far more accurate than structures obtained using either method alone.

High-throughput selective 2' hydroxyl acylation analyzed by primer extension (SHAPE) utilizes a novel chemical probing technology, reverse transcription, capillary electrophoresis and secondary structure prediction software to determine the structures of RNAs from several hundred to several thousand nucleotides at single nucleotide resolution.

Understanding the function of RNA involved in biological processes requires a thorough knowledge of RNA structure. Toward this end, the methodology dubbed ...

Assessing Murine Resistance Artery Function Using Pressure Myography

Pressure myograph systems are exquisitely useful in the functional assessment of small arteries, pressurized to a suitable transmural pressure. The near physiological condition achieved in pressure myography permits in-depth characterization of intrinsic responses to pharmacological and physiological stimuli, which can be extrapolated to the in vivo behavior of the vascular bed. Pressure myograph has several advantages over conventional wire myographs. For example, smaller resistance vessels can be studied at tightly controlled and physiologically relevant intraluminal pressures. Here, we study the ability of 3rd order mesenteric arteries (3-4 mm long), preconstricted with phenylephrine, to vaso-relax in response to acetylcholine. Mesenteric arteries are mounted on two cannulas connected to a pressurized and sealed system that is maintained at constant pressure of 60 mmHg. The lumen and outer diameter of the vessel are continuously recorded using a video camera, allowing real time quantification of the vasoconstriction and vasorelaxation in response to phenylephrine and acetylcholine, respectively.
	To demonstrate the applicability of pressure myography to study the etiology of cardiovascular disease, we assessed endothelium-dependent vascular function in a murine model of systemic hypertension. Mice deficient in the &alpha;1 subunit of soluble guanylate cyclase (sGC&alpha;1-/-) are hypertensive when on a 129S6 (S6) background (sGC&alpha;1-/-S6) but not when on a C57BL/6 (B6) background (sGC&alpha;1-/-B6). Using pressure myography, we demonstrate that sGC&alpha;1-deficiency results in impaired endothelium-dependent vasorelaxation. The vascular dysfunction is more pronounced in sGC&alpha;1-/-S6 than in sGC&alpha;1-/-B6 mice, likely contributing to the higher blood pressure in sGC&alpha;1-/-S6 than in sGC&alpha;1-/-B6 mice. 
	Pressure myography is a relatively simple, but sensitive and mechanistically useful technique that can be used to assess the effect of various stimuli on vascular contraction and relaxation, thereby augmenting our insight into the mechanisms underlying cardiovascular disease.

In pressure myography, an intact small segment of a vessel is mounted onto two small cannulas and pressurized to a suitable luminal pressure. Here, we describe the method to measure vasorelaxation response of the mouse 3rd order mesenteric arteries in c57 and sGC&alpha;1-/- mice using pressure myography.

Pressure myograph systems are  exquisitely useful in the functional assessment of small arteries, pressurized  to a suitable transmural pressure. The  ...

Coupled Assays for Monitoring Protein Refolding in Saccharomyces cerevisiae

Proteostasis, defined as the combined processes of protein folding/biogenesis, refolding/repair, and degradation, is a delicate cellular balance that must be maintained to avoid deleterious consequences 1. External or internal factors that disrupt this balance can lead to protein aggregation, toxicity and cell death. In humans this is a major contributing factor to the symptoms associated with neurodegenerative disorders such as Huntington's, Parkinson's, and Alzheimer's diseases 10. It is therefore essential that the proteins involved in maintenance of proteostasis be identified in order to develop treatments for these debilitating diseases. This article describes techniques for monitoring in vivo protein folding at near-real time resolution using the model protein firefly luciferase fused to green fluorescent protein (FFL-GFP). FFL-GFP is a unique model chimeric protein as the FFL moiety is extremely sensitive to stress-induced misfolding and aggregation, which inactivates the enzyme 12. Luciferase activity is monitored using an enzymatic assay, and the GFP moiety provides a method of visualizing soluble or aggregated FFL using automated microscopy. These coupled methods incorporate two parallel and technically independent approaches to analyze both refolding and functional reactivation of an enzyme after stress. Activity recovery can be directly correlated with kinetics of disaggregation and re-solubilization to better understand how protein quality control factors such as protein chaperones collaborate to perform these functions. In addition, gene deletions or mutations can be used to test contributions of specific proteins or protein subunits to this process. In this article we examine the contributions of the protein disaggregase Hsp104 13, known to partner with the Hsp40/70/nucleotide exchange factor (NEF) refolding system 5, to protein refolding to validate this approach.

Coupled Assays for Monitoring Protein Refolding in Saccharomyces cerevisiae

This article describes the use of a firefly luciferase-GFP fusion protein to investigate in vivo protein folding in Saccharomyces cerevisiae. Using this reagent, refolding of a model heat-denatured protein can be monitored simultaneously by fluorescence microscopy and an enzymatic assay to probe the roles of proteostasis network components in protein quality control.

Proteostasis, defined as the combined processes of protein folding/biogenesis, refolding/repair, and degradation, is a delicate cellular balance that must ...

Autonomously Bioluminescent Mammalian Cells for Continuous and Real-time Monitoring of Cytotoxicity

Mammalian cell-based in vitro assays have been widely employed as alternatives to animal testing for toxicological studies but have been limited due to the high monetary and time costs of parallel sample preparation that are necessitated due to the destructive nature of firefly luciferase-based screening methods. This video describes the utilization of autonomously bioluminescent mammalian cells, which do not require the destructive addition of a luciferin substrate, as an inexpensive and facile method for monitoring the cytotoxic effects of a compound of interest. Mammalian cells stably expressing the full bacterial bioluminescence (luxCDABEfrp) gene cassette autonomously produce an optical signal that peaks at 490 nm without the addition of an expensive and possibly interfering luciferin substrate, excitation by an external energy source, or destruction of the sample that is traditionally performed during optical imaging procedures. This independence from external stimulation places the burden for maintaining the bioluminescent reaction solely on the cell, meaning that the resultant signal is only detected during active metabolism. This characteristic makes the lux-expressing cell line an excellent candidate for use as a biosentinel against cytotoxic effects because changes in bioluminescent production are indicative of adverse effects on cellular growth and metabolism. Similarly, the autonomous nature and lack of required sample destruction permits repeated imaging of the same sample in real-time throughout the period of toxicant exposure and can be performed across multiple samples using existing imaging equipment in an automated fashion.

Mammalian cells expressing the bacterial bioluminescence gene cassette (lux) produce light autonomously. The resulting bioluminescent dynamics upon chemical exposure have been demonstrated to reflect the treatment effects on cellular growth and metabolism, making these cells an inexpensive, continuous, real-time toxicity screening tool that can easily be adapted for high-throughput automation.

Mammalian  cell-based in vitro assays have been  widely employed as alternatives to animal testing for toxicological studies but  have been limited due to ...

Selected Reaction Monitoring Mass Spectrometry for Absolute Protein Quantification

Absolute quantification of target proteins within complex biological samples is critical to a wide range of research and clinical applications. This protocol provides step-by-step instructions for the development and application of quantitative assays using selected reaction monitoring (SRM) mass spectrometry (MS). First, likely quantotypic target peptides are identified based on numerous criteria. This includes identifying proteotypic peptides, avoiding sites of posttranslational modification, and analyzing the uniqueness of the target peptide to the target protein. Next, crude external peptide standards are synthesized and used to develop SRM assays, and the resulting assays are used to perform qualitative analyses of the biological samples. Finally, purified, quantified, heavy isotope labeled internal peptide standards are prepared and used to perform isotope dilution series SRM assays. Analysis of all of the resulting MS data is presented. This protocol was used to accurately assay the absolute abundance of proteins of the chemotaxis signaling pathway within RAW 264.7 cells (a mouse monocyte/macrophage cell line). The quantification of Gi2 (a heterotrimeric G-protein &#945;-subunit) is described in detail.

This protocol describes how to perform absolute quantification assays of target proteins within complex biological samples using selected reaction monitoring. It was used to accurately quantify proteins of the mouse macrophage chemotaxis signaling pathway. Target peptide selection, assay development, and qualitative and quantitative assays are described in detail.

Absolute quantification of target proteins within complex biological samples is critical to a wide range of research and clinical applications. This ...

Detection of Intracellular Gene Expression in Live Cells of Murine, Human and Porcine Origin Using Fluorescence-labeled Nanoparticles

The reprogramming of somatic cells to induced pluripotent stem cells (iPS) has successfully been performed in different mammalian species including mouse, rat, human, pig and others. The verification of iPS clones mainly relies on the detection of the endogenous expression of different pluripotency genes. These genes mostly represent transcription factors which are located in the cell nucleus. Traditionally, the proof of their endogenous expression is supplied by immunohistochemical staining after fixation of the cells. This approach requires replicate cultures of each clone at this early stage to preserve validated clones for further experiments. The present protocol describes an approach with gene-specific nanoparticles which allows the evaluation of intracellular gene expression directly in live cells by fluorescence. The nanoparticles consist of a central gold particle coupled to a capture strand carrying a sequence complementary to the target mRNA as well as a quenched reporter strand. These nanoparticles are actively endocytosed and the target mRNA displaces the reporter strand which then start to fluoresce. Therefore, specific target gene expression can be detected directly under the microscope. In addition, the emitted fluorescence allows the identification, isolation and enrichment of cells expressing a specific gene by flow cytometry. This method can be applied directly to live cells in culture without any manipulation of the target cells.

This manuscript describes a novel technique which allows the detection of intracellular gene expression after endocytosis of fluorescence-labeled nanoparticles directly in live cells. The method does not require manipulation of the cells and is not restricted with respect to the target gene or species.

The reprogramming of somatic cells to induced pluripotent stem cells (iPS) has successfully been performed in different mammalian species including mouse, ...