Name: harvesting venom toxins from assassin bugs and other heteropteran insects
Uploaded: 2018-04-21T13:00:00
Description: Watch this Scientific Journal Video about Harvesting Venom Toxins from Assassin Bugs and Other Heteropteran Insects at JoVE.com

We acknowledge financial support from the Australian Research Council (Grants DP130103813 and LP140100832 to G.F.K., DECRA Fellowship DE160101142 to EABU), the Australian National Health &amp; Medical Research Council (Principal Research Fellowship APP1044414 to G.F.K.), and The University of Queensland (Postdoctoral Fellowship to A.A.W.).

This protocol complies with The University of Queensland&#39;s policy set out in Responsible Care and Use of Animals in Teaching and Research (PPL 4.20.11) as well as the National Health and Medical Research Council&#39;s Australian code for the care and use of animals for scientific purposes (8th Edition 2013).
Caution: Take care not to be envenomated when handling assassin bugs. Take care to protect the eyes when handling species that spit venom defensively. Take...

<ol>
	<li>Walker, A. A., Weirauch, C., Fry, B. G., King, G. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Venoms+of+heteropteran+insects:+A+treasure+trove+of+diverse+pharmacological+toolkits.">Venoms of heteropteran insects: A treasure trove of diverse pharmacological toolkits.</a> Toxins. 8 (2), 43 (2016).</li><li>Ribeiro, J. M. C., Assump&#231;&#227;o, T. C., Francischetti, I. M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+insight+into+the+sialomes+of+bloodsucking+Heteroptera.">An insight into the sialomes of bloodsucking Heteroptera.</a> Psyche (Stuttg). 2012, 1-16 (2012).</li><li>Ambrose, D. P., Maran, S. P. 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H., 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=Anticoagulant+activity+of+Triatoma+infestans+and+Panstrongylus+megistus+saliva+(Hemiptera/Triatominae).">Anticoagulant activity of Triatoma infestans and Panstrongylus megistus saliva (Hemiptera/Triatominae).</a> Acta Tropica. 61, 255-261 (1996).</li><li>Ribeiro, J. M., Marinotti, O., Gonzales, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+salivary+vasodilator+in+the+blood-sucking+bug,+Rhodnius+prolixus.">A salivary vasodilator in the blood-sucking bug, Rhodnius prolixus.</a> British Journal of Pharmacology. 101 (4), 932-936 (1990).</li><li>Ribeiro, J. M., Schneider, M., Guimar&#227;es, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+and+characterization+of+prolixin-S+(nitrophorin+2),+the+salivary+anticoagulant+of+the+blood-sucking+bug+Rhodnius+prolixus.">Purification and characterization of prolixin-S (nitrophorin 2), the salivary anticoagulant of the blood-sucking bug Rhodnius prolixus.</a> Biochem Journal. 308 (1), 243-249 (1995).</li><li>Swart, C. C., Deaton, L. E., Felgenhauer, B. 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The most critical step in harvesting assassin bug venom is selecting the appropriate method depending on the purposes of the study. Each of the three methods presented for harvesting heteropteran venoms has advantages and disadvantages depending on downstream applications.
Inducing bugs to expel venom from the proboscis (Protocols 1-3) avoids contamination of venom by glandular tissues. In addition, these methods are non-lethal and can be repeated many times over the course of a bug's life. El...

Heteropteran venoms are potently bioactive substances1. For example, the venom/saliva secretions of blood-feeding Heteroptera such as kissing bugs (Triatominae) and bed bugs (Cimicidae) facilitates feeding by disrupting hemostasis2. Toxins in these venoms target multiple pathways including coagulation, platelet aggregation and vasoconstriction, as well as the pain and itch pathways. Venoms from most other heteropteran species are adapted to facilitate predation rather than blood-feeding. Their venoms cause paralysis, death and tissue liquefaction when injected into invertebrates3,4. When injected into vertebrates, their venom may also have drastic effects. For example, injection of venom from the assassin bug Holotrichius innesi into vertebrates causes pain, muscle paralysis and hemorrhage; mice envenomated by this bug die quickly due to respiratory paralysis5.
Transcriptomic and proteomic studies have revealed the protein composition of some heteropteran venoms. Venoms of predaceous species are rich in proteases, other enzymes, and peptides and proteins of unknown structure and function6,7,8. Kissing bug venom is rich in the triabin protein family, whose members profoundly affect coagulation, platelet aggregation, and vasoconstriction2,9. However, it is not known which toxins underlie most bioactivities of venom. For example, venom of the kissing bug Triatoma infestans has been reported to be analgesic and inhibit sodium channels10, but the components responsible remain to be elucidated. Likewise, it is not known what component(s) of assassin bug venom cause paralysis or pain. A prerequisite for identifying the toxins responsible for particular venom bioactivities, and for characterizing the structure and function of novel venom toxins, is obtaining venom.
Venom has been obtained from heteropterans by electrostimulation5,6,7,8,11,12,13, provocation of defensive responses4,8, mechanically squeezing the thorax12,14,15,16, dissecting out venom glands8,17,18,19,20,21,22, and application of agonists of the muscarinic acetylcholine receptor23. Judging the potential advantages and disadvantages of any method is complicated by the morphology of heteropteran venom glands, which consist of a main gland with two separate lumens, the anterior main gland (AMG) and posterior main gland (PMG), as well as an associated accessory gland (AG). These different gland compartments produce different protein secretions, which may be specialized for different biological functions including prey capture, defense and extra-oral digestion8,17. In peiratine and ectrichodiine assassin bugs, the AMG has been associated with prey capture and the PMG with extra-oral digestion17. However, in the harpactorine bug Pristhesancus plagipennis the PMG is specialized for prey capture and digestion whereas the AMG is hypothesized to secrete defensive venom8. The AG has been described as having little secretory function in assassin bugs8 or as a major site of protease storage in giant water bugs23. Clearly, further work is required to clarify the function of each gland compartment among various heteropteran subgroups, and to determine the function of most venom toxins. In this report we describe protocols for harvesting venom toxins from heteropterans toward this goal.

<table border="0" cellpadding="0" cellspacing="0" width="912">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Electostimulator</td>
			<td style="width:203px;">Grass Technologies</td>
			<td style="width:187px;">S48 Square Pulse Stimulator</td>
			<td style="width:307px;">Electrostimulator allowing pulsed electrostimulation</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Featherlight tweezers</td>
			<td style="width:203px;">Australian Entomological Supplies</td>
			<td style="width:187px;">E122B</td>
			<td>For handling live venomous insects</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Protease inhibitor cocktail</td>
			<td style="width:203px;">Sigma</td>
			<td style="width:187px;">4693124001</td>
			<td>For preventing autoproteolytic digestion of venom</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dissection equipment</td>
			<td style="width:203px;">Australian Entomological Supplies</td>
			<td style="width:187px;">E152Micro</td>
			<td>For fine dissections</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Insect pins</td>
			<td style="width:203px;">Australian Entomological Supplies</td>
			<td style="width:187px;">E162</td>
			<td>For fine dissections</td>
		</tr>
	</tbody>
</table>

harvesting venom toxins from assassin bugs and other heteropteran insects

Heteropteran insects such as assassin bugs (Reduviidae) and giant water bugs (Belostomatidae) descended from a common predaceous and venomous ancestor, and the majority of extant heteropterans retain this trophic strategy. Some heteropterans have transitioned to feeding on vertebrate blood (such as the kissing bugs, Triatominae; and bed bugs, Cimicidae) while others have reverted to feeding on plants (most Pentatomomorpha). However, with the exception of saliva used by kissing bugs to facilitate blood-feeding, little is known about heteropteran venoms compared to the venoms of spiders, scorpions and snakes.
One obstacle to the characterization of heteropteran venom toxins is the structure and function of the venom/labial glands, which are both morphologically complex and perform multiple biological roles (defense, prey capture, and extra-oral digestion). In this article, we describe three methods we have successfully used to collect heteropteran venoms. First, we present electrostimulation as a convenient way to collect venom that is often lethal when injected into prey animals, and which obviates contamination by glandular tissue. Second, we show that gentle harassment of animals is sufficient to produce venom extrusion from the proboscis and/or venom spitting in some groups of heteropterans. Third, we describe methods to harvest venom toxins by dissection of anaesthetized animals to obtain the venom glands. This method is complementary to other methods, as it may allow harvesting of toxins from taxa in which electrostimulation and harassment are ineffective. These protocols will enable researchers to harvest toxins from heteropteran insects for structure-function characterization and possible applications in medicine and agriculture.

Some heteropteran species, such as the harpactorine P. plagipennis and the reduviine Platymeris rhadamanthus, reliably yield large quantities (5-20 &#181;L) of venom in response to electrostimulation (Table 1). In general, most peiratine, reduviine, and harpactorine bugs yield venom in response to this method. Among stenopodaine bugs, electrostimulation elicited venom from Oncocephalus sp. but not Thodelmus sp. The holoptiline and emesi...

Watch this Scientific Journal Video about Harvesting Venom Toxins from Assassin Bugs and Other Heteropteran Insects at JoVE.com

Harvesting Venom Toxins from Assassin Bugs and Other Heteropteran Insects

Although many insects in the suborder Heteroptera (Insecta: Hemiptera) are venomous, their venom composition and the functions of their venom toxins are mostly unknown. This protocol describes methods to harvest heteropteran venoms for further characterization, using electrostimulation, harassment, and gland dissection.

Heteropteran insects such as assassin bugs (Reduviidae) and giant water bugs (Belostomatidae) descended from a common predaceous and venomous ancestor, ...

Assassin bugs are a group of insects that use venom to paralyze and pre-digest their prey. However, despite animal venoms being of interest as novel medicines, insecticides, and scientific tools, the toxins that they produce are almost entirely uncharacterized. One reason for this is that assassin bugs are less well-known in comparison to iconic venomous arthropods such as spiders and scorpions.Another reason is that until recently, little information has been available about how to harvest their toxins. In this video, we will present methods that will enable researchers to successfully harvest venom toxins from assassin bugs, and also related insects such as giant fish-killing water bugs. Protocol one describes how to harvest venom by electrostimulation.First, collect suitable insects. Adults and large nymphs are the easiest to work with. Using bugs two to seven days after feeding is ideal, to ensure the insects have accumulated venom stocks but do not starve.Prepare a pair of forceps with electrodes at the tips, and connect them to an electricity supply. Ideally, this supply should be an electrostimulator capable of delivering five millisecond pulses at five Hertz. Use peak voltages between 15 and 25 volts for small or large bugs, respectively.If an electrostimulator is not available, use constant voltages of five to 12 volts. Restrain the insect using rubber bands and a foam platform. Place the proboscis of the insect into a collecting tube.A P200 pipette tube is ideal for most assassin bugs. Optionally, a small amount of water can be added to the tip before harvesting, to ensure maximum recovery of venom. Apply conductive gel to the electrodes, switch on the power supply, and apply the electrified tweezers to the insect.Experiment with a range of contact points while monitoring venom expulsion from the proboscis. Store the venom at freezing temperatures to avoid autoproteolytic digestion. Repeat the electrostimulation with a new pipette tube until no more venom is forthcoming.Protocol two describes how to harvest venom by provoking a defensive reaction. Prepare and restrain a bug as described above, inserting the proboscis into a collecting tip. Gently harass the bug to provoke a defensive reaction, without injuring the animal.Sometimes, simply restraining the animal or inserting the proboscis into the collection tube can provoke a defensive reaction accompanied by venom expulsion from the proboscis. If not, gently touch the animal on the thorax, legs, abdomen, and especially the antennae, to elicit venom. In protocol three, in the written form of this article, we also describe how to harvest venom from species that spit venom defensively.Protocol four describes how to harvest venom directly from the venom glands by dissection. Anesthetize animals by exposure to carbon dioxide for 10 minutes. Insert three pins into the posterior abdomen to hold the insect down without puncturing the venom glands.Cut a short midline incision in the ventral surface of the abdomen using a miniature scalpel. Use miniature scissors to extend the midline in the anterior direction to the head, taking care to cut the exoskeleton only, and not damage internal structures. To expose the internal structures, make multiple lateral cuts extending from the midline incision to the side of the insect.The ventral exoskeleton between each two cuts can then be pinned back to reveal the internal structures. Flood the dissection tray using a saline solution until the bug is submerged, allowing the internal structures to float up and be more easily visualized. The venom glands will appear as translucent elongated structures extending on each side of the alimentary canal.Using tweezers and microscissors, carefully remove connective and nervous tissue and trachea, trying not to rupture the alimentary canal or the venom glands. The main gland is recognizable due to its characteristic structure, with anterior and posterior lobes, and two ducts meeting at the hilus. For assassin bugs, and perhaps other heteropterans, almost all toxins are stored in the lumens of the two lobes of the main gland.Therefore, after freeing the main gland from trachea and connective tissue, the two ducts leading from the hilus can be cut, and the main venom gland collected. If the accessory gland is also desired, it is usually closely opposed to the gut, and can be identified unambiguously by tracing the ducts from the hilus. In any case, take care not to break the glands prematurely and lose the venom into the surrounding saline.If the lobes of the main gland are to be separated, do this quickly after removal from the saline, and immediately proceed to harvest the contents of the gland lumens, as described in steps 4.6 and 4.7 of the written manuscript. Results will vary depending on the exact subprotocol and species of insect used. The first and second subprotocols presented in this video showed how to harvest venom toxins by electrostimulation and harassment, respectively.Both of these methods typically yield a concentrated liquid containing approximately 50 to 250 milligrams a mil of protein, and over 100 protein-based components, including enzymes, pore-forming toxins, and peptides. The principal advantage of both of these protocols is that they are quick, non-lethal, and venom is uncontaminated by glandular tissue. The greatest disadvantage for harvesting by electrostimulation or harassment is that the glandular source of the venom obtained is unknown, and the protein content of venom harvested may differ, depending on the protocol.Also, electrostimulation and harassment are not effective for all predatory species of heteroptera. In the last subprotocol, we showed how to dissect the engorged venom glands to harvest toxins directly. This technique also yields a cocktail of diverse proteins, although in this case the venom toxins may show some contamination with glandular tissue.However, an advantage of harvesting toxins from dissected glands is that the glandular compartment of origin is known exactly. In conclusion, we encourage researchers to select a harvesting method appropriate to their research question. For example, investigations into the biology of venom use within a species will benefit from employing multiple harvesting techniques.For bioprospecting studies, a single method for harvesting venoms from multiple species may be more economical, depending on the specific experimental design. We hope this video and the accompanying written article will facilitate researchers to harvest venom from assassin bugs and other heteropteran insects, which is a prerequisite to understanding its composition, bioactivity, and evolution.

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Environment

Helminth Collection and Identification from Wildlife

Wild animals are commonly parasitized by a wide range of helminths. The four major types of helminths are &#34;roundworms&#34; (nematodes), &#34;thorny-headed worms&#34; (acanthocephalans), &#34;flukes&#34; (trematodes), and &#34;tapeworms&#34; (cestodes). The optimum method for collecting helminths is to examine a host that has been dead less than 4-6 hr since most helminths will still be alive. A thorough necropsy should be conducted and all major organs examined. Organs are washed over a 106 &#956;m sieve under running water and contents examined under a stereo microscope. All helminths are counted and a representative number are fixed (either in 70% ethanol, 10% buffered formalin, or alcohol-formalin-acetic acid). For species identification, helminths are either cleared in lactophenol (nematodes and small acanthocephalans) or stained (trematodes, cestodes, and large acanthocephalans) using Harris&#39; hematoxylin or Semichon&#39;s carmine. Helminths are keyed to species by examining different structures (e.g. male spicules in nematodes or the rostellum in cestodes). The protocols outlined here can be applied to any vertebrate animal. They require some expertise on recognizing the different organs and being able to differentiate helminths from other tissue debris or gut contents. Collection, preservation, and staining are straightforward techniques that require minimal equipment and reagents. Taxonomic identification, especially to species, can be very time consuming and might require the submission of specimens to an expert or DNA analysis.

Wild animals are commonly parasitized by a wide range of helminths.&#160; The four major types of helminths are &#8220;roundworms&#8221; (nematodes), &#8220;thorny-headed worms&#8221; (acanthocephalans), &#8220;flukes&#8221; (trematodes), and &#8220;tapeworms&#8221; (cestodes).&#160; Here we describe how helminths are collected from a vertebrate animal and how they are preserved and taxonomically identified.&#160;

Wild animals are commonly parasitized by a wide range of helminths. The four major types of helminths are &#34;roundworms&#34; (nematodes), ...

Quantification of Heavy Metals and Other Inorganic Contaminants on the Productivity of Microalgae

Increasing demand for renewable fuels has researchers investigating the feasibility of alternative feedstocks, such as microalgae. Inherent advantages include high potential yield, use of non-arable land and integration with waste streams. The nutrient requirements of a large-scale microalgae production system will require the coupling of cultivation systems with industrial waste resources, such as carbon dioxide from flue gas and nutrients from wastewater. Inorganic contaminants present in these wastes can potentially lead to bioaccumulation in microalgal biomass negatively impact productivity and limiting end use. This study focuses on the experimental evaluation of the impact and the fate of 14 inorganic contaminants (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, V and Zn) on Nannochloropsis salina growth. Microalgae were cultivated in photobioreactors illuminated at 984 &#181;mol m-2 sec-1 and maintained at pH 7 in a growth media polluted with inorganic contaminants at levels expected based on the composition found in commercial coal flue gas systems. Contaminants present in the biomass and the medium at the end of a 7 day growth period were analytically quantified through cold vapor atomic absorption spectrometry for Hg and through inductively coupled plasma mass spectrometry for As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Sn, V and Zn. Results show N. salina is a sensitive strain to the multi-metal environment with a statistical decrease in biomass yieldwith the introduction of these contaminants. The techniques presented here are adequate for quantifying algal growth and determining the fate of inorganic contaminants.

Integration of microalgal cultivation with industrial flue gas will ultimately introduce heavy metals and other inorganic compounds into the growth media. This study presents a procedure used to determine the end fate and impact of heavy metals and inorganic contaminants on the growth of Nannochloropsis salina grown in photobioreactors.

Increasing demand for renewable fuels has researchers investigating the feasibility of alternative feedstocks, such as microalgae. Inherent advantages ...

Assaying Predatory Feeding Behaviors in Pristionchus and Other Nematodes

This protocol provides multiple methods for the analysis and quantification of predatory feeding behaviors in nematodes. Many nematode species including Pristionchus pacificus display complex behaviors, the most striking of which is the predation of other nematode larvae. However, as these behaviors are absent in the model organism Caenorhabditis elegans, they have thus far only recently been described in detail along with the development of reliable behavioral assays 1. These predatory behaviors are dependent upon phenotypically plastic but fixed mouth morphs making the correct identification and categorization of these animals essential. In P. pacificus there are two mouth types, the stenostomatous and eurystomatous morphs 2, with only the wide mouthed eurystomatous containing an extra tooth and being capable of killing other nematode larvae. Through the isolation of an abundance of size matched prey larvae and subsequent exposure to predatory nematodes, assays including both "corpse assays" and "bite assays" on correctly identified mouth morph nematodes are possible. These assays provide a means to rapidly quantify predation success rates and provide a detailed behavioral analysis of individual nematodes engaged in predatory feeding activities. In addition, with the use of a high-speed camera, visualization of changes in pharyngeal activity including tooth and pumping dynamics are also possible.

Assaying Predatory Feeding Behaviors in Pristionchus and Other Nematodes

Behavioral assays provide powerful tools for understanding neuronal function. Here we present several protocols for quantifying predatory feeding behavior found in the model nematode Pristionchus pacificus and its relatives. Additionally, we provide methods for analyzing predatory feeding adaptations including mouth structures and teeth.

This protocol provides multiple methods for the analysis and quantification of predatory feeding behaviors in nematodes. Many nematode species including ...

Extraction of Organochlorine Pesticides from Plastic Pellets and Plastic Type Analysis

Plastic resin pellets, categorized as microplastics (&#8804;5 mm in diameter), are small granules that can be unintentionally released to the environment during manufacturing and transport. Because of their environmental persistence, they are widely distributed in the oceans and on beaches all over the world. They can act as a vector of potentially toxic organic compounds (e.g., polychlorinated biphenyls) and might consequently negatively affect marine organisms. Their possible impacts along the food chain are not yet well understood. In order to assess the hazards associated with the occurrence of plastic pellets in the marine environment, it is necessary to develop methodologies that allow for rapid determination of associated organic contaminant levels. The present protocol describes the different steps required for sampling resin pellets, analyzing adsorbed organochlorine pesticides (OCPs) and identifying the plastic type. The focus is on the extraction of OCPs from plastic pellets by means of a pressurized fluid extractor (PFE) and on the polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and related compounds, including dichlorodiphenyltrichloroethane (DDT) and its two main metabolites, lindane and two production isomers, as well as the two biologically active isomers of technical endosulfan. This protocol constitutes a simple and rapid alternative to existing methodology for evaluating the concentration of organic contaminants adsorbed on plastic pieces.

Microplastics act as vector of potentially toxic organic contaminants with unpredictable effects. This protocol describes an alternative methodology for assessing the levels of organochlorine pesticides adsorbed on plastic pellets and identifying the polymer chemical structure. The focus is on pressurized fluid extraction and attenuated total reflectance Fourier transform infrared spectroscopy.

Plastic resin pellets, categorized as microplastics (&#8804;5 mm in diameter), are small granules that can be unintentionally released to the environment ...

Extraction and Characterization of Surfactants from Atmospheric Aerosols

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in the Earth&#39;s atmosphere, a central process in meteorology, hydrology, and for the climate system. But because specific extraction and characterization of these compounds have been lacking for decades, very little is known on their identity, properties, mode of action and origins, thus preventing the full understanding of cloud formation and its potential links with the Earth&#39;s ecosystems.
In this paper we present recently developed methods for 1) the targeted extraction of all the surfactants from atmospheric aerosol samples and for the determination of 2) their absolute concentrations in the aerosol phase and 3) their static surface tension curves in water, including their Critical Micelle Concentration (CMC). These methods have been validated with 9 references surfactants, including anionic, cationic and non-ionic ones. Examples of results are presented for surfactants found in fine aerosol particles (diameter &#60;1 &#956;m) collected at a coastal site in Croatia and suggestions for future improvements and other characterizations than those presented are discussed.

Methods are presented for the targeted extraction of surfactants present in atmospheric aerosols and the determination of their absolute concentrations and surface tension curves in water, including their Critical Micelle Concentration (CMC).

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in ...

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

Life tables provide a means of measuring the schedules of birth and death from populations over time. They also can be used to quantify the sources and rates of mortality in populations, which has a variety of applications in ecology, including agricultural ecosystems. Horizontal, or cohort-based, life tables provide for the most direct and accurate method of quantifying vital population rates because they follow a group of individuals in a population from birth to death. Here, protocols are presented for conducting and analyzing cohort-based life tables in the field that takes advantage of the sessile nature of the immature life stages of a global insect pest, Bemisia tabaci. Individual insects are located on the underside of cotton leaves and are marked by drawing a small circle around the insect with a non-toxic pen. This insect can then be observed repeatedly over time with the aid of hand lenses to measure development from one stage to the next and to identify stage-specific causes of death associated with natural and introduced mortality forces. Analyses explain how to correctly measure multiple mortality forces that act contemporaneously within each stage and how to use such data to provide meaningful population dynamic metrics. The method does not directly account for adult survival and reproduction, which limits inference to dynamics of immature stages. An example is presented that focused on measuring the impact of bottom-up (plant quality) and top-down (natural enemies) effects on the mortality dynamics of B. tabaci in the cotton system.

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

Life tables allow quantification of the sources and rates of mortality in insect populations and contribute to understanding, predicting and manipulating population dynamics in agroecosystems. Methods for conducting and analyzing cohort-based life tables in the field for an insect with sessile immature life stages are presented.

Life tables provide a means of measuring the schedules of birth and death from populations over time. They also can be used to quantify the sources and ...

Double-stranded RNA Oral Delivery Methods to Induce RNA Interference in Phloem and Plant-sap-feeding Hemipteran Insects

Phloem and plant sap feeding insects invade the integrity of crops and fruits to retrieve nutrients, in the process damaging food crops. Hemipteran insects account for a number of economically substantial pests of plants that cause damage to crops by feeding on phloem sap. The brown marmorated stink bug (BMSB), Halyomorpha halys (Heteroptera: Pentatomidae) and the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae) are hemipteran insect pests introduced in North America, where they are an invasive agricultural pest of high-value specialty, row, and staple crops and citrus fruits, as well as a nuisance pest when they aggregate indoors. Insecticide resistance in many species has led to the development of alternate methods of pest management strategies. Double-stranded RNA (dsRNA)-mediated RNA interference (RNAi) is a gene silencing mechanism for functional genomic studies that has potential applications as a tool for the management of insect pests. Exogenously synthesized dsRNA or small interfering RNA (siRNA) can trigger highly efficient gene silencing through the degradation of endogenous RNA, which is homologous to that presented. Effective and environmental use of RNAi as molecular biopesticides for biocontrol of hemipteran insects requires the in vivo delivery of dsRNAs through feeding. Here we demonstrate methods for delivery of dsRNA to insects: loading of dsRNA into green beans by immersion, and absorbing of gene-specific dsRNA with oral delivery through ingestion. We have also outlined non-transgenic plant delivery approaches using foliar sprays, root drench, trunk injections as well as clay granules, all of which may be essential for sustained release of dsRNA. Efficient delivery by orally ingested dsRNA was confirmed as an effective dosage to induce a significant decrease in expression of targeted genes, such as juvenile hormone acid O-methyltransferase (JHAMT) and vitellogenin (Vg). These innovative methods represent strategies for delivery of dsRNA to use in crop protection and overcome environmental challenges for pest management.

This article demonstrates novel techniques developed for oral delivery of double-stranded RNA (dsRNA) through the vascular tissues of plants for RNA interference (RNAi) in phloem sap feeding insects.

Phloem and plant sap feeding insects invade the integrity of crops and fruits to retrieve nutrients, in the process damaging food crops. Hemipteran ...

Laboratory and Field Protocol for Estimating Sheet Erosion Rates from Dendrogeomorphology

Sheet erosion is among the crucial drivers of soil degradation. Erosion is controlled by environmental factors and human activities, which often lead to severe environmental impacts. The understanding of sheet erosion is, consequently, a worldwide issue with implications for both environment and economies. However, the knowledge on how erosion evolves in space and time is still limited, as well as its effects on the environment. Below, we explain a new dendrogeomorphological protocol for deriving eroded soil thickness (Ex) by acquiring accurate microtopographic data using both terrestrial laser scanning (TLS) and microtopographic profile gauges. Additionally, standard dendrogeomorphic procedures, dependent on anatomical variations in root rings, are utilized to establish the timing of exposure. Both TLS and microtopographic profile gauges are used to obtain ground surface pro&#64257;les, from which Ex is estimated after the threshold distance (TD) is determined, i.e., the distance between the root and the sediment knickpoint, which allows de&#64257;ning the lowering of the ground surface caused by sheet erosion. For each profile, we measured the height between the topside of the root and a virtual plane tangential to the ground surface. In this way, we intended to avoid small-scale impacts of soil deformation, which may be due to pressures exerted by the root system, or by the arrangement of exposed roots. This may provoke small amounts of soil sedimentation or erosion depending on how they physically affect the surface runoff. We demonstrate that an adequate microtopographic characterization of exposed roots and their associated ground surface is very valuable to obtain accurate erosion rates. This finding could be utilized to develop the best management practices designed to eventually halt or perhaps, at least, lessen soil erosion, so that more sustainable management policies can be put into practice.

Characterizing erosion from dendrogeomorphology has usually focused on accurately finding the starting time of root exposure, by examining macroscopic or cell level changes caused by exposure. Here, we offer a detailed description of different novel techniques to obtain more precise erosion rates from highly accurate microtopographic data.

Sheet erosion is among the crucial drivers of soil degradation. Erosion is controlled by environmental factors and human activities, which often lead to ...

Chemical Isolation, Quantification, and Separation of Skin Lipids from Reptiles

Reptiles signal to conspecifics using lipids in their skin, primarily to enable mate tracking and assessment. The isolation of these lipids has utility in research focused on evolutionary patterns and mechanisms of chemical communication, in addition to understanding the waterproofing role of lipids in the evolution of terrestrial life. In an applied approach, such skin-based cues have potential use for wildlife managers dealing with invasive species. The main steps for quantifying reptile skin lipids in the protocol presented here include extraction, total lipid determination, and fractionation via column chromatography, the latter process resulting in purified eluates of compounds which can then either be analyzed to assign compound identifications (e.g., gas chromatography-mass spectrometry [GC-MS]) and/or used directly in more refined bioassays. Skin lipids can be extracted from living skin, shed skin, or dead whole animals, using nonpolar organic solvents (e.g., hexane, benzene, toluene). Extraction solubilizes the lipids and, then, the solvent can be evaporated to yield a measurable lipid-only extract. Fractionation involves the separation of the total lipid extract into specific eluates via traditional column chromatography. The total lipid extract is first bound to a substrate-based column (e.g., alumina) and, then, individual eluates (&#34;fractions&#34;) of solvent at specific volumes are passed sequentially through the column to elute sets of compounds from the lipid mixture based on common polarity. The fractions progress in polarity at a standardized sequence by increasing the relative amount of polar solvent (e.g., diethyl ether) in nonpolar solvent. In this manuscript, we describe several methods for extracting skin lipids of reptiles and, then, provide a standard protocol for isolating different sets of compounds based on polarity, using traditional column chromatography. Whole lipid extracts or specific fractions can, then, be used in bioassays to determine any biological activity elicited by the compounds therein.

In reptiles, skin lipids from conspecifics are crucial for sexual signaling, with potential use in invasive species management. Here, we describe protocols for extracting skin lipids from shed skin or whole animals, determining and analyzing the total lipid mass, and separating the lipids using fractionation via column chromatography.

Reptiles signal to conspecifics using lipids in their skin, primarily to enable mate tracking and assessment. The isolation of these lipids has utility in ...

Cortisol Extraction from Sturgeon Fin and Jawbone Matrices

The aims of this study were to develop a technique for the extraction of cortisol from sturgeon fins using two washing solvents (water and isopropanol) and quantify any differences in fin cortisol levels among three main sturgeon species. Fins were harvested from 19 sacrificed sturgeons including seven beluga (Huso huso), seven Siberian (Acipenser baerii), and five sevruga (A. stellatus). The sturgeons were raised in Iranian farms for 2 years (2017-2018), and cortisol extraction analysis was conducted in South Korea (January-February 2019). Jawbones from five H. huso were also used for cortisol extraction. Data were analyzed using the general linear model (GLM) procedure in the SAS environment. The intra- and inter-assay coefficients of variation were 14.15 and 7.70, respectively. Briefly, the cortisol extraction technique involved washing the samples (300 &#177; 10 mg) with 3 mL of solvent (ultrapure water and isopropanol) twice, rotation at 80&#160;rpm for 2.5 min, air-drying the washed samples at room temperature (22-28 &#176;C) for 7 days, further drying the samples using a bead beater at 50 Hz for 32 min and grinding them into powder, applying 1.5 mL methanol to the dried powder (75 &#177; 5 mg), and slow rotation (40 rpm) for 18 h at room temperature with continuous mixing. Following extraction, samples were centrifuged (9,500 x g for 10 min), and 1 mL supernatant was transferred into a new microcentrifuge tube (1.5 mL), incubated at 38 &#176;C to evaporate the methanol, and analyzed via enzyme-linked immunosorbent assay (ELISA). No differences were observed in fin cortisol levels among species or in fin and jawbone cortisol levels between washing solvents. The results of this study demonstrate that the sturgeon jawbone matrix is a promising alternative stress indicator to solid matrices.

In this study, we present a protocol for cortisol extraction from the fin and jawbone of sturgeon species. Fin and jawbone cortisol levels were further examined by comparing two washing solvents followed by ELISA assays. This study piloted the feasibility of jawbone cortisol as a novel stress indicator.

The aims of this study were to develop a technique for the extraction of cortisol from sturgeon fins using two washing solvents (water and isopropanol) ...