Name: how to create conditioned taste aversion for grazing ground covers in woody crops with small ruminants
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Duration: 5 min 55 s
Description: Watch this Scientific Journal Video about How to Create Conditioned Taste Aversion for Grazing Ground Covers in Woody Crops with Small Ruminants at JoVE.com

This work is part of a CICYT research project (AGL 2010-22178) of the Spanish Ministry of Science and Technology. The authors are grateful to Nic Aldam and Kristi Prunty for the English revision of the manuscript.

The protocol described below for inducing CTA towards woody crops follows the animal care guidelines of the &#34;Universitat Aut&#242;noma de Barcelona&#34; (Bellaterra, Spain) and is approved by the Ethical Committee of Animal and Human Experimentation for sheep and goats (CEEAH, references 770 and 998 respectively).
1. Preparation of LiCl Dose
<ol>
	<li>Make a 25% w/v (weight/volume) LiCl solution in distilled water. Alternatively, use clean tap water. The LiCl is extremely hygroscopic therefore it is necessary to take care when handling the powdered chemical.
	<ol>
		<li>Weigh 250 g of LiCl and dissolve it in distilled water (LiCl concentrate solution). As the reaction is exothermic, wait until the solution has returned to room temperature before continuing. Pour the solution in a volumetric flask and add distilled water to bring it to 1,000 ml.</li>
	</ol>
	</li>
	<li>Calculate the volume of solution for each animal (individual dose).
	<ol>
		<li>Weigh the animals to obtain their body weight (BW) and calculate the mL of LiCl needed for each animal following equation 1. The recommended dose for long-term persistence is 225 mg LiCl/kg BW in sheep10&#160;and 200 mg LiCl/kg BW in goats17. However, other doses used for grazing are shown in Table 1. 
		 
		(kg BW x LiCl dose in g/kg BW) /LiCl concentration in g/L = Volume of LiCl (L) [Eq. 1] 
		 
		For example: 
		Sheep = 60 kg BW; dose = 225 mg LiCl/kg BW; concentration of LiCl solution = 250 g/L 
		(60 kg x 0.225 g/kg) /250 g/L = 0.054 L = 54 mL 
		Goat = 35 kg BW; dose = 200 mg LiCl/kg BW; concentration of LiCl solution = 250 g/L 
		(35 kg x 0.200 g/kg) /250 g/L = 0.028 L = 28 mL</li>
	</ol>
	</li>
</ol>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>LiCl dose</td>
			<td>Mazorra et al. (2006)19</td>
			<td>Burritt et al. (2013)35</td>
		</tr>
		<tr>
			<td>Low</td>
			<td>100</td>
			<td>125</td>
		</tr>
		<tr>
			<td>Medium</td>
			<td>150</td>
			<td>150</td>
		</tr>
		<tr>
			<td>High</td>
			<td>225</td>
			<td>175</td>
		</tr>
	</tbody>
</table>
Table 1: LiCl dosage range. Range of LiCl doses (mg/kg Body Weight, BW) used by different authors to induce feed aversion.
2. Animal Selection and Facilities
<ol>
	<li>Choose adult, non-pregnant and dry animals, which have never previously eaten the target feed.</li>
	<li>Do not induce the CTA to more than 20 animals at the same time, to better control their behavior. Initially, only induce CTA to 5 animals.</li>
	<li>Allocate the animals in a place where the intake of the target feed can be recorded individually. Feed the animals once-a-day with a basal diet covering all their nutrient requirements and provide free access to water and to a mineral block. Assure an adequate salt intake to prevent LiCl toxic effects, since body cells can use Li instead of Na9.</li>
	<li>If the facilities are new to the animals, give them 1 week of adaptation time to become familiar with the environment and the basal diet.</li>
</ol>
3. Aversion Induction
<ol>
	<li>Remove the basal diet the evening before (day -1) and offer the target feed ad libitum to ensure that animals eat the target feed avidly on the following day12.</li>
	<li>On the following day (day 0), remove the orts in the morning and offer 200 g of target feed to each animal during 30 min. Weigh the orts thereafter.</li>
	<li>If the animals consume more than 20-30 g, administer the corresponding calculated volume of LiCl (ml calculated in 1.2) with a drenching gun as soon as is practically possible, not waiting more than 1 hr after consumption. If animals consume less than 20-30 g, repeat the procedure the following day. Due to their innate neophobic feed behavior, animals could need more than 1 day to begin consuming the target feed10,17,25-27.</li>
	<li>After LiCl administration, wait 2 hr before offering the basal diet.</li>
	<li>From day 1 to 3, do not offer the animals the target feed and check them periodically to detect any possible sign of severe illness, recording daily feed and water intake (by weight or by a check-list), respiratory rate and animal behavior. They could present dropped head and ears, inactivity, diarrhea, increased respiration rate and decreased water and diet intake during the days following the LiCl administration9-11,20,25.</li>
</ol>
4. Aversion Validation
<ol>
	<li>On days 4, 5, 6 and 7 after LiCl administration, repeat step 3.2.</li>
	<li>If the animals consume &#60;10 g (or &#60;4 bites) of the target feed, consider the CTA established.The threshold between zero (no consumption) and 10 g could depend on the circumstance of the target plant (toxic or not).</li>
	<li>If any animal consumes &#62;10 g, administer a new LiCl dose and repeat step 4.1. If the animal persists in consuming the target plant after the second dose, eliminate it from the CTA group. Social facilitation (e.g. mother, siblings and close mates) can modify CTA behavior in livestock. Animals which have been averted to a target plant easily consume it again when they graze with non-averted animals28.</li>
</ol>
5. Pasture Management
Note: The dose of LiCl used to induce CTA is completely excreted in a few days, mainly by urine.
<ol>
	<li>Although Li is widely distributed on the earth&#39;s crust, in order to avoid any possible contamination in the organic crop, wait 9-11 days before moving the animals to the crop (clearance time established with Li&#160;pharmacokinetic)11.</li>
	<li>Ensure that the crop ground cover is abundant and palatable throughout the grazing period to prevent the animals from sampling the target feed. Graze treated animals separately from non-treated.</li>
	<li>Allow the animals to graze a delimitated plot of the entire surface to obtain a uniform control of the grass height. Delimit the plot by using portable electric or metallic fences or using a shepherd to graze the animals between specific crop lines.</li>
	<li>Avoid overgrazing a plot, removing the animals before the ground cover becomes scarce (grass height of 5 cm)29.</li>
</ol>
6. Re-establishing the CTA
<ol>
	<li>Every year, before allowing the animals to return to graze the crop, repeat step 4.</li>
</ol>

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The authors have nothing to disclose.

The CTA is easily established in small ruminants if the target feed is a plant which the animal has never eaten before and does not contain an irreplaceable nutrient. Animals have a positive post-ingestive association with a non-toxic feed unless previous contact makes it difficult to change their perception of that particular feed7,33. The condition taste aversion is produced because LiCl stimulates the emetic system producing malaise or gastrointestinal discomfort34. It has been established that a...

The use of ground cover between woody crop lines mitigates soil erosion and degradation and increases water, organic carbon and nitrogen retention1-3. Additionally, ground cover maintains and increases biodiversity, supporting the balance between crop pests and their natural predators. Farmers tend to eliminate weeds by applying agrochemical products or using a reaper machine; thus reducing nutrient competition between crops and green cover. A cost effective way to control ground cover would be the use of small ruminant grazing. An additional benefit from animal grazing is the improvement in soil health and fertility. However, farmers are reluctant to implement this practice due to small ruminants damaging the crops by consuming young leaves and sprouts.
To prevent potential crop damage it is useful to induce conditioned taste aversion (CTA) in the sheep or goats within the flock or herd. The CTA is easily established for new feeds, due to the innate feed neophobia behavior4,5 of small ruminants, and because familiar feeds are positively associated with a &#34;learned safety&#34; status which is more difficult to change or manipulate6. Animals learn to reject a specific feed (conditioned stimulus) due to its negative post-ingestive effect (unconditioned stimulus). To induce CTA towards palatable and non-toxic plants, lithium chloride (LiCl; inductor agent) is orally administered after the animal consumes the target plant. While there are others inductor agents (e.g. apomorphine, ciclosphosphamide, thiabendazole), LiCl showed the strongest and most persistent CTA due to its effect on the emetic system by stimulation of the chemoreceptor trigger zone area and gastrointestinal distress7,8&#160;with mild signs of general discomfort. Lithium (Li) is absorbed from the upper gastrointestinal tract and distributed in the total body water space9. The animals can have a recovery period as short as two days7,10,11.
The LiCl can be administered by mixing it with the food12,13, in a gelatin capsule13,14 or in a solution administered orally by a drenching gun15-17. Although LiCl solution is caustic, no injury in mouth or esophagus was described. LiCl is used in the range of 100 to 400 mg LiCl/kg of body weight (BW), with better results (more persistent CTA) using higher doses16,18. Nevertheless, considering the known dosage effects towards different species and breeds, the lethal effect in some cases start at 400 mg LiCl/kg BW. The recommended dosage for an effective long-term CTA begins at 200 mg/kg BW for goats and 225 mg/kg BW for sheep10,17,19. Li used at these dosages is excreted within the first 4 days post-administration, mainly through urine (92 &#177; 4%), followed by feces (6.5 &#177; 1.3%) and milk (2.8 &#177; 0.4%)11. The complete estimated withdrawal period for a single dose of LiCl in plasma is 9 and 11 days for sheep and goats, respectively. Due to the minimal Li excretion in milk, CTA cannot be naturally established in the suckling off-spring11,20.
Long-term CTA persistence in sheep has been reported throughout an entire grazing season (3-4 months) when an alternative forage source was available14,21, being re-established to an almost complete aversion with a single LiCl dose at the next grazing season (9 months later)14. Moreover, CTA persistences of 2 and 3 years have been reported in cows under pasture conditions, without the need for reinforcement doses, when the target feed is a toxic but palatable plant22,23. The option of considering an alternative feed is critical for the animal to maintain the CTA against a non-toxic plant. Each time the animal consumes more than 10 g of the averted plant without resulting in gastrointestinal discomfort, the CTA would be compromised24.

<table><tbody><tr><td>Lithium Chloride PRS</td><td>Panreac</td><td>141392.1209</td><td>Different amounts of same product can be supplied by the same company.</td></tr><tr><td>Labelvage drencher 
&lt;p&gt;
70 mL
&lt;/p&gt;</td><td>Labelvage</td><td>240040</td><td>Similar product can be used (different brand or volume).</td></tr></tbody></table>

how to create conditioned taste aversion for grazing ground covers in woody crops with small ruminants

Conditioned taste aversion (CTA) is a learning behavior process where animals are trained to reject certain feed after gastrointestinal discomfort has been produced. Lithium chloride (LiCl) is the preferred agent used in livestock to induce CTA because it specifically stimulates the vomit center. In addition, LiCl is commercially available, and easy to prepare and administer using a drenching gun. Nevertheless, some factors have to be considered to obtain an effective long-lasting CTA, which allows small ruminants to graze during the cropping season. A key aspect is to use animals with no previous contact with the target plant (the plant chosen to be avoided; new feed). Due to their native neophobic feeding behavior, small ruminants can easily associate the negative feedback effects with the new feed, resulting in a strong and persistent CTA. The recommended doses are 200 and 225 mg LiCl/kg body weight (BW) for goats and sheep, respectively. To induce CTA, 100 g of the target plant should be individually offered for at least 30 min, and LiCl administered thereafter if the intake is greater than 10 g. Each time the animal eats the target plant without negative consequences, the CTA becomes weaker. Consequently, to minimize the risk of target plant consumption, it is essential to have sufficient palatable ground cover available. The presence of an alternative feed (of quality and quantity) prevents the accidental consumption of the target plant. A close monitoring of the flock is recommended to remove and re-dose any animal consuming more than 4 bites or 10 g of the target plant. At the beginning of each grazing season, check the CTA status of each animal before moving them to the crop.

The results described below were obtained by several studies in CTA toward woody crops in small ruminants conducted at the Universitat Aut&#242;noma de Barcelona and they provide evidence to establish the protocol proposed.
Doses of 175 and 200 mg LiCl/kg BW in goats and 200 and 225 mg LiCl/kg BW in sheep were successfully used to induce CTA against woody crops with a single administration, with the exception of two animals whic...

Watch this Scientific Journal Video about How to Create Conditioned Taste Aversion for Grazing Ground Covers in Woody Crops with Small Ruminants at JoVE.com

How to Create Conditioned Taste Aversion for Grazing Ground Covers in Woody Crops with Small Ruminants

Feeding behavior preferences in livestock can be modified to implement a grazing management plan in woody crops. Here, we present a protocol to show a lithium chloride dose after eating a new plant that induces conditioned taste aversion.

Conditioned taste aversion (CTA) is a learning behavior process where animals are trained to reject certain feed after gastrointestinal discomfort has ...

how-to-create-conditioned-taste-aversion-for-grazing-ground-covers

Universidad de Cartagena UDEC

Research

JoVE Journal

Environment

7.2K Views.  Universitat Autònoma de Barcelona. Feeding behavior preferences in livestock can be modified to implement a grazing management plan in woody crops. Here, we present a protocol to show a lithium chloride dose after eating a new plant that induces conditioned taste aversion. 

Video: How to Create Conditioned Taste Aversion for Grazing Ground Covers in Woody Crops with Small Ruminants

The Use of an Automated System (GreenFeed) to Monitor Enteric Methane and Carbon Dioxide Emissions from Ruminant Animals

Ruminant animals (domesticated or wild) emit methane (CH4) through enteric fermentation in their digestive tract and from decomposition of manure during storage. These processes are the major sources of greenhouse gas (GHG) emissions from animal production systems. Techniques for measuring enteric CH4 vary from direct measurements (respiration chambers, which are highly accurate, but with limited applicability) to various indirect methods (sniffers, laser technology, which are practical, but with variable accuracy). The sulfur hexafluoride (SF6)&#160;tracer gas method is commonly used to measure enteric CH4 production by animal scientists and more recently, application of an Automated Head-Chamber System (AHCS) (GreenFeed, C-Lock, Inc., Rapid City, SD), which is the focus of this experiment, has been growing. AHCS is an automated system to monitor CH4 and carbon dioxide (CO2) mass fluxes from the breath of ruminant animals. In a typical AHCS operation, small quantities of baiting feed are dispensed to individual animals to lure them to AHCS multiple times daily. As the animal visits AHCS, a fan system pulls air past the animal&#8217;s muzzle into an intake manifold, and through an air collection pipe where continuous airflow rates are measured. A sub-sample of air is pumped out of the pipe into non-dispersive infra-red sensors for continuous measurement of CH4 and CO2 concentrations. Field comparisons of AHCS to respiration chambers or SF6 have demonstrated that AHCS produces repeatable and accurate CH4 emission results, provided that animal visits to AHCS are sufficient so emission estimates are representative of the diurnal rhythm of rumen gas production. Here, we demonstrate the use of AHCS to measure CO2 and CH4 fluxes from dairy cows given a control diet or a diet supplemented with technical-grade cashew nut shell liquid.

The Use of an Automated System GreenFeed to Monitor Enteric Methane and Carbon Dioxide Emissions from Ruminant Animals

Accuracy and precision of the techniques used to measure methane emissions from ruminant animals are critically important for the success of greenhouse gas mitigation efforts. This manuscript describes the principles and operation of an automated system to monitor methane and carbon dioxide mass fluxes from the breath of ruminant animals.

Ruminant animals (domesticated or wild) emit methane (CH4) through enteric fermentation in their digestive tract and from decomposition of manure during ...

A Method for Remotely Silencing Neural Activity in Rodents During Discrete Phases of Learning

This protocol describes how to temporarily and remotely silence neuronal activity in discrete brain regions while animals are engaged in learning and memory tasks. The approach combines pharmacogenetics (Designer-Receptors-Exclusively-Activated-by-Designer-Drugs) with a behavioral paradigm (sensory preconditioning) that is designed to distinguish between different forms of learning. Specifically, viral-mediated delivery is used to express a genetically modified inhibitory G-protein coupled receptor (the Designer Receptor) into a discrete brain region in the rodent. Three weeks later, when designer receptor expression levels are high, a pharmacological agent (the Designer Drug) is administered systemically 30 min prior to a specific behavioral session. The drug has affinity for the designer receptor and thus results in inhibition of neurons that express the designer receptor, but is otherwise biologically inert. The brain region remains silenced for 2-5 hr (depending on the dose and route of administration). Upon completion of the behavioral paradigm, brain tissue is assessed for correct placement and receptor expression. This approach is particularly useful for determining the contribution of individual brain regions to specific components of behavior and can be used across any number of behavioral paradigms.

This protocol describes how to temporarily and remotely silence neuronal activity in discrete brain regions while rats are engaged in learning and memory tasks. The approach combines pharmacogenetics (Designer-Receptors-Exclusively-Activated-by-Designer-Drugs) with a behavioral paradigm (sensory preconditioning) that is designed to distinguish between different components of learning.

This protocol describes how to temporarily and remotely silence neuronal activity in discrete brain regions while animals are engaged in learning and ...

Behavior

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 ...

Biology

A Conditioned Place Preference Protocol for Measuring Incubation of Craving in Rats

A major cause of repeated relapses is a craving for the drug. Drug craving increases progressively during the abstinence period, a phenomenon termed incubation of drug craving. Here, we describe a morphine conditioned place preference (CPP) protocol for measuring the incubation of craving in rats. In this protocol, a CPP paradigm mainly employing somatosensory cues is used to establish a long-term reward memory of morphine. A three-chamber CPP box that differs in the texture of the chamber floor is constructed. First, the animals are tested for their baseline preference to the two side chambers for three consecutive days. Then, they are injected intraperitoneally with morphine/saline and put into their non-preferred/preferred chamber for 45 min. After 6 days of conditioning, their preference to the side chambers is tested for 15 min at different time points after the last conditioning session. With this paradigm, the reward memory of morphine could last for at least 18 days. To test whether the above-mentioned protocol can model increased craving, the number of entrances into the two side chambers are counted during the abstinence period. The results show that the entrances increased, suggesting that the CPP paradigm could mimic the incubation of craving. Future studies can employ this model to study neural mechanisms underlying long-term memory and incubation of craving.

Here, a morphine conditioned place preference (CPP) protocol is described to measure incubation of craving in rats.

A major cause of repeated relapses is a craving for the drug. Drug craving increases progressively during the abstinence period, a phenomenon termed ...

Ground-level Unmanned Aerial System Imagery Coupled with Spatially Balanced Sampling and Route Optimization to Monitor Rangeland Vegetation

Rangeland ecosystems cover 3.6 billion hectares globally with 239 million hectares located in the United States. These ecosystems are critical for maintaining global ecosystem services. Monitoring vegetation in these ecosystems is required to assess rangeland health, to gauge habitat suitability for wildlife and domestic livestock, to combat invasive weeds, and to elucidate temporal environmental changes. Although rangeland ecosystems cover vast areas, traditional monitoring techniques are often time-consuming and cost-inefficient, subject to high observer bias, and often lack adequate spatial information. Image-based vegetation monitoring is faster, produces permanent records (i.e., images), may result in reduced observer bias, and inherently includes adequate spatial information. Spatially balanced sampling designs are beneficial in monitoring natural resources. A protocol is presented for implementing a spatially balanced sampling design known as balanced acceptance sampling (BAS), with imagery acquired from ground-level cameras and unmanned aerial systems (UAS). A route optimization algorithm is used in addition to solve the &#8216;travelling salesperson problem&#8217; (TSP) to increase time and cost efficiency. While UAS images can be acquired 2&#8211;3x faster than handheld images, both types of images are similar to each other in terms of accuracy and precision. Lastly, the pros and cons of each method are discussed and examples of potential applications for these methods in other ecosystems are provided.

The protocol presented in this paper utilizes route optimization, balanced acceptance sampling, and ground-level and unmanned aircraft system (UAS) imagery to efficiently monitor vegetation in rangeland ecosystems. Results from images obtained from ground-level and UAS methods are compared.

Rangeland ecosystems cover 3.6 billion hectares globally with 239 million hectares located in the United States. These ecosystems are critical for ...

Catheterization of Intestinal Loops in Ruminants

The intestine is a complex structure that is involved not only in absorption of nutrients, but also acts as a barrier between the individual and the outside world. As such, the intestine plays a pivotal role in immunosurveillance and protection from enteric pathogens. Investigating intestinal physiology and immunology commonly employs 'intestinal loops' as an experimental model. The majority of these loop models are non-recovery surgical procedures that study short-term (&lt;24 hr) changes in the intestine (1-3). We previously created a recovery intestinal loop model to specifically measure long-term (&lt;6 mo) immunological changes in the intestine of sheep following exposure to vaccines, adjuvants, and viruses (4). This procedure localized treatments to a specific 'loop', allowing us to sample this area of the intestine. A significant drawback of this method is the single window of opportunity to administer treatments (i.e. at the time of surgery). Furthermore, samples of both the intestinal mucosa and luminal contents can only be taken at the termination of the project. Other salient limitations of the above model are that the surgical manipulation and requisite post-operative measures (e.g. administration of antibiotics and analgesics) can directly affect the treatment itself and/or alter immune function, thereby confounding results. Therefore, we modified our intestinal loop model by inserting long-term catheters into the loops. Sheep recover fully from the procedure, and are unaffected by the exteriorized catheters. Notably, the establishment of catheters in loops allows us to introduce multiple treatments over an extended interval, following recovery from surgery and clearance of drugs administered during surgery and the post-operative period.

We describe a novel surgical method for catheterizing 'intestinal loops' within the ileum of sheep. Once animals have recovered from surgery and have cleared antibiotics and analgesics, multiple treatments can be deposited directly in loops via the catheters.

The intestine is a complex structure that is involved not only in absorption of nutrients, but also acts as a barrier between the individual and the ...

The Use of Traditional Fear Tests to Evaluate Different Emotional Circuits in Cattle

Animal temperament is complex and has implications for productivity and economic profitability. Quantifying an animal&#39;s response to differing stimuli may facilitate breeding selections and identify animals that are better suited to specific management strategies. Multiple tests have been developed to evaluate cattle temperament (e.g., exit velocity, chute score, pen score, open field test, startle test, bovine zero maze), but each of these tests evaluates the animal&#39;s response to different stimuli (e.g., isolation, novel environment, startle, willingness to enter an enclosed area). Cattle temperament has been observed to be relatively stable over time. However, the evaluation of temperament has the potential to be influenced by current conditions, previous experiences, and observer bias. Many of these temperament tests have been improperly categorized as fear tests and have also been criticized for being subjective. This paper provides a framework for standardizing behavioral tests for cattle and suggests that these different evaluations assess different aspects of the animal&#39;s overall temperament.

Here, we present a protocol to conduct a variety of behavioral tests in cattle that have been designed to evaluate emotions. A battery of behavioral tests (open field test, startle test, bovine zero maze, exit velocity, pen score, and chute score) were conducted to evaluate different components of animal temperament.

Animal temperament is complex and has implications for productivity and economic profitability. Quantifying an animal&#39;s response to differing stimuli ...

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 ...

A Caenorhabditis elegans Nutritional-status Based Copper Aversion Assay

To ensure survival, organisms must be capable of avoiding unfavorable habitats while ensuring a consistent food source. Caenorhabditis elegans alter their locomotory patterns upon detection of diverse environmental stimuli and can modulate their suite of behavioral responses in response to starvation conditions. Nematodes typically exhibit a decreased aversive response when removed from a food source for over 30 min. Observation of behavioral changes in response to a changing nutritional status can provide insight into the mechanisms that regulate the transition from a well-fed to starved state.
We have developed an assay that measures a nematode&#39;s ability to cross an aversive barrier (i.e. copper) then reach a food source over a prolonged period of time. This protocol builds upon previous work by integrating multiple variables in a manner that allows for continued data collection as the organisms shift towards an increasingly starved condition. Moreover, this assay permits an increased sample size so that larger populations of nematodes can be simultaneously evaluated.
Organisms defective for the ability to detect or respond to copper immediately cross the chemical barrier, while wild type nematodes are initially repelled. As wild type worms are increasingly starved, they begin to cross the barrier and reach the food source. We designed this assay to evaluate a mutant that is incapable of responding to diverse environmental cues, including food sensation or detection of aversive chemicals. When evaluated via this protocol, the defective organisms immediately crossed the barrier, but were also incapable of detecting a food source. Hence, these mutants repeatedly cross the chemical barrier despite temporarily reaching a food source. This assay can straightforwardly test populations of worms to evaluate potential pathway defects related to aversion and starvation.

A Caenorhabditis elegans Nutritional-status Based Copper Aversion Assay

Here, we present a Caenorhabditis elegans-specific assay designed to evaluate changes in copper aversion behavior and the ability to locate a common food source, as the organism progresses from a well-fed to starved nutritional state.

To ensure survival, organisms must be capable of avoiding unfavorable habitats while ensuring a consistent food source. Caenorhabditis elegans alter their ...

Neuroscience

Milk Collection Methods for Mice and Reeves' Muntjac Deer

Animal models are commonly used throughout research laboratories to accomplish what would normally be considered impractical in a pathogen&#8217;s native host. Milk collection from animals allows scientists the opportunity to study many aspects of reproduction including vertical transmission, passive immunity, mammary gland biology, and lactation. Obtaining adequate volumes of milk for these studies is a challenging task, especially from small animal models. Here we illustrate an inexpensive and facile method for milk collection in mice and Reeves&#8217; muntjac deer that does not require specialized equipment or extensive training. This particular method requires two researchers: one to express the milk and to stabilize the animal, and one to collect the milk in an appropriate container from either a Muntjac or mouse model. The mouse model also requires the use of a P-200 pipetman and corresponding pipette tips. While this method is low cost and relatively easy to perform, researchers should be advised that anesthetizing the animal is required for optimal milk collection.

Milk collection from animal models facilitates various research avenues: understanding passive immunity, identifying pathogens responsible for vertical transmission and, through the use of transgenic mice, even commercial production of proteins found in human breast milk. Here we illustrate a simple method for milk collection in mice and Reeves&#8217; muntjac deer.

Animal models are commonly used throughout research laboratories to accomplish what would normally be considered impractical in a pathogen&#8217;s native ...

How to Create Conditioned Taste Aversion for Grazing Ground Covers in Woody Crops with Small Ruminants

Summary

Explore More Videos

Chapters in this video

The Use of an Automated System (GreenFeed) to Monitor Enteric Methane and Carbon Dioxide Emissions from Ruminant Animals

A Method for Remotely Silencing Neural Activity in Rodents During Discrete Phases of Learning

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

A Conditioned Place Preference Protocol for Measuring Incubation of Craving in Rats

Ground-level Unmanned Aerial System Imagery Coupled with Spatially Balanced Sampling and Route Optimization to Monitor Rangeland Vegetation

Catheterization of Intestinal Loops in Ruminants

The Use of Traditional Fear Tests to Evaluate Different Emotional Circuits in Cattle

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

A Caenorhabditis elegans Nutritional-status Based Copper Aversion Assay

Milk Collection Methods for Mice and Reeves' Muntjac Deer