Category: Uncategorized (Page 3 of 5)

This important topic is too often neglected in dealing with quality, fitness, and stress in insect rearing systems. I discuss this in depth in my rearing courses, and I provide here a sample of what I discuss.

First, it is important to realize that for nearly all metabolic functions, insects utilise oxygen and release carbon dioxide as a waste. the normal atmospheric O2 level is slightly under 21%, and the CO2 content is about 0.04% (often stated as 400 parts per million). In nature, insects generally have access to the normal levels of O2 and CO2, which raises the question of what levels of these gases are present in our rearing containers? Another important question is what are the consequences of abnormal levels of these gases? To begin to answer the first question, I used an O2 and CO2 measuring apparatus (see picture below) to determine the levels of these gases in a container where I was rearing painted lady butterfly larvae (Vanessa cardui).

Figures 1 and 2 show measurements of rearing containers for painted lady larvae. In the containers in Figure 1, we found the O2 content to be 19.4% and the CO2 content to be 0.4% (roughly 10 times normal atmospheric CO2). These readings indicate that even in non-crowded rearing conditions seen here, there is an indication that the insects may be chronically in an oxygen-depleted atmosphere (a hypoxic situation) and also in a chronically elevated CO2 atmosphere. This raises the question about what the possible effects are from this chronic “gas exchange stress.”

One hint as to the effects of this stress is to be derived from a recent paper by VandenBrooks et al. 2018, where the authors show that in Drosophila melanogaster, there are significant changes in the characteristics of the gas exchange system of D. melanogaster, the tracheoles, and the respiratory organelles, the mitochondria.

The implications of these findings are of potential great consequence in shaping the fitness of insects from our rearing systems where the conditions are often crowded and of untested atmospheres inside rearing containers.

This type of discussion is typical of what Professor Cohen covers in the current set of rearing courses. The potential for stress from all these parameters is ever-present: thermal, gas exchange, humidity, lighting, diet, microbes, and countless other conditions.

I have been teaching insect rearing on a regular basis for the past 20 years, and I actually taught my first course in insect rearing (at the University of Arizona) in 1981 and again in 1989. Over all these years of teaching, I have taught workshops (initially at Mississippi State University, then in Tucson, and most recently here at North Carolina State University). I have also taught a number of in person courses as well as several online (both synchronous and non-synchronous), and I have taught both for college credit and not-for-credit courses. I point this out to convey the idea that I have considerable experience with several forms of rearing education; I have given it considerable thought I have devoted to insect rearing education over the past 40 years; and I feel that I have some constructive perspectives about how rearing education can become a highly useful investment of resources.

Workshops vs. Courses: I use the term “workshop” to mean a compressed teaching/learning effort in a subject such as rearing. I see workshops as lasting from 1 or 2 days to 5 days, with each day being devoted to intense or concentrated lecture, demonstration, and discussion. To my knowledge, the insect rearing workshops have been 5 days long, with about 8 hours per day dedicated mainly to lectures on topics such as diets, facilities, environment, genetics, quality control, microbial relations, and safety, with some variation of these topics such as special attention to air handling systems. Again, to my knowledge, rearing workshops include tours of onsite rearing facilities to give participants direct observation experiences. Workshops generally are taught by several experts in various topics of insect rearing, and the experts’ presentations are coordinated by an organizer. One very popular aspect of workshops is that the participants travel to the site of presentations, getting to meet other participants and instructors and experiencing luncheons, banquets, visits to local attractions. The meeting opportunities are during meals, at breaks, and in evenings between workshop days. I have heard testimony from participants that the meeting with fellow rearing professionals was an extremely valuable aspect of the workshop experience. 

Downsides of the workshop format are that participants must devote at least 6 days to attend and travel to and from the workshop site; besides the time investment, there is a considerable financial investment including workshop fees, travel and per diem expenses. In the time of COVID-19, the risks and hardships of travel are prohibitive for many people. Pedagogical Downsides include the pace of information processing—learning is not efficient when too much new information is processed within a short period of time. Besides the rapid pace of information transfer, workshops are limited in opportunities for interaction between participants and instructors.

These thoughts about workshop limitations motivated me to offer courses in insect rearing for the past decade. In 2010, I offered a graduate seminar in insect rearing at North Carolina State University. The course was one hour a week for fifteen weeks, and most of the presentations were given by students on topics they selected. I felt that the seminar format lacked the scope and depth that was needed to convey the broad concepts and granular details of insect rearing. Therefore, in 2011, I offered the first 3-unit course in insect rearing where I lectured for 3 hours per week (for 15 weeks), and the students did projects where they reared insects of their choice and incorporated the materials taught in class. Students, working in groups of three, reared several species of insects that they were working with for their graduate studies or insects that lent themselves to gaining rearing experience (thrips, cockroaches, hornworms, lacewings, stink bugs, etc.), and they applied methods such as lipid, protein, and carbohydrate analysis, diet texture analysis, microscopic imaging studies, and other techniques that they could explore in my lab or in other facilities available at NCSU.

In the first (2011) class, there was no testing; grading was based on presentations as 1) posters, 2) PowerPoints, and 3) written papers in conventional scientific format. Despite the considerable time students spent with their team-based projects, I felt that learning was not as effective as possible due to the lack of testing. In subsequent offerings of the onsite rearing courses (in 2013, 2015, 2017, and 2019), I added two mid-term and one final exam, which consisted of take home, open-book essay questions. Because of the value of hands-on work, I retained the projects as part of the course requirements, and I offered opportunities for students to visit labs where they could learn about texture analysis (food rheology) and various analytical procedures in my lab. Student evaluations of these courses were very positive with many students writing that these courses were some of the best classes that they had taken and that every entomology student should take such a rearing course. Students, generally responded well to the course motto: “Know your insect.” Most students also got the point about the need to view insect rearing as a science, rather than an art.As a long-time educator, I was generally pleased with the onsite classes in insect rearing, but I was concerned that I was not able to reach the thousands of people who need and desire more opportunity to understand insect rearing in North America and world-wide. Therefore, I developed an online, non-synchronous course in rearing science and technology. I will make another post (soon to follow this one) on the further development of online courses.

HEREDITY OF BODY COLOR IN DROSOPHILA
T. H. MORGAN, 1912 Journal of Experimental Zoology
PLATE 1
EXPLANATION OF FIGURES
1. A normal female
2 A black female.
3 A brown female.
4 A yellow female.
Normal or gray female (the outer marginal vein is slightly exaggerated in
the figure).
The contrast between the black, yellow, and brown flies
is well brought out in the figures

These beautiful and historic drawings are from an early paper by the famous geneticist Thomas Hunt Morgan.  The many papers that he published helped establish modern-day genetics (not just insect genetics but ALL genetics).  These works and the other 150,000 papers on the various aspects of Drosophila genetics would not have been possible if it were not for the pioneering work of Delcourt, Baumberger, Guyenot, and other rearing pioneers.

Baumberger, J. P.  1917a. The food of Drosophila melanogaster Meigen.  Proceedings of the National Academy of Sciences of the United States of America: 3: 122-126.

Baumberger, J.P.  1917b. Solid media for rearing Drosophila.  American Naturalist.  51: 447-448.

Delcourt, A. and E. Guyenot. 1910. The possibility of studying certain Diptera in a defined environment. Comptes rendus hebdomadaires des séances de l’Académie des sciences (0001-4036), 151, p. 255-257.

Guyenot, E.  1913a. A biological study of a Drosophila ampelophila Low fly I – The possibility of an aseptic life for an individual and the line.  Comptes rendus des séances de la Société de biologie et de ses filiales (0037-9026), 74, p. 97-99.

In the previous post (Nov. 26), I brought up the subject of insect rearing infrastructure, and I showed a sterling example of a rearing system that has served the world well: the Pink Bollworm Rearing System: run by the USDA, APHIS in Phoenix, AZ (USA).  I showed a picture of the “pinkie” diet that was being mass-produced in a huge, industrial scale twin screw extruder.  Although the process is now practiced routinely by the highly skilled professionals at the Pinkie facility, the ideas and techniques behind this smooth operation did not “like Athena spring full-blown from the head of Zeus.”  There was an evolution of the process that serves today to produce up to 25,000,000 pinkie adults per day for sterile release.

So here is the pink bollworm system running at very high efficiency.  But how did it get that way?  What incremental steps went into the rearing system: the diet, the environmental conditions, the containers, the sanitation procedures, the genetic management of a highly domesticated insect, etc.?

Let’s take the diet as an example of the evolution of a mass-rearing system.  The above table is from a paper by Edwards et al.  (1996) cited below.  The Edwards paper describes how the twin screw extruder became incorporated into the mass-rearing system (another huge and important series of steps), but the formulation of the diet itself came from a complex of incremental processes, all of which had to be vetted.  Looking at the components, we see for example toasted soy flour, wheat germ, and agar.  Each of these components has a special role in the diet, nutrition, feeding stimulation, antimicrobial function, texture, stabilization, etc.  But where did the idea of soy flour come from?  It turns out that tracking soy flour (and other soy products) in insect diets requires some complex detective work (which I will discuss in another post).  However, it appears that soy products were first used by Japanese researchers who were trying to develop artificial diets for silkworms to reduce dependence on fresh mulberry leaves (please see my other posts on silkworms).  The soy/ silkworm papers began to appear in the early 1960s, and later in the ’60s other papers appeared where soy components were reported by Western researchers on insect diets.  I will treat the background in soy in insect diets in another post dedicated to this special topic.

Wheat germ is another component that is prominent in the pinkie diet and in diets for hundreds of other insect species. I have treated the history of wheat germ in my text, especially in the 2nd edition, and I will discuss it on a special topics page in a later blog, but for now let me point out that wheat germ made an inauspicious debut in 1959 and then a much greater impact study reported in 1960 (please see Vanderzant et al. 1959 and Adkisson 1960) .  Once the vast potential of wheat germ became recognized it has been of central importance in thousands of published studies where the insects could not have been available were it not for the excellence of what germ as a diet component.

The last item that I will mention here is agar.  It seems that agar has been around forever in insect diets, but it actually became a centerpiece of insect diets starting with a Drosophila paper by Baumberger (1917) and Baumberger and Glaser 1917.  Prior to 1917, media were being developed for Drosophila based on bananas and yeast, but the Baumberger laboratory borrowed from the then burgeoning programs in microbiology where agar was becoming a standard of many kinds of microbial media.  The advent of agar in insect diets revolutionized the potential for rearing hundreds of species of insects, yet the Baumberger and Baumberger and Glaser papers are cited only a total of 2 times since 1917!  This lack of citation and lack of recognition of some of the most influential achievements in insect rearing is a central topic of many of my writings and teachings.

Finally, the story of many of the other innovations and advancements is told remarkably well by Stewart (1984).  Again, I will treat the pinkie story in more detail in near future pages, but for now please understand my point about how much incremental progress must take place and should be recognized in the insect rearing systems upon which so much depends!

References Cited Here:

Adkisson, P. L., E. S. Vanderzant, D. L. Bull, and W. E. Allison.  1960b. A wheat germ medium for rearing the pink bollworm.  J. Econ. Entomol.  53: 759-762.

Baumberger, J.P.  1917. Solid media for rearing Drosophila.  American Naturalist.  51: 447-448.

Baumberger, J.P. and R. W. Glaser.  1917.  The Rearing of Drosophila Ampelophila Loew on Solid Media. Science.  45: pp. 21-22.

Edwards, R. H., E. Miller, R. Becker, A. P. Mossman, and D. W. Irving.  1996.  Twin screw extrusion processing of diet for mass rearing the pink bollworm.  Transactions of the American Society of Agricultural Engineering.  39 (5): 1789-1797.

Stewart, F. D.  1984.  Mass Rearing the Pink Bollworm, Pectinophora gossypiella.  In Advances and Challenges in Insect Rearing.  E.G. King and N.C. Leppla, Eds.  USDA, ARS.  Pp. 176-187. New Orleans, LA.

Vanderzant, E. S., C. D. Richardson, and T. B. Davich.  1959. Feeding and Oviposition by the Boll Weevil on Artificial Diets.  J. Econ. Entomol.  52: 1138-1142.

I am currently writing a paper on infrastructure of insect rearing.  On this WeRearInsects.com site, I have already begun some of my discussion about rearing infrastructure and what our rearing profession needs to improve infrastructure.

One of the prominent examples of large scale and HIGHLY successful insect rearing is to be found in the various USDA, APHIS facilities, including the Pink Bollworm Rearing Facility in Phoenix, Arizona.

The photos in this post are from the Phoenix facility, currently directed by Eoin Davis, and previously directed by Ernie Miller and prior to that Dr. Fred Stewart.  The photos were provided by Dr. Hannah Nadel, a supervisory entomologist with USDA, APHIS.  These photos depict just a few features of the incredible mass-rearing system that is used by the staff of the USDA facility to produce millions of pink bollworms to be used for sterile insect technique (SIT) and other functions to help control these most devastating cotton pests.  The top left photo shows the adult rearing containers with PVC tubes collecting the scales, and the tops of the cages lined with paper for egg collection.  The top right photo shows the eggs being dried out after being treated with anti-microbial treatments, and the bottom photo shows the diet production where freshly made diet (diet with a red/pink dye to mark insects from the APHIS facility).  One of this laboratory innovations is the application of food science technology where the large twin-screw extruder is used to make large quantities of highest quality diet economically and safely.

This system is one of many USDA, APHIS facilities that deserves recognition and understanding by the rearing community, the entomological community, and the public at large, who are so well-served by these kinds of mass-rearing programs.  Thanks to these programs (including the sterile screwworm program, and several fruit fly control programs), billions of taxpayer dollars are saved, and our world is cleaner, and our agriculture is more efficient!

I have mentioned elsewhere on this site, that the purpose of the website, WeRearInsects.com, is to advance insect rearing through raising awareness of all rearing issues.  I have strived for the past 4 decades to contribute to science and entomology by doing research and teaching in insect rearing, and besides my writing books and book chapters, and papers, and besides my providing insect rearing workshops, and teaching classes online and in person, I have chosen to write a website to give myself the latitude to provide my ideas and the ideas of others all for the advancement of insect rearing and the people who practice this discipline.

However, I feel the need to express some thoughts and ideas regarding my site in the context of the site’s not being a peer-reviewed construct.

After the recent elections in the US, issues of truth, validity, and facts have come into the forefront more than ever before.  There have been many cases of fake news.  In fact, those of us who teach, have warned students for a long time that they need to be careful about “facts” from online inquiries.  I use the Internet many times per day to get a take on various subjects.  I have found that with subjects of which I have a base of knowledge, sometimes the information is excellent, and sometimes, it’s very inaccurate and can be misleading.  Therefore, my warning to students is that they use their greatest resource for getting an accurate (truthful?) picture is to use critical thinking and multiple source inquiries.  Part of the critical thinking that I urge is asking the question, “who is providing the information?” and “what does the information provider have to gain?”  Along with these critical thinking questions, if the student/scholar wants to add a layer of protection (a “truthfulness coating”), she or he can do some comparisons from various sources.  Often, however, the comparisons lead to the phenomenon where multiple sources say the exact same thing.  This parroting of information may well be a sign that the information should be further questioned, rather than being taken at face value.

So now, all this being said, what about the information that readers find on my website, which you are now visiting?  I have cautioned readers that this site presents my perspectives about insect rearing and related issues.  As much as I try to always be objective in my teaching, my scientific research, my reviewing other people’s works, and all other ways that I deal with insect rearing, I am still human and am bound to have slants or biases in the information and explanations that I present.  When I am writing papers or funding applications, I have reviewers who are scientific experts, and they can do some of the vetting.  Then, once the works are published, the scientific community can come along with criticism and commentary, especially if they have tested the information that I am providing.  This is why peer-reviewed works are given so much importance in the scientific community, especially where people are applying for funds, for jobs, or for promotions.

In the context of openness, I always encourage readers to offer opinions and to ask for clarification of my points.  However, to keep the site free of distractions, such as commercial messages or opinions that do not provide constructive substance to the ideas and information that I am putting forward, I screen the comments and questions, and I post all the ones that help what is in my opinion the advancement of insect rearing.

So please read my pages and posts critically, and give me feedback about what is helpful, what is incorrect, and what needs clarification.

Signed photo of E. F. Knipling who was honored by USDA, ARS in an article in Agricultural Research Magazine

One of the most heralded programs in entomology, possibly in science as a whole is the sterile insect technique (SIT) for suppressing or eradicating screwworms.  I present here a little background on the connection between insect rearing and application of SIT.  I start with a quotation from E. F. Knipling, who had long been a supporter of insect rearing as a science that supported other insect management programs such as SIT and biological control (unknown to more casual observers, Dr. Knipling was a GREAT supporter of biological control, including augmentation.  He wrote a book on the efficacy and possibilities of biological control by parasites, and he included predators and augmentation of both predators and parasitoids as an important potential for pest management on an area-wide basis.  He wrote:

“Mass rearing of insects is still a young science. With the help of insect geneticists, insect nutritionists, and insect behaviorists, insects might be reared under conditions that will make them equally, if not more, vigorous and more adaptable to the environment than the wild population. These improvements are likely to occur after further experiences and research.”  E. F. Knipling 1979

In the 2016 ESA National Meeting, Dr. Knipling’s work (for example, see the quotation from the ESA Newsletter announcement of Dr. James’ lecture*).  I have used in a paper that I wrote for American Entomologist the quotation from E. F. Knipling’s 1979 chapter to fortify my discussion of the pivotal role of insect rearing in entomological programs.  The quote reflects Dr. Knipling’s recognition of rearing as a science and that with the right kinds of input can lead to production of better quality insects that are more available for various programs.  It is also clear that Dr. Knipling had the vision that further “experiences and research” were needed to improve rearing science.

But for the current blog page, I wanted to fortify the point about basic science, in general.  I have cited a recent paper in Animal Behaviour (by Brennen, Clark, and Mock 2014) about the importance of basic science.  The authors clearly convey that basic science is of value far beyond the immediate scope or vision that most of us have initially. Brennen et al. cite the widely discussed treatment of Dr. Knipling’s work on screwworms, where Knipling was “awarded” a Golden Fleece Award for his having been funded for $250,000 to study on “The Sexual Behaviour of the Screwworm Fly,”  It has become a near-legendary example of near-sightedness by politicians like Senator Proxmire (D-Wisconsin from 1957-1989) that Knipling’s funding to study the mating behavior of screwworms, which was the foundation of SIT: that a female fly mates once, while males (including sterile males) mate multiple times.  Brennen et al. pointed out that the leverage from the 1955 Knipling study was amplified from $250,000 to $20,000,000,000 advantage in reduction of damages to US cattle.  Of course this economic and environmental advantage has continued to amplify itself due to the continuing positive effects of screwworm eradication throughout the US and Central America.  A further advantage of the sterile screwworm program is the demonstration (proof of principle) of SIT for tephritid fruit flies, pink bollworm, coddling moth, and several kinds of disease-transmitting biting flies.

*“Dr. Anthony A. James, a distinguished professor at the University of California, Irvine, delivered the Founders’ Memorial Award lecture at the 2016 International Congress of Entomology (ICE 2016). The subject of Dr. James’ lecture was Dr. Edward F. Knipling, winner of the World Food Prize (1992), the Japan Prize (1995), the FAO Medal for Agricultural Science (1991), the President’s National Medal of Science (1967), and many other awards.”

“The Sexual Behaviour of the Screwworm Fly: One of the recipients of a Golden Fleece Award was E. F. Knipling for his research into the sex life of parasitic screwworm flies. Knipling developed the sterile male technique to eradicate this cattle pest, based on observations during the 1930s that male screwworm flies will mate with many females, while females will mate only once. He used this information to devise a male sterilization strategy using -rays. He released sterile males into the population and in a few generations completely eradicated this parasite. Knipling’s $250,000 grant from the Department of Agriculture led directly to a program estimated to have saved at least $20 billion for U.S. cattle producers. The sterile male technique is currently used as a standard eradication technique on many agricultural pests (Knipling, 2005; http://www.innovationtaskforce.org/docs/Screwworm.pdf).”

Brennen,

Knipling, E. F. 1979.  The basic principles of insect population suppression and management. USDA Agric. Handbook. 512.  659 pp.