Author: Allen (Page 2 of 4)

Allen Carson Cohen has been a researcher and teacher in insect rearing and related disciplines for more than 40 years. He has published books and more than 100 papers on insect rearing and related topics. He is dedicated to helping change insect rearing into a more scientifically-based practice and to help rearing specialists become more properly valued.

More about contents of insect rearing online courses

As discussed in the recent example regarding O2 and CO2 in rearing containers, a deficit of O2 or an excess of CO2 are forms of stress often faced by insects in rearing situations. A key point made in Professor Cohen’s classes is that stress factors can lead to reduction of quality or fitness of our target insects. A major topic in my lectures is oxidative stress and how insects deal with this universal factor. But in the context of the O2 and CO2 levels in the rearing containers, our reared insects can be “fitness-challenged” by diet factors as well as such environmental factors such as temperature and density of the insect populations.

In a reliable and meaningful quality control system, we try to find how well our insects are doing with their rearing conditions (their fitness), and a really sensitive and objective way of determining fitness responses to rearing factors is through analysis of the O2 utilisation and CO2 output. One of our current research inquiries is application of a respirometry system (the Q-Box Respiration Analyzer) to measure the O2 consumption and CO2 output under various rearing conditions. In our current inquiry into O2/CO2 metabolism, we are placing insects in the respirometer chamber and measuring their gas exchange under various conditions such as temperature variations, population density, and diet modifications (where proteins, lipids, and carbohydrates are provided in different proportions). This measurement of metabolism is a direct way of evaluating the degree of stress in our target insects. The setup can be seen in the image below:

Q-Box Respiration Measurement System

While the relationships between diet profiles, temperature, population density, etc. are complex, it becomes clear that determination of how the various rearing factors affect rearing outputs and fitness/quality. For some students in these courses, this model of inquiry is a guide to improving their own rearing systems. For other (most) students, the value of this discussion is to expand their awareness of the intricate and interactive factors that prevail in their rearing systems. The lesson that some seemingly simple factor such as changing the relative amount or type of carbohydrate in a diet (or lipid or protein) can drastically change the insects’ fitness and ability to fly or to store nutrient reserves.

The KNOW YOUR INSECT lesson becomes part of the students’ thinking habits as they go about approaching their rearing systems.

Gas Exchange in Rearing Systems

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).

Figure 1. Measuring O2/CO2 in Painted Lady Containers

Figure 2. Measuring gas exchange in Painted Lady Rearing Units

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.

Figure 3. Tracheole diameter (in microns) at 3 levels of O2 in rearing atmosphere (12, 21, and 31%) redrawn from VanderBrooks et al. 2018. The authors showed that there were significant changes in the diameter, branching, and numbers of tracheoles as well as significant changes to the biomass of mitochondria as a function of chronic hyperoxia and hypooxia conditions.

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.

New Courses Starting in October, 2021

Allen Carson Cohen will be offering the three live online courses in Insect Rearing Systems, starting in October (5) and ending in December (30), 2021. The live, synchronous courses include extensive treatment (lectures, videos, tutorials, and discussions) of the basics of insect rearing. Professor Cohen’s emphasis in the three courses is on treating rearing systems in a scientific way, applying design of experiments extensively. Students with little or no background in statistics will learn how the most up-to-date procedures in insect rearing can be developed and improved through using designs such as response surface, full-factorial, and mixture designs. The courses are based on Professor Cohen’s recent books Insect Diets: Science and Technology (2015) and Design, Operation, and Control of Insect Rearing Systems (2021), both from CRC Press.

The courses treat all aspects of rearing, starting with basic understanding of the biology of the insects that we rear and the basic biological, physical and chemical characteristics of diets, environments, microbial interactions, genetics, and facilities. Once the basics are established Professor Cohen guides students through the implications of the various fundamentals and concepts to fitness and quality of reared insects. Professor Cohen draws from literature that covers the oldest works on insect rearing through publications that are recently published.

In these courses, Professor Cohen takes the approach of understanding the insects through the concepts of homeostasis and stress factors that stem from all levels of rearing system organization. Furthermore, Cohen constantly applies the rearing background to the specific issues of interest to students. Registration costs are $250 per course, or $750 for all three courses (which may be taken out of sequence). The courses each last for 4 weeks (8 lectures), for a total of 12 weeks of learning experiences for the whole sequence. Courses are taught through Zoom and Moodle, and students are provided with course materials (lecture notes, and many PDFs of relevant and current materials). The three courses constitute more than 52 hours of instruction plus the option of post-class discussions of topics of special interest to students. Please see future blog pages for further discussion of the unique nature of these courses.

Just Finished Live, Online Courses in Insect Rearing

We just finished our first year of teaching live, online courses in rearing! The courses consisted of 3-courses, each course lasting for one month, with Course 1 on insect diets, Course 2 on rearing operating systems, and Course 3 focusing on design and control of rearing systems. About 40 students/participants were in the courses, which consisted of eight 2.5 hour lectures, with discussion and plenty of examples of rearing fundamentals. One of the key features of these courses was the LIVE tutorials on applying JMP’s Design of Experiments and statistical process/quality control.

One of the major themes of these courses is the quest to understand the totality of rearing systems in terms of interacting components. Professor Cohen emphasizes that your rearing system is an artificial ecological niche, and just as organisms’ ecology must be understood from the perspective of their NATURAL niches, in rearing systems, we are best served by understanding the artificial niche conditions that we impose on our rearing subjects

The Diet Matrix (from Cohen 2004 and 2015), showing a few of the interactions between diet components and the target insect.

The figure here shows an artificial diet containing soy flour, wheat germ, agar, and other typical diet components. The theme of this picture is the complexity of diet components such as the electropherogram (lower right) showing the effects of cooking soy proteins (lanes 6, 7, and 8) vs. presenting raw soy proteins (lanes 3, 4, and 5). The cooked proteins are denatured, a process which limits the anti-nutritional qualities of soy (removing inhibition of proteases and other “killing’ other enzymes that are potentially damaging to the insects. The lipids (in red) interact with the proteins in a way that makes the lipoprotein complexes more available to the insects’ digestive system. The various proteins interact with the agar (or other gelling agents) to make the texture of the diet more palatable to the insect, and the interactions may help stabilize the various diet components so that the oxidation of lipids and other damaging reactions such as destruction of ascorbic acid is averted or reduced in rate of deterioration. All these (AND MANY MORE) interactions are part of the concept of diet matrix characteristics.

These are a few of the typical topics that we take up in the live, synchronous rearing courses. It’s certainly complex, but it’s what we need to understand to make our rearing systems work the way we want them to work!

Cohen’s Synchronous Online Courses (2020, 2021)

Evaluating live (synchronous, via Zoom) online courses. The current series of 3 courses {on 1) diets, 2) rearing systems operations, and 3) design and control of insect rearing systems} include more hours of instruction than workshops (60 hours vs. 40 hours of instruction); the courses cost less than the workshops {registering for all 3 courses costs $750 vs. more than $1000 for workshops}; the live online courses are spread over 3 months; there is time for interaction between participants and the instructor, including opportunity to ask questions between classes. The opportunity for feedback between participants and the instructor is in my opinion a very important part of the learning experience. For example, I have spent considerable time during this series of classes responding to questions and modifying the presentations to help amplify important points about the topics covered. In some cases, I have added through the online Moodle system (please see this website for further explanation of what I mean by referring to Moodle: https://docs.moodle.org/310/en/About_Moodle) many supplements and enrichments to add enriched content of the Zoom courses. For example, I have developed several tutorials that further explain concepts and procedures discussed in the live Zoom presentations. The flexibility of Moodle is virtually limitless, and I have been using it to deliver supplementary materials that allow participants to go into depth beyond what can be covered in class. The enrichment materials include many of my own tutorials, diagrams, images, and various other aids for learning about insect rearing science. This includes a major source of learning enrichment in the form of PDFs of open access papers that are sources of in depth information on rearing-related topics.

For more information about these classes, visit these links: 

Insect Diet Science and Technology

Insect Rearing Systems Operations

Design and Control of Insect Rearing Systems

Insect Rearing Education: trying to reach the rearing community one person at a time: workshops or courses?

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.

The 2011 insect rearing class (first onsite, for-credit class in rearing science). Bottom row, left to right: John Hanley, Jona- than Cammack, Alana Jacobson, Rick Santangelo, Kelly Oten; top row (left to right): Allen Cohen, Andrew Ernst, Amy Lockwood, Michelle Meck, Nancy Brill, Heather Moscrip, and Micah Gardner

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.

Active vs. Passive Learning in Insect Rearing Education

While teaching my latest series of courses on insect rearing, using Zoom and Moodle, I have had some thoughts about the value of this teaching approach: online synchronous (= live) teaching. I am sharing some of these thoughts about insect rearing education.

Above: Professor Allen Carson Cohen showing silkworms to 2nd grade classes during a COVID-19 home-learning lesson.

I have been an educator for much of the past 55 years (I started teaching at Buena Park High School in California in 1965), and one of the most important lessons that I learned is that students who are actively involved in their education learn best. Several websites present information about the various ways people learn (for example: https://blog.prezi.com/the-four-different-types-of-learners-and-what-they-mean-to-your-presentations-infographic/). In that excellent website, Chelsi Nakano discusses these types of learning: Visual, Auditory, Reading/Writing, and Kinesthetic (learning by doing—actually physically performing the process that the student is trying to learn). She uses the acronym VARK to help us remember these “learning styles.” Dr./Ms. Nakano authored that blog in 2016, before the times of COVID-19, which makes the understanding of learning style all the more compelling for those of us who teach online courses!

Recognizing that optimal learning situations differ from person to person, and our population consists of these types of learners, dedicated educators must shape their educational approaches to these learning types. Besides the adjustment to the “VARK” learning styles, I have also learned that THE most important component of learning is the students’ motivation to learning, which translates to their involvement in their education process.

No matter how good the teaching resources are, the most important determinant of learning is each student’s commitment to learning. Along with commitment, there must be involvement in the learning process. As I try to convey the importance of heat transfer in diet processing, for example, I can talk about the process (auditory), show pictures of diet heating (visual), or ask students to go into the lab and make up diet (kinesthetic or learning by doing), the learning process is not effective unless the student has “bought into” learning about the heating process. Therefore, I try, as much as possible, to get students to anticipate outcomes, form hypotheses about the processes in question, answer questions about how factors such as heat transfer coefficients, mixing, temperature differentials, etc. influence the cooking process. 

In the next few days, I will be posting specifics about how I try to reach the students’ minds and hearts to help motivate their involvement—all through a distance-learning medium such as Zoom and Moodle.

December 19, 2020

Finishing the First Live, Online Courses

Yesterday (December 17, 2020) we finished the 6th out of 8 “synchronous” (= live) classes in the 3rd course in insect rearing systems. Our classes consist of small groups of professionals in insect rearing and some students who are especially interested in the science of rearing insects. As a long-time teacher, I have been very pleased with the dynamics of the live, Zoom-based classes. Through the “Share Screen” function, I can deliver lectures that consist of PowerPoint and videos, with some “live action” demonstrations.

For example, in yesterday’s lecture, I guided the students through an experiment based on design of experiments format (from JMP by SAS). We used the JMP full-factorial analysis program to set up an experiment with types of gelling agents and types of beans as variables that we planned to test.

Figure December 17, 2020. Manduca sexta neonates on new bean diet.

What was most rewarding for me (and I hope for the students) was that we were able to interactively (students, teacher, and JMP system) set up the experiment, so that over the next week, we can use the JMP system to interpret the outcome of this experiment. We formulated hypotheses about the outcomes (would agar be a superior gelling agent over carrageenan; would pinto beans be a superior nutrient source than soy beans?) More about this in my next entry.

Wonderful World of Silkworms

We have presented a PDF version of a talk that I gave to some classes of 2nd graders in North Carolina, during the time of COVID-19.

We presented pictures of silkworms in different stages of their life cycle (eggs–>larvae–>pupae (in their white cocoons)–>adults.

Silkworm Adults and Cocoons (pupae)

Latest Courses Completed

We are now completing the first 3 synchronous (live) online courses in insect rearing systems. The sequence began in October 2020 with Insect Diet Science and Technology (Course 1), then followed in November 2020 with Insect Rearing Systems Operations (Course 2), and finished in December 2020 with Design and Control of Insect Rearing Systems. All classes met two days a week for 2.5 hours and were featured with powerpoint lectures, videos, and discussions of all aspects of insect rearing from a “systems” point of view. The Zoom format provided an immediacy and involvement that static online formats do not provide.

Professor Cohen lectured and discussed with participants diets, feeding biology, insectary environments, genetics and epigenetics, microbial relations, in several established rearing systems. Rearing was treated constantly as a science-driven process, and Cohen illustrated (with involvement from participants) how to use design of experiments and statistically-based quality and process control to develop and better understand standard operating procedures (SOPs) to meet the needs of our insects in rearing systems. Cohen applied the “Know Your Insect” axiom to reinforce the power of careful observation, data mining, and analysis-based inquiry to help strengthen participants grasp of the complexities of the interactive components of rearing system.

We are now ready to launch the next set of three courses set for January, February, and March of 2021.

The Origins of Modern Insect Rearing: Drosophila

HEREDITY OF BODY COLOR IN DROSOPHILA T. H. MORGAN, 1912 Journal of Experimental Zoology PLATE 1 EXPLANATION OF FIGURES 1 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

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.

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