August 2020 Newsletter N0 36

Woven Network Webinar Series

The “Ask the Expert” series begins at 13:00 UK time on 18 September 202 Arnold van Huis

Since 2015 Professor van Huis has been emeritus professor to the Laboratory of Entomology, University of Wageningen, Netherlands. He concentrates on insects as food and feed, and is chief editor of the Journal of Insects as Food and Feed.
The webinar starts at 13:00 UK time (UTC+1)


is from the SHOP section of the website – LINK.

Next Webinars

16 October - Robert Nathan Allen, Founder and Director of Little Herds, Austin, Texas, Director North American Coalition for Insect Agriculture
13 November - David Drew, Agriprotein
11 December - Jo Wise, Monkfield Nutrition

Webinar Recording, Friday 19 June -

Insects as food and feed

A one-hour recording of this webinar summarised is available on YouTube. This may be found on the Woven Network Channel.

A synopsis of the webinar was included in the July edition of Woven News, No 35.

Insects in the media

Countryfile on 9 August included a 5-minute piece 37 minutes into the programme on cricket farming in the Mallerstang Valley in Cumbria. Twenty kg per week of crickets are raised on corrugated cardboard in plastic storage boxes for eating whole, or dried and ground for cricket flour. Produce is sent to wholesalers in London, and to a local baker who produces high-energy protein bakes for athletes.
Good that more than 5 million viewers were made aware that insects can be raised in the UK for human consumption both whole and as a flour ingredient. What was not obvious was that this was one of the historical fillers from three years ago that these programmes have been using to augment the loss of new material caused by the restrictions of Covid-19. The farm no longer raises crickets because technical and logistical issues put paid to increasing production to useful amounts, but the knowledge acquired by Howard Bell is available through his consultancy: Highfield Biological Consulting and on Linkedin
Most disappointing was the hammily acted pretend ‘yuk’ response by Adam Henson when he tasted the high-energy protein bakes prepared using cricket flour. Subsequent declaration was that they were delicious.


The Insect Protein Association of Australia are holding a virtual annual general meeting on 3 September at 7 pm local time, UTC+10, 10 am UK time. Agenda. Zoom: 



Buzzing is a newsletter about the rise of insects as food and feed by Emilie Filou, a freelance journalist specialising in business and sustainability issues and with a long-standing interest in Africa.
Subscribe or buy a coffee. The cricket avatar was designed by Sheila Lukeni.

Cricket farmer and Benjamin Kennedy, invertebrate vet, in conversation

Farmer We have no experience of diseases of Acheta domesticus; so I’d be grateful to learn how to recognise, avoid, and treat them.
Benjamin How to prevent and control disease depends on the farm system you have. You need to identify the risks and opportunities for disease within your system, then have protocols to mitigate them. You need good stockmanship, and monitoring and surveillance to discover problems before they affect adversely your production. This can be regular examination, or something more advanced such as histology, or culture and sensitivity.
To help me discuss disease prevention and surveillance with you:
  • How do you control humidity and temperature? What ventilation do you have?
  • What is your production in terms of yield, and for what yield are you aiming?
  • What is your feed, and what do you do with waste?
  • What animal and personnel movements are there between your farm and the outside?
  • Do you rear stock exclusively at home or import stock?
I cannot do a farm visit, but please send some pictures.
Farmer My first question is why would Acheta domesticus become much darker? About 10-15 days ago when outside temperatures increased, crickets in the whole farm got darker.

  • Are they all darker or is the darkening specific to certain areas? Darkening can be concerning as insects express inflammation through melanisation.
  • Have you noticed any changes in behaviour? The way they move or tremoring.

  • How do you maintain temperature in your thermostatically controlled insulated building? Do you have single or multiple thermostats?
Farmer They behave as usual. In one room, we experimented with the watering system. The moisture increased, but this was only in the room for breeders. The colour of adults is darker in all rooms. We have a thermostatically controlled building, and we can control heat separately in each room. Ventilation is by a recuperation system which draws air once an hour. The temperature inside the rooms is 30-31 °C. In the rooms where crickets are large, at one end temperature rises to 34-35 °C. When the room gets to 34-35 °C, they start to make noises, which disappears when temperature drops.
Also, the size of the crickets of the same age differs in the same box.  
Benjamin Variation in size is a sign that something is not quite right. The variation should be minimal with equal growth. Its means that a lot of the crickets have had a net loss or gain over the average. It can be one of those signs that something is amiss in lots of animals. It’s good stockmanship to notice that. It’s one of the criteria that I’m considering as a metric for cricket fitness.
Do you have only one thermostat in each room, and do you measure independently the temperature in all rooms? Sometimes in larger rooms with one thermostat, the temperature is not even throughout. Do you find that you have these problems at the turn of the seasons, spring and autumn, when temperatures change? I would have a few separate temperature probes recording minimum and maximum temperatures to confirm that ventilation achieves uniform temperatures and responds quickly enough to changes in ambient temperature. The differences in humidity could cause problems, but this is an unlikely cause if all the crickets are affected.
If this becomes a recurring problem with the next batches, an acute stressful event is less likely and there may be a problem with your system. You could take 10-20 of your crickets from healthy and unhealthy batches and send them to me pre-fixed. Drop them into either a high alcohol solution or into formalin - 70% isopropanol or 10% formalin. The ideal is Kahle’s solution, but this is not obtained easily and needs to be made up. They should be sent in the liquid. the ratio to cricket to liquid should be 1:10. You should send overall less than 50 ml formalin in the pack and they should be marked clearly as research samples. You should ensure that any vials of liquid are double packed in watertight containers and that they are well protected. Formalin is toxic and carcinogenic, so it is very important that they are secure. They can be sent via whatever delivery is economic. I will send them on to my lab once I have inspected them. I would like a selection of your worst effected and also a selection your most normal. Ideally 10 crickets from each batch. I will inspect them visually and then select the best ones and see what pathology I can detect. I usually also send a few crickets from my own collection, so I have a normal comparison.
I usually anaesthetise insects before putting them into the solution. I would recommend either fixing them directly or refrigerating them for 5-10 mins before immersing them in formalin. Ideally, they should be fixed as soon after death as possible to produce the best histology. I can then do histology to discover if there is anything going on internally. I won't be likely to get you an answer for a week or two because the processing takes a long time. I would view it as a way of evaluating your system and checking to see if there are any other problems that could be the cause. Ideally, I would visit and do clinical examinations and record key metrics.

With improvements in rearing crickets and other insects, a fall in production may be seen in populations that are surviving rather than thriving. It would be interesting to see the effect that darkening, which I assume is melanisation, has on the final product.

Farmer Each room has one main thermostat which is connected to the system. There are 2-3 separate thermostats to check moisture and heat in different corners of the room. This is how we detected that heat at one extremity of the room is was 3-4 °C higher. What temperature you would suggest during the summertime?
Benjamin I would suggest reducing the temperature in your rooms and seeing if the darkening continues. I'm wondering if your system is struggling with the additional summer heat. Similar things happen in poultry systems.

Farmer We will work with ventilation in separate rooms and will record the changes. How fast do you think a visible change in darkening could be expected if this were due to changes in temperature and moisture that were resolved?
Benjamin I suspect this current batch will continue to have size differences. I would expect that darkening caused by melanisation would be moulted away over the next few weeks if the crickets became less stressed. The next batches and generations will indicate if there is a continuing problem.

Farmer All rooms in farm are affected; so I can obtain non-dark samples only from frozen stock. Would this be ok? Or should I look for more and less affected in livestock? There are two main questions: why has the darkness appeared and why do the sizes of crickets differ?

… … … Conversation interrupted whilst histology performed … … …

Benjamin The provisional histology report is that there isn't an obvious melanisation but there is generally more staining within the tissues. There isn’t much evidence of infection. The changes appear more consistent with heat stress. The changes are much more subtle than usual. What is happening clinically?
Farmer Production is improving. The darkening has disappeared. We have changed our recuperation and ventilation systems, and this is controlling the moisture as well. Moisture is necessary for young crickets, but when moisture exceeds 50% for adults, darkening begins. When the temperature exceeded 35 °C inside the box for crickets aged 2-4 weeks, they stopped developing normally; so this may explain why the crickets differed in size. 

Now we are about to integrate remote control for carbon dioxide and ammonia, moisture and temperature throughout the farm to detect and deal with any overheating.
Here is the colour of crickets of the same age
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