Cold is Cold and Hot is Hot- Or Maybe Not?

Temperature is a major issue with rearing BSF in colony. Adults are highly susceptible to temperatures below 21C (will survive but not mate when temperatures are lower), while larvae show an ability to mass produce heat and avoid these issues; however, this ability becomes a problem during the warm months of the year when their heat production can cause temperatures above 40C.  

In such cases, larvae die or attempt to escape from their containers- both scenarios are not good for anyone wanting to mass produce the BSF.

I am reviewing the paper listed below as a "shout out" to my friends and colleagues in the southern hemisphere that are quickly preparing for winter and associated low temperatures and resulting consequences (e.g., death of BSF and low egg production). As a side note, I have to admit, weather in Texas is quite nice right now (21C and holding with blue skies).  

Spranghers, T., A. Noyez, K. Schildermans, and P. De Clercq. 2017. Cold hardiness of the black soldier fly (Diptera: Stratiomyidae). Journal of Economic Entomology 110: 1501-1507.

This study was conducted by colleagues in Belgium, and it should be noted they initiated their BSF colony, which was used in their research, from material received out of south Georgia, USA (assuming original BSF population used in early research and has served as seed material for a number of colonies around the world).

• Major finding was the ability of BSF to survive 5C was primarily governed by stage of development. 
• Prepupae could survive (50% survival) at 5C for approximately 23 days.
• They hypothesize 50% individuals in the field could survive up to 47 days at that temperature.
• As they point out, this study is population and diet specific. Yes, what they reared the larvae on could impact their ability to survive cold temperatures.

My take away from this study is:

• These results are very informative but are population specific. Do not expect the same for your population even if you are working with the same source material (things change).
• You might be able to select for more cold tolerant populations through a general experiment of exposing material and getting those to survive to mate and lay eggs for the next generation.
• Be careful- selection of a cold tolerant population could result in a population not capable of handling high temperatures.

I hope you all enjoyed this post- let me know if you have anything you would like to have reviewed... that's what this blog is for! 

All the best-

Jeffery K. Tomberlin, PhD & BSF weather guide
Director, EVO Conversion Systems
​Twitter: @FliesFacility