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Mealworms Eating Pupa

Hi,

I have recently started trying to farm mealworms in a plastic container set up. Despite my best efforts, it seems that the majority of my pupa are being eaten by the mealworms (saved ~10 but have found over 50 dead). I have been checking twice a day and searching for pupa to move to a separate container, however, the mealworms are attacking too fast. Any suggestions? I thought it might be because not enough moisture sources only 3 carrots for 2000 mealworms, so I just added more and will see how that goes... or the container area is too small ~35cmx40cmx(10cm of oats)...? There are also a large number of dead (black) mealworms around..

Any advice would be great...

Thanks!

Alex

Comments

  • Hey there Alex,

    Welcome to the forum!

    I'm fairly new to farming mealworms, but I have had some success in creating my first breeding stock (I'm aiming for 500 beetles). Like you, I've also used a plastic bin with rolled organic oats as substrate (mixed with bran and wholegrain wheat and rye flours). So far, I have had very few casualties (out of 400 pupae, only 3 have been cannibalised). In my bin, the moisture sources are evenly spread out and I have bits of chemical-free cardboard for them to climb on. I even keep a big piece of carrot in the pupa container, so the freshly hatched beetles don't cannibalise their kin before I can put them in the breeding container.

    Mealworms will cannibalize each other if the space they're kept in is too crowded or they don't have enough easily accessible food and moisture. They will also cannibalize the pupa for moisture (as will the adult beetles).

    Is the environment in the box very dry? Do the carrots dry out quickly?

    You could try

    • Slice up the carrots and spread them out more evenly
    • Use a bigger container
    • Use finer bedding (add wheat germ, bran or flour to your oats)
    • Give the pre-pupal mealworms something non-toxic to climb onto, so they can get away from the others. They will then pupate in this "safe space", which should make it easier for you to move them.

    Hope this helps!

    I'm sure the more experienced members of this forum can give you much more useful advice.

  • Hi hjalmarssonsara,

    Thanks for your response. I will add some bran/rye flours/whole grain wheat in the substrate, extra carrots, as well as cardboard. I think the issue may have been that it was too dry and not enough moisture sources. Will keep trying and let you know how it goes.

    Thanks a lot for your advice

    Alex

  • From March 2014 Forum thread "Frass and some other questions" - Mealworm frass has the compound farnesol, which induces the expression of what is called the "juvenile hormone" (hormone keeps larva from adulthood).

    When the level of juvenile hormone rises then the larva will molt again, but not pupate; in laymans terms too much frass increases the repetition of instars by the larvae. Numerous instars lead to larger larvae moving about & actually they are not likely to go after one another.

    However, they are prone to cannibalize those in the metamorphosis stage of pre-pupae which are vulnerable because those are not moving (larvae which look kind of crooked & when touch don't respond). Females are more susceptible to juvenile hormone ratios & respond to elevated levels by cycling their number of instars more than males do (in response to high amounts of juvenile hormone).

    Larval programing, during what is meant to be the last instar coincides with their brain pro-thoracico-tropic hormone still inhibited by juvenile hormone. The juvenile hormone must clear out of the larval haemolymph (insect circulatory fluid) to let the pro-thoracico-tropic hormone become active before metamorphosis is possible into pupae (no more instars).

  • @gringojay, I've read that giant mealworms are raised such that they are prevented or delayed from pupating so they grow larger. Is farnesol what is used to produce giants?

  • Hi Lin, - "Giant"mealworms are produced via a commercial application of misted juvenile hormone on the Tenebrio molitor larvae. They don't pupate in a normal sequence & grow big. I don't know the schedule of dosage tactics & presume it is a proprietary technique. Whether the spraying is combined with any farnesol tactics, again, I don't know.

    Zophobas atratas (a.k.a. Z. morio) mealworms are sometimes also called giant mealworms. This is confusing & these are usually called "Super" mealworms; so presumably you were not refering to these.

  • @gringojay, You are correct, I was not referring to "super" mealworms. Thanks for the info!

  • @gringojay, It does seem reasonable to postulate that Farnesol might do the same thing. I'll have to do some research...

  • Hi Lin, - Farnesol is made through the mevalonate pathway (ie: uses mevalonic acid) -> isopentyl pyrophosphate -> geranyl pyrophosphate -> farnesyl pyrophosphate -> which creates the option of making farnesol or continuing to make geranylgeranyl (which can make geranylgeraniol) pyrophosphate. Both farnesol & geranylgeraniol can tag onto proteins that change the protein to membrane interactions; or simply protein to protein interactions .

    If you wanted a cheap source of farnesol it is in the oil derived from the 3 weeks of growing "squares" (floral bud) of cotton. Farnesol is produced in other plants; for example trans-farsenol & farnesene in cassava help make it relatively bug resistant.

    Farnesol repels ants, parasitic wasps, termites & cockroaches; which helps make mealworm colonies less vulnerable to them. Curiously it attracts mites & this has been exploited as a way to draw spider mites to agricultural poison formulas.

    It is hydro-phobic (rejects association with water) & a compound of trans- farnesol affects cell membranes so they tighten up; there's fluid retention based on the amount & duration of exposure to farnsesol- which might be a factor in "giant" mealworms plumping up. Europeans use Linden tree extract, which has farnesol, as a skin tonic & it makes the pores size get smaller.

  • @ gringojay, Very interesting! Thank you for the info.

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