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Beauveria bassiana

It would appear that i am facing yet another problem. After getting rid off our flour moths (using feromone traps) i have noticed another development, which would appear to be serious, the pupas not extracted in time from the containers would appear calcified, after searching for information it would appear to be a fungal infection. I am reading different things on the net but cant really find any solutions to get rid of the fungus, i have red some places about an antifungal treatment called "Captan 50W" or another one "Calcium Hydroxide" but i mean to ask if aany of you have any tips or encountered this problem and if yes how did you treat it.

Thanks in advance


  • Hi richardfv, - What insect do you rear? Bee propolis is anti-fungal ... we humans can consume it. Calcium hydroxide is quite alkaline & likely too caustic to protein of salvageable bugs.

    Captan may be tricky to use, even though for agricultural pest management it is combined with specific insecticides when want a combined anti-fungal with insecticidal spray. If (?) we can extrapolate from crab research. It speeds up egg hatching & full grown adults survive fine on 340 micro-gram/liter exposure. However their larvae don't survive beyond a week on 450 micro-gram/liter exposure.

  • A ppm Captan reference of Drodophila melanogaster is that 0.015ppm begins to show cell toxicity affecting emergence, although not hatching & survivorship. Reproductive impact requires 125 ppm Captan & 1,250 ppm see tissue damage by 2nd day.

    The pollination insect Osmia lingaria has been found to be very susceptible to damage from Captan. One of the issues seems to be Captan causes interference with fungal chitin & that can also impact larval chitin.

  • Thanks @gringojay the bee propolis sounds like a perfect treatment and non toxic, what form and how would you apply it? I rear mealworms.

  • Hi richardfv, - Remember you never want to expose your entire bug colony to an experimental practise, which I consider propolis usage to be. Unless you have ready access locally to bee keepers I assume you are considering working with a store propolus product.

    You can make an alcohol tincture from crude propolis, but probably can buy it already made. The water extract of propolis is not as active against fungus than an alvohol extract.

    My initial tactic would be to spray undiluted alcohol extract (tincture) of propolis on clean bran & let the alcohol evaporate before settling some larvae onto that bran. The assumption being the larvae will coincidentally ingest with their bran meal some propolis active compound(s) concentrated into the fluid extract.

    Furthermore, while churning through the bran some propolis compounds might adhere to their exo-skeleton. Prepared propolis is not cheap, so impractical to continuously pre-treat bran/feed with; the intent is to get a small population exposed that is no longer recontaminating their bin.

    One unknown is the fact that propolis sourced from different apiaries have been shown to posses variable anti-microbial potency. Another issue is that, based on the fact some humans have negative reactions to propolis, I am unable to say all stages of mealworms will react positively to contact with it.

    Be that as it may, a second tactic (again not on entire colony)would be to see if direct application as a way to reach minute nooks & crannies of the insect works better. For this I would try to evaporate off a significant proportion of the alcohol tincture & re-solubilize the resulting concentrate with distilled water for misting bugs (or disposible glove hand rubbing a writhing bunch) when have taken them out of any bran/feed. Put them back into their substrate after they air dried & propolis compound had external contact time (not at too high a temperature or risk dessicating them).

    I would aim to evaporate off the alcohol so there is about 3% (-5%) alcohol left & definitely not evaporate extract down to sludge state (which would probably be very resistant to re-solubilization). Of course an over the counter tincture is unlikely to be high in alcohol to begin with so don't just figure on evaporating away 97% of initial volume; my best guess is you'll find store tinctures have 30% alcohol (so need to do some math factoring).

    A third tactic on an isolated population would be to combine external exposure to them outside of any sustrate, naked so to speak. Then when dried place those in popolis pre-treated bran on the assumption they'll get maximum exposure.

    You may look into "potassium bicarbonate" as an alternative anti-fungal. See Forum WEB version search bar for link to post with an introductory research study.

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