Locusts hatch rate low

Hi,

I’ve been breeding Locusta Migratoria for some time now.

All seems to be going well, apart from hatch rates - I seem to be getting only few (I’d say 5-20) hoppers from a pod, rather than the 50-100 as mentioned in most literature. Has anyone encountered this before? Any ideas on what might be causing this?

Also, probably connected but not sure if it’s the entire problem - a lot of the hatchlings seem to stay underground and die. They just don’t reach the surface, they even do the first moult in the cavity left by the eggpod. It’s hard to photo this, but here goes: https://pasteboard.co/HQd8E6p.jpg

I use a transparent plastic tub, about 10x10x10cm, with potting soil and a thin layer of sand on top. Hatching looks like this: https://pasteboard.co/HQd4H9d.jpg (on this particular occasion I didn’t see any other hopper emerge after the 4 pictured)

@EntoJesse, you seem to have a deep knowledge regarding locusta, do you have any ideas what I might be doing wrong?

Thank you in advance

Comments

  • Hi slupik, - Nishide & team have several studies on L. migratoria. One thing is they use ~18% moisture for the egg sand.

    Another research team following team Nishide's methods actually plastic bagged (allowing gas exchange, so not closed) their egg trays for an initial period & only exposed the sand when incubation phase was leading to hatching time. Maybe your soil is complicating moisture for the eggs' need to avoid drying too much; if you are using a commercial bagged "soil" that can have unknown ammendments (ex: wetting agents to make the product particles "wick" water to it). For reference team Nishide used sand & no soil.

    In Nishide, et als. (2017) " The hatching time of Locusta migratoria under outdoor conditions: role of temperature and adaptive significance" ( free full pdf available online) they found egg hatching response is best when there is a timely rise in temperature; whereas average (mean) temperature is less inducive of egg hatching. Team Nishide's (2015) " Egg hatching of two locusts S. gregaria and L. migratoria in response to light and temperature" describes how Locusta migratoria in nature hatch best in light & not covered; meaning you might try to plastic bag uncovered eggs & time their uncovering under constant light (one lab specified it used 24 hour light for eggs).

    Recent reports have disclosed that eggs in groups hatch best & they trigger one another. An early tactic used by some was to vigorously shake egg trays to induce contact vibration for hatching. Recently I saw a reference that egg emergence was even improved by playing them Mozart; as per "Hatching synchronicity is controlled by a two step nechanism in the migratory locust ...: roles of vibratory stimuli."

    One last thought - if you are feeding the locust on so called "organic" grown plant matter. The "natural" insecticide azadirachtin (from neem tree) is now quite commonly used. In low dose exposure it is not always killing a bug, but non-fatal doses can cause some reproductive impact (varying with when the bug was exposed in it's life cycle to what dose of azadirachtin). In simple terms there can be thinning of the egg surface (easier to dry out) & also developmental deformities going on inside (hormone phases altered) ; which may relate to those you found not moving to the surface & dying off.

  • Hi @gringojay, Thank you so much for your reply. I will try the suggestions you mentioned (actually already have pure sand and closed tub experiments set up) and go through the studies. I appreciate your help!

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