Mating Siblings

[trembo3578]

Everyone probably knows that mating between siblings or inbreeding is not biologically the best thing to do. I was wondering how dangerous it is in rearing leps that are offspring of sibling pairs. I've heard that it doesn't matter all that much for insects but I've also heard it can be the cause of loosing an entire generation of larva? Can anybody shed light on the topic from experience?

[nomihoudai]

It really depends on the species, nevertheless I would say that one generation of inbreeding never causes trouble.

For example a friend of mine brang back caterpillars from Thailand, we then breed ( with inbreeding ) 3 generations making out of 10 caterpillars that he brought back over 1000 adult specimens ! The stock is now "extinct" as far as I am aware, but probably not due to the inbreeding and the viability of the stock but rather disinterest of new breeders.

Another example is Actias dubernardi which got heavily breeded in Germany, it took over a year to get strong inbreeding defects into the stock, which resulted mainly in very tiny specimens.

In my eyes the biggest threat to healthy breed specimens is overpopulation of your breeding cage and not enough fresh food for the caterpillars, this results in smaller specimens overall, I once received some stock from a French breeder that is known for massbreeding species and the specimens that hatched later have been tiny compared to their natural wild pendants. I was rather disappointed with those.

So if you got fresh eggs from the wild and want to keep the larvae for a second generation just go for it and mate siblings.

[bobw]

As Nomihoudai says, it depends on the species, or probably the group.

I've generally found that Saturniidae tend not to be very tolerant of inbreeding and show problems (e.g. cripples, low fertility, refusal to pair, susceptibility to disease) after two or three generations. Some butterflies are much more tolerant. A couple of examples: I kept E. aurinia in captivity for 15 years with no new blood and even at the end they showed no sign of weakness. The Wood Walton L. dispar batavus have been captive bred for very many generations now with no sign of weakness.

Gregarious species seem to be more tolerant of many things, obviously particularly overcrowding. The main things are to keep all breeding equipment scrupulously clean and avoid overcrowding in solitary larvae.

Bob

[starlightcriminal]

It really depends on ploidy I bet. A "simple" organism doesn't necessarily have a simple genome (the reverse can also be true- look at Cheetahs). In medicine, mice are regularly inbred to create knockdowns and such for research. It has no noticeable effect after many pairings save if you have caused a mutation on purpose that might be fatal in the homozygous individuals or something like that. But "naturally" it has no noticeable affect on mice at all after many many generations.

I frequently wonder this when I am collecting males that my females call in- often I have released multiple males (native AND local of course) before a female ecloses and in some cases I strongly suspect that some of the males I released have returned to mate with their sister (eeewwwwww.....). If a moth will only fly a mile or so to find a female then it stands to reason that quite a few might come right back. Anyone able to confirm or refute this?

I think that the whole "inbreeding caused all my caterpillars to die" or "made the adults eclose poorly" is something we think when we can't explain the loss. I would wager that it is most often user error, not poor genetics, that is the culprit but since we can't ID the exact problem we like to think it was something out of our control.

I'm with Bob- probably most often from overcrowding and having a less than a spotless eclosure. You can't see virus/fungal spores any better than you can see the genotype of a moth.