Thanks for posting this. I am interested in silkworm genetics, but don't know too much. I guess having hybrids would give you a variety of genes to pick out. I don't know about silkworms, but according to my father and some of my past experience, hybrid chickens are initially much larger and more productive because of something I believe is called hybrid vigor. However, after several generations of purposeful hybridizing and taking those hybrids and breeding them together, one gets chickens that are more and more like their tropical fowl ancestors. Are silkworms similar if you breed hybrids to each other over and over again?
Hi Charlie, Good question. I can tell this from what I have researched and from my own experience. I am sure Eika San can give you her professional and scientific opinion.
You are totally right about the hybrid vigor. In fact, everything we eat these days are pretty much genetically improved upon for a specific reason. Take tomatoes, for example, they are now better looking, longer shelf live, more uniform for better packaging, productivity/yield, flavor and color etc. Those big, funny looking tomatoes that we call heirlooms are no longer found commercially and they maintain the characteristics of their ancestors throughout. Same in chickens. I own a few hybrid chickens as well. They are the eggs of free rangers. All mixed. I have to say, they are for sure more "wilder" than your domestically bred ones. In Chinese, we call it "tu ji". Their meat is probably tougher but more flavorful. Although only 2 months old chicks without a hen, they can fend off predators with their rambunctiousness, as opposed to my full grown, store bought silkie chickens which I've lost all to predators in the past month. Anyway, back to silkworms. Yes, hybrids are commercially bred for hardiness. What I have noticed though, from what I could remember, is that these hybrids (the zebras ones- can get really fat. Fattest I have seen.) They also tend to whip back more than the white ones I remember from my childhood. This is definitely an insect instinct. If you have ever owned hornworms, hornworms tend to do this quite frequently. They whip back and can nip at you. (they are just caterpillars and I've bred some!).. in fact, the larger hornworms, when starved, can actually cannibalize the younger larva (I've read and heard from chameleon owners). Now, when you google on tiger silkworms, a lot of the chinese forums will mention that the tiger silkworms, when starve will eat the younger larva. I don't know if this is true or not, and don't intend on seeing this happen. For all I know, it could be just a myth or urban legends that chinese parents like to scare their kids with. But in thinking back about hornworm behavior, I can't come out and blatantly dispute that notion with the tiger silks. With this brood of zebras that I am raising, I've noticed the whipping action more often. With my previous brood of silkworms, I noticed the moths tend to flutter quite a bit, and were escaping their rearing boxes. Remember Michelle, she said that she is keeping a line that she found to be 'flying' a bit.
Now, back to zebras and tigers, according to our friend, all colored lepidoptera are in general more hardy than the white ones, and by being hardy that usually means they are a multivoltine strain, coming from warmer climates. Now, in linking back warmer climates with voltinity and hardiness, is it safe to say there is some reverence to hybridized silkworms displaying more of their innate insect characteristics? It's all about selective breeding. All animals look for genetics outside of their community to bring in more genetic variety and vigor, for one purpose or another! And supposedly, if we eat more meat, we tend to grow more body/facial hair! LOL Am I making sense?