I have noticed that all the milkweed bugs seem to suck all the juices out of the green pods. They then turn brown, without opening yet. Will this affect the seed development?
Probably. I never used seed that has supported MBs or too many aphids.
Just to be safe and to obtain the strongest stock, I'd go for the noninfested plants.
I have plenty of incarnata (Swamp) seed for SASBE if you need more seed. I also will have tuberosa Butterfly Weed) and syriaca (Common) within weeks now.
I've opened a few of the pods that have been effected by those seed-eating bugs. You can obviously tell the seeds that have been shredded. There are also some that appear intact, but seem to have a dullness or mildew-like change in color. Some can still look pretty normal, and I wonder if those might still be viable. However, I would not depend on those or use them for trades with others who are counting on good germination. I might just toss them into a spot in a ditch or spare area that could benefit from some milkweed volunteers.
Catherine, I'm not sure what effect milkweed bugs have, but my guess would be they DO effect seed viability.
I took seeds from some aphid infested plants a couple years ago and the germination rate was HORRIBLE.
Maybe the seeds get nourishment from the pod casing and when the milkweed bugs and aphids suck all the juice out of the pod, there's nothing left for the seeds.