cross pollination rates with sweat bees?

[bower]

I usually amend my container soils with commercial compost, but this year it wasn't available, so I used my own compost from the garden - a place where insects rule supreme. I've never used any pesticides and come summer the place is buzzing with bumblebees and many many insects I don't even know what they are.

The upshot... my "pollinator excluded" greenhouse has its own bees this year. Bees I didn't know about or even recognize, but which Carolyn had mentioned as important pollinators of tomatoes: "sweat bees" aka halictid bees. They are tiny, metallic instead of furry, and nest in soil.. yep, I must have brought them in with the compost. Besides the green one shown in the picture, I also have seen a bright blue one, and a shiny brown one, like this one resting on leaves. I haven't seen them buzzing the flowers at all (some species may be nocturnal or 'vespertine' afaik?) If you look at the side of the green bee in the picture, you can see by the yellow bulges, this one has been busy collecting pollen, so the deed has been done if not witnessed.

I guess my question is, what rate of crossed seed is expected where sweat bees are common?

[carolyn137]

Originally Posted by bower

I usually amend my container soils with commercial compost, but this year it wasn't available, so I used my own compost from the garden - a place where insects rule supreme. I've never used any pesticides and come summer the place is buzzing with bumblebees and many many insects I don't even know what they are.

The upshot... my "pollinator excluded" greenhouse has its own bees this year. Bees I didn't know about or even recognize, but which Carolyn had mentioned as important pollinators of tomatoes: "sweat bees" aka halictid bees. They are tiny, metallic instead of furry, and nest in soil.. yep, I must have brought them in with the compost. Besides the green one shown in the picture, I also have seen a bright blue one, and a shiny brown one, like this one resting on leaves. I haven't seen them buzzing the flowers at all (some species may be nocturnal or 'vespertine' afaik?) If you look at the side of the green bee in the picture, you can see by the yellow bulges, this one has been busy collecting pollen, so the deed has been done if not witnessed.

I guess my question is, what rate of crossed seed is expected where sweat bees are common?

And I found out about the importance of sweat bees from an article Jeff McCormack wrote when he owned SESE and here it is:

http://www.southernexposure.com/isol...es-ezp-35.html

Please keep in mind that Jeff was doing seed production for a lot of the varieties he listed at SESE and IMO his isolation distances are too conservative.And they were since he WAS commercial.

What is very valuable are all the other variables that he mentioned that can determine the occurence and rates of X pollination.

Carolyn

[bower]

Thanks so much, Carolyn! I'll read it.

[bower]

Well... the isolation distance in the greenhouse is pretty much zero. I guess I should consider bagging some blossoms.
I was thinking perhaps the earliest fruit would be okay, but I don't know exactly when these critters emerged, either. And they do seem to have a secretive lifestyle..

This is a great video of a sweat bee on a tomato flower!
https://www.youtube.com/watch?v=iXHksIkAqLA