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Happenings in the insect world
by Bracey Tiede
on December 28, 2016 at 8:13 AM
We have some monarchs that have been breeding and eclosing here in Santa Clara County all winter chowing down on Asclepias curassavica and we have released them to Ardenwood in Fremont where there is an overwintering population. East of the Rockies sites say that the OE parasite that is hosted by A. curassavica and is a serious pest of the butterflies. To prevent its spread, they say don't grow Asclepias curassavica during the winter. Is there any research that confirms this is a problem here in California over the winter? Any help would be appreciated. Thank you.
by Kathy Keatley Garvey
on December 29, 2016 at 4:31 PM
Bracey, thank you for your comment. About OE or Ophryocystis elektroscirrha:  
According to Art Shapiro, UC Davis distinguished professor of evolution and ecology: "In southern California Monarchs have been winter-breeding heavily on A. curassavica for several years (they never did before; they are supposed to be in reproductive diapause, which is photoperiod-regulated). Because it is the only host available, the same plants get used over and over again and eventually get contaminated with OE. To my knowledge this has not become a significant problem in the north state, but it probably will be eventually. We do not understand why an increasing percentage of Monarchs are failing to cluster and go reproductively dormant. I was just advised that Monarchs are overwintering in Kern County this year (!) but I don't know how many and if they are trying to breed.  
The easiest way to deal with the problem, and it helps with managing Oleander Aphid too, is to cut your plants back heavily a few times a year. This will induce OE-free fresh young growth."
by Bracey Tiede
on December 30, 2016 at 8:43 AM
Thank you, Kathy, for the information. We will take heed and prevent the spread of OE as best we can. Happy New Year. Cheers, Bracey
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