Mar 18, 2013 | View All Issues
We sampled a VMB population last Friday (15-Mar) in Carneros. Roughly 92% of our sampled individuals were 1st or 2nd instar nymphs, and all were found under the bark. We did not find any adults or eggs. We also found evidence of parasitism---both empty mummies and full mummies.
The somewhat explosive VMB populations in 2012 could be explained in part by (1) a diverse population earlier in the season than normal (in April 2012, all life stages were present), and (2) a late start on our treatments to target this population with overlapping generations. Thus, we should pay particular attention to VMB development in 2013, potentially targeting control practices for earlier in the season.
Earlier season insecticide sprays that target nymphs under the bark could be implemented. Also, the parasitoid, Anagyrus pseudococci targets mainly 3rd instar nymphs (some 2nd instars) for egg-laying. Female Anagyrus lay eggs at temperatures above 57.2 degrees F; Anagyrus larvae develop at temperatures between 52.9 and 96.8 degrees F.
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