Vineyard Mealybugs

We are finding mostly 1st instar nymphs (crawlers) at a sampling site in Carneros. We also found new eggs in ovisacs. This is indicative of a new generation that is currently hatching.

We found most nymphs under the bark, and a few on the leaves. Other growers have reported finding some portion of the population on the leaves in Carneros. 

Last week, on April 17, in Oakville, we found 1st and 2nd instar GMB under the loose bark of spurs and canes. 

At this time of year, they are moving between the leaves and the loose bark of spurs and canes, as this generation develops. 

We are finding all life stages of VMB at Carneros and Howell Mountain sampling sites. We found all VMB under the bark.

We found evidence of parasitism and predation at the Carneros site--both empty and full mummies, and mealybug destroyer beetle larvae. 

Careful monitoring of VMB is highly encouraged. Large populations with overlapping generations can be very challenging to control. Multiple, early intervention strategies can keep VMB populations low. Rotation of insecticidal materials is also highly encouraged to decrease the potential for resistance to develop and to protect products for future use. 

We found 1st instar GMB in Oakville vineyards last week. All nymphs were found under the bark--either of spurs or canes. The shoots at all sampled vineyards were 1 inch or less in length, so we were not finding nymphs on the leaves yet. As the canopy grows over the next several weeks, the nymphs should move between the leaves and protected locations under the bark, as this generation develops. 

Will you be using pheromone-baited sticky traps to monitor mealybugs? You can learn to identify the male mealybugs (grape, vine, and grass) in sticky traps at an informal, open house session. 

April 18, 2013

9 am to 12 pm

UC Oakville Experimental Vineyard (1380 Oakville Grade Road)

Drop-in at your convenience, any time during the 9-12 time period. You can expect to spend 15-30 minutes learning to identify males. Please RSVP so that we can measure interest in this session. 

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. 

The summer generation of the GMB is currently hatching at all of our sampling sites (Carneros, Oakville, and Pope Valley).

We are finding 1st instar nymphs on leaves, and under the bark of cordon and spurs. We also found one 1st instar on a berry. 

There are still some eggs that haven't hatched, but >90% of the life stages that we found are 1st instar nymphs. 

We found mostly VMB eggs and young nymphs at our Carneros sampling site. We found the eggs under the bark. Young nymphs (1st instars) are under the bark and on the leaves. 

77.2% of the VMB population under the bark is eggs and 1st instar nymphs. 

99.2% of the VMB population on the leaves is 1st instar nymphs. 

We also found many mealybug destroyer larvae feeding on VMB eggs under the bark. 

We are finding GMB eggs in ovisacs. We have not yet found hatched eggs or crawlers of the summer generation. 

At our Carneros site, eggs are 91.4% of the sampled population; at our Oakville site they are 100%, and in Pope Valley they are 75% of the sampled population.

The remaining portion of the population at each site is female GMB. We also found one, 3rd instar nymph in Carneros.   

The GMB population is mostly in the 2nd instar stage at vineyards in Pope Valley and Oakville. We are still finding some 1st instar GMB.

We found GMB under the bark (on canes and spurs) and also on the leaves.