Geiger, C.A., Daane, K.M., Bentley, W.J., Yokota, G.Y., & Martin, L.A. 2001 Sampling program for grape mealybugs improves pest management.. California Agriculture 55(3): 19-27.
Notes: The results of a mealybug study in Central Valley vineyards, designed to develop sampling guidelines, reveal that mealybug distribution on vines varies greatly through the season and that mealybugs usually prefer concealed locations, such as under bark. This combination makes sampling difficult. A number of sampling techniques were compared. Three-or 5-minute timed counts were most efficient because samplers could follow the mealybugs' movement over the season. Midseason counts were much better predictors of damage at harvest than early season counts. This research confirms past control guidelines and opens new control options. Grape bunches touching vine trunks or spurs will have higher damage. Removing these bunches or using barriers between bunches and mealybug oviposition sites can also reduce damage. Five mealybug species are pests of California table, raisin and wine grapes. The great majority of mealybugs collected in San Joaquin Valley are the grape mealybug (Pseudococcus maritimus), while the closely related obscure (Pseudococcus affinis) and longtailed (Pseudococcus longispinus) mealybugs are more common in coastal vineyards. Two other mealybug species are relatively new pests to California: the vine mealybug (Planococcus ficus), found predominantly in Coachella Valley and in isolated fields of San Joaquin Valley, and the pink hibiscus mealybug (Maconellicoccus hirsutus), recently discovered for the first time in Imperial County. Because many of these mealybug species look outwardly similar, specimens should be preserved in alcohol and sent to experts for identification. The grape mealybug, commonly found in San Joaquin Valley, is closely related to obscure and longtailed mealybugs, common to coastal vineyards. Longtailed mealybugs are easily distinguished by having a tail sometimes longer than the body. Grape and obscure mealybugs are very difficult to distinguish. Grape and vine mealybug species currently cause the most economic damage, although pink hibiscus mealybug might be a serious pest if it becomes established here. The other species are generally sporadic or occasional pests.