Population growth of Brevipalpus lewisi McGregor (Acarina: Tenuipalpidae) on grapevines.
In the Mildura district of Victoria (Australia), Brevipalpus lewisi McG. is responsible for 'bunch mite' symptoms on grapevines. Age-specific life and fecundity tables compiled in the laboratory showed B. lewisi to be capable of positive population growth over a range of temperatures and relative humidities commonly encountered in the field. The maximum value of rm obtained in the laboratory was 0.04/day, at 28 deg C and 35% RH. A field study of the seasonal abundance and intra-vine distribution of B. lewisi showed that populations increased about 60-fold during a season. The rate of population increase during summer was similar to laboratory estimates of population growth potential. Although the mites were present solely at the base of canes early in the season, later all green parts of the plant became infested. B. lewisi was preyed on by Typhlodromus reticulatus Oudm., which also preyed on Eriophyes vitis (Pgst.) and was itself preyed on by an unidentified cheyletid mite. T. reticulatus was adversely affected by benomyl. Predation and loss associated with leaf fall reduced the numbers of B. lewisi overwintering. Populations were further reduced by removal of mites during pruning.