Drought Stress Increases Densities but Not Populations of Two-spotted Spider Mite on Buddleia davidii `Pink Delight'

Abstract

<jats:p>Two experiments were conducted to determine the effect of drought stress on the susceptibility of <jats:italic>Buddleia davidii</jats:italic> Franch. `Pink Delight' to the two-spotted spider mite (<jats:italic>Tetranychus urticae</jats:italic> Koch). In the first experiment, drought stress was imposed by withholding water until predawn xylem pressure potential fell below -1 MPa. Shoot growth was 75% less in drought-stressed than in nonstressed plants. Mite population densities were not affected, but noninfested leaf area was 14% higher, and degree of mite damage was lower, in nonstressed plants. Evidently, the greater amount of new growth in nonstressed plants leads to lower spider mite densities by diluting populations. In a second experiment, nonstressed <jats:italic>B. davidii</jats:italic> `Pink Delight' plants were watered every 1 to 2 days and drought-stressed plants were watered every 3 days. Spider mite populations were monitored by sampling newly expanded and mature foliage. Mite populations on mature foliage were not affected by stress, but stressed plants grew less and had larger spider mite populations on their newly expanded foliage than did nonstressed plants.</jats:p>

Climate of origin influences how a herbivorous mite responds to drought-stressed host plants

“…This pattern was also observed in Tetranychus urticae and Oligonychus pratensis on maize (Chandler et al, 1979), and in a mixed mite population of Tetranychus pacificus and Panonychus citri on almond (Youngman and Barnes, 1986;Youngman et al, 1988). Gillman et al (1999) observed that the damage caused by T. urticae increased on drought stressed buddleia plants. Ximénez-Embún et al (2016, 2017a, 2017b observed a global increase of performance of three important tomato mite pests, Tetranychus evansi, T. urticae and Aculops lycopersici, reared on drought-stressed tomato plants, especially for tomato-adapted strains in the case of T. urticae.…”

The response to drought-stressed host plants varies among herbivorous mite populations from a climate gradient

“…This pattern was also observed in Tetranychus urticae and Oligonychus pratensis on maize (Chandler et al, 1979), and in a mixed mite population of Tetranychus pacificus and Panonychus citri on almond (Youngman and Barnes, 1986; Youngman et al, 1988). Gillman et al (1999) observed that the damage caused by T. urticae increased on drought stressed buddleia plants. Ximénez-Embún et al (2016, 2017a, 2017b) observed a global increase of performance of three important tomato mite pests, Tetranychus evansi, T. urticae and Aculops lycopersici , reared on drought-stressed tomato plants, especially for tomato-adapted strains in the case of T. urticae .…”