Table 3 Comparison of infestation rates across all tree species, crown and stem injury ratings, and infestation rates of individual tree species by two invasive ambrosia beetles, polyphagous shot hole borer (PSHB), Euwallacea whitfordiodendrus, and Kuroshio shot hole borer (KSHB), E. kuroshio, in southern California, USA. Only tree species occurring in survey plots for both PSHB and KSHB are included in this analysis
Parameter | Species | X 1 2 | P value | |
|---|---|---|---|---|
Infestation | PSHB | KSHB | ||
Total | 59.3% (1473/2483) | 65.1% (384/590) | 6.38 | 0.01 |
Native trees | 60.4% (963/1594) | 70.1% (326/465) | 14.0 | < 0.01 |
Ornamental trees | 57.4% (510/889) | 46.4% (58/125) | 4.9 | 0.03 |
Crown rating | ||||
  1 | 61.3% (1523/2483) | 53.3% (252/473) | 10.4 | < 0.001 |
  2 | 17.7% (439/2483) | 17.1% (81/473) | 0.00 | 1 |
  3 | 8.62% (214/2483) | 19.5% (92/473) | 49.1 | < 0.001 |
  4 | 5.44% (135/2483) | 1.69% (8/473) | 12.2 | < 0.001 |
  5 | 5.64% (140/2483) | 7.82% (37/473) | 2.99 | 0.08 |
Stem injury rating | ||||
  1 | 30.8% (764/2483) | 13.2% (78/590) | 72.9 | < 0.001 |
  2 | 8.74% (217/2483) | 9.49% (56/590) | 0.25 | 0.62 |
  3 | 20.1% (498/2483) | 41.9% (247/590) | 122 | < 0.001 |
Infestation by species | ||||
  American sweetgum, Liquidambar styraciflua L. | 25.5% (13/51) | 0% (0/10) | 1.90 | 0.17 |
  Evergreen ash, Fraxinus uhdei (Wenz.) Lingl. | 23.0% (32/139) | 0% (0/8) | 1.20 | 0.27 |
  Arroyo willow, Salix lasiolepis Benth. | 83.3% (10/12) | 72.1% (235/326) | 0.25 | 0.62 |
  Fremont cottonwood, Populus fremontii S. Watson | 56.2% (50/89) | 46.2% (24/52) | 0.95 | 0.33 |
  Goodding’s black willow, Salix gooddingii C.R. Ball | 77.3% (51/66) | 81.0% (17/21) | 0.003 | 0.96 |
  Southern magnolia, Magnolia grandifolia L. | 0.00% (0/7) | 9.09% (1/11) | 0.00 | 1.00 |
  Western sycamore, Platanus racemosa Nutt. | 80.0% (340/425) | 79.0% (45/57) | 0.00 | 1.00 |
  Castorbean, Ricinus communis L. | 71.4% (20/28) | 60.0% (3/5) | 0.00 | 1.00 |