Specialist and generalist phytoseiid mites are widely used for biological
control of spider mites. Understanding dispersal attributes of these mites is
important to implementing more stable, cost-efficient integrated pest management.
In this regard, we studied dispersal of phytoseiid mites from a local ambulatory
phase of movement within a prey patch to a longer-range phase that includes
emigration (aerial take-off and dispersal distance) and immigration to a new plant.
Specialist phytoseiids showed higher ambulatory and aerial dispersal than
generalist species. Somewhat different dispersal strategies were seen between
Neoseiulus fallacis (more specialized predator) and N. calfornicus (more
generalized predator): The most important difference was earlier and continuous
dispersal of N. californicus from a prey patch. Cues from spider mite infestation
suppressed the dispersal rates for specialists, but either increased or did not change
the dispersal rates for generalist phytoseiids.
Aerodynamic calculations support the hypothesis that Phytoseiulus
persimilis may not require a standing take-off behavior to become airborne.
However, with less vertical profile, a mite may become airborne more by standing
erect (N. fallacis), than a species that does not show standing take-off (N.
calfornicus). Jumping behavior by P. persimilis was observed for the first time
among Phytoseiidae.
Falling speed ranged from 0.4 to 0.73 m/s for 13 phytoseiid species and
0.79 to 0.81 for two-spotted spider mite. These values were quite similar to
theoretical estimates for specialist phytoseiids, but less for generalists. From falling
speed estimates and other morphological data, it was possible to predict aerial
dispersal distance of phytoseiids using analytical models.
After landing on bare soil following aerial dispersal, high mortality of N.
fallacis was observed in the field during summer. Distance from the landing point
to target plants showed negative log linear relationships. Soil surfaces and
management actions influenced survival and recovery. Environmental conditions
greatly affected survival of the predator. We speculated that phytoseiids that fell on
ground were moving to the target plants via both ambulatory and aerial means. / Graduation date: 2001
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32729 |
| Date | 11 January 2001 |
| Creators | Jung, Chuleui |
| Contributors | Croft, Brian A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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