Type of Document Master's Thesis Author Andrews, Heather Elizabeth Author's Email Address email@example.com URN etd-03292011-112552 Title Monitoring and management of thrips populations in vegetables, row crops, and greenhouse crops in Virginia Degree Master of Science In the Life Sciences Department Entomology Advisory Committee
Advisor Name Title Kuhar, Thomas P. Committee Chair Pfeiffer, Douglas G. Committee Co-Chair Herbert, David Ames Jr. Committee Member Schultz, Peter B. Committee Member Keywords
- Frankliniella fusca
- Frankliniella tritici
- Frankliniella occidentalis
Date of Defense 2011-03-03 Availability unrestricted AbstractThrips are pests in a variety of crops and are responsible for millions of dollars in damage
worldwide. In Virginia there are a few key thrips species that cause a large portion of damage to
both vegetable and floricultural crops. Three prominent pests include Frankliniella tritici
(Fitch), Frankliniella fusca (Hinds), and Frankliniella occidentalis (Pergande). Significant yield
losses in row crops such as cotton, peanuts and vegetables have been attributed to feeding and
oviposition of these insects in high densities. In addition, both F. fusca and F. occidentalis can
transmit plant pathogenic tospoviruses, such as tomato spotted wilt virus (TSWV), in certain
susceptible crops. While all of these thrips species are difficult to detect due to their cryptic
lifestyles, F. occidentalis is a particularly challenging pest to manage due to its resistance to
many insecticides commonly used for thrips treatment.
Early spring weeds were sampled for the presence of F. occidentalis in 2008 and 2009 in
eastern Virginia. Weed samples consisted of mustard, henbit and wild radish and were collected
from several different sites on the Eastern Shore of Virginia. During the summer of 2008, 2009
and 2010 various agroecosystems were sampled for the relative incidence of F. occidentalis.
Overall, thrips numbers were very low in weed samples. F. occidentalis was detected in early
spring weed samples in 2009 at a few of the sites sampled. In nearly every habitat, the species
composition was dominated by F. fusca and F. tritici, with F. occidentalis occurring in very low
Two different lures were evaluated in their ability to attract Frankliniella spp. thrips. The
lures included Chemtica P-178 floral kairomone (AgBio Inc., Westminster, CO), a floral
iii kairomone lure composed of a proprietary floral compound mixture, and ThriplineAMS (Syngenta
Bioline Ltd., Oxnard, CA) pheromone lure, containing the aggregation pheromone of F.
occidentalis. In spring 2009 and 2010 lure experiments were conducted in several different
agroecosystems including: a tomato and potato field in Painter, VA, a cotton and peanut field in
Suffolk, VA, and grass fields near a greenhouse in Virginia Beach, VA, and a high tunnel in
Chesapeake, VA, as well as within these structures. Baited and non-baited sticky cards were
arranged in a completely randomized design, with a pan trap located in the center of each plot.
Traps were collected approximately twice weekly. F. fusca numbers were low and catches on
sticky cards were not significantly affected by either lure. Sticky cards baited with the
kairomone caught more flower thrips than traps baited with the pheromone, or the non-baited
traps, especially when thrips numbers were high.
Several biologically derived insecticides including: essential oils, spinetoram, spinosad,
pyrethrins, and azadirachtin, were evaluated in their efficacy against thrips in several different
crops. Randomized complete block design experiments were carried out in: tomatoes, snap
beans, collards, soybeans, cotton and peanuts grown in several locations in southeastern Virginia
in 2009 and 2010. Both spinetoram and spinosad reduced thrips numbers the most effectively
compared with the untreated control. Peanut and cotton treated with spinosad, and treatments
containing spinetoram suffered less thrips injury compared with the control, and yield was higher
in cotton plots treated with spinetoram.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access Andrews_HE_2011.pdf 3.02 Mb 00:13:59 00:07:11 00:06:17 00:03:08 00:00:16
If you have questions or technical problems, please Contact DLA.