Title page for ETD etd-03292011-112552

Type of Document Master's Thesis
Author Andrews, Heather Elizabeth
Author's Email Address heather8@vt.edu
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
  • IPM
  • insecticides
  • pheromone
  • Frankliniella fusca
  • Frankliniella tritici
  • Frankliniella occidentalis
  • thrips
  • kairomone
Date of Defense 2011-03-03
Availability unrestricted
Thrips 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.

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