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Theses and Dissertations

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Browsing Theses and Dissertations by Subject "Agronomy"

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    Integrated pest management of tomato/potato psyllid, Paratrioza cockerelli (SULC) (Homoptera: Psyllidae) with emphasis on its importance in greenhouse grown tomatoes
    (Colorado State University. Libraries, 1999) Al-Jabr, Ahmed Mohammad, author; Cranshaw, Whitney S., advisor; Bojstad, Louis B., committee member; Kondratieff, Boris C., committee member; Moore, Frank D., committee member
    The tomato (potato) psyllid, Paratrioza cockerelli (Sulc), has developed into a key insect pest of greenhouse tomatoes of western North America and few options have been available for its management. A series of trials were thus conducted to identify techniques that could be used in establishing an integrated pest management (IPM) program for the insect. In studies investigating improvements in sampling methods for tomato psyllid, the effects of trap color, trap orientation and height in respect to the crop were evaluated. Greatest captures of adult psyllids occurred on neon-green, neon-orange and standard yellow colored traps. Traps hung near the top of tomato plants captured significantly more psyllids than traps placed near the base of plants. Traps that were shaded or not orientated to receive direct sunlight caught fewer adult psyllids than did sun-exposed traps. Screening of potential psyllid control products emphasized those that were efficacious but also compatible with other insects used in greenhouse tomato production (e.g., parasitoids for whitefly control, pollinators). Tested materials included insecticides of microbial origin (Beauveria bassiana, Verticillium lecanii, Metarhizium anisopliae), microbial-derived insecticides (spinosad), selective synthetic insecticides (acetamiprid, pymetrozine) and selective botanical products (neem) for tomato psyllid control. The capability of B. bassiana to infect tomato psyllid and produce high mortality is reported for the first time. Acetamiprid, spinosad and formulations of Beauveria bassiana were particularly effective for control of tomato psyllid, consistently providing in excess of 80 percent control. As the latter two also are reportedly compatible with beneficial insects used in greenhouse tomato production they appear to show greatest potential for use in an integrated pest management program on the crop. Also, in trials of various repellents (Azatin XL, Trilogy, SunSpray and Garlic Barrier) for deterring oviposition, SunSpray and Trilogy did result in significant reductions in oviposition on treated leaves. Two species of green lacewings, Chrysoperla carnea Stephens and C. rufilabris (Burmeister) were evaluated for potential use as biological controls of tomato psyllid. Both species were capable of completing their life cycle on tomato psyllid. Chrysoperla carnea larvae consumed approximately twice as many psyllids as did C. rufilabris, but development of the latter was 50% faster (8 days vs. 12 days). An outdoor field trial involving applications of C. carnea eggs to psyllid-infested potatoes did not produce reductions in psyllid numbers. As soil applications of imidacloprid had previously been found to be highly effective for tomato psyllid, and had registration for use on field grown tomatoes, investigations were conducted on possible non-target effects on pollinators, specifically the bumble bee Bombus terricola occidentalis (Greene). Indications of adverse effects from imidacloprid were observed during these trials, including reduced activity of bees within the hive, reduced visitation to flowers, and often, reduced survival.