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ARS Home » Research » Publications at this Location » Publication #82916
Title: AN EVALUATION OF RESISTANCE TO BT TOXINS IN NATIVE POPULATIONS OF THE PINK BOLLWORM

Author
item Bartlett, Alan
item DENNEHY, TIM - UNIV OF ARIZONA, TUCSON
item ANTILLA, LARRY - ACRPC, TEMPE, AZ

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 6/1/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: In 1996 approximately 25t of the cotton acreage in Arizona was planted with transgenic varieties of cotton. These varieties produce a specific insect control protein (derived from Bacillus thuringiensis) in their leaves, stems, and fruiting parts which is very toxic to the pink bollworm. Unfortunately, the effectiveness of these transgenic plants in controlling pink bollworm also assures that high selective pressure will be placed on the insect which could produce resistance to that toxic protein. To measure the present levels of resistance to this toxin, we exposed first instar pink bollworm larvae from cotton fields in five locations in Arizona (Stanfield, Yuma, Buckeye, Parker, and Marana) to artificial diet containing doses of a purified solution of the Bacillus thuringiensis (bt) entomotoxin cryIA(c). Newly hatched larvae from two established laboratory strains, APHIS (a bt toxin susceptible strain) and SOOTY-BTX (a bt toxin resistant strain) were also exposed to the same doses of bt toxin. No mature individuals (individuals which were able to pupate) were produced from any of the native strains or from the APHIS strain at toxin doses exceeding 0.005 ug/ml. Mature individuals were found at all doses administered to the resistant strain. Some third instar larvae were found at toxin doses higher than 0.005 ug/ml, but none completed development during the duration of the tests. At present, the levels of resistance to this toxin are low in Arizona populations of the pink bollworm.

Technical Abstract: Bolls infested with pink bollworm were collected from cotton fields in five locations in Arizona (Stanfield, Yuma, Buckeye, Parker, and Marana). Eggs were then gathered from the adult pink bollworm resulting from those collections and newly hatched larvae from those eggs were subjected to artificial diet containing doses of a purified solution of the Bacillus thuringiensis (bt) entomotoxin crylA(c). The dosages of toxin were 0.00125 0.0025, 0.005. 0.01, 0.02 0.04, and 0.0 ug/ml. Newly hatched larvae from two established laboratory strains, APHIS (a bt toxin susceptible strain) and SOOTY-BTX (a bt toxin resistant strain) were also exposed to the same doses of bt toxin. No mature individuals (individuals which were able to pupate) were produced from any of the native strains or from the APHIS strain at toxin doses exceeding 0.005 ug/ml. Mature individuals were found at all doses administered to the resistant strain. Some third instar larvae ewere found at toxin doses higher than 0.005 ug/ml, but none which complete development during the duration of the tests.