Effects of transgenic Bacillus thuringiensis cotton on insecticide use, heliothine counts, plant damage, and cotton yield: A meta-analysis, 1996-2015

Authors: FLEMING, DANIEL - Mississippi State University; MUSSER, FRED - Mississippi State University; REISIG, DOMINIC - North Carolina State University; GREENE, JEREMY - Clemson University; TAYLOR, SALLY - Virginia State University; PARAJULEE, MEGHA - Texas A&M University; LORENZ, GUS - University Of Arkansas; CATCHOT, ANGUS - Mississippi State University; GORE, JEFF - Mississippi State University; KERNS, DAVID - Texas A&M University; STEWART, SCOTT - University Of Arkansas; Boykin, Deborah; CAPRIO, MICHAEL - Mississippi State University; Little, Nathan

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2018
Publication Date: 7/19/2018
Citation: Fleming, D., Musser, F., Reisig, D., Greene, J., Taylor, S., Parajulee, M., Lorenz, G., Catchot, A., Gore, J., Kerns, D., Stewart, S., Boykin, D.L., Caprio, M., Little, N. 2018. Effects of transgenic Bacillus thuringiensis cotton technologies on heliothine counts, plant damage, and cotton yield: a meta-analysis, 1996-2015. PLoS One. 13(7):e0200131. https://doi.org/10.1371/journal.pone.0200131.
DOI: https://doi.org/10.1371/journal.pone.0200131

Interpretive Summary: Since the mid-1990s, cotton expressing insecticidal toxins (Bt cotton) has been the primary means of controlling caterpillar pests. We examined the effects of different Bt cotton technologies for control of two of these pests, bollworm and tobacco budworm, across a 20 year span by performing meta analyses on caterpillar densities, damage to cotton fruiting structures, and lint yield. All published literature and data from unpublished tests pertaining to natural caterpillar populations in field trials that contained both Bt and non-Bt cottons were used to evaluate the effectiveness of Bt at reducing synthetic insecticide applications, lessening damage to fruiting structures, and increasing lint yield. Analyses of published and unpublished data revealed a reduction in the usage of synthetic insecticides for caterpillar control in Bt cotton over the 20 year span of this study. It also revealed a slight decline in the efficacy of some Bt technologies with regard to caterpillar control and the resultant damage to cotton fruiting structures. After 20-plus years of use, Bt cotton remains an economically effective tool for producers to control caterpillar pests in cotton.

Technical Abstract: The primary management tactic for lepidopteran pests of cotton in the United States of America (USA) is the use of transgenic cotton modified to express Bacillus thuringiensis Berliner (Bt) toxins. The primary target pests of this technology are Helicoverpa zea (Boddie) and Heliothis virescens (F.) in the eastern Cotton Belt of the USA. Concerns over the evolution of resistance in H. zea to Bt toxins and scrutiny of the necessity of Bt crops has escalated. This project reviewed the body of literature for field trials of Bt cotton in the eastern Cotton Belt of the USA to evaluate the effectiveness of Bt cotton technologies (Bollgard®, Bollgard® II, WideStrike®, WideStrike® 3, and TwinLink®) at reducing insecticide usage, to determine if changes in efficacy or yield of Bt cotton has changed over time, and to evaluate the efficacy of Bt cotton technologies relative to non-Bt varieties and each other. Evaluations of Bt cotton technologies revealed that Bt cotton technologies reduced insecticide usage, reduced heliothine pest numbers and damage, provided a yield benefit, and that Bollgard II and WideStrike efficacy is declining in the Midsouth. Taken together, the results of this study revealed that Bt technology remains a valuable tool for managing heliothine pests in cotton, but Bollgard II and WideStrike technologies are losing efficacy.