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Feeding and dispersal behavior of the cotton leafworm, Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), on Bt and non-Bt cotton: implications for evolution and resistance management.

Ramalho FS, Pachú JK, Lira AC, Malaquias JB, Zanuncio JC, Fernandes FS - PLoS ONE (2014)

Bottom Line: There was a greater acceptance by live neonate A. argillacea larvae for the non-Bt cotton plants compared with the Bt cotton plants, especially in the time interval between 18 and 24 h.The percentages of neonate A. argillacea larvae found on Bt or non-Bt plants were lower when exposed to temperatures of 31 and 34 °C.Therefore, our results are extremely important for the management of resistance in populations of A. argillacea on Bt cotton.

View Article: PubMed Central - PubMed

Affiliation: Unidade de Controle Biológico, Embrapa Algodão, Campina Grande, Paraíba, Brazil.

ABSTRACT
The host acceptance of neonate Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) larvae to Bt cotton plants exerts a strong influence on the potential risk that this pest will develop resistance to Bt cotton. This will also determine the efficiency of management strategies to prevent its resistance such as the "refuge-in-the-bag" strategy. In this study, we assessed the acceptance of neonate A. argillacea larvae to Bt and non-Bt cotton plants at different temperatures during the first 24 h after hatching. Two cotton cultivars were used in the study, one a Bt DP 404 BG (Bollgard) cultivar, and the other, an untransformed isoline, DP 4049 cultivar. There was a greater acceptance by live neonate A. argillacea larvae for the non-Bt cotton plants compared with the Bt cotton plants, especially in the time interval between 18 and 24 h. The percentages of neonate A. argillacea larvae found on Bt or non-Bt plants were lower when exposed to temperatures of 31 and 34 °C. The low acceptance of A. argillacea larvae for Bt cotton plants at high temperatures stimulated the dispersion of A. argillacea larvae. Our results support the hypothesis that the dispersion and/or feeding behavior of neonate A. argillacea larvae is different between Bt and non-Bt cotton. The presence of the Cry1Ac toxin in Bt cotton plants, and its probable detection by the A. argillacea larvae tasting or eating it, increases the probability of dispersion from the plant where the larvae began. These findings may help to understand how the A. argillacea larvae detect the Cry1Ac toxin in Bt cotton and how the toxin affects the dispersion behavior of the larvae over time. Therefore, our results are extremely important for the management of resistance in populations of A. argillacea on Bt cotton.

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Related in: MedlinePlus

Relationship between the mean percent of neonate larvae of A. argillacea recovered from plants of Bt cotton (y = 115.47 – 3.04x, R2 = 0.87, F1, 3 = 19.90, P<0.0210) and non-Bt cotton (y = 123.90 – 1.78x, R2 = 0.81, F1, 3 = 13.09, P<0.0363) and temperature after 24 h.Original data.
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pone-0111588-g002: Relationship between the mean percent of neonate larvae of A. argillacea recovered from plants of Bt cotton (y = 115.47 – 3.04x, R2 = 0.87, F1, 3 = 19.90, P<0.0210) and non-Bt cotton (y = 123.90 – 1.78x, R2 = 0.81, F1, 3 = 13.09, P<0.0363) and temperature after 24 h.Original data.

Mentions: A linear model best described the percentage of live A. argillacea larvae recovered from Bt or non-Bt cotton plants as a function of temperature (Fig. 2). The linear models showed that 81% and 87% of the variation for the average percentage of live A. argillacea larvae recovered from the non-Bt and Bt cotton plants, respectively, was explained by temperature (Fig. 2). However, the percentage of live A. argillacea larvae recovered from the cotton plants ranged from approximately 10.93% (34°C) to 48.60% (22°C) in Bt cotton plants, whereas it ranged from 63.80% (34°C) to 84.70% (22°C) in non-Bt cotton plants (Fig. 1A and Fig. 2).


Feeding and dispersal behavior of the cotton leafworm, Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), on Bt and non-Bt cotton: implications for evolution and resistance management.

Ramalho FS, Pachú JK, Lira AC, Malaquias JB, Zanuncio JC, Fernandes FS - PLoS ONE (2014)

Relationship between the mean percent of neonate larvae of A. argillacea recovered from plants of Bt cotton (y = 115.47 – 3.04x, R2 = 0.87, F1, 3 = 19.90, P<0.0210) and non-Bt cotton (y = 123.90 – 1.78x, R2 = 0.81, F1, 3 = 13.09, P<0.0363) and temperature after 24 h.Original data.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219722&req=5

pone-0111588-g002: Relationship between the mean percent of neonate larvae of A. argillacea recovered from plants of Bt cotton (y = 115.47 – 3.04x, R2 = 0.87, F1, 3 = 19.90, P<0.0210) and non-Bt cotton (y = 123.90 – 1.78x, R2 = 0.81, F1, 3 = 13.09, P<0.0363) and temperature after 24 h.Original data.
Mentions: A linear model best described the percentage of live A. argillacea larvae recovered from Bt or non-Bt cotton plants as a function of temperature (Fig. 2). The linear models showed that 81% and 87% of the variation for the average percentage of live A. argillacea larvae recovered from the non-Bt and Bt cotton plants, respectively, was explained by temperature (Fig. 2). However, the percentage of live A. argillacea larvae recovered from the cotton plants ranged from approximately 10.93% (34°C) to 48.60% (22°C) in Bt cotton plants, whereas it ranged from 63.80% (34°C) to 84.70% (22°C) in non-Bt cotton plants (Fig. 1A and Fig. 2).

Bottom Line: There was a greater acceptance by live neonate A. argillacea larvae for the non-Bt cotton plants compared with the Bt cotton plants, especially in the time interval between 18 and 24 h.The percentages of neonate A. argillacea larvae found on Bt or non-Bt plants were lower when exposed to temperatures of 31 and 34 °C.Therefore, our results are extremely important for the management of resistance in populations of A. argillacea on Bt cotton.

View Article: PubMed Central - PubMed

Affiliation: Unidade de Controle Biológico, Embrapa Algodão, Campina Grande, Paraíba, Brazil.

ABSTRACT
The host acceptance of neonate Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) larvae to Bt cotton plants exerts a strong influence on the potential risk that this pest will develop resistance to Bt cotton. This will also determine the efficiency of management strategies to prevent its resistance such as the "refuge-in-the-bag" strategy. In this study, we assessed the acceptance of neonate A. argillacea larvae to Bt and non-Bt cotton plants at different temperatures during the first 24 h after hatching. Two cotton cultivars were used in the study, one a Bt DP 404 BG (Bollgard) cultivar, and the other, an untransformed isoline, DP 4049 cultivar. There was a greater acceptance by live neonate A. argillacea larvae for the non-Bt cotton plants compared with the Bt cotton plants, especially in the time interval between 18 and 24 h. The percentages of neonate A. argillacea larvae found on Bt or non-Bt plants were lower when exposed to temperatures of 31 and 34 °C. The low acceptance of A. argillacea larvae for Bt cotton plants at high temperatures stimulated the dispersion of A. argillacea larvae. Our results support the hypothesis that the dispersion and/or feeding behavior of neonate A. argillacea larvae is different between Bt and non-Bt cotton. The presence of the Cry1Ac toxin in Bt cotton plants, and its probable detection by the A. argillacea larvae tasting or eating it, increases the probability of dispersion from the plant where the larvae began. These findings may help to understand how the A. argillacea larvae detect the Cry1Ac toxin in Bt cotton and how the toxin affects the dispersion behavior of the larvae over time. Therefore, our results are extremely important for the management of resistance in populations of A. argillacea on Bt cotton.

Show MeSH
Related in: MedlinePlus