Intercrops can mitigate pollen-mediated gene flow from transgenic cotton while simultaneously reducing pest...

Area of Science:

• Agricultural Science
• Ecology
• Genetics

Background:

• Genetically modified (GM) cotton expressing Bt toxins is widely used in China for insect resistance.
• Pollen-mediated gene flow (PGF) from GM crops poses potential ecological risks.
• Understanding PGF mitigation strategies is crucial for sustainable agricultural practices.

Purpose of the Study:

• To evaluate the effectiveness of intercropping sunflower, buckwheat, and soybean in reducing PGF from GM cotton.
• To assess the impact of these intercrops on insect pest populations in cotton fields.
• To determine the best-fit model for pollen dispersal from GM cotton.

Main Methods:

• A two-year field trial (2017-2018) was conducted with GM cotton intercropped with sunflower, buckwheat, and soybean.
• DNA testing of hybridized seeds was used to quantify PGF rates.
• Insect pest populations were monitored on cotton plants in intercropping treatments.
• Pollen dispersal was modeled using an exponential decay function.

Main Results:

• PGF was significantly lower in cotton intercropped with buckwheat or sunflower compared to monoculture.
• PGF decreased exponentially with increasing distance from GM cotton fields, modeled by Y = -lnx.
• Sunflower and buckwheat intercrops reduced populations of certain aphids and whiteflies but increased spider mite densities.
• Buckwheat intercrops attracted natural enemies of pests, contributing to pest control.

Conclusions:

• Sunflower and buckwheat are effective intercrops for reducing PGF from GM cotton.
• Intercropping can be a valuable strategy for managing PGF in insect-pollinated GM crops.
• Intercropping offers potential co-benefits for pest management in agricultural landscapes.