Question

Fractions of a field of Bt crops planted with non-Bt-expressing varieties: Select all that apply.

ensure that selection for Bt resistance is not too intense within herbivore populations.

lead to higher losses to pests in the short term than if no fractions were planted with non-Bt-expressing varieties, but maintain the effectiveness of Bt in protecting crops in the long term.

ensure that herbivore genes conferring susceptibility to Bt are well represented in the next generation.

impede the complete eradication of important agricultural pests.

Answer 1

1 ensures that selection for Bt resistance is not too intense within herbivore populations.

2. ensure that herbivore genes conferring susceptibility to Bt are well represented in the next generation.

3. lead to higher losses to pests in the short term than if no fractions were planted with non-Bt-expressing varieties, but maintain the effectiveness of Bt in protecting crops in the long term.

(The commercialization of plants that express Cry proteins from Bt for management of insects revolutionize agriculture and is an important tool for IPM. Thu Bt crops ensure reduced use of insecticides as well as suppression of important agricultural pests. However, this benefit is limited due to the evolution of resistance. The strategy most commonly used to delay pest resistance to Bt crops is the use of non-Bt host plants as a refuge for Bt susceptible genotypes. Fractions of a field of Bt crops planted with non-Bt-expressing varieties ensure that selection for Bt resistance is not too intense, herbivore genes conferring susceptibility to Bt are well represented in the next generation and if no fractions are planted leads to higher losses to pests).