MODELING INVASION OF PESTS RESISTANT TO Bt TOXINS PRODUCED BY GENETICALLY MODIFIED PLANTS: RECESSIVE VS. DOMINANT INVADERS

. There is a growing public concern about the ecological and evolutionary consequence of the use of genetically modified organisms. We study the impact of Bt resistant pests on genetically modified Bt crops and compare exposure of Bt plants to recessive and dominant Bt resistant invaders. To simulate pest invasion we develop a conceptual reaction‐diffusion model of the Bt crop Bt susceptible insects Bt resistant insects for both the recessive and dominant pests. We show by means of computer simulations that there is a key parameter which we define as the growth number that characterizes the insects' fitness. We also show that the Bt resistant insects' invasion can lead to inhomogeneity in plant and insect spatial distributions. The plant and insect spatial patterns resulting from the Bt resistant insects' invasion are found to be dependent on the duration of the Bt resistant insect reproduction period. We compare averaged plant biomass resulting from the invasion of the dominant insects with the averaged plant biomass resulting from the invasion of the recessive insects. As a result, we show that in contrast to the recessive insects, the dominant ones initiate destruction of the plant population if the inflow of Bt susceptible insects is more than a critical value. In this case the plant biomass decays to zero. Otherwise, the plant biomass under the invasion of both the dominant and recessive insects depends on the duration of the insect reproduction period. We conclude that under invasion of dominant Bt resistant pests, the refuge strategy which has received wide acceptance in agricultural practice may not be scientifically sound practice.