Shifts in Ecological Dominance between Two Lepidopteran Species in Refuge Areas of Bt Cotton

Abstract

Competition behavior involving agricultural pest species has long been viewed as a powerful selective force that drives ecological and phenotypic diversity. In this context, a Game Theory-based approach may be useful to describe the decision-making dilemma of a competitor with impacts to guarantee its superiority in terms of ecological dominance or sharing of the food resource with its competitor. In an attempt to elucidate the consequences of competitive dynamics for the ecological dominance of these species in refuge areas of Bt cotton, we conducted a study that was divided into two parts. The first study consisted of an evaluation of interactions involving Spodoptera frugiperda (JE Smith, 1797) and Helicoverpa armigera (Hübner, 1808) on non-Bt cotton plants in a field trial. In the second study, we explored the data matrix collected in the field to parameterize a model of Cellular Automata (CA) with update rules inspired by Game Theory. Computer simulations were analyzed in hypothetical scenarios involving the application (or not) of insecticides in the refuge areas in combination with the resistance factor of one or both pest species to the insecticides used in the refuge areas. H. armigera had superior competitive performance in relation to S. frugiperda only at high densities. According to the density-mediated shift in dominance of the species, the resistance of S. frugiperda to insecticides is seen as a risk factor for the production of susceptible individuals of H. armigera on a large scale in the refuge areas. Additionally, S. frugiperda insecticide resistance may potentially impact the resistance evolution of the H. armigera population to Bt cotton. Thus, ecological dominance could diverge by the presence of a resistance allele to insecticides with interspecific competition perhaps subordinate to evolutionary processes.

Intercropped Bt and non‐Bt corn with ruzigrass (Urochloa ruziziensis) as a tool to resistance management of Spodoptera frugiperda (JE Smith, 1797) (Lepidoptera: Noctuidae)

“…[72][73][74] These cause high levels of mortality in susceptible and heterozygous larvae, even when initially fed with non-Bt corn for a period of 10 days, 65 and have a high effectiveness in the field. 37 Studies that aim to understand larval movement between plants and the interactions with other trophic levels, 22,26 such as other pest species 75 and Bt plant physiology, 76 are necessary to predict the consequences on resistance evolution. This should allow more informed recommendations for the intercropping of ruzigrass with Bt or non-Bt corn.…”

Modeling the Resistance Evolution to Insecticides Driven by Lepidopteran Species Competition in Cotton, Soybean, and Corn Crops

“…To prevent or significantly delay insect resistance to Bt crops, such as cotton, corn, or soybean, refuge areas should be planted with non-Bt plants and cover a significant percentage of the acreage in the field [ 8 , 9 , 10 , 11 ]. Malaquias et al [ 8 ] analyzed how the adoption of insecticide and the competition between the lepidopteran species S. frugiperda and H. armigera could impact the production of susceptible individuals in refuge areas of Bt cotton.…”

“…To prevent or significantly delay insect resistance to Bt crops, such as cotton, corn, or soybean, refuge areas should be planted with non-Bt plants and cover a significant percentage of the acreage in the field [ 8 , 9 , 10 , 11 ]. Malaquias et al [ 8 ] analyzed how the adoption of insecticide and the competition between the lepidopteran species S. frugiperda and H. armigera could impact the production of susceptible individuals in refuge areas of Bt cotton. They warned that ecological dominance may diverge due to resistance alleles because insecticide resistance in S. frugiperda could impact the production of susceptible H. armigera individuals on a large scale in refuge areas.…”

“…Game theory provides a mathematical framework for examining the evolution of behavioral strategies that can be employed during competition [ 13 ]. A game model can be defined as a competitive activity involving skill, chance, or endurance on the part of two or more players who make strategic decisions [ 8 ]. Mathematical games have strict rules and specify what is allowed and what is not.…”

Evolutionary process modeling with Bayesian inference of Spodoptera frugiperda ballooning and walking dispersal in Bt and non‐Bt cotton plant mixtures

“…The bulk of Bt crops is grown in the USA, Brazil, Argentina, India, Canada, and China (ISAAA, 2016). Resistance evolution in targeted insects, negating the toxicity of Bt crops, is a great concern (Malaquias et al, 2021). In some cases, if steps are not taken to manage the evolutionary process, resistance could render Bt crops ineffective in a few insect generations.…”