Complex Outcomes from Insect and Weed Control with Transgenic Plants: Ecological Surprises?

Abstract

Agriculture is fundamental for human survival through food production and is performed in ecosystems that, while simplified, still operate along ecological principles and retain complexity. Agricultural plants are thus part of ecological systems, and interact in complex ways with the surrounding terrestrial, soil, and aquatic habitats. We discuss three case studies that demonstrate how agricultural solutions to pest and weed control, if they overlook important ecological and evolutionary factors, cause "surprises": (i) the fast emergence of resistance against the crop-inserted Bt-toxin in South Africa, (ii) the ecological changes generated by Bt-cotton landscapes in China, and (iii) the decline of the monarch butterfly, Danaus plexippus, in North America. The recognition that we work with complex systems is in itself important, as it should limit the belief in reductionist solutions. Agricultural practices lacking eco-evolutionary understanding result in "surprises" like resistance evolution both in weeds and pest insects, risking the reappearance of the "pesticide treadmill"-with increased use of toxic pesticides as the follow-up. We recommend prioritization of research that counteracts the tendencies of reductionist approaches. These may be beneficial on a short term, but with trade-off costs on a medium-to long-term. Such costs include loss of biodiversity, ecosystem services, long-term soil productivity, pollution, and reduced food quality.

Can the growing of transgenic maize threaten protected Lepidoptera in Europe?

“…Modeling and detailed field studies would still be needed to understand why GM maize in North America threatens the monarch butterfly (Stenoien et al, 2018)-similar studies are sorely lacking in Europe (but see Holst et al, 2013). Conditions in the current European cultivated landscapes are rarely favorable for butterflies (Bubova et al, 2015), and additional changes in landscapes and cultivation practices, both of which will be unavoidable under widespread GM crop cultivation (Bøhn & Lövei, 2017), will be unlikely to improve the current suboptimal situation for butterflies. Butterfly diversity is still high in some agricultural settings in Europe, for example, in Romania (Loos et al, 2014(Loos et al, , 2015, and GM crop cultivation could affect this high level of species richness.…”

Transgenic Cotton (Gossypium hirsutum L.) to Combat Weed Vagaries: Utility of an Apical Meristem-Targeted in planta Transformation Strategy to Introgress a Modified CP4-EPSPS Gene for Glyphosate Tolerance

“…Crop improvement through genetic engineering has given the feasibility to engineer plants to combat herbicides being sprayed and thus help in the safety of the crops without major yield losses (Benbrook, 2016;Bohn and Lovei, 2017). Various genes that confer herbicide tolerance have been identified, validated, and introgressed into a multitude of crops including cotton (Awan et al, 2015;Liang et al, 2017;Zhang et al, 2017).…”

Understanding the impact of Bacillus thuringiensis proteins on non-target organisms

“…Contrasting evidence of effects on non-targets, ranging from unobservable effects of intake of Bt transgenic crops [41,42,43,44], to number of harmful effects (viz. delay in development, reduction in weight gain, changes in behavior or increased mortality) on beneficial organisms like pollinators [45], non-target arthropods [46,47,48], parasitoids [49] and predators [50,51] are present.…”