Field Performance of a Self-Limiting, Genetically Engineered Fall Armyworm for Biological Pest Management

Catherine E. Reavey^1*Felipe A. Domingues²Kyla Ercit¹Ricardo L. Pinto²Neil Naish¹Mayur Yadav¹Tamires Frazon²Katarzyna Cabala¹Edward Sulston¹Angela Pickl-Herk¹Matt Edwards¹Leonardo L. Miraldo²Dyrson Abbade Neto²Mike Darrington¹Larissa Silva²Flavia E. Furquim²Juliana G. Rodrigues²Isabella de Oliveira Simoni²Túlio Silva²Welton Magalhaes²Thea Marubbi¹Mattia Poletto¹Benjamin D. Sperry¹David Treanor¹Jordan McAlinden¹Sam Buckby¹Thais de Andrade Bettoni²Hellen M. Couto de Abreu²Natalia C. Verza²Nathan R. Rose¹Grey K. Frandsen¹Neil I. Morrison¹Kelly J. Matzen^1*

• ¹Oxitec (United Kingdom), Abingdon, United Kingdom
• ²Oxitec do Brasil, Campinas, São Paulo, Brazil

The fall armyworm is one of the most globally significant agricultural pests, damaging corn, sorghum and other crops central to food production. It has developed resistance to several classes of chemical insecticides and, more recently, insect-resistant 'Bt' biotech corn varieties. As Bt varieties constitute the great majority of corn acreage in Brazil, proactive resistance management strategies are required to protect the durability of insecticidal efficacy of those cultivars. Previously, we reported on the development of a 'self-limiting' fall armyworm strain, called OX5382G, which -after release in the field -is engineered to suppress populations of fall armyworm and manage resistance to Bt crops in treated populations of this pest. Here, we build on this work by carrying out contained studies which empirically demonstrated the pest suppression and resistance management benefits of releasing OX5382G males. We also report on the first open field releases of the OX5382G self-limiting strain in Brazil. Over two corn seasons, OX5382G males showed comparable performance with wild-type counterparts in terms of dispersal and mating ability. Post-release monitoring demonstrated that OX5382G moths show lifespans typical of fall armyworm moths. Following commercial biosafety approval of this strain by Brazilian government regulators, we then assessed deployment-relevant OX5382G male performance, in larger, operational trials in Brazil, showing that OX5382G mated effectively in the field and that relatively modest release rates can achieve over-flooding ratios expected to exert suppression and/or resistance management. All assessments to date suggest that self-limiting fall armyworm is a promising future tool for managing fall armyworm and extending the durability of Bt crops' effectiveness against damaging lepidopteran pests.