New strategies to combat an invasive agricultural pest

Abstract

The Old World Cotton Bollworm, Helicoverpa armigera, is one of the most injurious pests of agriculture in Asia, Africa, and Australia. And now this pest species has invaded Brazil and is spreading to other countries in South America. It has the potential to hybridize with a closely related native pest, the Corn Earworm Helicoverpa zea, which has an even wider host range. Helicoverpa zea could previously be controlled by chemical insecticides because it had not developed resistance, but H. armigera attacks many of the same crops and cannot be controlled using chemical sprays. There is genetic evidence for hybridization between the two species and hybrids could form a new super-pest. These issues are associated with objectives of the project "Young Investigators Awards" FAPESP (2014/11495-3)". Here, we built a strategic proposal to collaboration with Dr. David Heckel (Max Planck Institute in Germany) with the overall goals of our study to determine the nature of the problem and to propose new strategies to control the pest and to assess the danger of hybridization. Both the German and Brazilian teams are at the top of their respective fields, as can be seen by the publications of participating personnel. ESALQ is the leading agricultural institution in Brazil. The Max Planck Institute for Chemical Ecology is the leading institute in chemical ecology worldwide. Thus, our specific objectives are Aim 1) To determine the levels of resistance to chemical insecticides and Bt toxins of invasive H. armigera populations in Brazil, compared with tolerance levels of the native H. zea, to determine the extent of the resistance problem in the invasive pest. Aim 2) To determine the sex pheromone composition emitted by invasive H. armigera females, and the maximally attractive blend to invasive H. armigera males, compared with the pheromones of the native H. zea, to evaluate the potential for use of pheromones in monitoring and population suppression. Aim 3) To assess the levels of hybridization of field populations of H. armigera and H. zea using molecular markers, to determine the likelihood that hybridization could produce a super-pest. Aim 4) To survey Brazilian populations of the invasive H. armigera and the native H. zea for parasites, specifically a neogregarine parasite Ophryocystis sp found in Australian H. armigera populations, in order to investigate the possibility of releasing this parasite as a biological means of pest control. This proposal is the first step to consolidate to the application of new research tools, directions, and synergistic collaborations to investigate the interactions between insects and agroecosystems. This research will not only lead to the development of durable solutions that improve insect pest management but provide a training opportunity for students to integrate basic and foundational science with applied and practical problems. We believe that a formal partnership with Dr. David Heckel is one more step to consolidate the Arthropod Molecular Ecology applied to agriculture insects in Brazil. (AU)