- Fruits: apples, cherries, general tree fruits
- Pest Management: chemical control, integrated pest management
Obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), is one of the most destructive lepidopteran pests of tree fruits in Washington, causing severe damage by feeding on leaves and developing fruits. The use of broad-spectrum insecticides such as organophosphates (OPs) against OBLR for decades has led to the development of resistance in this pest leading to control failure in some cases. In this situation, the recently developed highly selective reduced-risk OP alternatives with novel modes of action, such as rynaxypyr and spinetoram, show promise for controlling OBLR. Now that OPs are being phased out, it is critical for growers to incorporate these novel chemicals into the OBLR management programs, but resistance remains a threat. Resistance management strategies are usually developed after it has occurred in the field, which is too late. Understanding of genetic, biochemical and molecular basis of resistance before its occurrence in the field would be a proactive approach, and could be extremely valuable in developing strategies to manage susceptibility leading to delay the development of resistance. This project is proposed to assess current levels of resistance and cross-resistance of OBLR populations, genetic potential of OBLR to develop resistance, and biochemical as well as molecular basis of resistance against the recently registered reduced-risk OP alternatives, rynaxypyr and spinetoram. It will allow growers to incorporate these chemicals into IPM programs for OBLR in a way that will minimize selection pressure on OBLR populations in orchards leading to delay the resistance evolution as much as possible, thereby providing for successful control of OBLR with highly selective and environmentally friendly chemicals on sustainable basis.
Project objectives from proposal:
The primary goal of this project is to provide tree fruit growers with information that will enable them to incorporate the recently developed reduced-risk OP alternatives, rynaxypyr and spinetoram, into IPM programs to control OBLR on sustainable basis in an economical and environmentally friendly manner. This goal will be achieved under the main objectives, which are to: 1) determine the current levels of resistance and cross-resistance in field-collected populations of OBLR to the novel reduced-risk chemicals, 2) assess the genetic potential of OBLR to develop resistance against the novel reduced-risk chemicals, and 3) determine the biochemical and molecular basis of underlying mechanisms of resistance against these chemicals in OBLR. Once available, this information will enable tree fruit growers and pest management consultants to design sustainable IPM programs for OBLR, and help them in the process of transitioning from OPs to the reduced-risk alternatives, especially at this time when OPs are being phased out by the Environmental Protection Agency (EPA).
Timeline: I (the graduate student) have already started working on objectives 1 and 2. The work on objective 1 will be completed in the field season of 2010 by conducting a statewide survey of field-collected OBLR populations to determine the current (at the time) levels of resistance and cross-resistance to these chemicals. The work on objective 2 has already been started in the form of selecting for resistance in the laboratory, and it will continue until significant levels of resistance against rynaxypyr and spinetoram have developed and/or further increase in LC50 values in the selected population ceases, probably in spring 2010. The work on objectives 3 will be started as soon as the populations being selected for resistance have developed high levels of resistance and/or further increase in LC50 values in the selected population ceases, probably in spring 2010 and will be completed by the end of summer 2010. The graduate student in cooperation with the major advisor will disseminate information generated in this study as it becomes available, through all means mentioned in Publications and Educational Materials and Outreach Plan sections. The surveys to determine producer adoption will be conducted at the end of the 2010 field season as mentioned in Producer Adoption section. Finally, the progress report will be submitted by the graduate student to Western SARE authorities after completing the analysis of data collected in the 2010 field season and summarizing the results of the producer adoption assessment surveys.