Location: Great Basin Rangelands Research
Project Number: 2060-22000-025-011-I
Project Type: Interagency Reimbursable Agreement
Start Date: Oct 1, 2021
End Date: Sep 30, 2026
Building on research progress made under a prior IAA, ARS-Reno will continue explorations in the native ranges of targeted invasive annual grasses (IAGs) for natural enemies (e.g. insects and mites), in collaboration with in-country scientists. Natural enemies of IAGs that are discovered in these surveys will be biologically evaluated for their suitability for release in the Intermountain West as biological control agents (BCAs). Explorations will also continue in the Intermountain West to determine whether native range natural enemies of IAGs have been introduced along with their hosts and, if so, whether these natural enemies appear to be limiting IAG population growth.
The immediate goals of this IAA and the approaches are as follows: 1. Continue native range explorations for candidate BCAs of medusahead and cheatgrass, as well as red brome (Anisantha rubens) and wiregrass (Ventenata dubia), the latter of which is a new target weed that was recently added to the ARS IAG biocontrol program due to its rising stakeholder interest. These explorations will be performed in conjunction with in-country collaborators in Europe and/or central Asia. 2. Biological evaluations of A. altamurgiensis, A. dicristinae, S. tectori, T. amica. Colonies of these candidates will be maintained (or established) in the laboratories of native range, in-country collaborators to provide mites and insects for testing host-specificity, as well as to determine the type and extent of damage caused by the natural enemies to their host plants and what effect this damage would have on invasive populations of the host plants. Candidate BCAs may also be imported into a collaborator’s quarantined laboratory at ARS-Albany for additional host-specificity and impact studies. 3. Continue surveys of the Intermountain West invaded range of the targeted IAGs. Given the discovery of A. altamurgiensis in California, it is imperative to determine what is the geographical distribution of this mite in America, not least to know whether it is having any effect on the invasive medusahead population(s) that it infests. Surveying for A. altamurgiensis in multiple states with invasive medusahead populations will also be essential. We will also survey all targeted IAGs in the Intermountain West for natural enemies. 4. To supplement the traditional “collect and dissect” methods of surveying for natural enemies of IAG, we will begin employing a metagenomic protocol for surveying IAG populations for natural enemies. Because many of the natural enemies of these small target plants are themselves very small (indeed, eriophyid mites are invisible to the naked eye) and the damage they cause to their hosts is often difficult to notice without extensive biological studies (e.g. damage to seeds that reduces germination or seed parasitism), we will collect plants from the field, return them to the laboratory, where they will be flash frozen and freeze-dried, then extract their DNA and test that DNA with PCR primers specific to mites, midges, weevils, and other prospective natural enemies. Inconspicuous mites or tiny insects that were infesting these plants would have their DNA extracted, along with the host plant; the PCR will detect that mite or insect with the possibility of also matching it to known species.