Location: Invasive Plant Research Laboratory
Project Number: 6032-22000-013-156-A
Project Type: Cooperative Agreement
Start Date: Sep 22, 2025
End Date: May 30, 2026
Objective:
Develop potential agents from Australia, Japan, and South Korea to assist American farmers control cogongrass in the USA. These include three stem boring species The host range and impact of these species will be evaluated for biological control
Develop rearing techniques and perform a field evaluation of host range and impact for the stem borers across multiple plant genotypes.
Conduct molecular analysis of cogongrass and stem borers collected during field evaluations will be used to estimate their host range relative to US invasive cogongrass genotypes, I. brasiliensis, and I. brevifolia.
Approach:
We will work with native range collaborators to colonize prioritized agents in local laboratories and greenhouses. To optimize insect acceptance of rearing, plants will be grown with regular irrigation, fertilizer, and pruning. Colonies will be shipped to US quarantines in FL to develop rearing methods. At the end of the project herbivores will be assessed and prioritized based on observations including literature records, impact, field specificity, abundance, regulation by natural enemies including by parasitoids, and life cycle information.
Plants will be propagated either from rhizome or from whole plants collected from local populations. They will be maintained under optimal conditions to produce healthy robust growth. After rhizome or field collected plants reach eight weeks, they will be transplanted to pots (size as needed) and grown in an outside garden or glasshouse. Pesticides will be used if needed. Pesticide and fertilizer applications will be discontinued at least one week prior to the start of colonization, after which plants will only receive daily watering and hand-removal of pests. Appropriate plant stage and tissues will be provided to colonizing species depending on the insect life history and feeding preference.
DNA will be extracted from leaf material and preserved insect specimens. Phylogenetic and population genetics analysis will be performed using the cogongrass DNA, and DNA barcoding will be performed for the stem borers. Through this analysis we will understand the specific association of the herbivores with native range plant genotypes as well as an understanding of the phylogenetic relationship between the host plants. Together with data from US collections of cogongrass we will determine whether our collections relate to international types, or their hybrids. The phylogenetic relationship between these different lineages and Imperata species that occur in the US will be assessed.