Location: European Biological Control Laboratory
Project Number: 0212-30400-002-000-D
Project Type: In-House Appropriated
Start Date: Dec 2, 2025
End Date: Dec 1, 2030
Objective:
Objective 1: Identify specific locations in the native range of prioritized weed targets that include but are not limited to annual grasses, stinkwort, tree of heaven, and conduct exploration for natural enemies that can be collected and studied as biological control agents.
Objective 2: Perform taxonomic, including molecular, studies of target weeds and related biological control agents to better understand the origin of invasive populations, arthropod-microbes-plant relationships, and clarify weed and natural enemy species status.
Objective 3: Identify the biological, physical, and chemical parameters that affect the efficacy,
specificity, and safety of biological control agents, and investigate how to incorporate new technologies, such as manipulation of plant immunity using endophytes or effectors, that can enhance the interactions between target weeds and biological control agents.
Approach:
For Objective 1, the research goal is to discover natural enemies of weed targets to be evaluated as prospective BCAs and to continue exploration for BCAs that were previously found during the previous 5- year plan (e.g. stinkwort, Sahara mustard, tree of heaven, medusahead, etc.). Projects are initiated either when new weed targets are identified, or when previous research indicates the need to search for new agents of existing targets. This is non-Hypothesis research with the goal of discovering potential biological control agents. For Objective 2, Adult or juvenile specimens of natural enemies or parasitized stages of the host in the native range will be collected directly in the field when present (for example, parasitized egg masses) or within infested plant parts and returned to EBCL and held for further development of stages in quarantine. An estimate is between 10 and 20 specimens per site or population. Once collected in the field, arthropod specimens could also be immediately preserved in absolute or 95°ethanol or RNAlater® and shipped to EBCL. Genomic DNA will preferentially be extracted using nondestructive techniques via commercial kits. For larger specimens, a leg will be carefully removed using sterile forceps and the DNA extracted using a destructive method that has been used in past investigations. These two approaches allow direct association of genetics with morphological data, and to keep specimens as vouchers in U.S. natural history collections. For Sub-objective 2A and 2C, this is non-hypothesis driven research with a goal of investigating the distribution and identify of species of weed pathogens to select potential biocontrol agents, and to identify species or sub-specific populations or hybrids and assess the presence of hidden species within natural enemies in the native range to retain safe effective biocontrol agents and ultimately facilitate decision-making, respectively. For Sub-objective 2B, this is hypothesis driven as knowing the center(s) of origin of invasive weed populations in California will aid in streamlining foreign exploration for candidate biological control agents in the native range. For Objective 3, we will maintain a colony of Condica viscosa in controlled conditions and conduct host specificity testings for determining its feeding range. For the chemical approach, the research will follow a 2-step plan and will use the colony of C. viscosa established in EBCL’s quarantine as part of Sub-objective 3A. Step 1 (Year 2) will consist of designing and optimizing an adequate experimental setup to test the olfactory preferences of C. viscosa. Noctuid moths have been tested with success in wind tunnel and olfactometer bioassays. Sub-objectives 3A, 3B and 3C, are hypothesis driven, aimed at selecting high specific and effective BCAs, like Condica viscosa (Noctuidae) on tested plant species phylogenetically and chemically related to stinkwort will help avoiding non-target impacts (3A, 3C) and the noctuid Condica viscosa is attracted by volatiles of its host plant but not by volatiles of non-host plants (3B).