1) Biological Control Development

Biological control or ‘biocontrol’ is the introduction of predators or parasites that regulate populations of pest organisms in the region where these pests, whether animal or plant, originated so that the same predator-prey or host-parasite relationships can be utilized for invasive species management in infested ecosystems. The overarching objective of our research is to evaluate the use of host-specific parasitic organisms, with an initial focus on the castrating trematode (Microphallus sp.), as a safe, sustainable and cost effective means to suppress NZMS abundance in North America. The introduction of a biocontrol agent depends on establishing that the organism causes substantial pest impact (efficacy) and poses no significant risk to non-target species (safety), including species from the same spring snail family (Hydrobiidae), many of which are sensitive or highly restricted in their geographic ranges.

Specific objectives of our research are to:

• Establish procedures for inducing infection of P. antipodarum by Microphallus
• Conduct host-range tests with non-target taxa, both within the Hydrobiidae family and subsequently with less closely related snails
• Determine effects of modulating environmental parameters on Microphallus infectivity to NZMS haplotypes present in North American
• Determine if and how infection affects susceptibility to predation by final hosts (ducks), and if parasites have any effects on these hosts
• Examine NZMS invasion in Australia to determine whether the parasite regulates populations there [where it was fortuitously introduced along with the parasite] and whether Microphallus infects any Australian snails
• Initiate a public outreach campaign if biocontrol appears justifiable
• Conduct a Cost/Benefit assessment using research results and other available information to evaluate ecological and economic effectiveness of biocontrol program implemention

2) Ecological Assessments

In support of the NZMS biocontrol development effort, we  are also investigating the ecology of NZMS and its impacts to North American stream ecosystems with a series of field and laboratory studies. Resulting information will be used to evaluate whether the costs and potential risks posed by introducing biocontrol agents into the ecosystem can be justified by the anticipated ecological and economic benefits from NZMS biocontrol. In addition, pre-release population information is necessary in order to document the effectiveness of biocontrol agents in actually controlling the invasive snails, when and if the program is implemented.

Ecological studies:

• Document the status of P. antipodarum invasion in the Pacific Southwest (California/Nevada/Arizona) by regular monitoring of existing population patterns, and assessment of new establishment by NZMS across the region
• Conduct experiments to measure effects of temperature, light and resource conditions on P. antipodarum growth and survival rates, and reproduction
• Characterize effects of snail grazing on algal resource quantity and composition (as the resource base for other aquatic organisms)
• Test presence and strength of competition between NZMS and native Hybrobiidae, other stream invertebrates, especially aquatic insects (the primary resource base for stream fish), and vertebrate herbivores, particularly amphibian larvae or tadpoles [e.g. western toad (Bufo boreas) as a surrogate for the endangered arroyo toad- (Anaxyrus californicus; formerly Bufo canorus) or introduced bullfrog (Rana catesbiana) larvae as a proxy for  relict leopard frog (Rana onca) and red-legged frog (Rana draytonii)
• Evaluate NZMS as a food resource for invertebrate and vertebrate stream predators, both as a resource for native consumer feeding and growth (being operculate, they often pass through the guts undigested) and for the potential of native predators to provide some level of NZMS populations control
• Predation studies include feeding and growth trials with common stream fishes, using them as closely related surrogates of endangered taxa (e.g. unarmored threespine stickleback (Gasterosteus aculeatus williamsoni), Santa Ana sucker (Catostomus santaanae), tidewater goby (Eucyclogobius newberryi), Virgin River chub (Gila seminuda), Woundfin - Plagopterus argentissimus) and others.

These and other results and relationships will be chronicled on our website  and disseminated to the public and natural resource managers through various methods, including sponsoring a ‘virtual symposium’ on the website in which electronic participants can display posters of their NZMS-related research and post comments and questions to the presenters, in effect creating both an interactive community of interested people along with reducing research redundancy while creating new partnerships that will increase the understanding of non-indigenous mollusk invasions and how to manage them.