Apple snail, (Pomacea canaliculata), a highly invasive pest affecting wetland crops in 18 countries including the U.S., is listed as one of the 100 Worst Global Invaders. One study showed that due to its voracious appetite, present value damage from the snail could cost Philippine rice production as much as 2.3 billion dollars annually. In Hawai`i, the apple snail invasion has reduced taro harvests for the small and mid-sized farms that comprise the local taro industry by 18% to 25% annually. This project will research a unique control for apple snail on Hawai`i's wetland taro production using the unrefined glycerin co-product (UCP) from biodiesel production as a soil conditioner. The research will identify a uniform product, test the product on non-target species and conduct field trials on wetland taro to determine efficacy in controlling apple snail and impacts on soil and plant health. The end goal will be to develop a marketable product that provides environmentally safe control of apple snail on taro and enhances the efficiency and profitability of small taro farms. Locally manufacturing an agricultural amendment, Aina Mo, for use in Hawaiian taro production saves energy through import substitution. Developing value-added co-products from biodiesel refining will improve profitability for the renewable fuels industry. Sustaining and increasing wetland taro production will revitalize rural areas and preserve wetland habitat. Developing a natural organic compound that effectively controls this invasive pest will preserve water quality in streams and coastal waters and has potential applications for wetland rice production and preservation of wetlands globally. OBJECTIVES: This project will research the viability of a unique control for apple snail, (Pomacea canaliculata), on Hawai`i's wetland taro (Colocasia esculenta) production using the unrefined glycerin co-product from biodiesel production as an agricultural amendment. The objectives of this research are to: 1) identify combination of compounds found in the unrefined glycerin co-product that is most effective in deterring apple snail under the environmental conditions prevalent in wetland taro production, 2) evaluate impacts on non-target vertebrate and non-vertebrate species commonly found in Hawai`i's wetland ecosystems from application of the unrefined glycerin co-product at rates established in Phase I, 3) assess impacts on plant and soil health as well as water quality in wetland taro and non-target species including apple snail from controlled application of the unrefined glycerin co-product over the life cycle of a taro crop, and 4) identify the best distribution method and pricing strategy to affect penetration of the Hawai`i taro market for the trademarked product Aina Mo and which markets outside Hawai`i offer the greatest expansion potential. The goal of this research is to use the results of the Phase I research to develop a uniform product that will first be tested on non-target species and then conduct field testing of the product on wetland taro in Hawai`i. The end goal will be development of a marketable commercial soil amendment that provides environmentally safe control of apple snail on taro and enhances the efficiency and profitability of Hawaii's small farm taro industry through better soil and plant health. A secondary goal is to improve profitability of small scale biodiesel production by developing a value-added co-product from the biodiesel refining process. APPROACH: Phase I determined the active ingredient (AI) in the unrefined co-product (UCP) contributing to apple snail mortality. Other active compounds in the UCP may interact with the AI to increase toxicity. To identify the highest mortality rates and to develop a uniform product, potential candidate compounds in the UCP will tested on apple snails. Using the LC50 of the UCP established in Phase I, apple snails will be exposed for 96 hours to determine sub-chronic toxic effects. Apple snails will be exposed to the UCP at 3 temperatures; mortality and water samples analyzed. Product safety and potential impacts to aquatic fauna will be assessed on non-target species using surrogate non-native fish, snails, and insect larvae. Fish species tests will be conducted with a purified diet and a controlled temperature water bath. A range finder study will be conducted and a 96 hours exposure test will be conducted to determine the LC50 of the UCP. The impact of the UCP on Scarlet dragonfly larvae will be assessed through exposure tests at 3 temperatures over 3 time periods. Acute toxic effect of the UCP on two snail species found in wetland taro will be assessed using protocols described above. Field tests will be conducted on 7 small taro patches or "units". No additional fertilizers or rooting dip will be used in the first cycle of trials. In the second cycle, 3 units will receive conventional fertilizer applications and no rooting treatment and 3 units will receive rooting treatment and no chemical fertilizer. A protocol for field preparation and planting will be followed with three taro varieties used in the field tests. Baseline soil sampling will be done and repeated 3 times in each cycle to determine effects on soil quality and nutrients. Tissue sampling will be used to determine effects of UCP on growth rate, overall plant health, on corm quality and flavor, and determine the presence/absence of the UCP in taro plants. Water samples will be evaluated to determine when the UCP is no longer detectable. A baseline survey of snail population density and size will be conducted using standard sampling protocols to quantify snail and egg populations. Impacts of the UCP on other non-target aquatic fauna species studied in the laboratory setting will be assessed under field conditions. Ducks used to help control apple snail populations in wetland taro will be observed within the units, immersed in UCP treated water, and released after 48hrs. Commercialization plans will address state regulations and conduct research on market size/characteristics. A distribution system for transporting product to existing potential customers, farmer education materials, and in-field training protocols will be developed. Pricing for the Aina Mo product will be developed using production economics and focus groups/interview responses. Markets for Aina Mo for international wetland crops will be investigated to expand distribution beyond Hawai`i and agreements developed to negotiate partnerships. Aina Mo use in U.S. wetland conservation areas will be investigated and strategies identified to address federal and state regulatory issues
