Progress 09/01/17 to 04/30/19
Outputs
Target Audience:During this reporting period, SDC reached out to a number of commercial entities in the pest control services industry and commercial entities involved in storage, handling and processing of food ingredients and food products. SDC's objective was to inform these commercial firms of the advantages of SDC's electronic sensor product compared to the present techniques used to monitor insect and larva activity in their stored products. SDC's final objective was to gain acceptance of our concept by these commercial entities and achieve their written support for our efforts. SDC succeeded in gaining Letters of Support from Insects Limited, Inc., Copesan, The Stafford County Flour Mill Co., Lundberg Family Farms, The California Walnut Board and the California Dried Plum Board. SDC visited Lundberg Family Farms. Nestle U.S.A., Archer Daniels Midland (rice milling), Mars, Inc., Bayer (crop sciences), The California Almond Board and J.P. Morgan (ship and rail transport of food products) are also members of SDC's target audience. SDC visited Archer Daniels Midland's rice milling operation near Sacramento, California SDC also has letters from the USDA ARS San Joaquin Valley Agricultural Sciences Center and from Insects Limited, Inc. confirming their intent to collaborate with SDC on a Phase II SBIR project which SDC has proposed to NIFA. Changes/Problems:A change was made to Technical Objective 3. In the proposal as awarded, the objective was stated as follows: Technical Objective 3: Confirm presence of volatile compounds in headspace gas over stored product with IMM larvae. Technical Objective 3 had two subordinate Tasks: Task 1: What is the volatome of gases over stored product with IMM larvae present? Task 2: What are the physico-chemical properties of the IMM semiochemicals? Task 1 has been expanded to include the larva and cocoon volatome. It is being completed and is being reported in the Accomplishments section of the final report on the REEport Portal. Task 2, characterization of the synthesized semiochemical materials, was planned to quantify what was expected to be a very low gas phase concentration in the event that it was not possible to get the material into pressurized tanks for lab system testing. But, the material was successfully containerized. So, resources were reprioritized away from this work and the field trial was expanded to include sensing and quantifying pupae in cocoons on the recommendation of SDC's USDA collaborators. What opportunities for training and professional development has the project provided?The project gave a UC Davis PhD student working at USDA ARS Parlier, CA an opportunity for new innovative means of identifying larval biomarkers and to work with an industrial commercial partner. How have the results been disseminated to communities of interest?SDC has communicated results of the field trial by close collaboration effort with USDA ARS personnel at the Parlier, CA station. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Acquired adult, larval Indianmeal moth (IMM) marker VOCs in suitable form for lab work. Insects Limited, Westfield, IN synthesized 9,12-tetradecadienylacetate, adult female IMM pheromone. SDC made it into a test gas, 2 ppm in dry N2 cylinder to use in SDC's lab test system. Round 1 chip response work used a commercially available surrogate for the semiochemicals in larva saliva, feces, frass. SDC's USDA collaborators (San Joaquin Valley Station, Parlier, CA) synthesized one of the larval semiochemicals. This work was done under an SDC CRADA with USDA ARS Parlier. SDC made the semiochemical into a test gas, 2 ppm in dry N2 cylinder for Round 2 work. 2. Selected un-catalyzed and catalyzed tin oxide sensor chips for testing; devised/applied ways to enhance chip sensitivity and selectivity. Lab Work to Select Chips: SDC's available chips are un-catalyzed chips and chips doped with catalysts, 8 total options. Sensitivities were defined by injecting 200 ppb of IMM pheromone or semiochemical in air onto each chip and computing the conductance change per change in analyte concentration: the Specific Net Conductance, SNC (nanomhos/ppb). Chip production process changes and post-production treatments were evaluated to enhance performance and stability. "Two-gas" experiments addressed sensitivity and selectivity. Round 1 used an un-catalyzed and a catalyzed chip with the adult pheromone and the surrogate larval semiochemical. Round 2 used an un-catalyzed chip and a catalyzed chip and an un-catalyzed chip with a second catalyzed chip; analytes were the adult pheromone and the synthesized larval semiochemical. SDC's concentration calculation uses the idea that each chip responds to each analyte independently. Chip conductance with multiple analytes is the sum of these contributions. The chip sensitivity to one analyte (the SNC), measured for each gas/chip pair before the chips are put into service, is used to compute the contribution of each analyte. Analyte concentrations (correlated to insect count) are calculated using well-known math techniques. The two gas lab experiments used this method. The Round 1 capping run with adult pheromone and surrogate larval semiochemical showed that an un-catalyzed chip and the first catalyzed chip can detect the adult pheromone and surrogate larva semiochemical. The expected concentration of both analytes is 100 ppb. Three replicate runs gave (pheromone/semiochemical) concentrations of (67/23), (74/19), and (83/79) ppb. The Round 2 capping run with adult pheromone and synthetic semiochemical showed that an un-catalyzed chip paired with the second catalyzed chip and with the first catalyzed chip can detect the adult pheromone and synthetic larva semiochemical selectively. The un-catalyzed chip and second catalyzed chip gave (pheromone/semiochemical) concentrations of (48/99) ppb when (100/100) ppb were expected. Un-catalyzed chip and the second catalyzed chip gave (pheromone/semiochemical) concentrations of (68/36) ppb when (100/100) ppb were expected. Conclusion: adult pheromone and larval semiochemical can be sensed selectively in the presence of the other analyte with un-catalyzed, and catalyzed chips. Additional two-gas experiments were run. Uncatalyzed chip SNCs (nanomhos/ppb) averaged 65.6+13.6 for the larva synthetic semiochemical and 178.5+16.1 for adult pheromone. The first catalyzed chip SNCs averaged 3.42+0.83 for the larva synthetic semiochemical and 7.61+0.41 for adult pheromone. Calculated (semiochemical/pheromone) concentrations using average SNCs and sensor signals when the two analytes were injected simultaneously at 100 ppb gave the following ppb concentrations for 6 runs: (207/108), (22/191), (108/152),(133/100), (100/181), (90/138). Conclusion: the electronic device provides information accurate enough for warehouse or bin managers to make decisions about taking action before larva/insect infestations occur. Ran successful field trial to show prototype capability with live insects, larvae and cocoons. The sensor chips used were un-catalyzed, and two catalyzed chips. Table 1 shows SNCs. Table 1: Sensitivities of chips (SNCs) for Marker Compounds No cat-Chip Chip-calyst 1 Chip-catalyst 2 Marker Volatile Adult Pheromone 184 74 272 Larval Semiochemical 80 37 142 The USDA Parlier, CA trial used a "reference" pail of clean flour always free of insects, and a "sample" pail of clean flour with stored product insects inserted. Jars of 5, 20, and 75 adult female IMM, IMM larvae and IMM larvae in cocoons were used. USDA's entomologist provided the insects and larvae, ensuring that they were the right sex and healthy. A fourth jar of each stage was provided to test the predictive ability of SDC's sensor. The entomologist knew the count, SDC workers did not. Adjusting a T-valve connecting the pails to SDC's prototype to sample headspace gas from the "reference" pail with "clean" flour determined a baseline resistance. Meanwhile, insects were put into the "sample" pail. Then, the T-valve was switched to the "sample" pail. Its resistance was used with the baseline resistance to calculate a Net Resistance. This sequence was repeated for insects introduced in the following order and number: 5, 25 (5+20), 100 (5+20+75). This was done for adult insects, larvae and for larvae in cocoons. Net Resistance was correlated with the counts of adults, larvae and larvae in cocoons. Insect, larva and cocoon counts were predicted from curves correlating the resistance change from the reference pail to the sample pail to larvae, cocoon or adult insect counts. The data fit to a mathematical curve. The curves allow computation of unknown larva, cocoon or adult counts from known resistance changes. Also, "blind test" predictions are shown. These are the counts of larvae, larvae in cocoons and adult female moths predicted using SDC's correlation with "blind" samples provided by the USDA entomologist as described in the description of the experiment. Table 2 comparing these computed counts to the known counts shows the correlation to be very good. Table 2: Correlation of Prototype signal to Larvae, Cocoons, Insect Count Live Larvae Cocoons Adult Females Chip Known Predicted Known Predicted Known Predicted 5 10 5 4 5 5 Pos #2 - 25 26 25 25 no reading no reading Uncatalyzed 100 52 100 99 100 75 Blind Test 150 304 150 123 75 51 Variation is seen at very low analyte concentration with live larvae. Live larvae are over estimated in the blind test. Adult moths are under estimated. Live insects and larvae produce amounts of semiochemicals that vary with time of day, expected to be less consistent than flow from lab gas cylinders. Technical Objective 3, Task 1 defining the larvae and cocoons volatome is in progress. A peak consistent with 4-hydroxy-2-oleoylcyclohexane-1,3-dione was observed in GC/MS. This 393 mass/charge peak has a retention time slightly longer than 2-oleoylcyclohexane-1,3-dione, consistent with that reported in Howard & Baker, Comp.Biochem.Physiol.,Part B 138 (2004)193-206. 4-Hydroxy-derivative synthesis is underway as are other analytical methods to confirm identification. Technical Objective 3, Task 2 was planned to quantify the gas phase concentration of a high molecular weight semiochemical, expecting that it lacked the vapor pressure to be containerized and detected. This became moot when the material was successfully containerized and detected. Resources were shifted from this work to field trial activity and analysis sensing cocoons.
Publications
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