Recipient Organization
KANSAS STATE UNIV
(N/A)
MANHATTAN,KS 66506
Performing Department
(N/A)
Non Technical Summary
This is an integrated project. Bhadriraju Subramanyam from Kansas State University will lead the project as project director; Kaliramesh Siliveru and Xinyi E are two project co-directors. Flour mills are ideal habitats for stored-product insect pests due to the warm temperatures and availability of food. Until the phase out, methyl bromide had been widely used to fumigate the flour mills for disinfection and disinfestation. In light of finding new alternatives, this proposed project will investigate multiple potential IPM strategies for the flour mill. Chlorine dioxide gas, a biocide, will be evaluated as a potential flour mill fumigant. In addition, the use of chlorine dioxide solution during wheat tempering will be evaluated to achieve the goal of deactivating pathogens and mycotoxins in wheat. The efficacy of four insecticides including pyriproxyfen, esfenvalerate, β-cyfluthrin, and deltamethrin against stored product insects will be determined when applying them as sprays to treat the floor surface in flour mills. Economic analysis of these methods will be performed to determine the feasibility of adopting these MB alternatives in real practice. The results from the proposed project will be delivered to food industry especially the International Association of Operative Millers (IAOM) stakeholder groups through seminars held at association meetings, extension publications, and workshops.
Animal Health Component
50%
Research Effort Categories
Basic
30%
Applied
50%
Developmental
20%
Goals / Objectives
The phase-out of methyl bromide (MB) had an economic impact on the agricultural and food industry including flour mills nationwide. The purpose of this proposed project is to build an integrated pest management program based on several MB alternatives including chlorine dioxide fumigation, application of approved residual insecticides to cracks and crevices and non-food areas of flour mills, and the use of chlorine dioxide solution for tempering wheat prior to flour milling to reduce pathogen loads, an issue considering recent recalls of flour products.Investigate efficacy and cost-effectiveness of using chlorine dioxide fumigation as a structural treatment to control life stages of the red flour beetle and pathogens in commercial flour mills.Explore the use of chlorine dioxide solution to control pathogens on wheat kernels. Optimize the dosage of chlorine dioxide to achieve significant log-reduction of pathogens on wheat kernels in laboratory scale tests. Establish a realistic application method to efficiently distribute the chlorine dioxide solution to the wheat mass during wheat tempering in flour mills (commercial scale). Investigate the applications of pyriproxygen, esfenvalerate, β-cyfluthrin, and deltamethrin to cracks and crevices and non-food areas in flour mills to control red flour beetle adults.Integrate chlorine dioxide fumigation, wheat tempering by chlorine dioxide solution and floor treatment by contact insecticides to existing stored product pest management tactics, to not only improve the efficacy, but also to reduce cost.This project supports discovery and implementation of novel yet practical pest management alternatives to MB through research in laboratories and commercial facilities. Further outreach and extension activities will be carried out to promote the new technology to International Association of Operative Millers (IAOM) and National Pest Management Association (NPMA) stakeholders.
Project Methods
1.Prior to fumigation of K-State's pilot flour mill, bioassays with life stages of the red flour beetle will be conducted in a trailer equipped with a chlorine dioxide gas generator. The efficacy of chlorine dioxide gas will be determined in snap-cap vials following protocols developed by Xinyi et al. (2017). The working principle of gas generation and insect exposure in vials are described in detail in Xinyi et al. (2017). The vials are 23 mm in diameter and 55 mm in height with 250 µm mesh bottoms and caps to ensure penetration of chlorine dioxide through the vials, and also to prevent insects from escaping. Eggs, young larvae (first instars), old larvae (22-d-old), pupae, and adults (2 wk-old) of the red flour beetle will be placed in separate vials with 5 g of whole wheat flour (see Mahroof et al., 2003). Each vial will hold 50 individuals of a life stage. The vials will be placed in a in a polyacrylamide chamber (Xinyi et al., 2017) inside a trailer donated to K-State by PureLine Systems (www.pureline.com), Bensenville, Illinois, that produces the gas electrochemically. Infested vials unexposed to the gas will serve as controls. There will be five replications for each concentration-time exposure for each life stage. After exposure all vials will be brought to the laboratory and placed in an environmental growth chamber at 28ºC and 65% RH. Adults will be checked 24 h after exposure, whereas the immature stages will be reared to adulthood. Mortality will be calculated based on number of dead adults out of total exposed, or number of adults that emerged from the number of immatures exposed. Mortality in treatments will be corrected for mortality in control treatments. The concentration-time (dosage) mortality data will be subjected to probit analysis to determine dosage that provides 99% mortality of each life stage. The minimum dosage that provides 99% mortality of all life stages will be used for pilot mill fumigations.Temperature and humidity during trailer fumigations will be measured using HOBO® sensors (Onset Computer Corp., Bourne, MA).2.Chlorine dioxide solutions with different concentrations (3000, 4500, and 6000 ppm) will be provided by PureLine. These concentrations were chosen based on preliminary experiments. The pH of the solutions will be adjusted to a range of 2-3. The efficacy of wheat tempering with chlorine dioxide solution will be tested against spoilage and foodborne pathogenic microorganisms. Wheat samples will be obtained from commercial mills. The amount of chlorine dioxide solutions added to the wheat will be calculated based on the difference between initial moisture content and the target moisture content following tempering (typically 16%). Tempering process will be 24 hours. First, bacterial reduction on the surface of wheat kernels after tempering with chlorine dioxide solutions will be evaluated based on mesophilic aerobic plate counts, and yeast and mold counts. Twenty-five grams of sample will be rehydrated at room temperature for 15 min prior to homogenization in 225 ml buffer peptone water. Serial dilutions will be prepared. Mesophilic count will be performed on 3MTM PetrifilmTM Rapid Aerobic count plates (3M, St. Paul, MN) and incubated at 35°C for 48 hours. Yeast and molds count will be performed on 3MTM PetrifilmTM Rapid Yeast and Mold Count Plate. Samples will be incubated at 28°C for 72 hours. Secondly, Salmonella and Escherichia coli cocktails will be also used for the wheat tempering study in our BSL2 laboratory, since both pathogens were associated with several recent flour recalls (Crowe et al. 2017). Salmonella entericaserovars Typhimurium (ATCC 14028), Newport (ATCC 6962) and Senftenberg 775W (ATCC 43845) will be mixed from overnight lawns in equal proportion in a tube and use to inoculate the samples.3.Fixed and variable costs of applying the treatments will be estimated using partial budgeting for equivalent comparison with alternative treatments. Treatment costs for the alternative methods include costs of chemicals and supplies (e.g. chlorine dioxide and insecticides), energy, labor (time needed for all components of a treatment), monitoring labor (counting and recording insects collected in traps, and replacing or restocking traps, and managing data collected), investment in equipment, safety training, management, and downtime or other disruption in production processes. Since no insect pest control method guarantees 100% suppression, the tradeoff between insect control cost and level of insect control will be evaluated using the model developed by Tilley et al. (2007). Deviations for each control strategy replication will be measured using a target mortality goal of 100%. When the model allows deviations below the target of 100%, cost of pest management decreases. By varying the total deviations allowed, the tradeoff between cost and total deviation below the target insect mortality rate can be measured. Variations of this model (e.g., Niu and Adam 2015; Niu 2016) allow tradeoffs to be evaluated. For example, the objective of minimizing insect pressure can be examined in relationship to other objectives such as minimizing cost. Another type of risk arises from delaying insect control measures too long, so that damage occurs, or applying those measures too early, incurring needless expense and potential hazards associated with insect control measures. A real option approach such as that used by Duan and Adam (2017) will be used for the second type. This method estimates an "option" price, and provides a dollar value measure of the risk for straightforward comparison with other costs.