Location:2012 Annual Report
1a. Objectives (from AD-416):
Evaluate efficacy of potential alternatives to the use of methyl bromide as a structural treatment and improve Integrated Pest Management (IPM) programs for stored-product insect pests in food facilities such as wheat flour mills, rice mills, pet food facilities, and their associated warehouses with the goal of reducing the number of methyl bromide critical use exemptions (CUEs) requested or the amount of methyl bromide used.
1b. Approach (from AD-416):
A four part approach, based on priorities identified by stakeholders at the NP308 program review, will be used to meet this objective. (1) Obtain information on the field efficacy of alternative structural treatments, such as sulfuryl fluoride or heat, compared with methyl bromide. (2) Evaluate the impact of some alternative tactics, such as reduced-risk aerosol insecticides or targeted treatment with residual contact insecticides, as part of an IPM or systems approach to eliminate the need for, or reduce the frequency of, fumigations or other structural treatments. (3) Develop improved monitoring tools and strategies to evaluate the need for and effectiveness of different management tactics to improve the implementation of an IPM program (in association with Gainesville). (4) Develop models using the above information with which to determine optimal management strategies using methyl bromide alternatives.
3. Progress Report:
Under Objective 1, significant progress was made in understanding stored-product insect population dynamics in commercial food facilities and the impact of treatment with alternatives to the structural fumigant methyl bromide (MB) such as the fumigant sulfuryl fluoride (SF), high temperature treatments, or Integrated Pest Management (IPM) programs. Stored-product insect monitoring before and after treatment was conducted in multiple commercial food facilities. Analysis of SF fumigation efficacy against red flour beetle in rice mills was conducted using a large dataset collected earlier. Because pest dispersal behavior contributes to avoiding treatments and recolonizing after treatment, flight behavior of the red flour beetle was evaluated. Research under this objective is supplying critical information to food facility managers and to the pest control industry on fumigation efficacy and factors that impact efficacy, and also providing information to validate population models developed in Objective 4. Under Objective 2, significant progress has been made on determining the impact of reduced-risk insecticides on pest insect populations. Studies were conducted to evaluate residual efficacy of insecticides, including determining how sealing concrete surfaces increases length of time applied insecticides are effective and how presence of food material impacts the effectiveness of aerosol insecticide applications. Infrared radiation, a non-chemical tactic, was evaluated against different red flour beetle life stages. Studies examining impact of regular aerosol applications of reduced-risk insecticides on population growth of red flour beetles in small-scale storage facilities were completed. Studies evaluating the spatial pattern in aerosol insecticide deposition and ability to disperse under obstructions were conducted. More effective use of these insecticides as part of an IPM program could reduce the need to conduct structural fumigations, facilitating the phase-out of MB. Under Objective 4, to better understand how different alternatives to MB affect population rebound following treatment, a simulation model for red flour beetle population dynamics in flour mills was refined with the inclusion of heat, aerosol insecticide, and sanitation treatments, in addition to MB and SF fumigation, in the model. Development of a simulation model for warehouse beetle populations was initiated. An Indianmeal moth simulation model was used to evaluate the impact of timing and frequency of applications of different insecticides on growth of populations. These models will provide important information for managers to determine optimum integrated pest management strategies for food facilities. The research conducted in this project will contribute to the development of more effective pest management programs with the potential benefit of reducing the number of MB critical use exemptions requested or the amount of MB used.
1. Efficacy of structural fumigations for management of red flour beetles in rice mills. The red flour beetle is the most important insect pest infesting rice mills, and management has historically relied on structural fumigation with methyl bromide. Because this use of methyl bromide is being phased out under the Montreal Protocol, there is a critical need to evaluate the efficacy of alternative treatments. Scientists at ARS in Manhattan, KS, and Kansas State University determined that the average reduction in capture of beetles in pheromone traps after 25 sulfuryl fluoride fumigations in six mills was 66%. Beetle captures inside mills tended to follow a seasonal pattern of increased captures in warm months and decreased captures in cool months. Captures inside the mills were correlated with outside captures. The reduction in captures, and the rate at which beetle captures returned to pre-treatment levels was strongly influenced by seasonal patterns of insect abundance (which contrasts with previously reported patterns in wheat mills). These data suggest fundamental differences in red flour beetle populations in rice and wheat mills and how the timing of fumigation is critical for maximizing fumigation efficacy.
2. Optimal timing and frequency of insecticide treatments for Indianmeal moths. Insecticides are used to control insects in stored commodities, but it is difficult to determine the long-term impact of different insecticide application strategies on insect population growth. ARS scientists in Manhattan, KS, developed a computer model that simulates population growth of the Indianmeal moth, a major pest of stored grains and dried fruits. The model was used to simulate the impact of timing and frequency of applications of different types of insecticides on long-term growth of Indianmeal moth populations. The most effective strategy tested for controlling Indianmeal moth populations was the use of biweekly applications of insecticide. The results will help pest managers in the food industry select strategies for use of insecticides.
3. Catalytic infrared heater used to disinfest stored wheat. The red flour beetle is a common pest of stored wheat. Few new insecticides are being developed for control of stored-grain insects. A catalytic heater using propane gas can be used to produce heat that can kill insects in grain. Scientists at ARS in Manhattan, KS, and Kansas State University determined the effectiveness of infrared radiation at killing different stages of red flour beetle in stored wheat. Grain temperature was a function of exposure time, distance from the emitter, and amount of grain, with all life stages of the red flour beetle being killed after a 60-second exposure at a distance of 8.0 cm from the emitter. Pupae were the least susceptible, followed by eggs, adults, and larvae. These results indicate that flameless catalytic infrared technology may be a possible option for controlling insects in stored grain in the future.
4. Factors affecting red flour beetle flight. The red flour beetle is one of the major pests in stored grain and in grain processing facilities throughout the world. Traps are used to monitor their movement to aid in making pest management decisions, but we don’t fully understand the factors that cause their movement. ARS scientists in Manhattan, KS, investigated the variables that affect red flour beetle flight behavior. Our results suggest that the red flour beetles uses flight as a mechanism to disperse to new environments during almost any part of their life span, unlike some other stored-product beetles that fly mostly when they are young. These results will help to develop better methods for interpreting trap catches from pest monitoring programs.
5. Aerosols control flour beetles in mills. Combinations of pyrethrin and insect growth regulator methoprene insecticides are used as aerosol treatments to control red flour beetle and confused flour beetle. However, there is little information on the duration of insect control after application of the insecticide combination. Scientists at ARS in Manhattan, KS, and Kansas State University investigated the duration of insect control provided by different insecticide combinations on red- and confused flour beetles. Results of this research indicate that the formulation with 1% pyrethrin can be used if red flour beetle is the target pest, but that 3% pyrethrin formulation should be used to control the confused flour beetle.
Semeao, A.A., Campbell, J.F., Beeman, R.W., Lorenzen, M.D., Whitworth, R.J., Sloderbeck, P.E. 2012. Genetic structure of Tribolium castaneum (Coleptera: Tenebrionidae) populations in mills. Environmental Entomology. 41(1): 188-199. doi: http://dx.doi.org/10.1603/EN11207.