Electronic sensors for monitoring phosphine fumigations have become available for use in moving railcar within the last decade. These technologies were deployed to help the grain industry understand current railcar fumigation performances and consider improved practices. Phosphine concentrations and temperature fluctuations were monitored during 24 separate railcar fumigation events that were carried out in moving freight railcars during 2018, 2019, 2021, and 2023 at two locations using portable gas sensing devices. The efficacies of the fumigation were predicted by calculating a Concentration & lowast;Time (Conc & lowast;T) to summarize each trial which were classified as strong (Conc & lowast;T > 25,000 ppm & lowast;hr), mid (15,000 to 25,000 ppm & lowast;hr), or weak (<15,000 ppm & lowast;hr), which were based on prior fumigation studies using adult phosphine resistant insects. We achieved mid or strong fumigations in about 63% of the railcars tested, yet 37% of the railcars were weak and were predicted to result in low control of phosphine resistant strains. The lower Conc & lowast;T values could have resulted from leaky railcars or poor railcar sealing practices. We tested fumigation efficacies at two different facilities (A and B). Facility B was used for one year and tended to have weak fumigations. Facility A was used in three years. Although, fumigation efficacies at A started weak, they improved over time because the staff took additional steps to seal the railcars better, such as tarping the doors to reduce leakage. Temperature data was collected during all fumigations monitoring events and it was correlated to changes in phosphine concentration. Daily changes in temperature had a secondary effect on the phosphine concentration and could have resulted in sublethal doses of phosphine at various times during the transit fumigations. Overall, our study shows that real-time fumigation monitoring is a valuable tool to determine the actual fumigation effectiveness during transit, which can reduce post-harvest losses during transit.

Introduction Bulk railcars are a common method of moving commodities in the USA. Allowances are given for the practice of treating railcars with fumigates during transit because the routes are limited access and not on public roads. Recent technology has become available for monitoring phosphine gas (PH 3 ) fumigation on railcars which logs the phosphine concentration and temperature of the test point in the railcars. Materials and Methods Two hopper bottom railcar shipments of corn grit were monitored for phosphine during 8-day transit from mill to processor. Several phosphine-sensing units were used in each railcar and spaced across the top layer. Mathematical modeling of the railcar fumigation was carried out using computational fluid dynamic software. Because access to lower depths in the railcar was not available, supplement experiments were performed with small columns of corn grits (2.5 m height x 0.55 m diameter) to test for phosphine at greater depths. Also, in the grain columns, bioassays of both phosphine susceptible and resistant, adult Rhyzopertha dominica (F.), lesser grain borer, and Tribolium castaneum (Herbst), red flour beetle, were included at the 0 cm, 25 cm, and 60 cm below the surface. Results The phosphine concentrations in the railcar headspace varied with time with phosphine spiking over 1600 ppm and gradually settling to over 300 ppm at the end of the 8 days. Total gas dosage was estimated as concentration*time (CT) over the 8 days as 115,000 and 125,000 ppm*h at the top of each railcar. The supplement grain column fumigation tests found significant phosphine penetration into the column at 2 m depth with ~380 ppm after 2 days which reduced to ~260 ppm after 8 days, and all insects, at all locations, were dead after 8 days. The CFD simulation models were shown to provide estimates of the phosphine concentration and distribution which matched well with the observed data, validating the CFD approach as a useful tool. Discussion The simulation models were shown to provide estimates of the phosphine concentration and distribution which matched well the observed data, validating the CFD approach as an efficient tool for future planning and analysis of similar fumigations.

Within integrated pest management options, fumigation of stored products is one method to help control post-harvest insect infestations in our food and agricultural products. Fumigant gas concentration monitoring is important to confirm that the treatment was adequate to achieve the desired insect control, but monitoring can be relatively expensive and labor intensive. This study evaluated how accurately dosimeter tubes could monitor phosphine fumigation treatments. The dosimeter tube is designed to continuously react with phosphine gas during the fumigation period and yields a measurement in terms of concentration * time product or CT, which can be interpreted as cumulative exposure. Two models of dosimeter tubes were evaluated (high range and low range). The reference method for these trials were wireless phosphine monitoring sensors, which recorded gas concentrations at hourly intervals during an exposure, and from this a CT product was also calculated. Model LPG-1, high-range dosimeter tube, measured within ? 25% of the phosphine monitoring sensors for CT dosages less the 70,000 ppm*hr. Model LPG-2, low-range tube, tended to significantly over-estimate phosphine CT dosage by 50%e10 0% of the phosphine monitoring sensor references. Secondly, bioassays of fumigant efficacy were performed using susceptible and resistant adult Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), lesser grain borers, and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), red flour beetle, for estimating insect control at the varied fumigation CT treatments. For the susceptible strains, CT dosages-5000 ppm*hr controlled both species. However, the insect control varied from 60% to 100% for resistant adults at CT dosages of-20,000 ppm*hr. The dosimeter tubes function in these ranges of dosages where each insect species are controlled and the dosimeter tube model LPG-1 provides reasonable estimates of the fumigation dosage for a given treatment level. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Fumigation of grain bins with phosphine tablets is one method of insect control for stored products. Monitoring the concentration of the toxic gas at many locations over several days for a given structure or container can be challenging. In this study, a commercially-available system that wirelessly measures phosphine was evaluated in small-scale and large-scale tests. Small-scale testing was performed to study the repeatability and accuracy of the sensors. The wireless sensors were within 30 ppm of each other, over a range of 700 ppm phosphine. Large-scale testing evaluated the system during the fumigation of wheat stored in 7 m diameter, 120 metric ton, steel grain bins. As a reference, monitoring lines were distributed at several positions and depths in the bin in order to sample phosphine gas concentrations. A series of three fumigation trials were performed, with each lasting for over six days. The wireless devices collected local phosphine concentrations and temperatures every two hours without assistance from personnel. Although the fumigation trials were significantly different in terms of patterns in gas concentration over time, the two sampling methods gave similar trendlines. However, the automated data provided a more detailed picture of the fumigation process. This information may help fumigation managers to better evaluate fumigations and assure successful insect control.

The Solar Biomass Hybrid Dryer (SBHD) is a new technology developed in Ghana for grain drying and utilizes biomass (agro-residues, timber scraps, etc.) along with solar drying, and is especially useful for drying during rainy periods of the year when solar drying cannot be relied on. This study assessed the effectiveness of a 5.0-MT SBHD comprising a solar tent and a furnace for thermal drying and disinfestation of maize. Mortalities of adults of Sitophilus zeamais (Motschulsky), Tribolium castaneum (Herbst) and Cryptolestes ferrugineus Stephens were assessed. Additionally, mortalities of immatures of these three species were assessed. Internal and cage temperatures (degrees C) in the SBHD, sun drying (SD) and laboratory (control) were monitored, as were moisture content (MC) and thermally (stress) damaged kernels (TDK) (%). During the 7-h experiment, mean internal temperatures in the SBHD, SD and laboratory were 52.3 +/- 1.0 degrees C, 41.4 +/- 0.8 degrees C and 30.3 +/- 0.2 degrees C, respectively. Similarly, temperatures in cages in the SBHD (49.5 +/- 1.0 degrees C) were higher than those for cages in the laboratory (29.9 +/- 0.2 degrees C) and SD (38.2 +/- 0.6 degrees C). Reduction in the moisture content of maize dried using SBHD, SD and under laboratory conditions were 7.7, 5.2 and 2.9%, respectively. This corresponded to grain MC reduction rates of 1.1%, 0.74% and 0.4% per hour. There was 100% mortality of S. zeamais and C ferrugineus adults achieved in only the SBHD; some immatures of all three species survived in all three treatments. However, survival of immatures was highest in the laboratory, followed by SD and lowest in the SBHD for all three species. Percent TDK was higher in the SBHD (6.7 +/- 0.9) than SD (3.3 +/- 0.3) and laboratory (2.7 +/- 0.3). These data show that the SBHD is effective for both drying and disinfestation of grain. (C) 2019 Elsevier Ltd. All rights reserved.

The occurrence of horizontal transfer of the insect growth regulator (IGR) methoprene on confined populations of Tribolium castarneum (Herbst), either with or without hidden refugia, was determined through a series of experiments. Multiple applications were made with the IGR alone or combined with synergized pyrethrin, and compared to untreated controls which received no insecticide applications or were treated with the carrier Isopar M that was a component of the pyrethrin formulation. The total number of living beetles from test colonies inoculated with adults that were treated with Isopar M or with no adults (control) was significantly greater than those colonies that were inoculated with adults treated with either synergized pyrethrin or methoprene (P < 0.05). There was no difference in the number of living individual in the larval, pupal, and adult stages and the instantaneous rate of increase (r(i)) in established populations treated with methoprene and containing a hidden refugia compared to those which received the pyrethrin applications (P >= 0.05). Sanitation levels of two different flour quantities nested inside the treatment groups also had no effects (P >= 0.05), suggesting that populations in hidden refugia can persist even with multiple applications of methoprene and synergized pyrethrin. Populations with an accessible hidden refugia that were exposed to synergized pyrethrin and methoprene had a lower number of living adult and a lower r(i) value than populations that were exposed to synergized pyrethrin alone (P < 0.001). Additionally, populations which received one, two, or three aerosol applications had similar numbers of living adults and r(i) but were significantly different from populations which received four aerosol applications. Results suggest multiple applications of methoprene and synergized pyrethrin could be more effective than synergized pyrethrin alone for control of T. castaneum. Published by Elsevier Ltd.

Methyl bromide is a commonly used fumigant for controlling insects in food processing facilities. However, it has been designated as an ozone depleter and is becoming less available and more costly. Integrated pest management (IPM) is an alternative, and may additionally reduce insecticide resistance, improve worker safety, and reduce environmental concerns and consumer concerns about pesticide residuals. However, little is known about the costs and efficacy of IPM in food processing facilities. Here, we consider several IPM approaches and measure both the treatment costs as well as the costs of failing to control insects for each approach. The results will provide managers economic information to choose a better insect control method in their goal of producing wholesome, pest-free and profitable products.