Heat treatment of grain-processing facilities for insect management: a historical overview and recent advances

Abstract

Purpose of review:Tactics to manage infestations of stored-product insects in grain-processing facilities historically included the use of heat treatments and the fumigant methyl bromide. The phase out of methyl bromide in the USA in 2005, because of its adverse effects on stratospheric ozone, has renewed interest in using heat treatments. In this review, a brief history regarding the use of heat treatments in grain-processing facilities, such as flour mills, is described along with recent research developments and future research needs. Findings: Scientific literature published during the last decade shed new light on the following areas: identification of a heat-tolerant stage of a species based on stage-specific susceptibility at different constant elevated temperatures; differences in susceptibility among stored-product insect species to elevated temperatures; confusion in determining a heat-tolerant stage during commercial heat treatments of grain-processing facilities; impact of sanitation on insect responses; degree and duration of insect suppression obtained following a heat treatment intervention; development and validation of a thermal death kinetic model to predict survival of heat-tolerant insect life stages as a function of time-dependent temperature data; and development of software programs to estimate the heat energy required including costs of a heat treatment based on fuel used and predicting survival of heat-tolerant insect stages in "real time" during heat treatments. Directions for future research: Temperature-time mortality relationships have been developed for a few economically important insect species and additional species should be evaluated in both laboratory and field conditions. Very little is understood about the impact of the lethal and sub-lethal elevated temperatures used during heat treatments on insect behaviour and reproduction. The costeffectiveness of combining elevated temperatures with other chemical or nonchemical methods in grain-processing facilities also should be explored.

Comparison of different traps and attractants in 3 food processing facilities in Greece on the capture of stored product insects

“…This finding deserves additional attention given that it could be used to inform facility managers about the efficacy of different control tactics deployed. For instance, all 3 facilities perform at least 1 heat treatment throughout the year, and it has been reported that T. castaneum was more tolerant than other species such as L. serricorne to heat (Subramanyam et al 2011). Deploying multiple trap types to monitor population levels before and/or after heat treatments and other pest management strategies can provide useful information about why the relative abundance of certain species changes over time.…”

“…This finding deserves additional attention given that it could be used to inform facility managers about the efficacy of different control tactics deployed. For instance, all 3 facilities perform at least 1 heat treatment throughout the year, and it has been reported that T. castaneum was more tolerant than other species such as L. serricorne to heat (Subramanyam et al 2011).…”

Evolution of Stored-Product Entomology: Protecting the World Food Supply

“…Overall, the use of heat treatments for stored-product pest control has had a circular history (66,137). Once replaced by methyl bromide fumigation, heat treatments are now replacing methyl bromide, which is being banned as an ozone depleter.…”

Genetic Characterization of Fungal Biodiversity in Storage Grains: Towards Enhancing Food Safety in Northern Uganda

“…In sub-Saharan Africa, the storage of grains is unavoidable to maintain a constant supply given the periodic production pattern [6]. Storage of grains in many rural African settings, typical of northern Uganda, comes with an elevated cost of grains contamination with fungi due to inappropriate storage structure [7]. The common grain storage structure comprises; sisal bags, pits, wood and wire cribs, wooden open-air, polythene bags, and heaping on floor [8].…”