Role of Modified Atmosphere in Pest Control and Mechanism of Its Effect on Insects

Abstract

Pests not only attack field crops during the growing season, but also damage grains and other food products stored in granaries. Modified or controlled atmospheres (MAs or CAs) with higher or lower concentrations of atmospheric gases, mainly oxygen (O2), carbon dioxide (CO2), ozone (O3), and nitric oxide (NO), provide a cost-effective method to kill target pests and protect stored products. In this review, the most recent discoveries in the field of MAs are discussed, with a focus on pest control as well as current MA technologies. Although MAs have been used for more than 30 years in pest control and play a role in storage pest management, the specific mechanisms by which insects are affected by and adapt to low O2 (hypoxia) and high carbon CO2 (hypercapnia) are not completely understood. Insect tolerance to hypoxia/anoxia and hypercapnia involves a decrease in aerobic metabolism, including decreased NADPH enzyme activity, and subsequently, decreases in glutathione production and catalase, superoxide dismutase, glutathione-S-transferase, and glutathione peroxidase activities, as well as increases in carboxyl esterase and phosphatase activities. In addition, hypoxia induces energy and nutrient production, and in adapted insects, glycolysis and pyruvate carboxylase fluxes are downregulated, accompanied with O2 consumption and acetate production. Consequently, genes encoding various signal transduction pathway components, including epidermal growth factor, insulin, Notch, and Toll/Imd signaling, are downregulated. We review the changes in insect energy and nutrient sources, metabolic enzymes, and molecular pathways in response to modified O2, CO2, NO, and O3 concentrations, as well as the role of MAs in pest control. This knowledge will be useful for applying MAs in combination with temperature control for pest control in stored food products.

Modified Atmosphere Does Not Reduce the Efficacy of Phytosanitary Irradiation Doses Recommended for Tephritid Fruit Flies

“…In general, insects exposed to functional hypoxia-a condition characterized by the inadequate oxygen supply to meet the ATP demands of an organism despite compensations [45], can use acute and chronic cellular responses to prevent damage due to oxygen deprivation [46]. Short-term strategies mediated by sensory neurons drive acute responses, whereas long-term strategies mediated by hypoxia-inducible factors (HIF), among others [20,21,47], drive chronic responses to ensure normal development and survival [45,[48][49][50][51][52][53]. In B. dorsalis, for example, exposure of third instars to a severe hypoxic treatment (~0.2% O 2 ) for up to 15 h induced the expression of HIF-1α and HIF-1-responsive genes, which, ultimately, rescued survival after reoxygenation [54].…”

Disinfestation techniques for major cereals: A status report

“…In a review on modified atmosphere treatments in pest control by Cao et al. (2019), the mechanism of modified conditions such as lower oxygen (hypoxia: O 2 < 21%) and higher carbon dioxide (hypercapnia) conditions on insects is explained. It was also observed that the arthropod mortality rate was higher at increased carbon dioxide concentrations than at lower‐oxygen atmospheres.…”

“…Cao et al. (2019) reported that a carbohydrate called trehalose protects insect cells from low‐oxygen stress, and in some insects, triacylglycerol and other polysaccharides help in the development of resistance to modified atmospheres. The insects’ adaptation techniques to hypoxia conditions by regulating various gene expressions are also discussed.…”

Combination of Modified Atmosphere and Irradiation for the Phytosanitary Disinfestation of Trogoderma granarium Everts (Coleoptera: Dermestidae)

“…Ionizing radiation at a low dose has been used to prevent the development and reproduction of arthropod pests, a minimum absorbed dose of 200 Gy is required for preventing reproduction (failure of F 1 egg-hatch) of the khapra beetle adult, the most radiation-resistant stage [ 19 , 20 ]. However, both MA and irradiation treatment involves a decrease in aerobic metabolism in insects; they are slow-acting control methods that need longer exposure times [ 21 , 22 , 23 , 24 ]. For example, Zhang found that the minimum times leading 100% mortality of T .…”