Dissection of Insect-Plant-Environment Interaction via Molecular and Genomic Approaches Grant uri icon

abstract

  • Worldwide losses in stored grains and other agricultural products caused by insects have been estimated to be between 5-10%, and this number can reach 10-40% in some developing countries (Shaaya, Kostjukovski et al. 1997, Weaver and Petroff 2005). Direct consumption of kernels by the insects results in reduction in weight, nutritional value and germination rate of stored seeds. Insect infestation also causes sanitary problems due to accumulations of frass, exuviae, webbing and insect cadavers. Grain of such quality may completely lose its market value, as they are no longer acceptable for processing into food for human consumption.The most effective current method to control storage insects is through fumigation with chemical insecticides. Use of these chemicals, however, can result in excessive pesticide residues in treated grain or grain products that cause human health and environmental problems, as well as potential resistance development in insects. For example, methyl bromide has largely been phased out in developed countries due to its damage to the earth's ozone layer (Fields and White 2002). Another common fumigant, phosphine, has lost its effectiveness because of resistance development (Benhalima, Chaudhry et al. 2004, Collins, Daglish et al. 2005, Pimentel, Faroni et al. 2009).Modified atmospheres with low O2 (hypoxia) and/or high CO2 (hypercapnia) environments in airtight storage withhold the O2 required for insect development, thus preventing damage by insect pests in stored grain (Banks and Annis 1990, Fleurat-Lessard 1990, Sanon, DabirĂ©-Bins et al. 2011, Navarro, Timlick et al. 2012). Alteration of the composition of the storage atmosphere can be achieved biologically; the respiration of any insects present, together with the respiration of grain embryos, converts O2 into CO2, altering the internal atmosphere. A modern method modifies the atmosphere by purging the storage container with CO2 or N2 and then sealing it hermetically. Such hermetic storage is a cost-effective and environmentally friendly alternative measure to chemical fumigation, and has been used to control postharvest insect pests and various pests that affect a large number of raw and manufactured food products (Fleurat-Lessard 1990, van Epenhuijsen, Carpenter et al. 2002). Over the last several decades, considerable research has been carried out on the effectiveness of control via modified atmospheres using different gas compositions for various stored pests, especially well-known cosmopolitan pests such as Tribolium castaneum, T. confusum, Sitophilus zeamais, S. oryzae, Rhyzopertha dominica, Cryptolestes ferrugineus and Oryzaephilus surinamensis (Finkelman, Navarro et al. 2006, Chiappini, Molinari et al. 2009, Lord 2009, Noomhorm, Sirisoontaralak et al. 2009, Riudavets, Castane et al. 2009). However, knowledge gaps still remain. For example, although sensitivity of insects to low O2 is known to be dependent on the species and life stage (Hoback and Stanley 2001), little is understood of the underlying molecular mechanisms leading to injury or adaptation in stored insects, nor the association between O2 demand and hypoxic tolerance.........

date/time interval

  • 2018 - 2023