11 th International Working Conference on Stored Product Protection 781 Is combining different grain protectants a solution to problems caused by resistant populations of stored-product insects? Kljajić, P. 1 , Kavallieratos, N.G.# 2,3 , Athanassiou, C.G. 4 , Andrić, G.* 1 1 Pesticide and Environment Research Institute, Banatska 31b, 11080 Belgrade, Serbia 2 Laboratory of Agricultural Zoology and Entomology, Department of Crop Science, Agricultural University of Athens, 75 Iera Odos str., 11855, Athens, Attica, Greece 3 Benaki Phytopathological Institute 8 Stefanou Delta str., 14561, Kifissia, Attica, Greece 4 Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Plant Production and Rural Environment, University of Thessaly, Phytokou str., 38446 Nea Ionia, Magnesia, Greece *Corresponding author: Email: goran.andric@pesting.org.rs #Presenting author: Email: nick_kaval@hotmail.com DOI: 10.14455/DOA.res.2014.118 Abstract Insect control during storage of grains can utilize grain protectants. Decades of continuous use of contact insecticides, particularly organophosphates and pyrethroids, have led to recurring instances of resistance of various populations of stored-product insects to those insecticides, which is now one of the most limiting factors for their continued use in the future. The search for a solution to the problem of resistance relies on its timely detection, regular monitoring and holding at an acceptable level, and on the use of highly effective alternative control measures. A way to manage the problem of resistance is to introduce new insecticides with novel mechanisms of activity, but it is a costly and long process, so that only diatomaceous earth (DE) and spinosad have proved over the past two decades to be adequate alternatives to contact insecticides. However, some of their deficiencies have prevented their widespread use. The current anti-resistance tactics therefore based on the available grain protectants as their combined application may be a solution against resistant populations. Besides synergistic effects, combined application may also alleviate the negative effects of some substances and so meet the increasingly restricting criteria for food safety and protection of human health and the environment. The present paper focuses primarily on the results of a research into the efficacy of different combinations of contact insecticides, DE, botanicals and some additional measures against susceptible and resistant populations of stored-product insects. Keywords: stored-product insects, resistance, grain protectants, combined use 1. Contact insecticides/grain protectants and resistance of stored-product insects Despite of recurring consideration of biorational approaches to the management of stored-product insects intending to avoid chemical insecticides (Phillips and Throne, 2010), contact insecticides as grain protectants are still the most effective alternative to the fumigant methyl bromide (Zettler and Arthur, 2000; Fields and White, 2002; Arthur, 2012). Since the introduction of a number of compounds in the late 1960s, their selection has changed with the deepening knowledge and new standards of application for different insecticides in storage ecosystems. Organophosphates (OP) and pyrethroids (PY), as well as insect growth regulators (IGR) to some extent, are the most intensively used chemicals on a global scale, and the choice of registered products based on different active ingredients depends on the needs of any particular country. White and Leesch (1996), Couteux and Lejeune (2005), Collins (2006), Whitehead (2007) and MacBean (2012) have shown that malathion, dichlorvos, chlorpyrifos-methyl, pirimiphos-methyl and fenitrothion