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Ecology and Behavior Effect of Gamma Irradiation on Fecundity, Sterility, and Female Sex Pheromone Production of Callosobruchus chinensis (Coleoptera: Bruchidae) Kashinath Chiluwal, 1,2, Junheon Kim, 3 Soon Do Bae, 4 Gwang Hyun Roh, 5 Hae Jun Park, 6 and Chung Gyoo Park 1,7 1 Division of Applied Life Science (BK21 + Program)/Institute of Life Science, Gyeongsang National University, Jinju 52828, Republic of Korea, 2 Nepal Agricultural Research Council (NARC), Kathmandu, Nepal, 3 Forest Insect Pest and Disease Division, National Institute of Forest Science, Seoul 02512, Republic of Korea, 4 Department of Southern Area Crop Science, National Institute of Crop Science, Rural Development Administration, Miryang 50424, Republic of Korea, 5 Agroecosystem Management Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Lincoln, NE 68583, 6 Biotechnology Division, Advanced Radiation Technology Institute, KAERI, Jeongeup-si, Jeollabuk-do 580-185, Korea, and 7 Corresponding author, e-mail: parkcg@gnu.ac.kr Subject Editor: Lisa Neven Received 10 April 2018; Editorial decision 24 September 2018 Abstract Azuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Bruchidae), is a feld-to-storage pest of legumes and its females produce sex pheromone components with two isomers: (2Z,6E)-7-ethyl-3,11-dimethyl-2,6,10-dodecatrienal (2Z-homofarnesal) and (2E,6E)-7-ethyl-3,11-dimethyl-2,6,10-dodecatrienal (2E-homofarnesal). Two-day-old virgin adults were treated with different doses (0, 200, 300, 400, 500, and 600 Gy) of gamma radiation and the effects on adult survivorship, fecundity, sterility, and pheromone production were studied. The longevity of both sexes and female fecundity were dose dependently affected by the gamma irradiation revealing that the fecundity was more reduced when the female adults were irradiated. Adults of both sexes were totally sterilized by the doses of gamma radiation tested in this study as depicted by the null hatchability of the laid eggs. The results from analyses by gas chromatography–mass spectrometry for solid phase micro-extraction revealed that both of the female sex pheromone components were signifcantly reduced by 300 Gy. Though signifcantly less, there was release of some amount of pheromone components by the irradiated female azuki bean beetles revealing the possibility of pheromonal attraction of males to the irradiated females. It is a pre-requisite for the successful sterile insect technology that the sterility of azuki bean beetle is induced without the total disruption of the calling behavior. Key words: Azuki bean beetle, cobalt-60, homofarnesal, solid-phase micro-extraction Ionizing radiation is becoming a popular weapon of insect pest man- agement programs especially those utilizing in sterile insect technique (SIT) (Ayvaz and Yilmaz 2015). The main action mode of radiation is sterilization, either by oxidative reactions which alter irreversibly the organic molecules or by chromosomal fragmentation (leading to dominant lethal mutations, translocations, and other chromosomal aberrations) at the cytological level (Mastrangelo and Walder 2011). Other studies have postulated that irradiation is an effective treatment against stored product insect pests (Tilton and Burditt 1983, Hasan and Khan 1998, Phillips 2006, Hallman 2013) and is a promising phytosanitary treatment worldwide (Hallman 2011). Ionizing radiation is suggested as a potential alternative as there is reduced risk of resistance in insect pests (Follett 2006). Absence of residual effects in treated products and applicability to packed com- modities in transits are other benefts of using irradiation treatments (Follett and Neven 2006). Similarly, high tolerance and preserva- tion of the nutritive contents of the treated products have favored the use of irradiation as a safer alternative (Heather and Hallman 2008). Moreover, the phase-out of methyl bromide (a widely used quarantine fumigant) (United Nations Environment Programme [UNEP] 2006), development of resistance to another popular fumi- gant, phosphine (Pimentel et al. 2007), and the serious impacts of the fumigants on environmental safety and human health have triggered the search for safer alternatives. Azuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Bruchidae), is a ubiquitous feld-to-storage pest of pulse crops worldwide with broad host range including azuki beans (Tuda et al. 2005). The infestation of the pest results in substantial qualitative and quantitative damage manifested by nutritional loss and severe germination deterioration (de Sá et al. 2014). Larvae, the destructive Journal of Economic Entomology, 112(1), 2019, 156–163 doi: 10.1093/jee/toy317 Advance Access Publication Date: 15 October 2018 Research Downloaded from https://academic.oup.com/jee/article-abstract/112/1/156/5132809 by Gyeongsang National University user on 14 February 2019