Performance of triple bagging hermetic technology for postharvest storage of cowpea grain in Niger I.B. Baoua a , V. Margam b, c , L. Amadou a , L.L. Murdock b, * a Institut National de la Recherche Agronomique du Niger (INRAN), BP 240 Maradi, Niger b Department of Entomology, Purdue University, 901 West State Street, West Lafayette, IN 47907, USA c Computational Bioscience Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia article info Article history: Accepted 31 July 2012 Keywords: Bruchids Cowpea Hermetic Triple bag Postharvest Callosobruchus maculatus Storage abstract Triple bagging technology for protecting postharvest cowpea grain from losses to the bruchid, Calloso- bruchus maculatus Fabricius (Coleoptera: Chrysomelidae: Bruchinae) is currently being adopted on a fairly large scale in ten West and Central African countries, including Niger. The triple bag consists of two inner high-density polyethylene bags acting as oxygen barriers, which in turn are encased in an outer woven polypropylene bag that serves primarily for mechanical strength. These hermetic bags, available in either 50 or 100 kg capacity, are called Purdue Improved Cowpea Storage (PICS) bags. Adoption of PICS technology in West and Central Africa has been driven by its effectiveness, simplicity, low cost, durability, and manufacture within the region. From surveys on adoption we discovered that farmers have begun to re-use bags they had used the previous year or even the previous two years. In the present study, we compared the performance of three different types of PICS bags: (1) new 50 kg (2) new 100 kg bags and (3) once-used 50 kg bags, all filled with naturally infested untreated cowpeas. In these PICS bags the O 2 levels within the bags initially fell to about 3 percent (v/v) while the CO 2 rose to nearly 5 percent (v/v). After five months of storage, new and used 50 kg bags and new 100 kg bags preserved the grain equally well. There were greatly reduced numbers of adults and larvae in the PICS bags versus the controls, which consisted of grain stored in single layer woven bags. The proportion of grain having C. maculatus emergence holes after five months of storage in PICS bags was little changed from that found when the grain was first put into the bags. The PICS technology is practical and useful in Sahelian conditions and can contribute to improved farmers’ incomes as well as increase availability of high quality, insecticide-free cowpea grain as food. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Cowpea (Vigna unguiculata (L.) Walp) is the principal legume crop in the West African Country of Niger and a key grain crop of the Sahel and savannahs of much of West and Central Africa. It is particularly vital for Niger, both as a source of food as well as a source of income. In 2010, the area under cowpea cultivation in Niger was estimated to be about 5.6 million hectares with production of 1.97 million tons. This represents 24% of the total national agricultural production of the country and more than 80% of cash crop production (Anonymous, 2010a). Cowpea is produced under rain fed conditions and occupies second place in terms of area planted after millet, and third place after sorghum and millet in terms of biomass production. Niger is the second largest cowpea producer in Africa after Nigeria. Niger cowpea is produced primarily for export, particularly to Nigeria, Benin, Ghana and Togo. It represents the third-ranked export product of Niger after uranium and livestock/livestock products. Cowpea is also impor- tant for Nigerien households; the consumption of pulses is about 8 g per head per day in urban areas compared to 23 g in rural areas. It is 3e4 times richer in protein than millet and sorghum, making it a particularly important food for children (Anonymous, 2010b). Cowpea yields in Niger are low, from 150 to 400 kg/ha, far below the yield potential. Cowpea grain harvested by producers is commonly damaged by Callosobruchus maculatus during post- harvest storage. Simple technologies for safely storing cowpea grain without using insecticides have been available for the last 25 years (Murdock et al., 1997, 2003). However, a study conducted between 2004 and 2005 reported that only a small proportion of Nigerien * Corresponding author. Tel./fax: þ1 765 494 4592. E-mail address: murdockl@purdue.edu (L.L. Murdock). Contents lists available at SciVerse ScienceDirect Journal of Stored Products Research journal homepage: www.elsevier.com/locate/jspr 0022-474X/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jspr.2012.07.003 Journal of Stored Products Research 51 (2012) 81e85