Evaluation of Purdue Improved Crop Storage Triple Layer Hermetic Storage Bag against Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae).

Kimondo Mutambuki,Dieudonne Baributsa,Hippolyte Affognon,Paddy Likhayo

doi:10.3390/insects10070204

Abstract

Hermetic technologies are being promoted in Africa as safer and more effective methods of grain storage on smallholder farms. However, farmers and policy makers lack knowledge of their efficacy in controlling major stored grain pests. An on-station study was conducted to evaluate the triple layer Purdue Improved Crop Storage (PICS) airtight bags against two major storage insect pests. Two sets each of PICS, jute and polypropylene bags were filled with 50 kg maize grain per bag. Each set was replicated four times. One set of PICS bags was each infested with 50 insects each of the larger grain borer P. truncatus and the maize weevil S. zeamais; while the other set was not. One set of jute and polypropylene woven bags was treated with a cocktail of 1.6% Pirimiphos methyl and 0.3% Permethrin, serving as positive controls; while the remaining sets with untreated maize grain formed negative controls. Gas analysis in the PICS bags followed the expected trend with oxygen levels falling sharply below 10% and carbon dioxide increasing to almost 10% after 12 weeks hence resulting in insect death. After 16 weeks, increase in oxygen levels may be attributed to perforation of the bags from outside by the P. truncatus. Results showed that PICS bags were significantly (P < 0.05) superior to treated and untreated controls of polypropylene and jute bags in suppressing insect development, maize grain damage and weight loss during storage. Weight loss in polypropylene and jute bags reached 40% and 41%, respectively, at 24 weeks after storage compared to PICS (2.4–2.9%). These results demonstrate that PICS bags can be used to store maize against P. truncatus and S. zeamais attack.

Highlights

Maize (Zea mays L.) is an important cereal grain grown widely in sub-Saharan Africa as a staple food crop [1,2] and contributes to food security of small-scale farmers [3]
Carbon dioxide levels increased from 0.02% to 7.8% for Purdue Improved Crop Storage (PICS) non-infested and 8.3% for PICS infested bags
The present study demonstrates the significant dust weight, grain damage and weight loss in maize stored in treated and untreated polypropylene and jute bags compared to that stored in PICS bags

Summary

Introduction

Maize (Zea mays L.) is an important cereal grain grown widely in sub-Saharan Africa as a staple food crop [1,2] and contributes to food security of small-scale farmers [3]. While improved maize production practices have resulted in increased yields, poor on-farm postharvest handling and storage [4,5,6,7] have resulted in high grain losses. In Kenya, estimates of postharvest losses of maize caused by major storage insect pests vary from 24 to 48.5% [8,9,10,11,12,13] for untreated grains after six to nine months. The major storage insect pests include the larger grain borer Prostephanus truncatus (Horn). The control of stored product insect pests on smallholder farms remains a major challenge. Synthetic insecticides are widely used to control insect pests of stored grains [17]. Less than 25% of applied insecticides achieve good results leading to misperception of ineffectiveness [12]

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Discussion

Conclusion