The effects of four agrobotanical extracts and three types of bags on the control of insect pests and moulds of stored yam chips
A study was conducted to evaluate the effects of four agrobotanical extracts and three types of storage bags as alternative options to the use of agrochemical insecticides for yam chip storage. Dried yam chips were obtained from Shaki area of Oyo State, Nigeria and treated with extracts from Azadiractha indica (neem) leaf, Xylopia aethiopica(uda) pod, Occimum graticimum (nche anwu) leaf and Zingiber officinale (ginger) stem tuber. The storage bags were 0.05mm gauge polythene bags, 0.05mm gauge polythene-lined-jute bags and jute bags. After 3 or 6 months of storage, chip weight loss was always low at 1-5% with Azadiractha indica, Occimum graticimum, Zingiber officinale compared with the weight loss of 13 to 24% obtained where no agrobotanical was applied. At either 3 or 6 months of storage, insect damage through boring of holes was evident but was significantly higher with no agrobotanical treatment or with X. aethiopica than with the other agrobotanical treatments especially at 6 months of storage. There was little or no mould growth at 3 months of storage while at 6 months, mould growth was rather enhanced by X. aethiopica, Z. officinale and O. gratissimum and by to a lesser extent. The type of storage bag did not significantly improve the various criteria measured at either 3 or 6 months of storage. However insect damage appeared lower and chip quality assessment showed lower blemishes in polythene-lined-jute or jute bag alone. A. indica followed by O. graticimum gave better chip quality than the other treatments irrespective of the type of storage bag. Correlation analysis revealed that chip weight loss was highly and positively related with insect damage (r = 0.92) and highly but negatively related with quality assessment (r = - 0.89). Insect damage was also negatively related with chip quality score at the end of storage (r = -0. 87).
Keywords: Agrobotanicals, Storage bags, Storage pests, yam chips
Agro-Science Vol. 5 (1) 2006: pp. 8-12