Utono, Iliyasu Mohammed and Gibson, Gabriella (2015) New ‘stimuli-enriched’ laboratory bioassay used to identify improved botanical repellent treatment, Lem-ocimum, to control the stored-grain pest Tribolium castaneum. Journal of Stored Products Research, 64 (Part A). pp. 27-35. ISSN 0022-474X (doi:https://doi.org/10.1016/j.jspr.2015.08.002)

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Abstract

A laboratory study of Tribolium castaneum, a major pest of stored grain, was conducted to develop a more efficient and effective ‘choice’ bioassay for identification of new repellent botanical treatments. Standard bioassays to test the repellency of candidate plants include pit-fall traps and open arena choice tests, environments lacking in some of the most important natural stimuli that guide the movement of food-searching beetles, e.g., 1) materials they can burrow through, which stimulate ‘positive thigmotaxis’, 2) a range of light and dark areas, which stimulate ‘negative phototaxis’ and 3) three-dimensional habitats, which stimulate ‘positive geotaxis.’ The lack of these stimuli can lead to two common problems; ‘low efficiency’ (high proportion of beetles remain in the area that surrounds treatments without making a ‘choice’), and ‘low efficacy’ (high variability in proportions found in control and treated samples). The new ‘stimuli-enriched’ bioassay, which included all three of the above stimuli, was significantly more efficient (P < 0.0001) and effective than three standard bioassays. The stimuli-enriched bioassay was used to compare the repellency of four candidate plants; Ocimum basilicum (Sweet Basil) and Cymbopogon nardus (Lemongrass) were significantly more repellent than Vernonia amygdalina or Nauclea diderrichii (Tukey Contrasts; P < 0.01). A novel method of applying repellent material (a paste of repellent plant is applied between the layers of double bagged grain) was tested on the most promising repellent plants materials; a combination of C. nardus and O. basilicum (‘Lem-ocimum’) at 0.5% w/w of each was significantly more effective than O. basilicum on its own (Tukey Contrasts; P < 0.05). These results show that the stimuli-enriched bioassay provides more consistent and accurate assessments than the standard bioassays of the repellency of candidate botanicals, and that Lem-ocimum treated double-bags are a promising new method of protecting sorghum from T. castaneum.

Item Type:	Article
Uncontrolled Keywords:	Tribolium castaneum; Bioassay; Botanicals; Repellents; Geotaxis; Phototaxis; Thigmotaxis
Subjects:	Q Science > Q Science (General)
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > Natural Resources Institute
Last Modified:	17 Sep 2019 13:39
URI:	http://gala.gre.ac.uk/id/eprint/13872

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