Relative Susceptibility of Dried Root/Tuber and Musa Chips to Red Flour Beetle (Tribolium casteneum) (Herbst) (Coleoptera: Tenebrionidae) Infestation

Abstract

Three Musa cultivars (false horn, french, and cooking banana) and eight roots/tubers (Colocasia esculenta, C. esculenta var antiquorum, Xanthosoma sagittifolium, Dioscorea alata, D. dumentorum, D. rotundata, sweet cassava and bitter cassava) were assayed for their relative susceptibility to flour beetle (Tribolium casteneum Herbst.) (Coleoptera: Tenebrionidae) damage. Ten adult beetles (1- 7 days old) (5 males: 5 females) were introduced in containers to which 20 g of each dried chip sample was placed and arranged in completely randomised design with three replications. Susceptibility assessment was based on rate of chip damaged, percentage weight loss and adult survival, weight of powder produced and chips left. Bioassay on chips proximate, mineral and anti-nutrient compositions was also carried out. Rate of damage was higher amongst the agbagba (20.04 mg/day) compared to other Musa spp. Bitter cassava recorded the highest damage rate of 24.32 mg/day amongst the chips assayed, which was also higher than other cassava cultivars. X. sagittiffolium (5.57mg/day) and C. esculenta var antiquorum (6.14 mg/day) maintained higher rates of damage relative to C. esculenta (1.13 mg/day) in cocoyams. On yams, damage rate was significantly (p<0.05) higher on D. rotundata (12.24mg/day) compared to D. dumentorum (2.24mg/day) and D. alata (1.43) mg/day. Correlation and biplot analyses showed that though the susceptibility of bitter cassava to the pest attack was strong, it could not be tied to the biochemical contents analysed. Conversely, the resistance of C. esculenta was attributed to its strong and positive relationships to phenol, tannin, calcium and Fe. This result provides baseline information for breeders against stored produce pests.