Evaluation of Four Analytical Methods to Detect Weevils in Wheat: Granary Weevil, Sitophilus granarius (L.), in Soft White Wheat

Abstract

Soft white wheat was infested with adult granary weevils under controlled conditions at 3 levels of infestation, and samples were removed for testing 6 times over a total of 48 d. Three analytical methods available for use in FDA laboratories were compared along with a simple counting of the visually-detectable, insect-damaged kernels in a 100-g sample. The objective of the study was to determine how the analytical results compared with one another and with the levels of infestation. Data confirmed that the more rapid visual exam of wheat is not reliable for indicating the hidden, internally-developing weevils. Analysts should be aware of the possibility that wheat inspected visually could be passable with respect to insect-damaged kernels, but still may produce violative flour due to high insect fragment counts when processed. More research is needed to correlate insect infestation in wheat with insect fragment counts in flour. The two methods which could be used to estimate potential flour contamination caused by weevils are the x-ray exam and the cracking and flotation method, since both of these reveal the stages of weevil development inside the kernels. Tables present the results of the analyses and relate them to the number and sex of the founding adults in each level of infestation.