Repellent and Feeding Deterrent Effects of Turmeric Oil, Sweetflag Oil, Neem Oil, and a Neem-Based Insecticide Against Lesser Grain Borer (Coleoptera: Bostrychidae)

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Abstract
Repellency of oils of turmeric, Curcuma longa (L.), sweetflag, Acorus calamus (L.), neem, Azadirachta indica A. Juss, or a neem-based insecticide (Margosan-O, Vikwood Botanicals, Sheboygan, Wis.) was monitored against the lesser grain borer, Rhyzopertha dominica (F.), for 8 wk. In a choice test, filter paper strips treated with the test materials at 200,400, or 800 μg/em2 repelled the insect. Turmeric oil and sweetflag oil were significantly more repellent during the first 2 wk than neem oil and Margosan-O, but thereafter, their repellency decreased more rapidly than that of neem oil or Margosan-O. R. Dominica adults made significantly fewer and smaller feeding punctures in filter paper disks (7 em diameter) treated with the test materials at 100, 500, or 1,000 μg/em2 than in control disks. Because of greater persistence, neem oil and Margosan-O deserve to be evaluated in field trials against storage pests.