The effects of grasshopper carcasses as dockage in stored wheat

摘要

In years of high grasshopper field populations, large numbers may be collected with harvested grain and deposited into storage. Little is known about the impact of grasshopper carcasses on stored-wheat quality; therefore, this study was conducted to determine such effects. Ninety-six glass bottles (237 mL capacity) were filled with 120 g of clean No. 1 wheat conditioned to 14.5% or 15.5% moisture content. Two-striped grasshoppers, Melanoplus bivittatus were collected in the summer of 2004 near Elie, MB, Canada and euthanized. Six grams of whole grasshoppers were mixed into half the bottles of each moisture content. All bottles were sealed and 12 bottles with and without grasshoppers were incubated at 25 degrees C and 50% relative humidity (r.h.), 25 degrees C and 75% r.h. 30 degrees C and 50% r.h. and 30 degrees C and 75% r.h. for 24 wk. Four bottles with and without insects were assessed every 4 wk for fat acidity value, seed microfioral infection and germination. The experiment was repeated and data pooled for statistical analysis (ANOVA). Significant differences (P < 0.05) arose between grasshopper and control treatments. Mean fat acidity values for wheat reached 32.99 mg KOH/100 g with grasshoppers compared to 25.23 mg KOH/100 g without carcasses. Initial seed germination of 98% rapidly declined to below 20% with grasshoppers between 4 wk and 8 wk; the majority of seeds were dead in the 75% r.h. treatments by 12 wk. Mean infection by the post-harvest fungi, Aspergillus glaucus group with grasshoppers ranged from 80.5 to 92% compared to 25-79.8% in controls. Penicillium spp. infection at 25 degrees C and 75% r.h. was 16.8% with grasshoppers and 4.2% without. Results from this experiment clearly demonstrate that the presence of grasshopper carcasses in stored wheat has negative consequences on grain quality. The implications of our research are discussed with respect to harvest practices and climate change. Crown Copyright (C) 2019 Published by Elsevier Ltd. All rights reserved.