Effects of long-term low oxygen storage treatment on survival of rice weevil (Sitophilus oryzae) and confused flour beetle (Tribolium confusum)

Authors: Liu, Yong Biao

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2022
Publication Date: 6/13/2022
Citation: Liu, Y.-B. 2022. Effects of long-term low oxygen storage treatment on survival of rice weevil (Sitophilus oryzae) and confused flour beetle (Tribolium confusum). Journal of Economic Entomology. Article toac106. https://doi.org/10.1093/jee/toac106.
DOI: https://doi.org/10.1093/jee/toac106

Interpretive Summary: There is a need for alternative treatments for stored product insects. In this study, long-term controlled atmosphere (CA) treatments with low oxygen levels were studied for effects against two major stored product insects: rice weevil and confused flour beetle. Eggs of the two insects were exposed to CA treatments with 3, 5, 6.5, and 8% oxygen for 45 days to determine effects on their survival and development. In addition, 14-day CA treatment with 5% oxygen was tested against different life stages to determine variations among different life stages to the low oxygen treatment. Rice weevil was found to be more susceptible to low oxygen treatments than confused flour beetle. Eggs and adults of rice weevil were more susceptible than larvae and pupae to low oxygen treatment. For confused flour beetle, eggs were most susceptible to low oxygen treatment and adults were most tolerant to low oxygen treatment. Results of this study suggest that long-term CA treatment with low oxygen has potential to control stored product insects. Long-term CA treatment with =6.5% and =5% oxygen are expected to be effective to control rice weevil and confused flour beetle, respectively.

Technical Abstract: There is a need for alternative treatments for postharvest pest control on stored products. In this study, 45-day long-term controlled atmosphere (CA) treatments with 3%, 5%, 6.5%, and 8% O2 were studied to determine effects on development and survival of rice weevil (Sitophilus oryzae) and confused flour beetle (Tribolium confusum) eggs and susceptibility of the insects to 14-day 5.0% low oxygen CA treatment at different life stages. CA treatments were effective in controlling rice weevil and confused flour beetle. The 45-day treatments with 6.5, 5, and 3 % low oxygen CA treatments resulted in 0.26, 0.004, and 0% survival rates respectively for rice weevil eggs and 6.51, 0.14, and 0% survival rates respectively for confused flour beetle eggs. For both species, eggs were more susceptible to low oxygen treatment than larvae and pupae. A 14-day CA treatment with 5% O2 resulted in 4.9 and 3.3% survival of eggs of rice weevil and confused flour beetle, respectively, as compared with over 50% survival of larvae and pupae for both species. Rice weevil adults, however, were very susceptible to low oxygen treatment and 14-day exposure to 5% O2 atmosphere resulted in zero survival. In contrast, the 14-day exposure to 5% O2 atmosphere resulted in over 94% survival for confused flour beetle adults. This study suggested there were considerable differences between stored product insects in susceptibility to low oxygen treatment and that long-term CA storage treatments with a low oxygen level of =6.5% and =5% have potential in controlling rice weevil and confused flour beetle, respectively.