Effect of Hypoxia on the Lethal Mortality Time of Adult Sitophilus oryzae L.

Abstract

Sitophilus oryzae is one of the most destructive pests of stored grains. It leads to significant quantitative and qualitative losses, resulting in food and income insecurity among farmers. Chemical pesticides are the most common methods used by farmers and other grain value chain actors to manage this pest. However, pesticides are increasingly becoming unattractive for pest control due to health hazards posed to applicators, consumers, the environment, and insect resistance. Modified atmospheres have the potential to manage stored insect pests as an alternative to pesticides. There is limited understanding of when insect pests die when grain is stored in airtight containers. This experiment was conducted to assess the time required to reach mortality of adult S. oryzae when exposed to 1, 3, and 5% oxygen levels. Results revealed that the LT50 for 1, 3, and 5% of oxygen were reached after 69.7 h, 187.8 h, and 386.6 h of exposure, respectively. No adult emergence was observed on infested grains following exposure to 1 and 3% oxygen levels. This result provides vital rationale for storing grain in hermetic storage conditions for at least 39 days to achieve adult S. oryzae mortality and minimize grain reinfestation.

Enhancing Airtight Storage with Germinating Cowpea Seeds: Impacts on Insect Mortality, Progeny and Grain Quality

“…No adults emerged within 50 days post-treatment after insects were exposed to hypoxia from 20 and 30 germinating seeds for 120 and 96 h, respectively. Previous research showed that exposure of insects to low oxygen (e.g., 1%) for a few days resulted in no adult emergence within 45 days post-treatment [22,25]. Similar results were achieved using other gases, such as CO 2 .…”

“…A higher number of germinating seeds led to quicker oxygen depletion and earlier adult mortality. Similar adult mortality (within 4 days) was observed when oxygen levels were maintained at 1% using nitrogen [22,36]. Faster oxygen depletion meant that insects experienced prolonged exposure to lower hypoxia, accelerating adult mortality.…”

“…Several approaches are used to enhance the efficacy of hermetic storage. These include using oxygen scavengers or gases such as nitrogen and carbon dioxide to remove the residual oxygen [21][22][23]. Flushing nitrogen (N 2 ) or CO 2 into hermetic storage systems can speed up insect death compared to relying on natural processes such as insects and micro-organisms [24,25].…”

A Scientometric Review of Grain Storage Technology in the Past 15 Years (2007–2022) Based on Knowledge Graph and Visualization

“…From the perspective of international research and development dynamics, the focus of technological innovation in the coming period is to research and develop automatic control systems for grain storage ventilation and cooling with artificial intelligence [ 67 ]. The main purpose of air conditioning grain storage technology is to kill pests by changing the concentration of O 2 , N 2 , and CO 2 in the air [ 69 ]. Although the cost of fumigation is higher than the general fumigation technology, it can effectively maintain the grain quality without any pollution of the stored grain and does not affect human health [ 70 ].…”

Seed Longevity and Deterioration

“…Some insects can survive and propagate under rather dry conditions, till about 30% RH (Roberts 1972), but insects are sensitive to sub-zero temperatures and hypoxia. Both conditions are recommended as alternative for chemical fumigation (Kalpana et al 2022;Kandel et al 2021). However, it should be considered that the eggs or pupae can have, related to their low metabolic activity, a greater tolerance compared to the adult insects and modified atmospheric treatments can take some weeks, also depending on the temperature.…”