Behavioral and Physiological Response of Tribolium castaneum (Herbst) Exposed to Hypoxia
thesisposted on 2022-01-31, 15:21 authored by Kabita KharelKabita Kharel
Hermetic storage systems represent viable pest control methods for postharvest crop storage. Nevertheless, there is limited understanding of how insect respond to hypoxic conditions inside hermetic storage. This study was conducted to investigate: i) the oxygen consumption behavior of T. castaneum under hermetic conditions, and effects of hypoxia exposure on: ii) the survival of different life stages after hypoxia iii) their feeding and movement (activity), and iv) the cellular energy as a measure of adenylate energy charge (AEC). T. castaneum consumed 6.80 ± 0.45 mL of oxygen during egg-to-adulthood while adults consumed 5.37 ± 0.30 mL of oxygen during 21-d at 27°C. The daily rate of oxygen utilization increased with increasing temperature and in larger volume containers. Eggs and young larvae were the most susceptible stages, experiencing total mortality when exposed to 2% oxygen level for 3d compared to larvae and pupae (required ≥10 d), and adults (required ≥15 d). At 4% oxygen level, total mortality was achieved for eggs and other life stages at 5 d and ≥15 d, respectively. By contrast, the 8% oxygen level was not lethal except for eggs, but it caused significant developmental delays in immatures. Likewise, the ultrasonic device revealed that hypoxia exposure could affect insect activity within the first 30 minutes of treatments. Furthermore, the AEC index of T. castaneum adults at normoxia control was 0.70 ± 00, while the AEC at <1%, 2, 4, 8% oxygen levels were 0.18 ± 0.0, 0.19 ± 0.01, 0.25 ± 0.02, and 0.58 ±0.01, respectively suggesting that hypoxia diminish energy production in insect cells. Complete mortality of T. castaneum adults was achieved when exposed to <1% oxygen levels for 96 h. In conclusion, exposing T. castaneum to <2% oxygen levels for 15 d produce total mortality; however, even the higher levels of oxygen at 4-8% can subtly affect insect population development.