Food Protectants and Infestation Control Department, CSIR-Central Food Technological Research Institute, Mysore 570020, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
Food Protectants and Infestation Control Department, CSIR-Central Food Technological Research Institute, Mysore 570020, India.
Ecotoxicol Environ Saf. 2021 Mar 1;210:111877. doi: 10.1016/j.ecoenv.2020.111877. Epub 2021 Jan 4.
Fumigant toxicity of phytochemical volatiles has been widely reported against stored product insect pests. Such volatiles are considered as natural fumigants and bio-fumigants in post-harvest food protection research. In the present study, persistence and ingestion of diallyl disulfide, citral, eucalyptol, eugenol and menthol were investigated in Sitophilus oryzae adults in comparison with fumigant toxicity and microstructural impact in elytra. The fumigant toxicity bioassay was performed with increasing concentrations of phytochemical volatiles at 25, 125, 250 and 500 μL/L air against S. oryzae adults in 50 mL glass vials. The phytochemical residues were examined from the treated adults by Gas Chromatography coupled with Flame Ionization Detector (GC-FID) and their pathological impacts on the elytral surface was observed under Scanning Electron Microscopy (SEM). After 72 h of fumigation, diallyl disulfide and eucalyptol were identified as potential fumigants with 5.24 and 8.30 μL/L air LC values, respectively. GC-FID analyses showed that diallyl disulfide and eucalyptol molecules persistence (1.29 and 2.60 ppb persistence with 0.94 and 0.90 r values respectively at 72 h exposure) on the body surface of weevil was positively correlated with the fumigation exposure and toxicity. Whereas, phytochemical molecules ingestion into the body of weevils was not directly linked with the insect mortalities. The SEM observations indicated that diallyl disulfide and eucalyptol molecules caused severe microstructural impacts on the elytra of weevils compared to other molecules. As a result, the present study suggested that phytochemical fumigants are persisted on the body surface and caused insecticidal toxicities in S. oryzae adults. In addition, it was predicted that persisted molecules might be entered into the body of weevils via cuticular penetration.
植物化学挥发物的熏蒸毒性已被广泛报道可用于防治仓储害虫。此类挥发物被认为是天然熏蒸剂和生物熏蒸剂，用于研究采后粮食保护。本研究比较了二烯丙基二硫醚、柠檬醛、桉油醇、丁香酚和薄荷醇在米象成虫体内的持久性和摄入情况，以及其对鞘翅微观结构的影响。在 50ml 玻璃小瓶中，采用浓度递增的植物化学挥发物对米象成虫进行熏蒸毒性生物测定，浓度分别为 25、125、250 和 500μL/L 空气。用气相色谱-火焰离子化检测器（GC-FID）从处理过的成虫中检测植物化学残留物，并在扫描电子显微镜（SEM）下观察其对鞘翅表面的病理影响。熏蒸 72 小时后，二烯丙基二硫醚和桉油醇被鉴定为有潜力的熏蒸剂，其空气 LC 值分别为 5.24 和 8.30μL/L。GC-FID 分析表明，二烯丙基二硫醚和桉油醇分子在象鼻虫体表的持久性（暴露 72 小时后的 1.29 和 2.60 ppb 持久性，r 值分别为 0.94 和 0.90）与熏蒸暴露和毒性呈正相关。然而，象鼻虫体内的植物化学分子摄入与昆虫死亡率没有直接关系。SEM 观察表明，与其他分子相比，二烯丙基二硫醚和桉油醇分子对象鼻虫的鞘翅造成了严重的微观结构影响。因此，本研究表明，植物化学熏蒸剂在米象成虫体表持久存在，并产生杀虫毒性。此外，预测这些持久性分子可能通过表皮渗透进入象鼻虫体内。
